Tellurium nitride

Tellurium nitride describes chemical compounds of Te containing N3−. Efforts have been made toward the binary nitrides but the results are inconclusive and it appears that such materials are unstable. Still unconfirmed is Te4N4, which would be an analogue of Se4N4 and tetrasulfur tetranitride (S4N4). It has long been known that ammonia reacts with tellurium tetrachloride, which is similar to the method of synthesis of S4N4. The reaction of TeCl4 with a THF solution of N(SiMe3)3 gives a well-defined tellurium nitride [Te6N8(TeCl2)4(THF)4].


Oxyyttropyrochlore-(Y)

Oxyyttropyrochlore-(Y), also referred to as "obruchevite" or "yttropyrochlore-(Y)", is a potential (not yet accepted) zero-valent-dominant mineral of the pyrochlore group. Its formula can be written as (Y,◻)2Nb2O2O.
The name "yttropyrochlore-(Y)" for this compound was used by Kalita (1957), and Ercit et al. (2003), but it has become obsolete and the mineral status is not yet clear. The yttropyrochlore-(Y) as mentioned by Tindle & Breaks (1998) is in fact "oxyyttropyrochlore-(Y)".


Calcium copper titanate

Calcium copper titanate (also abbreviated CCTO, for calcium copper titanium oxide) is an inorganic compound with the formula CaCu3Ti4O12. It is noteworthy for its extremely large dielectric constant (effective relative permittivity) of in excess of 10,000 at room temperature.
History.
CCTO was first synthesized in 1967 by Alfred Deschanvres and his coworkers. While the structural features were known, no physical properties had been measured. In 2000, Mas Subramanian and his colleagues at DuPont Central R&D discovered that CCTO displayed a dielectric constant greater than 10,000, compared to the normal dielectric SrTiO3, which has a constant of 300 at room temperature. Since then, it has found widespread usage in capacitor applications.
Synthesis and structure.
Most compounds which form this crystal structure are made under high-pressure conditions. Pure CCTO, however, can be easily synthesized by standard solid state methods via intimate mixtures of the metal carbonate and oxide precursors at temperatures between 1000 and 1200 °C.
The CaCu3Ti4O12 structure type is derived from the cubic perovskite structure, by an octahedral tilting distortion as is GdFeO3. In both cases the distortion is driven by a mismatch between the size of the A-cations and the cubic ReO3 network. However, CaCu3Ti4O12 and GdFeO3 adopt different patterns of octahedral tilting (a−b+a− and a+a+a+ in Glazer notation). The octahedral tilting distortion associated with the GdFeO3 structure leads to a structure where all of the A-cation environments are identical. In contrast, the octahedral tilting distortion associated with the CaCu3Ti4O12 structure produces a structure where 75% of the A-cation sites (A" sites) have square planar coordination, while 25% of the A-cation sites remain 12 coordinate. The square planar sites are almost always filled by Jahn-Teller ion such as Cu2+ or Mn3+, while the A' site is always occupied by a larger ion.
Dielectric properties.
Using the Clausius-Mossotti relation, the calculated intrinsic dielectric constant should be 49. However, CCTO exhibits a dielectric constant upwards of 10,200 at 1 MHz, with a low loss tangent until approximately 300 °C. In addition, the relative dielectric constant increases with decreasing frequency (in the range of 1 MHz to 1 kHz).
The colossal-dielectric phenomenon is attributed to a grain boundary (internal) barrier layer capacitance (IBLC) instead of an intrinsic property associated with the crystal structure. This barrier layer electrical microstructure with effective permittivity values in excess of 10, 000 can be fabricated by single-step processing in air at ∼1100 °C. CCTO is therefore an attractive option to the currently used BaTiO3-based materials which require complex, multistage processing routes to produce IBLCs of similar capacity.
Because there is a large discrepancy between the observed dielectric constant and the calculated intrinsic constant, the true origin of this phenomenon is still under debate.


Stearate


Yttrium(III) sulfate

 Yttrium(III) sulfate is an inorganic compound with the formula Y2(SO4)3. The most common form is the anhydrate and octahydrate.
Reactions.
Yttrium sulfate can form double salts such as MY(SO4)2 and M3Y(SO4)3:
Synthesis.
Yttrium(III) sulfate can be prepared using either corresponding oxide, hydroxide or carbonate.


Unpentnilium


Organonickel

Organonickel chemistry is a branch of organometallic chemistry that deals with organic compounds featuring nickel-carbon bonds. They are used as a catalyst, as a building block in organic chemistry and in chemical vapor deposition. Organonickel compounds are also short-lived intermediates in organic reactions. The first organonickel compound was nickel tetracarbonyl Ni(CO)4, reported in 1890 and quickly applied in the Mond process for nickel purification. Organonickel complexes are prominent in numerous industrial processes including carbonylations, hydrocyanation, and the Shell higher olefin process.
Overview.
Many complexes exist of nickel coordinated to an alkene. In these compounds nickel is formally zerovalent Ni0 and the bonding is described with the Dewar–Chatt–Duncanson model. One common representative is Bis(cyclooctadiene)nickel(0) (Ni(COD)2), which contains two cyclooctadiene ligands. It is a 18VE compound with 10 electrons provided by nickel itself and 4x2 electrons more by the double bonds. This solid, which melts at 60 °C, is used as a catalyst and as a precursor for many other nickel compounds.
Ni allyl complexes.
Allyl halides react with Ni(CO)4 to form pi-allyl complexes, (allyl)2Ni2Cl2. These compounds in turn are sources of allyl nucleophiles. In (allyl)2Ni2Br2 and (allyl)Ni(C5H5), nickel is assigned to oxidation number +2, and the electron counts are 16 and 18, respectively.
Cyclopentadienyl complexes.
Nickelocene NiCp2 with +2 Ni oxidation state and 20 valence electrons is the main metallocene of nickel. It can be oxidized by one electron. The corresponding "palladocene" and "platinocene" are unknown. From nickelocene, many derivatives are generated, e.g. CpNiLCl, CpNiNO, and Cp2Ni2(CO)3.
Nickel carbene complexes.
Nickel forms carbene complexes, formally featuring C=Ni double bonds.
Alkyl and aryl precatalysts.
A variety of Ni(II) alkyl and aryl complexes are known. Examples include [(dppf)Ni(cinnamyl)Cl)], "trans"-(PCy2Ph)2Ni("o"-tolyl)Cl]], (dppf)Ni("o"-tolyl)Cl]], (TMEDA)Ni("o"-tolyl)Cl, and (TMEDA)NiMe2.
Nickel compounds of the type NiR2 also exist with just 12 valence electrons. In solution however solvent always interact with the metal atom increasing the electron count. One 12 VE compound is di(mesityl)nickel prepared from (allyl)2Ni2Br2 and the corresponding Grignard reagent.
Reactions.
Alkene/alkyne oligomerizations.
Nickel compounds catalyze the oligomerization of alkenes and alkynes. This property validated the research and development of Ziegler–Natta catalysts in the 1950s. That discovery shown by nickel impurities originating from an autoclave which killed the propagation reaction ("Aufbau") in favor of termination reaction to a terminal alkene: the polymerization of ethylene suddenly stopped at 1-butene. This so-called nickel effect prompted the search for other catalysts capable of this reaction, with results in the finding of new catalysts that technically produced high molar mass polymers, like the modern Ziegler–Natta catalysts.
One practical implementation of alkyne oligomerization is the Reppe synthesis; for example in the synthesis of cyclooctatetraene:
This is a formal [2+2+2+2]cycloaddition. The oligomerization of butadiene with ethylene to trans-1,4-hexadiene was an industrial process at one time.
Formal [2+2+2]cycloadditions also take place in alkyne trimerisation. This extensible trimerisation can generally include benzyne. Benzyne is generated in situ from a benzene compound attached to a triflate and a trimethylsilyl substituent in the ortho- positions and reacts with a di-yne such as 1,7-octadiyne along with a nickel(II) bromide / zinc catalyst system (NiBr2 bis(diphenylphosphino) ethane / Zn) to synthesize the corresponding naphthalene derivative.
In the catalytic cycle elementary zinc serves to reduce nickel(II) to nickel(0) to which can then coordinate two alkyne bonds. A cyclometalation step follows to the nickelcyclopentadiene intermediate and then coordination of the benzyne which gives a C-H insertion reaction to the nickelcycloheptatriene compound. Reductive elimination liberates the tetrahydroanthracene compound.
The formation of organonickel compounds in this type of reaction is not always obvious but in a carefully designed experiment two such intermediates are formed quantitatively:
It is noted in one study that this reaction only works with acetylene itself or with simple alkynes due to poor regioselectivity. From a terminal alkyne 7 isomers are possibly differing in the position of the substituents or the double bond positions. One strategy to remedy this problem employs certain diynes:
The selected reaction conditions also minimize the amount formed of competing [2+2+2]cycloaddition product to the corresponding substituted arene.
Coupling reactions.
Nickel compounds cause the coupling reaction between allyl and aryl halides. Other coupling reactions involving nickel in catalytic amounts are the Kumada coupling and the Negishi coupling.
Ni carbonylation.
Ni catalyzes the addition of carbon monoxide to alkenes and alkynes. The industrial production of acrylic acid at one time consisted of combining acetylene, carbon monoxide and water at 40-55 atm and 160-200 °C with nickel(II) bromide and a copper halide.


Arenium ion

An arenium ion in organic chemistry is a cyclohexadienyl cation that appears as a reactive intermediate in electrophilic aromatic substitution. For historic reasons this complex is also called a Wheland intermediate, after American chemist George Willard Wheland (1907–1976), or a sigma complex or σ-complex. The smallest arenium ion is the benzenium ion (), which is protonated benzene.
Two hydrogen atoms bonded to one carbon lie in a plane perpendicular to the benzene ring. The arenium ion is no longer an aromatic species; however it is relatively stable due to delocalization: the positive charge is delocalized over 3 carbon atoms by the pi system, as depicted on the following resonance structures:
A complexed electrophile can contribute to the stability of arenium ions.
A benzenium ion can be isolated as a stable compound when benzene is protonated by the carborane superacid H(CB11H(CH3)5Br6). The benzenium salt is crystalline with thermal stability up to 150 °C. Bond lengths deduced from X-ray crystallography are consistent with a cyclohexadienyl cation structure.
In one study a methylene arenium ion is stabilized by metal complexation:
In this reaction sequence the R–Pd(II)–Br starting complex 1 stabilized by TMEDA is converted through dppe to metal complex 2. Electrophilic attack of methyl triflate forms methylene arenium ion 3 with (based on X-ray crystallography) positive charge located in aromatic para position and with the methylene group 6° out of the plane of the ring. Reaction first with water and then with triethylamine hydrolyzes the ether group.


Ruthenium(III) acetate

Ruthenium(III) acetate, commonly known as basic ruthenium acetate, describes a family of salts where the cation has the formula [Ru3O(O2CCH3)6(OH2)3]+. A representative derivative is the dihydrate of the tetrafluoroborate salt [Ru3O(O2CCH3)6(OH2)3]BF4(H2O)2, which is the source of the data in the table above. This and related salts are forest green, air-stable solids that are soluble in alcohols.
Basic ruthenium acetate features octahedral Ru(III) centers, a triply bridging oxo ligand, six acetate ligands, and three aquo ligands. The same structure is shared with basic acetates of iron, chromium, iridium, and manganese.
Preparation and reactions.
It is prepared by heating ruthenium trichloride in acetic acid in the presence of sodium acetate. The basic acetates of ruthenium were reported in the early 1950s but were not properly formulated.
Basic ruthenium acetate reacts with many ligands such as triphenylphosphine and pyridine concomitant with reduction. These derivatives [Ru3O(O2CCH3)6L3]0 are mixed valence compounds.


Nelotanserin

Nelotanserin (former developmental code name APD-125) is a drug developed by Arena Pharmaceuticals which acts as an inverse agonist on the serotonin receptor subtype 5-HT2A and was under development for the treatment of insomnia. It was shown to be effective and well tolerated in clinical trials, but development was halted in December 2008 because the substance did not meet the trial's effectiveness endpoints. Research continues on newer analogues which may potentially be more successful. More recently, nelotanserin has been repurposed for the treatment of Lewy body disease. As of 2017, it is in phase II clinical trials for this indication.


Terbium(III) chloride

Terbium(III) chloride (TbCl3) is a chemical compound. In the solid state TbCl3 has the YCl3 layer structure. Terbium(III) chloride frequently forms a hexahydrate.
Hazards.
Terbium(III) chloride causes hyperemia of the iris.
Conditions/substances to avoid are: heat, acids and acid fumes.


Metasilicate

Metasilicates are silicates containing ions of empirical formula . Common stoichiometries include MSiO3 and MIISiO3.
Common compounds containing metasilicate anion are:


Kovdorskite

Kovdorskite, Mg2PO4(OH)·3H2O, is a rare, hydrated, magnesium phosphate mineral. It was first described by Kapustin "et al.", and is found only in the Kovdor Massif near Kovdor, Kola Peninsula, Russia. It is associated with collinsite, magnesite, dolomite, hydrotalcite, apatite, magnetite, and forsterite.


Kalsilite

Kalsilite (KAlSiO4) is a vitreous white to grey feldspathoidal mineral that is found in some potassium-rich lavas, such as from Chamengo Crater in Uganda. It has a relative hardness of 5.5.


Dibromoiodoethylene

Dibromoiodoethylene is a dense organic liquid consisting of an ethylene core with two bromine atoms and one iodine atom as substituents. It is formed by the reaction of dibromoacetylene with hydrogen iodide.
There are three isomers of dibromoiodoethylene, varying in the position of the two bromine atoms compared to each other.


Sodium phosphide

Sodium phosphide is the inorganic compound with the formula Na3P. It is a black solid. It is often described as Na+ salt of the P3− anion. Na3P is a source of the highly reactive phosphide anion. It should not be confused with sodium phosphate, Na3PO4.
In addition to Na3P, five other binary compositions of sodium and phosphorus are known: NaP, Na3P7, Na3P11, NaP7, and NaP15.
Structure and Properties.
The compound crystallizes in a hexagonal motif, often called the sodium arsenide structure. Like K3P, solid Na3P features pentacoordinate P centers.
Preparation.
The first preparation of Na3P was first reported in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by treating molten sodium with phosphorus pentachloride.
Many different routes to Na3P have been described. Due to its flammability and toxicity, Na3P (and related salts) is often prepared and used in situ. White phosphorus is reduced by sodium-potassium alloy:
Phosphorus reacts with sodium in an autoclave at 150 °C for 5 hours to produce Na3P.
Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile NaxP phases (x < 3) that then react further with sodium. In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble sodium naphthalenide, which reduces the phosphorus.
Uses.
Sodium phosphide is a source of the highly reactive phosphide anion. The material is insoluble in all solvents but reacts as a slurry with acids and related electrophiles to give derivatives of the type PM3:
The trimethylsilyl derivative is volatile (b.p. 30-35 C @ 0.001 mm Hg) and soluble. It serves as a soluble equivalent to "P3−".
Indium phosphide, a semiconductor arises by treating in-situ generated "sodium phosphide" with indium(III) chloride in hot "N,N’"-dimethylformamide as solvent. In this process, the phosphide reagent is generated from sodium metal and white phosphorus, whereupon it immediately reacts with the indium salt:
Sodium phosphide is also employed commercially as a catalyst in conjunction with zinc phosphide and aluminium phosphide for polymer production. When Na3P is removed from the ternary catalyst polymerization of propylene and 4-methyl-1-pentene is not effective.
Precautions.
Sodium phosphide is highly dangerous releasing toxic phosphine upon hydrolysis, a process that is so exothermic that fires result. The USDOT has forbidden the transportation of Na3P on passenger aircraft, cargo only aircraft, and trains due to the potential fire and toxic hazards.


Unseptseptium


Zirconium propanoate

Zirconium propionate is a white powder with molecular formula Zr(CH3CH2COO)4. Its structure is complex, but is believed to be based on hydroxy-bridged zirconium polymers, with the propionate carboxyl group bonded to the zirconium. Propionates are salts or esters of propionic acid. It is not soluble in water, but dissolves in a solution of isopropanol, ethanol and ethyl acetate. When tamped or untamped, it has a density of 1.14 g/cm3 or 0.98 g/cm3 respectively. It is used to promote adhesion in solvent-based inks. Impurities of Hafnium are commonly present.


Zincoberaunite

Zincoberaunite is an iron and zinc phosphate mineral, the Zn analogue of beraunite. It was first described by Chukanov et al. for an occurrence in Hagendorf Sud pegmatite in Germany. Zincoberaunite occurs as a secondary mineral as an alteration product of primary phosphate minerals in granite pegmatites.
Beraunite crystallizes in the monoclinic crystal system with point group 2/m. Beraunite's formula is Zn Fe3+5(OH)5(PO4)4·4H2O.
Occurrence.
Zincoberaunite has been located so far in two localities in the world, the type locality, and Krasno, near Horní Slavkov (Czech Republic). It appears in two paragenesis, as an alteration of other phosphates in pegmatites: in one with jungle, phosphophyllite and mitridatite and in another with flurlite, plimerite, beraunite rich in zinc, schoonerite, parascholzite, robertsite and altered phosphophyllite. However, it is likely that a detailed study of the zinc-rich beraunite specimens will allow locating other localities for the zincoberaunite.
Physical and chemical properties.
Zincoberaunite contains Zn instead of ferrous iron. Before it was characterized as an independent species, specimens with a high zinc content had been found, but since the iron content was higher, they had been considered as varieties. In addition to the elements indicated in the formula, it contains small amounts of magnesium and calcium. In the type locality it appears as pale gray capillary microcrystals forming silky-looking aggregates. In a second locality it has been found as prismatic microcrystals with compositional zoning.


Segnitite

Segnitite is a lead iron(III) arsenate mineral. Segnitite was first found in the Broken Hill ore deposit in Broken Hill, New South Wales, Australia. In 1991, segnitite was approved as a new mineral. Segnitite has since been found worldwide near similar locality types where rocks are rich in zinc and lead especially. it was named for Australian mineralogist, gemologist and petrologist Edgar Ralph Segnit. The mineral was named after E. R. Segnit due to his contributions to Australian mineralogy.
Segnitite is not a primary ore mineral, but is found amongst other well known ore minerals such as galena, sphalerite, pyrite and more. Many minerals found with segnitite are important for industrial purposes. Minerals associated with segnitite make up metal alloys, batteries and even pigments. Carminite and beudanite are closely related to segnitite. In fact, forms of beudanite are commonly confused with segnitite, as the sulfate and arsenate anions readily exchangeable with each other. Other mineral relations include, goethite, coronadite, agardite, bayldonite, and mimetite.
Set parameters for the space group and chemical composition have yet to be confirmed. Segnitite has loose boundaries and conclusions about segnitite were derived from associated minerals. Chemically, there are many varieties of segnitite which affects space group measurements and chemical analysis interpretations. In other words, segnitite samples from around the world can be very different from one another making it difficult to provide accurate chemical measurements.
Chemical composition.
The mineral segnitite is a part of the alunite-jarosite family which is a part of the alunite supergroup, which has a general formula of AB3(TO4)2(OH)6. Minerals in the alunite-jarosite family have the general formula AB3(XO4)2(OH)6. More specifically, Segnitite is a part of the low-S lusungite group of alunite-jarosite minerals. The lusungite group falls on the lower third of the ternary diagram, with the jarosite group on top, having the highest content of sulfur. The beudantite-corkite group lies in the middle third on the ternary diagram, possessing intermediate amounts of sulfur. The lusungite group then has the lowest amount of sulfur, and has end members segnitite and lusungite, which then have varying amounts of arsenic to phosphorus; segnitite is the arsenic rich end member of the lusugnite group.
Through electron microprobe analysis on the basis of 14 oxygen atoms, the empirical formula of segnitite was found to be (Pb1.05-Ba0.03)1.08(Fe2.76Zn0.22Al0.17Cu0.01)3.16[(AsO4)1.85 (PO4)0.05-(SO4)0.04]1.94(OH,H2O)6.24. Four alternative and simplified versions include: (1) PbFe3(AsO4)2(OH)5*H2O, (2) PbFe3(AsO4)2(OH,H2O)6, (3) PbFe3(AsO4)(AsO3OH)-(OH)5, (4) PbFe3H(AsO4)2(OH)6, although the preferred formula is PbFe3H(AsO4)2(OH)6, which is most consistent with the space group (Rm) for Segnitite.
Crystal structure and habit.
Segnitite belongs to the trigonal crystal system, which is also a subcategory of the hexagonal crystal system. Segnitite occurs most commonly as rhombohedral crystals that can grow to around 5mm in height and as pseudo-octahedral crystals that typically measure about 1mm across. The habit of these segnitite clusters is often found to be hemispherical in shape. Rhombohedron {112} and Pinacoid {001} are the two most common forms of segnitite.
Occurrence.
Segnitite was first discovered in Broken Hill ore deposit in Broken Hill, New South Wales, Australia. It was first found in the oxidized zone of lead and zinc sulfide ores bodies of the Broken Hill ore deposit and forms in similar settings around the world. Segnitite is a relatively uncommon mineral, and it not found in very large quantities, but is found worldwide in similar areas. Segnitite has since been found in many localities in Western Europe, specifically in sites near Switzerland, Germany and Austria.
Segnitite is commonly found alongside many well known minerals including anglesite, galena, jamesonite, linarite, arsenopyrite, cerussite, covellite, cuprite, sphalerite, sulfur, beudantite, cassiterite, pyrite, smithsonite, carminite and plumbojarosite. Many of these minerals are important ore minerals. Segnitite poses some importance when considering the overall composition of surrounding rock.
Crystallography.
Through X-ray diffraction (XRD), which is either conducted through powder diffraction, or through single-crystal X-ray analysis, segnitite was found to belong to the hexagonal crystal system of minerals. Using angles 2θ< 66 degrees, cell parameters were estimated along with chemical composition.
Before segnitite was identified as a mineral, it was commonly mistaken for beudantite. There are close similarities in diffraction data when comparing low sulfate beundantite from the beudantite-corkite group, and segnitite of the lusungnite group. Beundantite, segnitite and plumbojarosite form solid solutions with each other; conditions that form these minerals are similar. The space group "R"m was determined for segnitite as the best fit based on the space group of beudantite, R3m as there is no well observed crystal structure. The difference between segnitite and beundantite is the replacement of the sulfate anion in beundantite with an arsenate anion to form segnitite.
Optical properties.
Segnitite exhibits weak pleochroism from a pale yellow to a more moderate yellow under different angles of plane polarized light, although the effects can be much more dramatic under polarized light. Dichroism and trichroism are both types of pleochroism. The term dichroism is used to describe optical properties of minerals that are uniaxial, including segnitite. Minerals that exhibit dichroism are generally trigonal, hexagonal and tetragonal. A response from UV light was not observed from segnitite.


Sodium peroxynitrate

Sodium peroxynitrate is the chemical compound with the formula . It is the sodium salt of peroxynitric acid. However, the only form of sodium peroxynitrate known to exist so far is sodium peroxynitrate octahydrate, with the formula NaNO3.H2O2.8H2O.
Preparation.
Sodium peroxynitrate can be made from an alkaline solution of sodium nitrate and hydrogen peroxide. The solution is evaporated until crystals start to form, and the solution is then mixed with alcohol, causing crystals of the octahydrate to form.


Unbipentium


Oxalyl fluoride

Oxalyl fluoride is a fluorinated derivative of oxalic acid. It is being investigated for use in etching as a replacement for compounds which have the liability of high global warming potential.


Cervandonite

Cervandonite is a rare arsenosilicate mineral. It has a chemical formula or . It has a monoclinic crustal structure with supercell (Z=6), the crystal structure was established as a trigonal subcell, with space group R3m and a = 6.508(1)Ǻ, c = 18.520(3) Ǻ, V 679.4(2) Ǻ3, and Z=3. It was first described by Buhler Armbruster in 1988, but it has proven to be problem due to the extreme scarcity of single crystals and its unusual replacement of silicon and arsenic. Cervandonite is named after the location where it was first described, Pizzo Cervandone (Scherbadung), Italy in the Central Alps.
Structure.
The current work is based on a single- crystal fragment of cervandonite measuring 0.08 X 0.03 X 0.02 mm. The exact fragment was re-examined with MoKα radiation using BRUKER Apex II diffractometer equipped with a 2K CCD detector. Through the use of X-ray diffraction, the unusual nature of the As to Si substitution found arsenic to be present as As3+ instead of As5+, with the presence of sorosilicate Si2076− anions were also established. The original description of the cervandonite mineral, , was rewritten to . The x and y values are 0.47 and 0.31. Even though the values were derived from a refined and disordered crystal, the new formula matches the charge balance [13 negative versus 12.75 positive charges] for the average chemical composition for the M(1)+M(2) sites. The As-containing silicates, none of which contained the Si2As7 composition, or arsenic in the 3+ state, where considered to be examples of As to Si diadochy. However, after accurate determination of the crystal structure the As and Si atoms where shown to occupy distinct cell sites. So far, the As-Si disorder is unique for the cervandonite mineral, and accounts for the As:Si ratio. Due to the unusual diadochy, the variable composition of cervandonite might consist of an assembly of more or less twinned microdomains. Since cervandonite contains different values of As/Si and unit- cell parameters, has observed one type of superstructure.
Physical properties.
Cervandonite- (Ce) has a monoclinic cell with Z=6. The monoclinic structure was refined as a trigonal subcell using 411 reflections with I > 2σ (I), R1=0.320, wR2=0.0887. The R- centered cell can be transformed with, a 6.508 (1), c 18.520 (3) Ǻ, V 679.4(2) Ǻ3, and Z=3. The structure has a space group of R3m, the solution of the cervandonite structure instantly revealed the presence of one eight-coordinated structure, REE-containing M(1) lying on the threefold axis and M(2) which includes Fe, Ti, or Al. The color of the mineral is a black, with transmitted light it will reflect a yellowish, reddish brown to black color. The mineral is brittle, porous, rosettelike aggregate, with adamantine luster, poorest at {001} cleavage, conchoidal fracture with a brownish-black streak, and a hardness= 5.0. Although cervandonite was found in Pizzo Cervandone, it is not the only rare mineral discovered there, much like the crystal fetiasite, which shares common morphology, fetiasite has a thin brown-red alteration layer with the perfect cleavage is on {100}. Cervandonite was discovered in the east region of Pizzo Cervandone, Alpe Devero, on the border of Italy and Switzerland, and on the west region of Cherbadung, Switzerland. This mountain is well known for Alpine excursionists and mineral collectors. It was known the 1960s as a site for rare and new minerals.


Unseptbium


Verbeekite

Verbeekite is a rare mineral consisting of palladium diselenide PdSe2. This transition metal dichalcogenide has an unusual monoclinic structure, with pairs of selenium atoms existing as dimers forming layers between palladium atom sheets. Unit cell dimensions are 1=6.710 b=4.154 c=8914 Å β=92.42° V=248.24 Å3. Palladium diselenide has five polymorphs. Verbeekite can be synthesised at 11.5 GPa pressure and 1300 °C.
Monolayer PdSe2 has been predicted and synthesized as an electronic material.
The mineral was discovered in 2002 from the Musonoi Cu-Co-Mn-U mine, in the Democratic Republic of the Congo. Verbeekite was named after geologist Théodore Verbeek who studied minerals at that mine between 1955 and 1967.


Oxoborane

In chemistry, an oxoborane is any chemical compound containing a boron atom with a terminal oxygen atom. The compound class is of some relevance to academic research. The parent compound, HBO, itself called "oxoborane", together with derivatives FBO (fluorine), ClBO chlorine, BrBO bromine, HOBO (hydroxyl) and MeBO (methyl) have been detected in matrix isolation or in the gasphase at high temperature. In these compounds the boron and oxygen form a triple bond prone to cyclotrimerization to boroxines.
Derivatives.
Although monomeric oxoboranes have not been isolated, derivatives have been described.
A Lewis acid-stabilized adduct of an oxoborane is (NacNacB=O.AlCl3. In this compound the oxygen atom is coordinated to aluminium chloride. The BO bond length is 130 pm (compare to 136 pm in regular boronic acids). Related systems are known.
In "trans"-[(Cy3P)2PtBr(BO)], platinum is coordinated to the BO unit. In this compound the BO bond length is 120 picometers.


Sperrylite

Sperrylite is a platinum arsenide mineral with formula PtAs2 and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits. It has a Mohs hardness of 6 - 7 and a very high specific gravity of 10.6.
It was discovered by Francis Louis Sperry, an American chemist, in 1889 at Sudbury.
The most important occurrence of sperrylite is in the nickel ore deposit of Sudbury Basin in Ontario, Canada. It also occurs in the layered igneous complex of the Bushveld region of South Africa and the Oktyabr'skoye copper-nickel deposit of the Eastern-Siberian Region, Russia.
Geologic occurrence.
Sperrylite is the most common platinum mineral, it generally occurs with a wide array of other unusual minerals, including cooperite [(Pt,Pd,Ni)S], laurite [RuS2], kotulskite [Pd(Te,Bi)], merenskyite [(Pd,Pt)(Te,Bi)2], iridium-osmium (Ir-Os) alloys, sudburyite [(Pd,Ni)Sb], omeiite [(Os,Ru)As2], testibiopalladite [PdTe(Sb,Te)], and niggliite [PtSn], to name a few. It does not readily decompose through normal weathering processes and, consequently, has been reported in widely scattered alluvial deposits.
It was first found as tiny crystals found with rhodolite garnet and corundum during alluvial gem mining in streams draining Mason Mountain, Macon County, North Carolina (Hidden 1898). Sperrylite has been identified in Finland from sulfide deposits generally associated with layered mafic-ultramafic complexes.
Structure.
Sperrylite belongs to the pyrite group of minerals and therefore it shares similar structure and crystal habits with them. Analyses typically show minor amounts of rhodium. Trace copper, iron, and antimony as well as intergrowths with Pt-Fe are reported from some occurrences. Sperrylite crystallizes in Pa3, with a =5.9681(l) A. (Szymański, 1979). It has very similar crystal structure as in platarsite (ideally PtAsS). Sperrylite crystals vary considerably in shape and size and are usually enclosed in a variety of host minerals. They are usually closely associated with basemetal sulfide. They are commonly at the edge and partially enclosed by pentlandite, pyrrhotite or chalcopyrite. Seabrook (2004).
Sperrylite is composed of loose aggregate of bright silver cubes, some with octahedral modifications. The grains are mostly anhedral, but a few euhedral grains could also be encountered. Sperrylite is formed by contact metamorphism, as in indicated by the development of triple point annealing contacts with pyrrhotite grains. The grains of sperrylite are surrounded by later veins of pyrite.
Sperrylite is cubic (2/m3) and is typically seen in well-developed cubes or cuboctahedra, some of which are so highly modified that crystal edges and comers appear rounded. (Nicol and Goldschmidt 1903) identified seventeen crystal forms exhibited by sperrylite, including four different trapezohedra, a trisoctahedron, five pyritohedra, and four diploids. Crystals to 2.5 cm have been reported.
Physical properties.
Sperrylite is a tin-white mineral known for its brilliant metallic luster, with a grey to black streak. It has indistinct cleavage on {001} and a conchoidal fracture and is brittle. Its hardness is between 6 and 7, and it is quite dense with a calculated specific gravity of 10.78. It has an isometric crystal system, Conchoidal fracture, non-magnetic and non-radioactive.
Discovery.
Sperrylite was first described by H. H. Wells in 1889 from material collected at the Vermilion mine in what is now the Sudbury district, Ontario, Canada. He named it for Francis L. Sperry, chief chemist with the Canadian Copper Company of Sudbury, who collected the original material in 1887 (Mitchell 1985). It occurred in weathered material with colorless transparent cassiterite [SnO2], which is thought to have been derived from the oxidation of stannite [Cu2(Fe,Zn)SnS4].


Oxalatonickelate

The oxalatonickelates are a class of compounds that contain nickel complexed by oxalate groups. They form a series of double salts, and include clusters with multiple nickel atoms. Since oxalate functions as a bidentate ligand it can satisfy two coordinate positions around the nickel atom, or it can bridge two nickel atoms together.
The shape around the nickel atom is octahedral for diaquabis(oxalato)nickelate. The colour of this is green due to the Ni(–O–)6 chromophore. The absorption in infrared is at 8,300 9,060 13,400, 15,260, and 26,160 cm−1. The ligand field parameters are 10 Dq=8800 cm−1 and B=1000 cm−1.
Because the Ni2+ ion resembles many other divalent metal ions, it can be substituted by them, or substitute for them in other oxalate compounds to form mixed oxalates where the proportions can vary continuously. For example, magnesium nickel oxalate dihydrate.


Pigeonite

Pigeonite is a mineral in the clinopyroxene subgroup of the pyroxene group. It has a general formula of (Ca,Mg,Fe)(Mg,Fe)Si2O6. The calcium cation fraction can vary from 5% to 25%, with iron and magnesium making up the rest of the cations.
Pigeonite crystallizes in the monoclinic system, as does augite, and a miscibility gap exists between the two minerals. At lower temperatures, pigeonite is unstable relative to augite plus orthopyroxene. The low-temperature limit of pigeonite stability depends upon the Fe/Mg ratio in the mineral and is hotter for more Mg-rich compositions; for a Fe/Mg ratio of about 1, the temperature is about 900 °C. The presence of pigeonite in an igneous rock thus provides evidence for the crystallization temperature of the magma, and hence indirectly for the water content of that magma.
Pigeonite is found as phenocrysts in volcanic rocks on Earth and as crystals in meteorites from Mars and the Moon. In slowly cooled intrusive igneous rocks, pigeonite is rarely preserved. Slow cooling gives the calcium the necessary time to separate itself from the structure to form exsolution lamellae of calcic clinopyroxene, leaving no pigeonite present. Textural evidence of its breakdown to orthopyroxene plus augite may be present, as shown in the accompanying microscopic image.
Pigeonite is named for its type locality on Lake Superior's shores at Pigeon Point, Minnesota, United States. It was first described in 1900.


Unquadunium


CE-7.5

The CE-7.5 is a cryogenic rocket engine developed by the Indian Space Research Organisation to power the upper stage of its GSLV Mk-2 launch vehicle. The engine was developed as a part of the Cryogenic Upper Stage Project (CUSP). It replaced the KVD-1 (RD-56) Russian cryogenic engine that powered the upper stage of GSLV Mk-1.
Overview.
CE-7.5 is a regeneratively-cooled, variable-thrust, staged combustion cycle rocket engine.
Specifications.
The specifications and key characteristics of the engine are:
Development.
ISRO formally started the Cryogenic Upper Stage Project in 1994. The engine successfully completed the Flight Acceptance Hot Test in 2008, and was integrated with propellant tanks, third-stage structures and associated feed lines for the first launch. The first flight attempt took place in April 2010 during the GSLV Mk.II D3/GSAT-3 mission. The engine ignited, but the ignition did not sustain as the Fuel Booster Turbo Pump (FBTP) shut down after reaching a speed of about 34,500 rpm 480 milliseconds after ignition, due to the FBTP being starved of Liquid Hydrogen (LH2). On 27 March 2013 the engine was successfully tested under vacuum conditions. The engine performed as expected and was qualified to power the third stage of the GSLV Mk-2 rocket. On 5 January 2014 the cryogenic engine performed successfully and launched the GSAT-14 satellite in the GSLV-D5/GSAT-14 mission.
Applications.
CE-7.5 is being used in the third stage of ISRO's GSLV Mk.II rocket.


Magnesium chlorate


Tetrabromo-o-xylene

α,α,α',α'-Tetrabromo-o-xylene is an organobromine compound with the formula C6H4(CHBr2)2. Three isomers of α,α,α',α'-Tetrabromoxylene exist, but the ortho derivatiive is most widely studied. It is an off-white solid. The compound is prepared by the photochemical reaction of o-xylene with elemental bromine:
Reaction of α,α,α',α'-tetrabromo-o-xylene with sodium iodide affords α,α'-dibromo-o-xylylene, which can be trapped with dienophiles to give naphthylene. In the absence of trapping agents, the xylylene relaxes to α,α'-dibromobenzocyclobutane:
Cycloadditions of these xylylenes provides a pathway to acenes.


Sayrite

Sayrite (Pb2(UO2)5O6(OH)24(H2O)) is an alteration product of uraninite named after the X-ray crystallographer David Sayre. Sayrite contains hydrogen, oxygen, uranium, and lead. It is mined at Shinkolobwe Mine, (Kasolo Mine), Kambove District, Haut-Katanga, Democratic Republic of the Congo. It is usually orange in color, but also can be reddish and yellowish. It is in the monoclinic crystal system.


Bromocyclohexane

Bromocyclohexane (also called Cyclohexyl bromide, abbreviated CXB) is an organic compound with the chemical formula C6H11Br.
It is used to match the refractive index of PMMA for example in confocal microscopy of colloids. A mixture of cis-decalin and CXB can simultaneously match optical index and density of PMMA. Due to the moderate dielectric constant of CXB (ε = 7.9 ), PMMA acquires charges that can be screened by the addition of salt (e.g. tetrabutyl ammonium bromide), leading to a very good approximation of colloidal hard sphere. A drawback is that CXB is a good solvent for PMMA, causing it to swell over time, which may lead to a poor determination of particle radii and determination of solid volume fraction.
Synthesis.
Bromocyclohexane can be prepared by the free radical substitution of bromine to the cyclohexane ring at high temperatures or in presence of electromagnetic radiation. But the reaction is not selective and it gives a mixture of polyhalogenated products. Another synthesis path is the addition of HBr on cyclohexene.
References.
http://web.pdx.edu/~wamserc/C334F99/Fans.htm


Olah reagent

The Olah reagent is a nucleophilic fluorinating agent. It consists of a mixture of 70% hydrogen fluoride and 30% pyridine; alcohols react with this reagent to give alkyl fluorides:
It acts as a stabilized, less volatile form of hydrogen fluoride. It is used in the fluorination of steroids and in deprotection of peptides. Instead of hydrogen fluoride, several other fluorinating agents can be used, such as diethylaminosulfur trifluoride (DAST).


Roflurane

Roflurane (INN, USAN, code name DA-893) is a halocarbon drug which was investigated as an inhalational anesthetic but was never marketed.


Iodotrifluoroethylene

Iodotrifluoroethylene is a chemical compound with the formula , belonging to the group of haloalkenes. It is a volatile colorless liquid. It is prepared by iodination of trifluorovinyl lithium.
It can be used to synthesize trifluoronitrosoethylene by its reaction with nitric oxide under UV light, producing iodine as a byproduct:


Nickel bis(dimethylglyoximate)

Nickel bis(dimethylglyoximate) is the coordination complex with the formula Ni[ONC(CH3)C(CH3)NOH]2. The compound is a bright red solid. It achieved prominence for its use in the qualitative analysis of nickel.
Structure.
Nickel(II) is square planar. It is surrounded by two equivalents of the conjugate base (dmgH−) of dimethylglyoxime (dmgH2). The pair of organic ligands are joined through hydrogen bonds to give a macrocyclic ligand. The complex is distinctively colored and insoluble leading to its use as a chelating agent in the gravimetric analysis of nickel.
The use of dimethylglyoxime as a reagent to detect nickel was reported by L. A. Chugaev in 1905.


Warikahnite

Warikahnite is a rare zinc arsenate mineral of the triclinic crystal system with Hermann- Mauguin notation , belonging to the space group P. It occurs in the Tsumeb mine in Namibia on corroded tennantite in the second oxidation zone under hydrothermal conditions in a dolomite-hosted polymetallic ore deposit. It is associated with adamite, stranskiite, koritnigite, claudetite, tsumcorite, and ludlockite. The origin of discovery was in a dolosmite ore formation within an oxidized hydrothermal zone, in the E9 pillar, 31st level of the Tsumeb Mine in Namibia, Southwest Africa. It has also been found at Lavrion, Greece and Plaka, Greece as microscopic white needles.
Discovery.
Warikahnite was discovered by Clive Queit at Tsumeb mine and was first described in 1979 by Keller, Hess, and Dunn. The name "warikahnite" honors Walter Richard Kahn, who was born in 1911. He was from Bad Bayersoien, Germany, and he was a dealer and collector that specialized in Tsumeb minerals. He was honored due to his support of research into rare secondary minerals. The type material is located at the University of Stuttgart, the Smithsonian Institution, and Harvard University.
Physical properties.
Warikahnite has perfect cleavage on the c-axis {001}; and good cleavage on both the a- and b-axes ({100} and {010}). It has bladed subhedral crystals up to 3 x .5 x .5 mm, elongated on {100} and flattened on {010}, with a hardness of approximately 2 as presented in table two. Its specific gravity is 4.24 and it exhibits a colorless to pale yellow hue, along with a white streak and vitreous luster. This triclinic specimen classified under the space group P features striated crystals up to two centimetres in radial to subparallel aggregates. The Handbook of Mineralogy further states the cell dimensions of biaxial Warikahnite to be calculated as a = 6.710(1) Å, b = 8.989(2) Å, and c = 14.533(2) Å, with unit cell volume as 788.58 Å.
Crystal structure.
The crystal structure of Warikahnite, determined from diffractometer data, contained six various coordination polyhedra of zinc with components of As, O, and H2O; with the coordination numbers six, five, and four; and with five different combinations of ligand. Also noted in the "Die Kristallstruktur von Warikahnit" article, is that the hydrogen bonds are discussed appertaining to both charge balance and infrared spectra. Recent data shows the Gladstone-Dale relation compatibility of Warikahnite is ranked as superior (-0.010).
Chemical composition.
Warikahnite has the chemical formula Zn3(AsO4)2•2H2O. Along with arsenate ions (AsO4)3−, the infrared spectrum revealed H2O . These water molecules present in the warikahnite sample were determined by thermo gravimetric analysis, and lost at 365°C. Both H2O and (AsO4)3− readily dissolved when hot hydrochloric acid (HCL) or nitric acid (HNO3) were added to the specimen. After a microprobe analysis, the weight percent oxides were calculated as follows in the table directly below.
Geologic occurrence.
Warikahnite's only known localities to date are the Tsumeb Mine in Namibia, South West Africa; and Plaka and Lavrion, Greece. The first discovery of this type specimen in the mine was found with white koritnigite, blue stranskiite, pale to emerald-green cuprian adamite, crystals of helmutwinklerite, and white corroded crystals of claudetite, ludlockite, tsumcorite, and lavendulan; while the second acquisition was only linked to quartz.


Fluoborite

Fluoborite has a chemical formula of Mg3(BO3)(F,OH)3. Its name comes from its main chemical components, FLUOrine and BORon. It was first described in 1926.
Fluoborite's crystal system is hexagonal, meaning it has one six-fold axis of rotation. It also has a mirror plane perpendicular to the c-axis. Fluoborite is uniaxial, just like all other hexagonal minerals. Uniaxial means it has only one optic axis. It is anisotropic. Its relief is low, and it is birefringent.
There are three major settings fluoborite is found. It is found in skarns developed in metamorphosed boron-rich magnesium rocks, contact metamorphosed marble, and in contact metasomatic magnetite deposits. There are two major type localities for fluoborite. One is Tall Mine, Kallmora, Norberg, Västmanland, Sweden. It is an iron mine in a contact metasomatic magnetite deposit. The other type locality is the Huerta del Vinagre mine, Spain.
It occurs associated with ludwigite, chondrodite, magnetite and calcite in the Tallgruvan, Sweden occurrence. It occurs with mooreite, willemite, fluorite, hydrozincite, pyrochroite, zincite and rhodochrosite at Sterling Hill, New Jersey.


Nutritional chemical elements


Meyrowitzite

Meyrowitzite, Ca(UO2)(CO3)2·5H2O, is a carbonate mineral verified in May of 2018 by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association. It is an extremely rare mineral, discovered in the Markey mine Utah, U.S.A. The mineral is a transparent yellow and has blades up to approximately 0.2 mm in length. It is soluble in water or aqueous solutions. Meyrowitzite is named in honor of Robert Meyrowitz (1916-2013), an American analytical chemist. After serving in WW II, he joined the United States Geological Survey (USGS). He was known for developing innovative new methods for analyzing small and difficult to study mineralogical samples along with his formulation of the high-index immersion liquids.
Occurrence.
Meyrowitzite was discovered underground in the Markey mine, Red Canyon, Suan Juan County, Utah, U.S.A. It has not been found in any other location. Mineralized channels of meyrowitzite are in the Shinarump Member of the Chinle Formation. The Shinarump member is made up of medium-to coarse-grained sandstone, conglomeratic sandstone beds, and thick siltstone lenses. Ore minerals were deposited as replacements of wood and other organic materials and as disseminations in the enclosing sandstone. Since the closing of the Markey mine, oxidation of primary ores in the humid underground environment has produced a variety of secondary minerals. These secondary minerals are primarily sulfates as efflorescent crusts on the surfaces of mine walls. It is found on calcite-veined asphaltum in association with gypsum, markeyite, and rozenite.
Properties.
Meyrowitzite has bladed crystals with a length up to about 0.2 mm. The blades are commonly irregular and radiating outward from a central point. Blades are elongate on [010], flattened on {100} and exhibit the forms {100}, {001}, {101}, {110}, and {011}. There was no twinning observed. It is a transparent yellow with vitreous luster and a very pale yellow streak. It displays variable fluorescence from weak greenish-yellow to moderate greenish blue under a 405 nm laser. It has a hardness of 2 based on Mohs hardness scale. It has brittle tenacity, irregular fracture, and one perfect cleavage on {-101}. The density was measured at 2.70(2) g*cm^-3 by flotation in a methylene iodide and toluene mixture. It is easily soluble in room temperature water. It is optically biaxial (+) with α = 1.520(2), β = 1.528(2), and γ = 1.561(2) measured in white light. The 2V measured using extinction data analyzed with EXCALIBRW is 53.0(6)°; the calculated 2V is 53.3°. The dispersion is weak, r > v. The optical orientation is Z = b, Y ^ a ≈ 19° in obtuse β. Crystals are weakly pleochroic in shades of pale yellow, X ≈ Y < Z. The Gladstone–Dale compatibility, 1 – (KP/KC) is –0.039 (excellent) using the empirical formula, and –0.035 (excellent) using the ideal formula, where k(UO3) = 0.134.
Raman spectroscopy.
Raman spectroscopy is a method of chemical analysis that is non-destructive. The analysis provides detailed information about chemical structure, phase, polymorphy, crystallinity, and molecular interactions. Meyrowitzite's Raman spectroscopy was conducted on a Horiba XploRA PLUS. The spectrum was recorded using a 785 nm diode laser because of significant fluorescence when using a 532 nm diode laser. Meryrowitzites spectrum is similar to that of Zellerites. However, Meyrowitzite's spectrum has a larger number of bands primarily in the UO2+2. This is most likely due to the site-symmetry which for Meyrowitzite is monoclinic and orthorhombic for Zellerite.
Chemical analysis.
Chemical Analysis of Meyrowitzite was performed on a Cameca SX-50 electron microprobe with four wavelength-dispersive spectrometers and using Probe for EPMA software at the University of Utah. The acceleration voltage was 15 keV, with a 10 nA beam current, and a beam diameter of 5μm. The raw X-ray intensities were corrected with a φρ(z) algorithm for the matrix effect. The concentration of the total oxygen and carbon, calculated from the ideal formula, were used in the matrix correction. Because of crystal dehydration, the surfaces suffered and it was impossible to obtain a well-polished crystal surface. The sample was not damaged because of the beam. The H2O and (CO2) amounts were calculated based on the structure determination (2 C and 13 O apfu) due to insufficient material instead of the more common method of direct determination. The empirical formula is Ca0.94(U1.00O2)(CO3)2·5(H2.02O). The ideal formula is Ca(UO2)(CO3)2·5H2O, which requires CaO 10.78, UO3 54.98, CO2 16.92, and H2O 17.32, totaling 100 wt%.
X-Ray crystallography and structure determination.
Powder and single-crystal X-ray studies were performed using a Rigaku R-Axis Rapid II curved imaging plate microdiffractometer with monochromatized MoKα radiation. A Gandolfi-like motion was used during the powder study on the φ and ω axes. This was done to randomize the sample which was several crystals thick. Using the JADE 2010 software, d values and intensities were derived by profile fitting. Unit-cell parameters from the powder data using JADE 2010 are a = 12.417(17) Å, b = 16.127(17) Å, c = 20.123(17) Å, β = 107.53(4)°, and V = 3842(7) Å3. Meyrowitzite crystals are relatively poor-quality for single-crystal study. The crystal fragment, measuring 80 × 80 × 30 μm, exhibited substantial mosaicity, some spot streaking, and some extra spots indicative of one or more satellite crystals. This crystal provided usable data to a resolution of .88Å. Structural data were determined with Rigaku CrystalCleal software. This included Lorentz and polarization corrections, and the application of an empirical absorption correction using the multi-scan method with ABSCOR. Rigaku XPlain program determined the space group P21/n, which led to a structural solution using SIR2011. Because of the imperfect crystal fragment, numerous reflections violated the extinction conditions for space group P21/n (n glide) and the commission of five poorly fitting reflections that did not violate the extinction conditions. SHELXL-2013 was used for the refining of the structure. The limited data set allowed refinement with anisotropic displacement parameters for all fully occupied sites, but not for four approximately half-occupied H2O sites (OW14, OW15, OW16, and OW17). It also did not allow the location of H sites in difference Fourier maps.
Structure.
Meyrowitzite has a crystal structure based on a unique corrugated uranyl carbonate heteropolyhedral sheet. Meyrowitzite is dimorphous with Zellerite but Zellerites structure is not known. The PXRD patterns for Meyrowitzite and Zellerite are quite different. Although the strongest peaks in the Zellerite pattern are represented in the Meyrowitzite pattern, the four strongest lines in the Meyrowitzite pattern are not in the Zellerite pattern.
There are three U sites in Meyrowitzite's structure. Two (U1 and U2) are surrounded by eight O atoms. This forms a squat UO8 hexagonal bipyramid. (U3) is surrounded by seven O atoms forming a squat UO7 pentagonal bipyramid. The two short apical bonds of all three bipyramids constitute the UO2 2+ uranyl group. Of the six CO3 2– groups in the structure, three centered by C1, C2, and C3 share alternating equatorial edges of the U1 hexagonal bipyramid, thereby forming the well-known uranyl tricarbonate (UTC) unit. The other three, centered by C4, C5, and C6, share alternating equatorial edges of the U2 hexagonal bipyramid, forming a second UTC unit. The five equatorial corners of the U3 pentagonal bipyramid are shared with O atoms of the C1, C2, C3, C4, and C6 carbonate groups. These linkages create a unique corrugated uranyl carbonate heteropolyhedral sheet parallel to {101}. The U2 UTCs are oriented perpendicular to the plane of the sheet with the unshared corner of the C5 carbonate group pointing away from the sheet. Three Ca atoms (Ca1, Ca2, and Ca3) are eightfold-coordinated to O atoms in the sheets and to OW atoms, although Ca3 is effectively only sevenfold-coordinated because two of its ligands (OW15 and OW16) are only half-occupied. The Ca polyhedra do not link to one another; instead, they share edges and corners with the polyhedra in the uranyl carbonate heteropolyhedral sheets, thereby linking the sheets into a framework. The fully occupied OW9 through OW13 sites and the half-occupied OW14 and OW17 sites are located in the cavities in this framework.


Disiloxane

Disiloxane has the chemical formula . It is the simplest known siloxane with hydrogen only R groups. The molecule contains six equivalent Si-H bonds and two equivalent Si-O bonds. Disiloxane exists as a colorless, pungent gas under standard conditions. However, it is generally safe for human use as evidence in its widespread use in cosmetics. It is also commonly known as disilyl ether, disilyl oxide, and perhydrodisiloxane
Structure.
Disiloxane has a simple structure that consists of a siloxane bond (Si-O-Si) and hydrogen R groups.
The structure of disiloxane has been studied by a variety of spectroscopic methods such as electron diffraction, dipole moment, and nuclear magnetic resonance. Commonly, the bond angles of the Si-O-Si bond are studied due to their unusual nature. These bonds are typically exhibit bond angles that are larger than average, around 130 to 160 degrees, larger bond lengths are not uncommon. Typical bond angles with oxygen atoms are around 105 to 125 degrees corresponding to the hybrid "s" and "p" orbitals. The abnormally large bond angle has led some scientists to believe that the molecule exhibits a linear geometry while others have collected data indicating that disiloxane exhibits a bent geometry. This disagreement usually depends on the spectroscopic technique used to analyze the compound.
The unusual bond angle may be due to unshared electron interactions from oxygen interacting with the "d" orbitals of silicon. It has been estimated that the two lone pairs of oxygen are each about 50% involved with π bond interactions with silicon’s "d" orbitals. There is also evidence of π bonding between the "p" and "d" orbitals which results in a bond shortening between Si-O which improves the overlap and overall stability of the molecule. Because of this shortening, the Si-O bonds can exhibit some partial double bond behavior.
In addition to studies of bond angles, vibrational analyses have also been done to determine the symmetry elements of disiloxane. IR and Raman spectroscopy have been used to propose a point group of D3d.
Synthesis.
Synthesis of disiloxane is typically done by taking a hydrosilane species with a substituent leaving group and reacting it with water to produce silanol. The silanol is then reacted with itself to produce the final disiloxane through dehydrogenative coupling. This is shown in the reactions below:
H3SiX + H2O → H3SiOH + HX (first step)
2 H3SiOH → H3SiOSiH3 + H2O (second step)
Other methods of synthesis involve the use of gold on carbon as a catalyst for the reaction carried out in water as well as InBr3- catalyzed oxidation of hydrosilanes.
Uses.
Disiloxanes can be used as sealants for construction, paints, inks, and coatings, cosmetics, mechanical fluids, textile applications, and paper coatings.
Commercial use of disiloxane is common in cosmetics. It is commonly found in products such as sunscreen, moisturizer, hair spray, eye liner, body spray, nail polish, makeup remover, and conditioner. The properties that disiloxane exhibits in these products include fast drying, oil reducing, moisturizing, skin conditioning, and defoaming agent (preventing formation of foam).
Disiloxanes have been approved as teen and child safe. Siloxanes of many kinds are found to be extremely safe for topical use but can be dangerous if ingested.
Variations.
The term disiloxane is commonly used to refer to structures that exhibit much more complex R groups than hydrogen. The most common molecule that makes use of this naming is Hexamethyldisiloxane which replaces the hydrogen groups with methyl groups. Other common variations include the use of disiloxanes as bridges and spacers in larger compounds such as polymers.


Vanadium(IV) oxide

Vanadium(IV) oxide or vanadium dioxide is an inorganic compound with the formula VO2. It is a dark blue solid. Vanadium(IV) dioxide is amphoteric, dissolving in non-oxidising acids to give the blue vanadyl ion, [VO]2+ and in alkali to give the brown [V4O9]2− ion, or at high pH [VO4]4−. VO2 has a phase transition very close to room temperature (~66 °C). Electrical resistivity, opacity, etc, can change up several orders. Owing to these properties, it has been used in surface coating, sensors, and imaging. Potential applications include use in memory devices, phase-change switches, aerospace communication systems and neuromorphic computing.
Properties.
Structure.
At temperatures below Tc = 340 K (67 °C), has a monoclinic (space group P21/c) crystal structure. Above Tc, the structure is tetragonal, like rutile . In the monoclinic phase, the V4+ ions form pairs along the c axis, leading to alternate short and long V-V distances of 2.65 Å and 3.12 Å. In comparison, in the rutile phase the V4+ ions are separated by a fixed distance of 2.96 Å. As a result, the number of V4+ ions in the crystallographic unit cell doubles from the rutile to the monoclinic phase.
The equilibrium morphology of rutile particles is acicular, laterally confined by (110) surfaces, which are the most stable termination planes. The surface tends to be oxidized with respect to the stoichiometric composition, with the oxygen adsorbed on the (110) surface forming vanadyl species. The presence of V5+ ions at the surface of films has been confirmed by X-ray photoelectron spectroscopy.
Electronic.
At the rutile to monoclinic transition temperature (67 °C), also exhibits a metal to semiconductor transition in its electronic structure: the rutile phase is metallic while the monoclinic phase is semiconducting. The optical band gap of VO2 in the low-temperature monoclinic phase is about 0.7 eV.
Thermal.
Metallic VO2 contradicts the Wiedemann–Franz law that holds that the ratio of the electronic contribution of the thermal conductivity ("κ") to the electrical conductivity ("σ") of a metal is proportional to the temperature. The thermal conductivity that could be attributed to electron movement was 10% of the amount predicted by the Wiedemann–Franz law. The reason for this appears to be the fluidic way that the electrons move through the material, reducing the typical random electron motion. Thermal conductivity ~ 0.2 W/m⋅K, electrical conductivity ~ 8.0 ×10^5 S/m.
Potential applications include converting waste heat from engines and appliances into electricity, or window coverings that keep buildings cool. Thermal conductivity varied when VO2 was mixed with other materials. At a low temperature it could act as an insulator, while conducting heat at a higher temperature.
Synthesis and structure.
Following the method described by Berzelius, is prepared by comproportionation of vanadium(III) oxide and vanadium(V) oxide:
At room temperature VO2 has a distorted rutile structure with shorter distances between pairs of V atoms indicating metal-metal bonding. Above 68 °C the structure changes to an undistorted rutile structure and the metal-metal bonds are broken causing an increase in electrical conductivity and magnetic susceptibility as the bonding electrons are "released". The origin of this insulator to metal transition remains controversial and is of interest both for condensed matter physics and practical applications, such as electrical switches, tunable electrical filters, power limiters, nano-oscillators, memristors, field-effect transistors and metamaterials.
Infrared reflectance.
 expresses temperature-dependent reflective properties. When heated from room temperature to 80 °C, the material's thermal radiation rises normally until 74 °C, before suddenly appearing to drop to around 20 °C. At room temperature is almost transparent to infrared light. As its temperature rises it gradually changes to reflective. At intermediate temperatures it behaves as a highly absorbing dielectric.
A thin film of vanadium oxide on a highly reflecting substrate (for specific infrared wavelengths) such as sapphire is either absorbing or reflecting, dependent on temperature. Its emissivity varies considerably with temperature. When the vanadium oxide transitions with increased temperature, the structure undergoes a sudden decrease in emissivity – looking colder to infrared cameras than it really is.
Varying the substrate materials e.g., to indium tin oxide, and modifying the vanadium oxide coating using doping, straining and other processes, alter the wavelengths and temperature ranges at which the thermal effects are observed.
Nanoscale structures that appear naturally in the materials' transition region can suppress thermal radiation as the temperature rises. Doping the coating with tungsten lowers the effect's thermal range to room temperature.
Uses.
Infrared radiation management.
Undoped and tungsten-doped vanadium dioxide films can act as "spectrally-selective" coatings to block infrared transmission and reduce the loss of building interior heat through windows. Varying the amount of tungsten allows regulating the phase transition temperature at a rate of 20 °C per 1 atomic percent of tungsten. The coating has a slight yellow-green color.
Other potential applications of its thermal properties include passive camouflage, thermal beacons, communication, or to deliberately speed up or slow down cooling (which could be useful in a variety of structures from homes to satellites).
Vanadium dioxide can act as extremely fast optical modulators, infrared modulators for missile guidance systems, cameras, data storage, and other applications. The thermochromic phase transition between the transparent semiconductive and reflective conductive phase, occurring at 68 °C, can happen in times as short as 100 femtoseconds.
Phase change computing and memory.
The insulator-metal phase transition in VO2 can be manipulated at the nanoscale using a biased conducting atomic force microscope tip, suggesting applications in computing and information storage.


Polysulfide bromide battery

The polysulfide bromide battery (PSB; sometimes "polysulphide bromide"), is a type of regenerative fuel cell involving a reversible electrochemical reaction between two salt-solution electrolytes: sodium bromide and sodium polysulfide. It is an example and type of redox (reduction–oxidation) flow battery.
In 2002, a 12 MWe prototype electrical storage facility was built at Little Barford Power Station in the UK, which uses polysulfide bromide flow batteries. Although the facility was completed, due to engineering issues in scaling up the technology, it was never fully commissioned. A similar demonstration plant located at the Tennessee Valley Authority (TVA) facility in Columbus, Mississippi, United States was never completed.
Chemistry.
Two different salt solution electrolytes are contained in two separate tanks. When energy is required, a solution of Na2S2 (sodium disulfide) is pumped to the anode, and NaBr3 (sodium tribromide) is pumped to the cathode. The anode and cathode, and their corresponding salt solutions, are separated by an ion exchange membrane. At the negative electrode, the anodic reaction is shown as:
2Na2S2 → Na2S4 + 2Na+ + 2e−
At the positive electrode, the cathodic reaction is shown as:
NaBr3 + 2Na+ + 2e−→ 3NaBr
As energy is drawn from the system, the sodium disulfide becomes sodium polysulfide, and the sodium tribromide becomes sodium bromide. This reaction can be reversed when a current is supplied to the electrodes, and the system chemical salts are "recharged". The system is defined as a fuel cell because the electrodes are not consumed by the reaction, they act only as a surface for the reaction. However, nor is the liquid a fuel that is consumed. It is a salt solution electrolyte that is changed by the process.


Tsumebite

Tsumebite is a rare phosphate mineral named in 1912 after the locality where it was first found, the Tsumeb mine in Namibia, well known to mineral collectors for the wide range of minerals found there. Tsumebite is a compound phosphate and sulfate of lead and copper, with hydroxyl, formula Pb2Cu(PO4)(SO4)(OH). There is a similar mineral called arsentsumebite, where the phosphate group PO4 is replaced by the arsenate group AsO4, giving the formula Pb2Cu(AsO4)(SO4)(OH). Both minerals are members of the brackebuschite group.
The brackebuschite group.
The minerals in the brackebuschite group have the general formula A2B(H2O,OH)(TO4)2 and crystallise in the monoclinic system, space group P21/m. The group includes:
Structure.
The structure of the brackebuschite group minerals is composed of B-(O,OH)6 octahedra, two non-equivalent TO4 tetrahedra, TO4(1) and TO4(2), and two different irregular polyhedra of large cations. B and T represent different elements in different members of the group. Chains formed from the B octahedra link through the oxygens of TO4(2) tetrahedra, while the large cation polyhedra form double chains parallel to the b crystal axis through edge sharing with TO4(1) tetrahedra. The result is a tight three-dimensional structure. In tsumebite copper ions occupy the B sites, and phosphorus and sulfur occupy the T sites. Lead is the large cation.
Unit cell.
Tsumebite belongs to the monoclinic crystal class 2/m, meaning that it has one twofold axis of symmetry perpendicular to a mirror plane. The space group is P 21/m, meaning that the crystal lattice is a primitive lattice, with structural elements only at the vertices of the unit cell. These structural elements are made up of two formula units (Z = 2).
Unit cell parameters are a = 8.69 Å, b = 5.78 Å, c = 7.86 Å, β = 111.87° or a = 8.70 Å, b = 5.80 Å, c = 7.85 Å, β = 111.5°.
Optical properties.
Tsumebite is an emerald-green color, transparent and green in transmitted light, with a green streak and an adamantine (diamond-like) to vitreous (glassy) luster. It is biaxial (+) with refractive indices Nx = 1.885 to 1.900, Ny = 1.920 and Nz = 1.942 to 1.956. It is faintly pleochroic with X = Y = very pale blue to colorless and Z = robin's-egg-blue.
Physical properties.
The mineral typically occurs as crusts of intergrown crystals on matrix. Cleavage is absent, but twinning is almost universal, and twins may be multiple, with serrated re-entrants. It is brittle, with an uneven fracture, hardness and specific gravity 6.13. It is readily soluble in hydrochloric acid HCl and slowly soluble in nitric acid HNO3. It is not radioactive.
Environment.
Tsumebite is a rare secondary mineral in the oxidised zone of some arsenic-bearing lead-copper deposits, with other lead-bearing phosphates and sulfates. Associated minerals include azurite, smithsonite, malachite, cerussite, mimetite, wulfenite and olivenite. The type locality is the Tsumeb mine, Tsumeb, Otjikoto Region, Namibia. The Handbook of Mineralogy states that the type material was destroyed by bombing, but does not indicate when or where.
Tsumebite occurs at Morenci, Arizona, predominantly as twinned crystals associated with wulfenite, olivenite and the hyalite variety of opal. At Broken Hill, New South Wales, Australia, tsumebite has been found as lustrous pale blue to bluish green crystals. It usually occurs with yellow crusts of corkite-hinsdalite, colorless to white pyromorphite needles and sprays of pale greyish green zincian libethenite. Less commonly found with scholzite and torbernite.


Caesium bisulfate

Caesium bisulfate or cesium hydrogen sulfate is an inorganic compound with the formula CsHSO4. The caesium salt of bisulfate, it is a colorless solid obtained by combining Cs2SO4 and H2SO4.
Properties.
Above 141 °C, CsHSO4 is a superionic conductor. The rapid ionic conductivity arise especially in the range of these temperatures due to the high activity of protons.
Based on the results of X-ray crystallography, the structure consists of tetrahedral sulfate centers that bridge caesium ions. The proton is associated with the oxygen on sulfate.
CsHSO4 goes through three crystalline phases that are referred to as phase III, II, and I. CsHSO4 is initially existing in phase III at a room temperature of 21 °C. Phase III ranges from 21 °C to 90 °C with a transition temperature of 90 °C to 100 °C between phase III and phase II. Phase II ranges from 90 °C to 140 °C. At 140 °C, CsHSO4 undergoes a phase shift from phase II to phase I.
Phase III (21 °C to 90 °C) and Phase II (90 °C to 140 °C) are referred to as the monoclinic phases, in which CsHSO4 exhibits its lowest proton conductivity. As the crystalline structure’s temperature is raised, it will show variations in the unit cell volume and the arrangement of its hydrogen bonds, which will alter the ability of a CsHSO4 crystalline structure to allow the displacement of protons.
At 141 °C, the CsHSO4 crystal structure experiences a structural change from monoclinic phase II to a tetragonal phase, becoming phase I. Phase I has more elevated crystal symmetry and widened lattice dimensions. Phase I is noted as the superprotonic phase (strong conducting phase), which triggers an extreme growth in proton conductivity by four orders of magnitude, reaching 10 mS/cm. This makes the conductivity of CsHSO4 ten-fold stronger than the conductivity of a sodium chloride aqueous solution. In the superprotonic phase, the movement of an SO4 tetrahedron generates a disruption of the hydrogen bond network, which accelerates proton transfer. The tetragonal anions available in the structure are accountable for the arrangement of the hydrogen bonds with the moving protons.
Potential applications.
The maximum conductivity of pure CsHSO4 is 10 mS/cm, which is too low for practical applications. In composites with SiO2, TiO2, and Al2O3) , the proton conductivity below the phase transition temperature is enhanced by a few orders of magnitude.
Unlike hydrated protonic conductors, the absence of water in CsHSO4 provides thermal and electrochemical stability. Electromotive force (EMF) measurements in a humidified oxygen concentration cell verified the high ionic nature of CsHSO4 in its superprotonic phase. Based on heat rotation, the voltage stayed the same for over 85 hours during the measurement, particularly at the high temperature. These results, demonstrate the thermal independence from humidity-type environments. Additionally, the crystal structure of CsHSO4 allows for quick transport of smaller charged ions, resulting in efficient energy transfer in electrochemical devices.


Zinc ferrite

Zinc ferrites are a series of synthetic inorganic compounds of zinc and iron (ferrite) with the general formula of ZnxFe3−xO4. Zinc ferrite compounds can be prepared by aging solutions of Zn(NO3)2, Fe(NO3)3, and triethanolamine in the presence and in the absence of hydrazine, or reacting iron oxides and zinc oxide at high temperature. Spinel (Zn, Fe) Fe2O4 appears as a tan-colored solid that is insoluble in water, acids, or diluted alkali. Because of their high opacity, zinc ferrites can be used as pigments, especially in applications requiring heat stability. For example, zinc ferrite prepared from yellow iron oxide can be used as a substitute for applications in temperatures above . When added to high corrosion-resistant coatings, the corrosion protection increases with an increase in the concentration of zinc ferrite. A recent investigation shows that the zinc ferrite, which is paramagnetic in the bulk form, becomes ferrimagnetic in nanocrystalline thin film format. A large room temperature magnetization and narrow ferromagnetic resonance linewidth have been achieved by controlling thin films growth conditions.


Dibromodiethyl sulfoxide

Dibromodiethyl sulfoxide is a sulfoxide (S=O) containing two 2-bromo-ethyl substituents.
Production.
Dibromodiethyl sulfoxide is produced from dibromodiethyl sulfide by oxidation by benzoyl peroxide.


Unbiseptium


Flexible silicon

Flexible silicon refers to a flexible piece of mono-crystalline silicon. Several processes have been demonstrated in the literature for obtaining flexible silicon from single crystal silicon wafers (either before or after fabrication of CMOS circuits).
Background.
According to beam theory and the 3-point test of a rectangular beam of an istoroptic linear material, a perpendicular specific force applied to a rectangular beam would cause it to deflect as a function of its dimension parameters and material properties (i.e. flexural modulus). All parameters fixed, the dependence of the deflection on thickness is inversely proportional, i.e. the thinner the beam the more it deflects when the same force is applied. In a simplistic manner, the applied force per unit area is the stress experienced by the beam. For two beams made of similar materials but one is thinner than the other, a lower force (stress) is required to achieve the same deflection in the thinner beam. This opens up a possibility of reducing a beam's thickness to adjust the amount of stress it can handle before physically breaking, if deflection requirement is the same. Applying this concept on the commonly used brittle Monocrystalline silicon (100) substrates, it can achieve some flexibility (note that silicon is an anisotropic material and requires dealing with elasticity matrix, a tensor, not a simple value for flexural modulus). This is done by using various micro-fabrication techniques and novel approaches to reduce the silicon substrate thickness to few to tens of micrometers, enabling bending up to 0.5 cm radius without breaking.
Processes.
Etch protect release approach and backside etch are few examples of how this can be achieved. These techniques have been extensively used to demonstrate flexible versions of traditional high-performance CMOS compatible devices, including 3D fin-field effect transistors (finFETs) and planar metal-oxide-semiconductor FETs (MOSFETs), metal-oxide semiconductor/metal-insulator-metal capacitors (MOSCAPs and MIMCAPs), ferroelectric capacitors and resistive devices, and thermoelectric generators (TEGs).


Unhexhexium


Vanadium(II) sulfate

Vanadium(II) sulfate describes a family of inorganic compounds with the formula VSO4(H2O)x where 0 ≤ x ≤ 7. The hexahydrate is most commonly encountered. It is a violet solid that dissolves in water to give air-sensitive solutions of the aquo complex. The salt is isomorphous with [Mg(H2O)6]SO4. Compared to the V–O bond length of 191 pm in [V(H2O)6]3+, the V–O distance is 212 pm in the [V(H2O)6]SO4. This nearly 10% elongation reflects the effect of the lower charge, hence weakened electrostatic attraction.
The heptahydrate has also been crystallized. The compound is prepared by electrolytic reduction of vanadyl sulfate in sulfuric acid. The crystals also feature [V(H2O)6]2+ centers but with an extra water of crystallization. The salt is isomorphous with ferrous sulfate heptahydrate. A related salt is vanadous ammonium sulfate, (NH4)2V(SO4)2·6H2O, a Tutton's salt isomorphous with ferrous ammonium sulfate.


Ytterbium hydride

Ytterbium hydride is the hydride of ytterbium with the chemical formula YbH2. In this compound, the ytterbium atom has an oxidation state of +2 and the hydrogen atoms have an oxidation state of -1. Its resistivity at room temperature is 107 Ω·cm. Ytterbium hydride has a high thermostability.
Production.
Ytterbium hydride can be produced by reacting ytterbium with hydrogen gas:


Zinc molybdate

Zinc molybdate is an inorganic compound with the formula ZnMoO4. It is used as a white pigment, which that is also a corrosion inhibitor. A related pigment is sodium zinc molybdate, Na2Zn(MoO4)2. The material has also been investigated as an electrode material.
In terms of its structure, the Mo(VI) centers are tetrahedral and the Zn(II) centers are octahedral.
Safety.
The LD50 (oral, rats) is 11,500 mg/kg. While highly soluble molybdates like e.g. sodium molybdate are toxic in higher doses, zinc molybdate is essentially non-toxic because of its insolubility in water. Molybdates possess a lower toxicity than chromates or lead salts and are therefore seen as an alternative to these salts for corrosion inhibition.


Alpha-Chlorocodide

α-Chlorocodide is an opioid analog that is a derivative of codeine in which the 6-hydroxy group has been replaced by chlorine.


Organopolonium chemistry

Organopolonium chemistry describes the synthesis and properties of chemical compounds containing a carbon to polonium chemical bond.
As polonium is a highly radioactive element (its most commonly used isotope, 210Po, has a half-life of about 138 days), organopolonium chemistry is mostly unexplored, and what is known is mostly confined to tracer-level studies due to self-destruction and charring of the compounds by the energetic alpha decay of polonium. Moreover, the C–Po bond is even weaker than the C–Te and C–Se bonds; compounds with those bonds tend to decompose over time to form elemental tellurium and selenium respectively.
Identification of such compounds has mostly been accomplished using chromatography, with analogous tellurium compounds as references, as classical chemical methods cannot be applied. Their production is often accomplished by the beta decay of 210Bi-containing organobismuth compounds. Some compounds have been claimed but not securely identified.
Relatively well-characterised derivatives are mostly restricted to dialkyl and diaryl polonides (R2Po), triarylpolonium halides (Ar3PoX), and diarylpolonium dihalides (Ar2PoX2). Polonium also forms soluble compounds with some chelating agents, such as 2,3-butanediol and thiourea.


Neodymium nitrate

Neodymium nitrate is a chemical compound with the formula Nd(NO3)3. It decomposes to NdONO3 at elevated temperature. This water soluble salt finds use in fabrication of perovskite based solid oxide fuel cells, synthesis of Nd3+ doped vanadium pentoxide nanostructure for potential usage in supercapacitors and as a catalyst for Friedlander synthesis of surface modified quinolones for application in medicinal chemistry.


Extinct isotopes of superheavy elements

Extinct isotopes of superheavy elements are isotopes of elements whose half-lives were too short to have lasted through the formation of the solar system and, because they are not replenished by natural processes, can nowadays only be found as their daughters trapped within sediment and meteorite samples dating billions of years ago.
Carbonaceous chondrite fission xenon.
Carbonaceous chondrite fission Xe, often abbreviated as CCF Xe, are a collection of different isotopes of xenon that were thought to have arisen from the decay of a superheavy element within the island of stability. Early studies proposed that the half life of the theoretical progenitor of CCF Xe to be on the order of 108 years. A later attempt at characterization of the progenitor in 1975 by Edward Anders, a professor of chemistry at the University of Chicago, and colleague John Larimer suggested a heat of vaporization of 54 kJ/mol and a boiling point of 2500K for the element and, based on estimated accretion temperatures, they also proposed elements 111 and 115 (today named roentgenium and moscovium) as the most likely candidates assuming the element condensed in pure form.
Allende meteorite.
Anders went on to study samples of the Allende meteorite, the largest carbonaceous chondrite ever found on Earth. Results of these studies suggested element 113-115 (today nihonium, flerovium, and moscovium) as the most likely candidates for the progenitor of CCF Xe. These studies also proposed that the progenitor condensed as an iron chromium sulfide. This is later called into question as iron chromium sulfide is very rare with a relative abundance of 0.4%.
Evidence against carbonaceous fission xenon.
By the 1980s, CCF Xe actually being the product of fission was doubtful, and the alternate theory that it had arisen from r-process (neutron capture) nucleosynthesis gained more ground. Researchers looked at the isotopic anomalies in neighboring elements Barium, Neodymium and Samarium isotopes and compared to the amount of Xe. Whether CCF Xe was produced by nucleosynthesis or fission, comparable amounts of barium 135 should be produced. When researchers compared the experimental data to predicted amounts of Barium following each model, neither model even came close to predicting the anomalies correctly, leading to Lewis and co. calling the experiment an "embarrassment" for both models. However, in the case of nucleosynthesis, it is possible that Sm, Nd, and Ba were separated from Xe by prior condensation in the supernova shell or plasma processes. Based on this data it was deemed unlikely that CCF Xe had actually arose from fission.
Plutonium-244.
Plutonium-244 is one of several extinct radionuclides that preceded the formation of the solar system. Its half-life of 80 million years ensured its circulation across the solar system before its extinction and indeed, 244Pu has not yet been found in matter other than meteorites. Radionuclides, such as 244Pu, undergo decay to produce fissiogenic - arising from fission - xenon isotopes that can then be used to time the events of the early solar system. In fact, by analyzing data from Earth’s mantle that indicate that about 30% of the existing fissiogenic xenon is attributable to 244Pu decay, the timing of Earth’s formation can be inferred to have occurred nearly 50-70 million years following the formation of the solar system.
Identification and discovery.
Preceding the analysis of mass spectra data obtained by analyzing samples found in meteorites, it was inferential at best to accredit 244Pu as being the nuclide responsible for the fissiogenic xenon found. But an analysis of a laboratory sample of 244Pu compared with that of fissiogenic xenon gathered from the meteorites Pasamonte and Kapoeta produced matching spectra that immediately left little doubt as to the source of the isotopic xenon anomalies. Spectra data was further acquired for another actinide, 244Cm, but such data proved contradictory and helped erase further doubts that the fission was appropriately attributed to 244Pu.
Both the examination of spectra data and study of fission tracks led to several findings of Plutonium-244. In Western Australia, the analysis of the mass spectrum of xenon within 4.1 - 4.2 Gy-old zircons was met with findings of diverse levels of 244Pu fission. Presence of 244Pu fission tracks can be established by using the initial ratio of 244Pu to 238U (Pu/U)0 at a time T0 = 4.58×109 years, when Xe formation first began in meteorites, and by considering how the ratio of Pu/U fission tracks varies over time. Examination of a whitlockite crystal within a lunar rock specimen brought over from the Apollo 14 mission established proportions of Pu/U fission tracks consistent with the (Pu/U)0 time dependence.


Dicobalt edetate

Dicobalt edetate is the coordination compound with the approximate formula Co2(EDTA)(H2O)6. It is a derivative of the (non-natural) amino acid ethylenediaminetetraacetate.
Solutions of this solid have been used in Europe as an antidote to cyanide poisoning, with the trade name Kelocyanor. However, dicobalt edetate is itself toxic, particularly if there is not enough cyanide in the blood to react with it, so it is only suitable for serious cases of poisoning. In the past, workplaces in the UK that handle cyanide were recommended to keep a 'Kelocyanor kit', to be taken to the hospital along with the patient, but this practice has been discontinued since it may mislead doctors into using the antidote unnecessarily.
Structure.
The compound is polymeric in the crystalline form. Half of the Co2+ ions are bound to the EDTA2− and the other Co2+ ions are bound to four water ligands as well as carboxylate ligands on the [Co(EDTA)]2− entity. In aqueous solution, depolymerization occurs to give [Co(EDTA)]2− and [Co(H2O)6]2+ ions, each of which is kinetically labile and has a high affinity for cyanide.
Related compounds.
Oxidation of [Co(II)(EDTA)]2− gives [Co(III)(EDTA)]−, which is so kinetically inert that it can be resolved optically.


Dimethyldichlorosilane

Dimethyldichlorosilane is a tetrahedral, organosilicon compound with the formula Si(CH3)2Cl2. At room temperature it is a colorless liquid that readily reacts with water to form both linear and cyclic Si-O chains. Dimethyldichlorosilane is made on an industrial scale as the principal precursor to dimethylsilicone and polysilane compounds.
History.
The first organosilicon compounds were reported in 1863 by Charles Friedel and James Crafts who synthesized tetraethylsilane from diethylzinc and silicon tetrachloride. However, major progress in organosilicon chemistry did not occur until Frederick Kipping and his students began experimenting with diorganodichlorosilanes (R2SiCl2) that were prepared by reacting silicon tetrachloride with Grignard reagents. Unfortunately, this method suffered from many experimental problems.
In the 1930s, the demand for silicones increased due to the need for better insulators for electric motors and sealing materials for aircraft engines, and with it the need for a more efficient synthesis of dimethyldichlorosilane. To solve the problem, General Electric, Corning Glass Works, and Dow Chemical Company began a partnership that ultimately became the Dow Corning Company. During 1941–1942, Eugene G. Rochow, a chemist from General Electric, and Richard Müller, working independently in Germany, found an alternate synthesis of dimethyldichlorosilane that allowed it to be produced on an industrial scale. This Direct Synthesis, or Direct process, which is used in today’s industry, involves the reaction of elemental silicon with methyl chloride in the presence of a copper catalyst.
Preparation.
Rochow's synthesis involved passing methyl chloride through a heated tube packed with ground silicon and copper(I) chloride. The current industrial method places finely ground silicon in a fluidized bed reactor at about 300 °C. The catalyst is applied as Cu2O. Methyl chloride is then passed through the reactor to produce mainly dimethyldichlorosilane.
The mechanism of the direct synthesis is not known. However, the copper catalyst is essential for the reaction to proceed.
In addition to dimethyldichlorosilane, products of this reaction include CH3SiCl3, CH3SiHCl2, and (CH3)3SiCl, which are separated from each other by fractional distillation. The yields and boiling points of these products are shown in the following chart.
Main reactions.
Dimethyldichlorosilane hydrolyzes to form linear and cyclic silicones, compounds containing Si-O backbones. The length of the resulting polymer is dependent on the concentration of chain ending groups that are added to the reaction mixture. The rate of the reaction is determined by the transfer of reagents across the aqueous-organic phase boundary; therefore, the reaction is most efficient under turbulent conditions. The reaction medium can be varied further to maximize the yield of a specific product.
Dimethyldichlorosilane reacts with methanol to produce dimethoxydimethylsilanes.
Although the hydrolysis of dimethoxydimethylsilanes is slower, it is advantageous when the hydrochloric acid byproduct is unwanted:
Because dimethyldichlorosilane is easily hydrolyzed, it cannot be handled in air. One method used to overcome this problem is to convert it to a less reactive bis(dimethylamino)silane.
Another benefit to changing dimethyldichlorosilane to its bis(dimethylamino)silane counterpart is that it forms an exactly alternating polymer when combined with a disilanol comonomer.
Sodium metal can be used to polymerize dimethyldichlorosilane, producing polysilane chains with a Si-Si backbone. Other types of dichlorosilane monomers, such as Ph2SiCl2, can be added to adjust the properties of the polymer.
In organic synthesis it (together with its close relative diphenyldichlorosilane) is used as a protecting group for "gem"-diols.
Applications.
The main purpose of dimethyldichlorosilane is for use in the synthesis of silicones, an industry that was valued at more than $10 billion per year in 2005. It is also employed in the production of polysilanes, which in turn are precursors to silicon carbide. In practical uses, dichlorodimethylsilane can be used as a coating on glass to avoid the adsorption of micro-particles.


Sodium polysulfide

Sodium polysulfide is a general term for salts with the formula Na2Sx, where "x" = 2 to 5. The species Sx2−, called polysulfide anions, include disulfide (S22−), trisulfide (S32−), tetrasulfide (S42−), and pentasulfide (S52−). In principle, but not in practice, the chain lengths could be longer. The salts are dark red solids that dissolve in water to give highly alkaline and corrosive solutions. In air, these salts oxidize, and they evolve hydrogen sulfide by hydrolysis.
Structure.
The polysulfide anions form chains with S---S bond distances around 2 Å in length. The chains adopt skewed conformations. In the solid state, these salts are dense solids with strong association of the sodium cations with the anionic termini of the chains.
Production and occurrence.
Sodium polysulfide can be produced by dissolving sulfur in a solution of sodium sulfide. Alternatively they are produced by the redox reaction of aqueous sodium hydroxide with sulfur at elevated temperatures. Finally they arise by the reduction of elemental sulfur with sodium, a reaction often conducted in anhydrous ammonia.
These salts are used in the production of polysulfide polymers, as a chemical fungicide, as a blackening agent on copper jewellery, as a component in a polysulfide bromide battery, as a toner in a photochemical solution, and in the tanning industry to remove hair from hides.
Reactions.
As exploited in the sodium-sulfur battery, the polysulfides absorb and release reducing equivalents by breaking and making S-S bonds, respectively. An idealized reaction for sodium tetrasulfide is shown:
Alkylation gives organic polysulfides according to the following idealized equation:
Alkylation with an organic dihalide gives polymers called thiokols.
Protonation of these salts gives hydrogen sulfide and elemental sulfur, as illustrated by the reaction of sodium pentasulfide:


Unquadbium


Silicon (journal)

Silicon is a peer-reviewed scientific journal published by Springer and founded in 2009 by editor in chief Stephen Clarson. It deals with all aspects of silicon. Published research involves materials biology, materials physics, materials chemistry, materials engineering, and environmental science. The journal caters to chemists, physicists, engineers, biologists, and environmental scientists.


Molybdenum oxytetrachloride

Molybdenum oxytetrachloride is the inorganic compound with the formula MoOCl4. This thermally unstable, dark green solid is used to prepare other complexes of molybdenum. It adopts a square pyramidal structure of C4v symmetry. As for other Mo(VI) compounds, it is diamagnetic. It decomposes thermally to MoOCl3.
Preparation.
It is prepared by treating molybdenum pentachloride with oxygen. It also arises by chlorination of molybdenum trioxide:


Tributyltin chloride

Tributyltin chloride is an organotin compound with the formula (C4H9)3SnCl. It is a colorless liquid that is soluble in organic solvents. The molecule has tetrahedral geometry.
Preparation and reactions.
The compound is prepared by a redistribution reaction by combining stannic chloride and tetrabutyltin:
Tributyltin chloride hydrolyzes to the oxide [(C4H9)3Sn]2O
Tributyltin chloride is used as a precursor to other organotin compounds and reagents, such as tributyltin hydride.