@article {2626, title = {Synthesis and Coordination Chemistry of a Tridentate o-Phenylene-Bridged Diphosphine-NHC System}, journal = {Organometallics}, volume = {28}, number = {9}, year = {2009}, note = {ISI Document Delivery No.: 441CETimes Cited: 8Cited Reference Count: 48Steinke, Tobias Shaw, Bryan K. Jong, Howard Patrick, Brian O. Fryzuk, Michael D.}, month = {May}, pages = {2830-2836}, type = {Article}, abstract = {The preparation of a di-o-phenylene-bridged tridentate PCP donor set is described starting with t-BOC-aniline followed by a series of steps that include lithiation, quenching with (Pr2PCl)-P-i, conversion to the phosphine sulfide, and assembling the unsaturated N-heterocyclic carbene unit. After desulfurization, the imidazolinium unit flanked by two phosphine units, represented as [(PCP)H]PF6 is obtained. Subsequent reaction with group 10 M(0) reagents (Ni(COD)(2), Pd(PPh3)(4), and Pt(PPh3)(4)) generates good yields of the Corresponding metal hydride complexes, [(PCP)MH]PF6 salts (where M = Ni(II), Pd(II), and Pt(II)). Each of these species has been characterized by elemental analyses, NMR spectroscopy, and X-ray crystallography. All of the structures show that the PCP unit is twisted with respect to the square plane of the d(8) metal complex.}, keywords = {BIS(BENZIMIDAZOLIN-2-YLIDENE) PALLADIUM, BONDS, C COUPLING REACTIONS, COMPLEXES, H, HETEROCYCLIC CARBENE COMPLEXES, IMIDAZOLIUM SALTS, LIGANDS, OLEFIN METATHESIS, ONE-POT SYNTHESIS, ORGANOMETALLIC CATALYSIS, OXIDATIVE ADDITION}, isbn = {0276-7333}, url = {://000265746100022}, author = {Steinke, T. and Shaw, B. K. and Jong, H. and Patrick, B. O. and Fryzuk,Michael D.} } @article {1105, title = {Characterization of a rhodium(III)-imine-orthometalated imine complex: Reversible C-H activation of a coordinated imine}, journal = {Organometallics}, volume = {24}, number = {15}, year = {2005}, note = {ISI Document Delivery No.: 945IGTimes Cited: 13Cited Reference Count: 40}, month = {Jul}, pages = {3753-3757}, type = {Article}, abstract = {Solutions of cis-[Rh(PPh3)(2)(solv)(2)]PF6 (solv = acetone or MeOH) react at room temperature under Ar with benzophenone imine to yield cis- [Rh(PPh3)(2)(eta(1)-NH=CPh2)(2)]PF6 (3), but depending on reaction conditions, one of the imine ligands undergoes orthometalation to give [RhH{NH=C(Ph)(o-C6H4)}(HN=CPh2)(PPh3)(2)]PF6 (2) with trans-phosphines; this is the first recorded complex containing an imine in its eta(1)-form and as an eta(2)-moiety formed via orthometalation. Complexes 2 and 3 are characterized by elemental analysis, H-1 and P-31-{H-1} NMR spectroscopy, and, in the case of 2, an X-ray crystal structure.}, keywords = {BEHAVIOR, BONDS, CATIONIC COMPLEXES, COMPLEXES, HYDROGENATION, METAL-COMPLEXES, OXIDATIVE ADDITION, RHODIUM(III), semicarbazones, TERDENTATE NITROGEN LIGANDS, UNIT}, isbn = {0276-7333}, url = {://000230495600021}, author = {Ezhova, M. B. and Patrick, B. O. and James, Brian R.} } @article {4669, title = {A computational study of two-state conformational changes in 16-electron [CpW(NO)(L)] complexes (L = PH3, CO, CH2, HCCH, H2CCH2)}, journal = {Chemistry-a European Journal}, volume = {5}, number = {5}, year = {1999}, note = {ISI Document Delivery No.: 194UQTimes Cited: 20Cited Reference Count: 52}, month = {May}, pages = {1598-1608}, type = {Article}, abstract = {Electronically and coordinatively unsaturated [Cp*W(NO)(L)] complexes have been postulated as intermediates in several related systems. Model [CpW(NO)(L)] compounds (L= PH3, CO, CH2, H2CCH2, HCCH) have been investigated theoretically by means of density functional theory computational techniques. The structural parameters calculated for saturated [CpW(NO)(PH,)(L)] complexes are in good agreement with the solid-state molecular structures determined crystallographically for the corresponding [Cp*W(NO)(PMe3)(L)] compounds. The 16-electron, singlet [CpW(NO)(L)] species have geometries comparable to those of the same fragment in the phosphine adducts and include a highly pyramidal conformation at W. The energy of the triplet spin state is calculated to be close to or even lower than that of the singlet state for these unsaturated compounds, and depends largely on the pi-bonding capabilities of L (Delta Es-t=Delta E-t-Delta E-s = - 3.3 kcalmol(-1) (PH3), + 2.8 (CO), + 2.4 (CH2), +6.3 (H2CCH2), -2.3 (HCCH)). The optimization of partially constrained structures in both spin states allows for a conformational analysis of the [CpW(NO)(L)] species. The inversion of the conformation of the pyramidal singlet [CpW(NO)(L)] complexes via the planar-at-W triplet species (two-state pathway) is calculated to be competitive with the equivalent process solely along the singlet spin hypersurface. Rotation of the W-CH, bond in the singlet carbene species is also found to proceed more readily via a two-state pathway. The preferred alkyne conformation, the unusually stable triplet states, and the strong W-to-L sc-donation observed in these systems may all be rationalized by the relatively high energies of the occupied orbitals of the formally WO compounds.}, keywords = {ACTIVATION, CROSSOVER, density functional calculations, H BOND, LIGAND, ligand effects, MOLECULAR CALCULATIONS, ORGANOMETALLIC NITROSYL CHEMISTRY, OXIDATIVE ADDITION, pi interactions, PIANO-STOOL COMPLEXES, REACTIVITY, REDUCTIVE ELIMINATION, SPIN, SPIN-STATE, TUNGSTEN}, isbn = {0947-6539}, url = {://000080212600026}, author = {Smith, K. M. and Poli, R. and Legzdins,Peter} } @article {4517, title = {Hydrocarbon C-H bond activation by a tungsten acetylene complex}, journal = {Organometallics}, volume = {18}, number = {17}, year = {1999}, note = {ISI Document Delivery No.: 230KBTimes Cited: 13Cited Reference Count: 60}, month = {Aug}, pages = {3414-3428}, type = {Article}, abstract = {Thermal activation of Cp*W(NO)(eta(2)-CPhCH2)(CH2SiMe3) (1) in neat hydrocarbon solutions transiently generates Cp*W(NO)(eta(2)-PhC=CH) (A), which subsequently activates solvent C-H bonds. For example, the thermolysis of 1 in benzene solution generates quantitatively Cp*W(NO)(eta(2)-CPhCH2)(Ph) (2) The thermolysis of 1 in solutions of methyl-substituted arenes such as toluene or p-, m-, or o-xylene provides mixtures of aryl and benzyl vinyl complexes of the general formulas Cp*W(NO)(eta(2)-CPhCH2)(aryl), Cp*W(NO)(eta(2)-CPhCH2)(eta(1)-benzyl), or Cp*W(NO)(eta(2)-benzyl)(eta(1)-CPh=CH2). Similarly, the thermolysis of 1 in (Me3Si)(2)O affords Cp*W(NO)(eta(2)-CPhCH2)(CH2SiMe2OSiMe3) (10). Mechanistic and kinetic studies support the proposal that the formation of A from 1 by elimination of silane is the rate-controlling process in these reactions. Intra- and intermolecular selectivity studies reveal that the strongest C-H bond (yielding the stronger M-C bond) is the preferred site of reactivity, as expected. Dual C-H bond activation of aliphatic hydrocarbons occurs during the thermal activation ;of I in solutions of these substrates. Consequently, metallacycles of the form Cp*W(NO)(eta(2)-CH(eta(2)-Ph)CH2CH(R)CH2) [(11)R = Pr-n; (12)R = Bu-n; (13)R = Bu-t; and (14)R = OEt] result from the dehydrogenation of n-pentane, n-hexane, 2,2-dimethylbutane, and diethyl ether, respectively. This dual C-H activation process displays a selectivity for substrates that contain an ethyl substituent. Dual C-H bond activation of 2,3-dimethyl-2-butene in the presence of 1 under thermolysis conditions regioselectively affords Cp*W(NO)(eta(3)-endo-CH2C(Me)C(Me)CH2(eta(1)-CPhMe)) (15), Attempts to trap acetylene complex A with PNMe3 result in the formation of the metallacyclopropane complex Cp*W(NO)(CH2SiMe3)(eta(2)-CH2CPh(PMe3)) (16). All new complexes have been characterized by conventional spectroscopic methods, and the solid-state molecular structures of compounds 11, 15, and 16 have been established by X-ray diffraction methods.}, keywords = {ELIMINATION, HYDROGEN-TRANSFER, ISOMERIZATION, LIGAND, METAL-COMPLEXES, MOLECULAR-STRUCTURE, ORGANIC-SYNTHESIS, ORGANOMETALLIC NITROSYL CHEMISTRY, OXIDATIVE ADDITION, REDUCTIVE, R{\textquoteright} =}, isbn = {0276-7333}, url = {://000082249400023}, author = {Debad, D. and Legzdins,Peter and Lumb, S. A. and Rettig, S. J. and Batchelor, R. J. and Einstein, F. W. B.} }