Metal carbonyl 18-electron complexes is sometimes catalysed by catalytic amounts of oxidants, via electron-transfer. Metal carbonyls react with reducing agents such as metallic sodium or sodium amalgam to give carbonylmetalate (or carbonylate) anions: For iron pentacarbonyl, one obtains the tetracarbonylferrate with loss of CO: Mercury can insert into the metal-metal bonds of some polynuclear metal carbonyls: The CO ligand is often susceptible to attack by nucleophiles. For example, trimethylamine oxide and bistrimethylsilylamide convert CO ligands to CO and CN, respectively. In the "Hieber base reaction", hydroxide ion attacks the CO ligand to give a metallacarboxylic acid, followed by the release of carbon
Mercury(II) bromide Mercury(II) bromide Mercury(II) bromide or mercuric bromide is the chemical compound composed of mercury and bromine with the formula HgBr. This white crystalline solid is a laboratory reagent. Like mercury(II) chloride, it is extremely toxic. Mercury(II) bromide can be manufactured by: adding potassium bromide to a solution of mercuric salt and crystallizing; by precipitation using a mercury(II) nitrate and sodium bromide solution; by dissolving mercury(II) oxide in hydrobromic acid. Also, Mercury(II) bromide can be created by reacting mercury with bromine. Mercury(II) bromide is used as a reagent in the Koenigs–Knorr reaction, which forms glycoside linkages on carbohydrates. It is also