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) nitrate made by reacting hot concentrated nitric acid with mercury metal, under these conditions, the nitric acid is an oxidizing agent. Dilute nitric acid would produce mercury(I) nitrate. Mercuric nitrate is used in mercuration reactions. In particular, it is used in reactions involving ketones. One of the chemicals which it is most effective with is acetone. This reaction uses mercuric nitrate, mercuric oxide, and calcium sulfate to change acetone, which is CHC(O)CH, into CHC(O)CHHg. Acetone is a compound for which most other methods of mercuration prove ineffective. The mercuric nitrate compound works because it is a strong oxidizing agent. In addition,