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
Wurtz reaction reaction occurs through a free radical mechanism. The reaction consists of a halogen-metal exchange involving the radical species R• (in a similar fashion to the formation of a Grignard reagent) with carbon–carbon bond formation occurring in a nucleophilic substitution reaction. One electron from the metal is transferred to the halogen to produce a metal halide and an alkyl radical. The alkyl radical then accepts an electron from another metal atom to form an alkyl anion. This intermediate has been isolated in several cases. The nucleophilic carbon of the alkyl anion then displaces the halide in an S2 reaction, forming a