These compounds are intermediates in reactions that involve carbon monoxide and carbon dioxide, these species are intermediates in the water gas shift reaction.
[1] Metallacarboxylic acids mainly arise by the attack of hydroxide on electrophilic metal carbonyl complexes.
An illustrative synthesis is the reaction of a cationic iron carbonyl with a stoichiometric amount of base:[2] When applied to simple metal carbonyls, this kind of conversion is sometimes called the Hieber base reaction.
[3] Metallacarboxylic acids exist in equilibria with the carboxylate anions, LnMCO2−.
Metallacarboxylate esters (LnMCO2R) arise by the addition of alkoxide to metal carbonyl: Metallacarboxylic amides (LnMC(O)NR2) arise by the addition of amide to metal carbonyl: Derivatives of metalladithiacarboxylic acids are also known.