metal carbonyl anion

Metal carbonyl anions are formed when neutral metal carbonyl compounds are reduced, resulting in the metal having a negative oxidation state. These anions are significant because they stabilize electron-rich metal complexes through back π bonding, where electron density shifts from the metal to the carbonyl ligands. This process is supported by physical data and influences the bond distances within the carbonyl group.1

Metal carbonyl anions are highly reactive and serve as valuable starting materials for synthesizing other organometallic compounds, finding applications in organic synthesis. For instance, they can be protonated, with the hydrogen ion typically attaching to the central metal atom. Their utility extends to reactions that extend carbon chains, leading to the production of aldehydes, ketones, or carboxylic acids.1