Iron carbonyl, $\mathrm{Fe}{\left(\mathrm{CO}\right)}_5$ is

• The phosphate is thought to reside centre of the structure, with Fe²⁺ and CO groups coordinated to it. Iron also forms a number of coordination complexes with CO
• Iron pentacarbonyl Fe(CO)₅. 

This ion is often called "carbonyl iron" to distinguish it from iron carbonyl, a gas that is the mixture of Fe(CO)₅ and CO.

Like other iron carboxylate complexes, iron pentacarbonyl dissolves in nonpolar solvents such as benzene, to give deep red solutions characterized by high spin low-spin mixed valence bonding.