Iron nonacarbonyl (Fe2​(CO)9​) is a chemical compound that belongs to the family of metal carbonyl complexes. It consists of iron (Fe) atoms bonded to nine carbon monoxide (CO) ligands. Iron nonacarbonyl is an example of a metal carbonyl compound, where metal atoms are coordinated with carbon monoxide molecules.

Here are some key points about iron nonacarbonyl:

1. Structure: Iron nonacarbonyl consists of two iron atoms (Fe2​) at its core, with each iron atom bonded to nine carbon monoxide (CO) ligands, resulting in a total of nine CO ligands.
2. Synthesis: Iron nonacarbonyl is typically prepared by reacting iron pentacarbonyl (Fe(CO)5​) with carbon monoxide gas under controlled conditions. The reaction leads to the replacement of one CO ligand in each iron pentacarbonyl molecule, forming the nonacarbonyl complex.
3. Properties: Iron nonacarbonyl is a volatile and air-sensitive compound. It is known for its distinct reddish-orange color. It is used as a source of carbon monoxide in various chemical reactions and as a precursor to other iron carbonyl compounds.
4. Applications: Iron nonacarbonyl is used as a source of pure carbon monoxide gas in industrial processes and laboratory settings. It can also serve as a starting material for the synthesis of other metal carbonyl complexes.
5. Reactivity: The CO ligands in iron nonacarbonyl can be displaced by other ligands in reactions, leading to the formation of new metal carbonyl complexes.
6. Toxicity and Handling: Iron nonacarbonyl is highly toxic and poses significant health risks if not handled properly. It is also sensitive to air and moisture, so it requires careful handling under controlled conditions.

As with all chemical compounds, safety precautions should be followed when working with iron nonacarbonyl or any other substances.