Assignment of the Vibrational Spectra of Diiron Nonacarbonyl, Fe₂(CO)₉

Abstract

Diiron nonacarbonyl, Fe2(CO)9, was discovered in 1905 and was the third metal carbonyl to be found. It was the first to be synthesized by a photochemical route. This is a challenging material to study: it is insoluble in virtually all solvents and decomposes at 373 K before melting. This means that only solid-state spectroscopic data are available. New infrared, Raman and inelastic neutron scattering (INS) spectra have been measured and used to generate a complete assignment of the vibrational spectra of Fe2(CO)9. Density functional theory (DFT) calculations are used to support the assignments; however, for this material, they are much less useful than expected, although the calculated intensities provide crucial information.

Keywords

• diiron nonacarbonyl
• inelastic neutron scattering spectroscopy
• infrared spectroscopy
• Raman spectroscopy
• density functional theory