A Ferrocene‐Based Dicationic Iron(IV) Carbonyl Complex

Abstract

Abstract The 16‐valence electron species [Cp* 2 Fe] 2+ (Cp*=η‐C 5 Me 5 ), formally featuring a tetravalent iron ion, quantitatively binds CO in HF solution to form the stable, diamagnetic carbonyl species [Cp* 2 Fe(CO)] 2+ . This dication forms salts in the presence of AsF 6 − and SbF 6 − that were crystallographically characterized. The molecular structure in crystals of [Cp* 2 Fe(CO)](AsF 6 ) 2 displays cyclopentadienyl rings that are clearly not parallel and an equatorially bound η 1 ‐CO ligand. The formal oxidation state +IV of iron was investigated by 57 Fe Mössbauer spectroscopy and is supported by DFT computational analysis. A detailed spectroscopic characterization of the hitherto unprecedented high‐valent iron carbonyl compounds is reported.