Spectroscopic and theoretical studies on a three-iron cluster with linear arrangement

The linear trinuclear iron complex Fe₃(SPh)₆(CO)₆ with bridging benzenethiolate ligands is the subject of temperature- and field-dependent Mössbauer studies. The results reveal the two terminal iron atoms to be diamagnetic (Fe(II) and the central iron atom to be high-spin Fe(II). The magnetic Mössbauer pattern of the latter is dominated by a positive (!) internal field. Complementary to the experimental studies, also theoretical studies are performed. Local density molecular orbital and ligand-field calculations yield an orbitally degenerate ground state that accounts for the unusual electronic and spectroscopic properties.