SPECTROSCOPIC AND THEORETICAL-STUDIES ON A 3-IRON CLUSTER WITH LINEARARRANGEMENT

The linear trinuclear iron complex Fe3(SPh)6(CO)6 with bridging benzen ethiolate ligands is the subject of temperature- and field-dependent M ossbauer studies and of temperature-dependent magnetic susceptibility studies. The results reveal the two terminal iron atoms to be diamagne tic Fe(II) and the central iron atom to be high-spin Fe(II). The latte r exhibits an enhanced effective magnetic moment compared to the (S = 2) spin-only value of 4.9 mu(B), and its magnetic Mossbauer pattern is dominated by a positive (!) internal field. Complementary to the expe rimental studies also theoretical studies are performed. Local density molecular orbital and ligand-field calculations yield an orbitally de generate ground state that accounts for the unusual electronic and spe ctroscopic properties. With these results inconsistencies in previousl y reported spectroscopic studies of Fe3(SPh)6 (CO)6 are resolved.