Benzenedithiolate-bridged MoFe complexes: structures, oxidation states, and reactivities

Abstract

Two benzendithiolate-bridged MoFe complexes, [(Me₃P)₂(CO)₂Mo(μ-S₂C₆H₄)Fe(CO)₃] (1) and [(Me₃P)(CO)₃Mo(μ-S₂C₆H₄)Fe(CO)₃] (2), were synthesized by reacting [Mo(S₂C₆H₄)(CO)₂(PMe₃)₂] (3) with Fe(CO)₅. Each complex has a direct Mo–Fe bond that is supported by a bridging benzenedithiolate ligand and a semi-bridging carbonyl ligand as elucidated by single-crystal X-ray diffractometry. The structural data and differences in reactivity of these complexes suggest that monophosphine complex 2 is formed via diphosphine complex 1. The reaction of 2 with PMe₃ gives the diiron bis(dithiolate) complex, [Fe(S₂C₆H₄)(CO)₂(PMe₃)]₂ (4), rather than 1. ⁵⁷Fe Mössbauer and X-ray photoelectron spectroscopy studies reveal the oxidation states of the metal centers in 2 to be Fe⁰ and Mo^II.