Influence of Tertiary Phosphanes on the Coordination Configurations and Electrochemical Properties of Iron Hydrogenase Model Complexes: Crystal Structures of [(μ‐S2C3H6)Fe2(CO)6–nLn] (L = PMe2Ph, n = 1, 2; PPh3, P(OEt)3, n = 1)

A series of mono‐ and disubstituted diiron complexes [(μ‐pdt)Fe2(CO)5L] [pdt = 1,3‐propanedithiolato; L = PMe3 (2), PMe2Ph (3PPh3 (4), P(OEt)3 (5)] and [(μ‐pdt)Fe2(CO)4L2] [L = PMe2Ph (6), PPh3 (7), P(OEt)3 (8)] were prepared as Fe‐only hydrogenase‐active‐site models by controllable CO displacement of [(μ‐pdt)Fe2(CO)6] by tertiary phosphanes. The coordination configurations of 3–6 were characterized by X‐ray crystallography. Disubstituted diiron complex 6 features an apical/apical coordination mode, instead of the typical transoid basal/basal configuration. The electrochemistry of 2–6 and 8 was studied by cyclic voltammetry to evaluate the effects of different tertiary phosphane ligands on the redox properties of the iron atoms of model complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)