Influence of Tertiary Phosphanes on the Coordination Configurations and Electrochemical Properties of Iron Hydrogenase Model Complexes: Crystal Structures of [(μ‐S 2 C 3 H 6 )Fe 2 (CO) 6– n L n ] (L = PMe 2 Ph, n = 1, 2; PPh 3 , P(OEt) 3 , n = 1)

A series of mono‐ and disubstituted diiron complexes [(μ‐pdt)Fe 2 (CO) 5 L] [pdt = 1,3‐propanedithiolato; L = PMe 3 ( 2 ), PMe 2 Ph ( 3 PPh 3 ( 4 ), P(OEt) 3 ( 5 )] and [(μ‐pdt)Fe 2 (CO) 4 L 2 ] [L = PMe 2 Ph ( 6 ), PPh 3 ( 7 ), P(OEt) 3 ( 8 )] were prepared as Fe‐only hydrogenase‐active‐site models by controllable CO displacement of [(μ‐pdt)Fe 2 (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)