Synthesis and electrochemistry of phenyl-functionalized diiron propanedithiolate complexes with bidentate phosphine ligands

Carbonyl substitution reactions of [μ-(SCH2)2CHC6H5]Fe2(CO)6 with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph2P)2N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH2)2CHC6H5]Fe2(CO)4(k2-dppv) and a symmetrically substituted bridging complex [(μ-SCH2)2CHC6H5]Fe2(CO)4[μ-(PPh2)2N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH2)2CHC6H5]Fe2(CO)4(k2-dppv) was investigated.