Synthesis, Characterization, and Crystal Structure of Tertiary Phosphine-Substituted Diiron Propanedithiolate Complexes

As the active site models of [FeFe]-hydrogenase, two new tertiary phosphine-substituted diiron propanedithiolate complexes [(μ-PDT)Fe2(CO)5L] (PDT = SCH2CH2CH2S, L = P(PhMe-m)3, 1; PPh2(CH2CH2CH3), 2) have been prepared through carbonyl substitution reactions of parent complex [(μ-PDT)Fe2(CO)6] (A) with P(PhMe-m)3 or PPh2(CH2CH2CH3) in the presence of the decarbonylating agent Me3NO·2H2O in MeCN at room temperature. The new complexes 1 and 2 were fully characterized by elemental analysis, FT-IR, 1H, 13C{1H}, and 31P{1H} NMR spectroscopy, as well as for 1 by X-ray crystallography. In addition, the crystal structure of 1 has indicated that the phosphorus atom of the P(PhMe-m)3 ligand resides in an apical position of the pseudo-square-pyramidal geometry of the tertiary phosphine-coordinated Fe2 atom.