Phenyl-functionalized diiron dithiolate complexes with one bidentate or two unidentate phosphine-containing ligands

Abstract

Treatment of diiron dithiolate complex, [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₆ (A), with one equivalent of bidentate phosphine-containing ligand N,N-bis(diphenylphosphine)butanamine [(Ph₂P)₂N-Bu-n] in refluxing xylene afforded the diphosphine-bridged complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄[(μ-PPh₂)₂N-Bu-n] (1) in high yield, while reaction of A with two equivalents of triphenylphosphine (PPh₃) in the presence of decarbonylating agent Me₃NO yielded the disubstituted complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(PPh₃)₂ (2) in low yield. Both complexes were characterized by spectroscopic methods and X-ray crystallography. In the solid state, two phosphines of (PPh₂)₂N-Bu-n bridge the two irons with cis basal-basal conformation, while PPh₃ occupies an apical position of the square pyramidal geometries of each iron. The influence of coordination manner on the electrochemical properties of both complexes was investigated by cyclic voltammetry.

Keywords:

• [FeFe]-Hydrogenase
• Diiron dithiolate complex
• Phosphine ligand
• Crystal structure
• Electrochemistry

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ Because (PPh₂)₂-N-Bu-n and bis(diphenylphosphine)methane have a similar backbone, we consider the Tolman cone angle of the former is close to that of the latter (121°) [34].