Redox-Active Dithiafulvenyldiphenylphosphine as a Mono- or Bidentate Ligand: Intramolecular Coupling Reaction in the Coordination Sphere of a Metal Carbonyl Fragment

The coordinating ability of dithiafulvenyldiphenylphosphine (P-DTF) has been investigated with cis-W(CO)4(piperi-dine)2. As shown by the metal carbonyl complexes obtained, this redox-active vinylphosphine can act as a monodentate (P) and as a bidentate (P,S) ligand. Oxidation of cis-M(CO)4(P-DTF)2, M = Mo and W, leads to the carbon−carbon bond formation between the two coordinated dithiafulvenyldiphenylphosphines. This chemical coupling of the dithiafulvenyl cores in the coordination sphere of M(CO)4 (M = Mo, W) fragment has been studied in the presence of various oxidizing agents. The use of (BrC6H4)3NSbCl6 or AgBF4 induces the formation of a five-membered metallacycle with a vinylogous TTF backbone while DDQ leads to a six-membered metallacycle. The syntheses, crystal structures, and electrochemical properties of the complexes obtained are described.