Rapid, Covalent Addition of Phosphine to Dithiolene in a Molybdenum Tris(dithiolene). A New Structural Model for Dimethyl Sulfoxide Reductase

Triphenylphosphine (PPh3) rapidly and reversibly adds to the bdt ligand in the molybdenum tris­(dithiolene) complex Mo­(tfd)2(bdt) [tfd = S2C2(CF3)2; bdt = S2C6H4], turning chelating bdt into the monodentate zwitterionic ligand SC6H4SPPh3. A second PPh3 molecule fills the newly created open site in the crystallographically characterized product Mo­(tfd)2(SC6H4SPPh3)­(PPh3), which is a structural model for dimethyl sulfoxide (DMSO) reductase. While the complex is only a precatalyst for reduction of DMSO by PPh3 (the initially low catalytic rate increases with time), Mo­(tfd)2(SMe2)2 was found to be catalytically active without an induction period.