A sulfur mimic of 1,1-bis(diphenylphosphino)methane: a new ligand opens up.

A simple method for synthesizing diphosphine monosulfide species was developed utilizing lithium sulfide and chlorophosphine starting materials. This afforded 1,1,2,2-tetraphenyldiphosphine monosulfide (1), as well as 1,1,2,2-tetracyclohexyldiphosphine monosulfide (2), which could be used as convenient ligand precursors. Upon addition of 1 or 2 to the ruthenium compound Ru(C5Me5)(cod)Cl, the diphosphine monosulfides rearranged to give bidentate bis(ditertiaryphosphino)thioether ligands in Ru(C5Me5)(PPh2SPPh2)Cl (3) and Ru(C5Me5)(PCy2SPCy2)Cl (4).