Multiple Pathways for the Oxygenation of a Ruthenium(II) Dithiocarbamate Complex:  S-Oxygenation and S-Extrusion

The reactions of Ru(bpy)2(N,N-dimethyldithiocarbamate)+, 1, with O-atom-transfer reagents such as hydrogen peroxide, m-chloroperoxybenzoic acid, and oxone have been studied and several resulting derivatives isolated and structurally characterized. Both S-oxygenation and S-extrusion may occur depending upon reagent and conditions. Excess peroxygenation leads to a stable dioxygenate, Ru(bpy)2(N,N-dimethylthiocarbamatesulfinate-S,S)+, 3. Stoichiometric oxygenation leads to mixtures of products from which two forms of monooxygenated species Ru(bpy)2(N,N-dimethylperoxydithiocarbamate-S,S), 2a, and Ru(bpy)2(N,N-dimethylperoxydithiocarbamate-O,S), 2b, and an S-extruded product, Ru(bpy)2(N,N-dimethylmonothiocarbamate)+, 4, have been isolated as PF6 - salts. The S,S-bound monooxygenate is unstable over time toward either O-atom-transfer reactions via disproportionation or reaction with phosphines or S-extrusion yielding complex 4 in which the thiocarbamate is bonded solely through the remaining S atom. All the complexes have been characterized by 1H NMR, UV−vis, and mass spectroscopies, and all but the highly reactive 2a structurally determined by X-ray crystallography.