Ruthenium-assisted insertion of isothiocyanates into the silicon-sulfur bond: A comparative study on the reactivity of the S-Si and S-H bonds in CpRu(PPh3)(2)SX (X = H, (SiPr3)-Pr-i) complexes

CpRu(PPh3)(2)(SSiPr3)-Pr-i (1) and CpRu(PPh3)(2)SH (2) reacted with phenyl, p-tolyl, and 1-naphthyl isothiocyanates, as well as with 1,4-phenylene dii sothiocyanate, to give the corresponding kappa S-2,S-dithiocarbamato comple xes, CpRu(PPh3)(S2CNRR2)-R-1 (R-1 = Si(i)Prs, R-2 = Ph (3a), p-Tol (3b), 1- Naphth (3c); R-1 = H, R-2 = Ph (3d), 1-Naphth (3e)) and 1,4-[CpRu(PPh3)S2CN R](2)C6H4 (R = (SiPr3)-Pr-i (4a), H (4b)), the result of insertion of the i sothiocyanates into the S-Si and S-H bonds, respectively. The reactions of 1 proceed via precoordination of the isothiocyanates to the ruthenium atom, followed by the formation of N-silyl kappa S-2,S-dithiocarbamates. The rea ctions of 2, at least in part, involve direct nucleophilic addition of the S-H bond to the isothiocyanates via kappa S-1-dithiocarbamato intermediates . Accordingly, CpRu(dppe)(SSiPr3)-Pr-i, where ligand exchange does not occu r, did not react, but CpRu(dppe)SH reacted with phenyl and 1-naphthyl isoth iocyanate to give the corresponding kappa S-1-dithiocarbamato complexes, Cp Ru(dppe)SC(S)NHR (R = Ph (9a), 1-Naphth (9b)), the reaction with 1-naphthyl isothiocyanate being reversible. The crystal structures of sc and 4a have been determined by X-ray diffraction.