Oxidative Addition of Rhodium Complexes Containing a Dithioimidodiphosphinate Ligand: Facile Reductive Elimination of Methyl Iodide from a Tetranuclear Rhodium Sulfido Cluster

Rhodium complexes containing the dithioimidodiphosphinate ligand [N(iPr(2)PS)(2)](-) have been synthesized and their oxidative addition of methyl iodide investigated. Treatment of [Rh(PPh3)(3)Cl] with K[N(iPr(2)PS)(2)] afforded [Rh{N(iPr(2)PS)(2)}-(PPh3)(2)] (1). Recrystallization of 1 from hexane in the presence of adventitious oxygen yielded the peroxo complex [Rh{ N(iPr(2)PS)(2)}(PPh3)(2)(eta(2)-O-2)] (2). Oxidative addition of methyl iodide to 1 gave [Rh(Me)(I){N(iPr(2)PS)(2)}(PPh3)(2)] (3), which reacted with K[N(iPr(2)PS)(2)] to afford [Rh(Me){N(iPr(2)PS)(2)}(2)] (4). Treatment of K[N(iPr(2)PS)(2)] with [Rh(coe)(2)Cl](2) (coe = cyclooctene) yielded the tetranuclear sulfido cluster [Rh-4(mu(3)-S)(2){iPr(2)PNP(S)iPr(2)}(2){N(iPr(2)PS)(2)}(2)] (5) containing two four-coordinate Rh-I and two five-coordinate Rh-III centers. Oxidative addition of methyl iodide to 5 gave the monomethyl compound [Rh-4(mu(3)-S)(2)(Me)(mu-I){iPr(2)PNP(S)iPr(2)}(2){N(iPr(2)PS)(2)} (2)] (6). In benzene solution, 6 underwent spontaneous reductive elimination of methyl iodide to give 5. The crystal structures of complexes 2-6 have been determined