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(iPr2PS)2] have been synthesized and their oxidative addition of methyl iodide investigated. Treatment of [Rh(PPh3)3Cl] with K[N(iPr2PS)2] afforded [Rh{N(iPr2PS)2}(PPh3)2] (1). Recrystallization of 1 from hexane in the presence of adventitious oxygen yielded the peroxo complex [Rh{N(iPr2PS)2}(PPh3)22-O2)] (2). Oxidative addition of methyl iodide to 1 gave [Rh(Me)(I){N(iPr2PS)2}(PPh3)2] (3), which reacted with K[N(iPr2PS)2] to afford [Rh(Me){N(iPr2PS)2}2] (4). Treatment of K[N(iPr2PS)2] with [Rh(coe)2Cl]2 (coe = cyclooctene) yielded the tetranuclear sulfido cluster [Rh43-S)2{iPr2PNP(S)iPr2}2{N(iPr2PS)2}2] (5) containing two four-coordinate RhI and two five-coordinate RhIII centers. Oxidative addition of methyl iodide to 5 gave the monomethyl compound [Rh43-S)2(Me)(μ-I){iPr2PNP(S)iPr2}2{N(iPr2PS)2}2] (6). In benzene solution, 6 underwent spontaneous reductive elimination of methyl iodide to give 5. The crystal structures of complexes 26 have been determined.