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( i Pr 2 PS) 2 ] – have been synthesized and their oxidative addition of methyl iodide investigated. Treatment of [Rh(PPh 3 ) 3 Cl] with K[N( i Pr 2 PS) 2 ] afforded [Rh{N( i Pr 2 PS) 2 }(PPh 3 ) 2 ] ( 1 ). Recrystallization of 1 from hexane in the presence of adventitious oxygen yielded the peroxo complex [Rh{N( i Pr 2 PS) 2 }(PPh 3 ) 2 (η 2 ‐O 2 )] ( 2 ). Oxidative addition of methyl iodide to 1 gave [Rh(Me)(I){N( i Pr 2 PS) 2 }(PPh 3 ) 2 ] ( 3 ), which reacted with K[N( i Pr 2 PS) 2 ] to afford [Rh(Me){N( i Pr 2 PS) 2 } 2 ] ( 4 ). Treatment of K[N( i Pr 2 PS) 2 ] with [Rh(coe) 2 Cl] 2 (coe = cyclooctene) yielded the tetranuclear sulfido cluster [Rh 4 (μ 3 ‐S) 2 { i Pr 2 PNP(S) i Pr 2 } 2 {N( i Pr 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 (μ 3 ‐S) 2 (Me)(μ‐I){ i Pr 2 PNP(S) i Pr 2 } 2 {N( i Pr 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.