Mixed bis(μ-silylene) and (μ-silylene)/(μ-germylene) complexes involving the Rh/Ir metal combination: Nature of the Si?Si interactions in the bis(μ-silylene) species

摘要

A series of mixed bis(μ-silylene) complexes of rhodium and iridium [RhIr(CO) _2(μ-SiHR)(μ-SiR ~1R ~2)(dppm) _2] (R = R ~1 = R ~2 = Ph (4); R = R ~1 = Ph, R ~2 = Cl (5); R = R ~1 = Ph, R ~2 = Me (6); R = _3,5-C _6H _3F _2, R ~1 = Ph, R ~2 = Me (7); R = _3,5-C _6H _3F _2, R ~1 = _2,4,6-C _6H _2Me _3, R ~2 = H (8)) have been synthesized by the reaction of the silylene-bridged dihydride complexes, [RhIr(H) _2(CO) _2(μ-SiHR)(dppm) _2] (1, R = Ph; _2, R = C _6H _3F _2), with a number of secondary or primary silanes (Ph _2SiH _2, PhClSiH _2, PhMeSiH _2, C _6H _2Me _3SiH _3). The influence of substituents and π-stacking interactions on the Si?Si distance (determined by X-ray crystallography) in this series and the implications regarding the nature of the Si?Si interactions are discussed. A series of novel (μ-silylene)/(μ-germylene) complexes, [RhIr(CO) _2(μ-SiHPh)(μ-GePh _2)(dppm) _2] (9) and [RhIr(CO) _2(μ-SiR ~1R ~2)(μ-GeHPh)(dppm) _2] (R ~1 = Ph, R ~2 = H (11); R ~1 = R ~2 = Ph (12); R ~1 = Ph, R ~2 = Me (13)), have also been synthesized by reaction of the silylene-bridged dihydride complex, [RhIr(H) _2(CO) _2(μ-SiHPh)(dppm) _2] (1), with 1 equiv of diphenylgermane and by reaction of the germylene-bridged dihydride complex, [RhIr(H) _2(CO) _2(μ-GeHPh)(dppm) _2] (3), with 1 equiv of the respective silanes. These complexes have been characterized by multinuclear NMR spectroscopy and X-ray crystallography.