Facile carbon-carbon bond formation and multiple carbon-hydrogen bond activations promoted by methylene-bridged iridium/ruthenium complexes

摘要

The methylene-bridged complex [IrRu(CO)_4(μ-CH _2)-(dppm)_2][BF_4] (1; dppm = μ-Ph _2PCH_2PPh_2) reacts with 1,1-dimethylallene nd 1,2-butadiene, resulting in coupling of the cumulene and the ridging methylene group, yielding the complexes [IrRu(CO)_4(k~1:k ~1-Me_2CdCCH_2CH_2)(dppm) _2][BF_4] (2) and [IrRu(CO)_4(k~1:k ~1-MeCHd CH_2CH_2)(dppm)_2][BF _4] (3), respectively, in which the resulting hydrocarbyl fragment is chelating on iridium. Reaction of 1 with 1,1-difluoroallene initially yields the analogous insertion product [IrRu(CO)_4(k~1:k ~1-F_2Cd CCH_2CH_2)(dppm) _2][BF_4] (6), which slowly converts to [IrRu(CO) _(3-)(k~1:k~(1-)F_2CdCCH_2CH _2CO)(dppm)2][BF4] (7) by carbonyl migratory insertion. Reaction of 1 with propadiene leads to the elimination of 1,3-butadiene and the formation of [IrRu(CO)4(dppm)2][BF4]. In the presence of excess 1,1-dimethylallene, compound 2 reacts further via multiple C-H bond activations to yield [IrRu(CO) _3(k~(1-)C(CH_2CH_3)dC(CH _3)_2)(μ-k~1:η~2-CtCC(CH _3)dCH_2)(dppm)_2][BF4] (8) with the elimination of H_2, together with [IrRu(CO)_3(k~(1-)C(CH _2CH_3)dC(CH_3)_2)(μ-k ~1:η~2-CtCCH(CH_3)_2)(dppm) _2][BF_4] (9). Complex 2 also reacts with propadiene to generate [IrRu(CO)_3(k1-C(CH_2CH_3)dC(CH _3)_2)(μ-k~1:η~(2-)CtCCH _3)(dppm)2][BF4] (10) and with 1,2-butadiene to yield [IrRu(CO) _3(k~(1-)C(CH_2CH_3)dC(CH _3)2)(μ-k~1:η~(2-)CtCCH_2CH _3)(dppm)_2][BF_4] (11) and [IrRu-(CO) _3(k~(1-)C(CH_2CH_3)dC(CH _3)2)(μ-k~1:η~(2-)CtCCHdCH _2)(dppm)_2][BF_4] (12).