Alkyne/Methylene Coupling Reactions at Adjacent Rh/Os Centers: Stepwise Transformations from C1- through C4-Bridged Species
| Autor: | Michael J. Ferguson, Amala Chokshi, Martin R. Cowie, Robert McDonald, James R. Wigginton, Todd W. Graham |
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| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | Organometallics. 24:6398-6410 |
| ISSN: | 1520-6041 0276-7333 |
| Popis: | Reaction of the methylene-bridged complex [RhOs(CO)3(μ-CH2)(dppm)2][CF3SO3] (dppm = μ-Ph2PCH2PPh2) with dimethyl acetylenedicarboxylate or hexafluorobutyne results in alkyne insertion into the Rh−CH2 bond, yielding [RhOs(CO)3(μ-η1:η1-RCC(R)CH2)(dppm)2][CF3SO3] (R = CO2Me (5), CF3 (6)). Carbonyl removal from each of these species results in a Rh-bound carbonyl being replaced by a triflate ion. Reaction of 5 with diazomethane results in CH2 insertion into the Rh−C(R) bond with accompanying C−H activation of the original osmium-bound CH2 group, yielding [RhOs(CO)3(μ-η1:η1-CH2C(R)C(R)CH)(μ-H)(dppm)2][CF3SO3] (R = CO2Me). Reaction of the alkyne-bridged species [RhOs(CO)3(μ-η1:η1-RCCR)(dppm)2][CF3SO3] (R = CO2Me) with diazomethane at −78 °C yields [RhOs(CO)3(μ-η1:η1-CH2C(R)CR)(dppm)2][CF3SO3] (12), which upon warming to ambient temperature, in the absence of diazomethane, undergoes alkyne deinsertion to yield [RhOs(CO)3(η2-RC⋮CR)(μ-CH2)(dppm)2][CF3SO3] (13). This species and the inserted product (12) appear to ... |
| Databáze: | OpenAIRE |
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