1263205-36-2Relevant academic research and scientific papers
Alkyne/methylene coupling at adjacent iridium/osmium centers: Facile carbon-carbon and carbon-oxygen bond formation
MacDougall, Tiffany J.,Llamazares, Angela,Kuhnert, Oliver,Ferguson, Michael J.,McDonald, Robert,Cowie, Martin
, p. 952 - 964 (2011)
The methylene-bridged complex [IrOs(CO)4(μ-CH 2)(dppm)2][CF3SO3] (dppm = μ-Ph2PCH2PPh2) (3) can be synthesized by the addition of diazomethane to [IrOs(CO)5(dppm)2][CF 3SO3] (1) or [IrOs(CO)4(dppm) 2][CF3SO3] (2). Reaction of 3 with dimethyl acetylenedicarboxylate (DMAD) leads to the insertion of the alkyne into the iridium-carbon bond, yielding both [IrOs(CO)4(μ- κ1:κ1-C(CO2CH3)= C(CO2CH3)CH2)(dppm)2][CF 3SO3] (5) and [IrOs(CO)3(μ- κ1:κ1-C(CO2CH3)= C(CO2CH3)CH2)(dppm)2][CF 3SO3] (6), each of which can be obtained as the exclusive product under either CO or an Ar purge, respectively. Hexafluorobutyne (HFB) fails to react with 3, but reacts with [IrOs(CO)3(μ-CH 2)(dppm)2][CF3SO3] (4) yielding [IrOs(CO)3(μ-κ1:κ1-C(CF 3)=C(CF3)CH2)(dppm)2][CF 3SO3] (7). Reaction of 7 with diazomethane results in the insertion of a second methylene unit into the iridium-carbon bond, yielding [IrOs(CO)3(μ-κ1:κ1-CH 2(CF3)C=C(CF3)CH2)(dppm) 2][CF3SO3] (9), which can be characterized by NMR spectroscopy only at low temperatures owing to deinsertion of the iridium-bound methylene group at ambient temperature. Compound 6 also reacts with diazomethane but in this case results in the formation of a new carbon-oxygen bond between the newly introduced methylene unit and a carbonyl oxygen of the inserted DMAD fragment. This bond formation is accompanied by carbon-hydrogen bond activation of the original osmium-bound methylene group, yielding [IrOs(CO)3(μ-H)(μ-κ1: κ1:κ1-CH2OC(OCH3)= CC(CO2CH3)=CH)(dppm)2][CF3SO 3] (8). Attempts to insert a methylene unit into the iridium-carbon bond of the alkyne-bridged complexes [IrOs(CO)3(μ- κ1:κ1-RC=CR)(dppm)2][CF 3SO3] (R = CO2Me (12), CF3 (13)) yields the C3-bridged complex [IrOs(CO)3(μ- κ1:κ1-CH2(CF3)C=CCF 3)(dppm)2][CF3SO3] (14) in the case of 13, but no further methylene incorporation is observed. Compound 12 reacts with diazomethane to give a number of unidentified products under a variety of conditions. The reactivities of the aforementioned complexes are compared to that of related late metal combinations.
