97690-08-9Relevant academic research and scientific papers
Binuclear diphosphine-bridged iridium complexes as models for the catalytic hydrogenation of alkynes in the presence of two metal centers. The structure of [Ir2Cl2(CH3O2CC=CHCO 2CH3)2(CO)2(DPM)2], a product of alkyne insertions into two Ir-H bonds
Sutherland, Bruce R.,Cowie, Martin
, p. 1801 - 1810 (2008/10/08)
The reactions of trans-[IrCl(CO)(DPM)]2 (1) and [Ir2(CO)2(μ-Cl)(DPM)2][BF4] (2) (DPM = bis(diphenylphosphino)methane) with H2 and the subsequent reactions of the dihydride products with dimethyl acetylenedicarboxylate (DMA) are reported. Compound 1 reacts with H2 yielding [Ir2(H)2Cl2(CO)2(DPM)2] (3) in which the hydrido ligands are mutually cis on adjacent metals. This product reacts with 1 equiv of DMA to give [Ir2HCl2(CH3O2CC=CHCO 2CH3)(CO)2] (6) in which alkyne insertion into only one of the Ir-H bonds has occurred. Reaction of 2 with H2 yields [Ir2(H)4Cl(CO)2(DPM)2][BF 4] (4), and H2 loss from this tetrahydride species yields [Ir2(H)2(CO)2(μ-Cl)(DPM) 2][BF4] (5), in which the two hydride ligands do not seem to be mutually cis. Compound 5 can also be generated from 3 by chloride ion abstraction using AgBF4. Compound 5 reacts with a twofold excess of DMA in CH2Cl2 to yield [Ir2Cl2(CH3O2CC= CHCO2CH3)2(CO)2(DPM)2] (7) as the major product. Alkyne insertion into both Ir-H bonds has occurred, and the additional chloride ion seems to come from the solvent. Compound 7 crystallizes in the space group P1 with a= 15.978 (2) A?, b = 20.460 (5) A?, c = 21.494 (2) A?, α = 107.86 (2)°, β = 90.46 (2)°, γ = 106.17 (2)°, and Z = 4. The structure, which confirms that alkyne insertion into each of the Ir-H bonds of the precursor has occurred, has refined to R = 0.061 and Rw = 0.090 based on 11275 observations and 545 parameters varied.
