ADDITION OF H(2)SIPH(2) TO IR(ACAC)(ETA-2-CH3O2C-C-C-CO2CH3)(PR(3)) - SYNTHESIS AND CHARACTERIZATION OF IR(ACAC)(C[CH(OCH3)OSIPH(2)]=CHCO2CH3)(PR(3)) (PR(3)=PIPR(3), PCY(3))

The complexes Ir(acac)(cyclooctene)(PR(3)) (PR(3) = PiPr(3) (2), PCy(3) (3)), which are prepared by reaction of Ir(acac)(cyclooctene)(2) (1) with the corresponding phosphine, react with carbon monoxide End acetylenedicarboxylic methyl ester to give Ir(acac)(CO)(PR(3)) (PR(3) PiPr(3) (4), PCy(3) (5)) and Ir(acac)(eta(2)-CH3O2C-C drop C-CO2CH3)(PR3) (PR3 = PiPr(3) (6), PCy(3) (7)). The reactions of 6 and 7 with H(2)SiPh(2) afford Ir(acac){C[CH(OCH3)OSiPh(2)]=CHCO2CH3}(PR(3)) (PR(3) = PiPr(3) (8), PCy(3) (9)). The X-ray crystal structure analysis of 9 (monoclinic, space group P2(1)/c with a = 21.408(1) Angstrom, b = 10.246(1) Angstrom, c 18.983(1) Angstrom, and beta 106.89(1)degrees) reveals that the bonding situation in the Ir-Si-O sequence could be described as an intermediate state between metal-silylene stabilized by an oxygen base and a tetrahedral silicon.