Addition of H2SiPh2 to Ir(acac)(.eta.2-CH3O2C-C.tplbond.C-CO2CH3)(PR3): Synthesis and Characterization of [cyclic] Ir(acac){C[CH(OCH3)OSiPh2]:CHCO2CH3}(PR3) (R = CHMe2, cyclohexyl)

Abstract

The complexes Ir(acac)(cyclooctene)(PR3) (PR3 = PiPr3 (2), PCy3 (3)), which are prepared by reaction of Ir(acac)(cyclooctene)2 (1) with the corresponding phosphine, react with carbon monoxide and acetylenedicarboxylic methyl ester to give Ir(acac)(CO)(PR3) (PR3 = PiPr3 (4), PCy3 (5)) and Ir(acac)(η2-CH3O2C-C≡C-CO 2CH3)(PR3) (PR3 = PiPr3 (6), PCy3 (7)). The reactions of 6 and 7 with H2SiPh2 afford Ir(acac){C[CH(OCH3)OSiPh2]=CHCO2CH 3}(PR3) (PR3 = PiPr3 (8), PCy3 (9)). The X-ray crystal structure analysis of 9 (monoclinic, space group P21/c with a = 21.408(1) Å, b = 10.246(1) Å, c = 18.983(1) Å, and β = 106.89(1)°) 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. © 1995 American Chemical Society.