METAL-ASSISTED CLEAVAGE OF A C-O BOND OF A P-BOUND BIFUNCTIONAL PHOSPHINE LIGAND

Treatment of [IrCl(C2H4)2]2 (1) with the phosphino ester iPr2PCH2CO2Me affords the mononuclear complex trans-[IrCl(C2H4)(Ipr2pch2co2me-kappa P2] (2), which reacts with CO to give trans-[IrCl(CO)(Ipr2pch2co2me-ka ppaP2] (3) and with HC=CR to give l-(Ipr2pch2co2me-kappaP)(Ipr2pch2co2 me-kappa2P,O)] (R = Ph (4), CO2Me (5)). Upon heating, the alkynylhydri doiridium compounds 4 and 5 rearrange to yield the isomeric vinylidene metal derivatives trans-[IrCl(=C=CHR) (Ipr2pch2co2me-kappaP)2] (R = Ph (6), CO2Me (7)). Reaction of 3, 6, and 7 with Al2O3/H2O leads to clea vage of a CH3-O bond of one phosphino ester ligand and gives the chela te complexes r(L)(Ipr2pch2co2me-kappaP)(iPr2PCH2CO2-kappa2P,O)] (L = C O (8), C=CHPh (9), C=CHCO2Me (10)) in 80-90 % yield. Compound 8 reacts with methyl iodide by oxidative addition to form the octahedral compl ex CO)(Ipr2pch2co2me-kappaP)-(Ipr2pch2co2-kappa2P,O)] (11). The X-ray crystal structure of 8 has been determined (triclinic, space group P1B AR (No. 2), with a = 9.124(5) angstrom, b = 11.301(7) angstrom, c = 12 .126(6) angstrom, alpha = 79.34(4)degrees, beta = 78.92(4)degrees, gam ma = 71.56(5)degrees, and Z = 2).