STABILIZATION OF IRIDIUM(I), IRIDIUM(III), AND IRIDIUM(V) IN AN OXYGEN-DONOR LIGAND ENVIRONMENT AND THE SELECTIVE DEHYDROGENATIVE SILYLATION AND HYDROSILYLATION OF ETHYLENE WITH (C(PH2P=O)3)IR(OL)2

Ir(I),-(III), and -(V) can be stabilized in an O-donor ligand environment, as shown by the preparation of (triso)Ir(0l)2 (1; triso = tris(diphenyloxophosphoranyl)methanide; 0l = C2H4 (a), cyclooctene (coe) (b)), (triso)Ir(SiPh3)H(C2H4) (2), and (triso)Ir(H)2(SiPh2Me)2 (3a). 1a,b are selective catalysts for the dehydrogenative silylation and hydrosilylation of ethylene with triphenylsilane and diphenylmethylsilane. Complex 2 is a rare example of an alkene silyl hydride and is a proposed catalytic intermediate.