THERMAL-REACTIONS OF ALKYL(HYDRIDO)(HYDROSILYL)IRIDIUM(III) COMPLEXES- GENERATION OF A HYDRIDO(SILYLENE)IRIDIUM(I) SPECIES VIA THE REDUCTIVE ELIMINATION OF ALKANE AND 1,2-H-SHIFT FROM THE SILICON ATOM TO THE IR(I) METAL CENTER

Heating of alkyl(hydrido)(hydrosilyl)iridium(III) complexes LnIr(R)(H) [L-n = {eta(2)-MesHSi(CH2)(2)PPh2}(PMe3)(2), Mes = 2,4,6-C6H2Me3, R = Me, Et] led to the reductive elimination of alkane. Subsequently, the resulting hydrosilyliridium(I) intermediate LnIr (A) activated the in tramolecular carbon-hydrogen bond to give H){eta(3)-CH2C6H2(CH3)(2)SiH (CH2)(2)PPh2}PMe3)(2). In the presence of MeOH, A was quickly trapped with MeOH to give a methoxysilyliridium(III) complex Ir(H)(2){eta(2)-M es(MeO)Si(CH2)(2)PPh2}(PMe3)(2). This reactivity of A with MeOH clearl y supports the occurrence of a 1,2-H-shift from the silyl silicon atom to the iridium center to generate a hydrido(silylene)iridium(I) speci es Ir(H)[eta(2)-{= SiMes(CH2)(2)PPh2}](PMe3)(2). (C) 1998 Elsevier Sci ence S.A.