Novel carbonyliridium and -rhodium complexes containing 2,6-bis[(4′S)-4′-isopropyloxazolin-2′-yl]pyridine (iPr-pybox) and 2,6-bis[(4′R)-4′-phenyloxazolin-2′-yl]pyridine (Ph-pybox) ligands

The iridium(i) complexes [Ir(CO)(kappa(3)-N,N,N-R-pybox)][PF6] [R-pybox = (S,S)-iPr-pybox (1), (R,R)-Ph-pybox (2)] have been prepared by reaction of their precursor complexes [Ir(eta(2)C(2)H(4))(2) (kappa(3)-N,N,N-R-pybox)][PF6] (R = iPr or Ph) with carbon monoxide. The analogous carbonylrhodium(i) complexes [Rh(CO)(kappa(3)-N,N,N-R-pybox)[PF6] [R-pybox = (S,S)-iPr-pybox (3), (R,R)-Ph-pybox (4)] have been synthesised by reaction of [Rh(mu-Cl)(eta(2)-C2H4)(2)](2), carbon monoxide, R-pybox and NaPF6. Complexes 1-4 undergo oxidative addition reactions with iodine and CH3I leading, with high stereoselectivity, to the complexes [Ml(X)(CO)(kappa(3)-N,N,N-R-pybox)][PF6] [M = Ir, R = iPr, X = 1 (5); M = Rh, R = iPr, X = 1 (6); M = Rh, R = Ph, X = I (7); M = Ir, R = iPr, X = CH3 (8); M = Ir, R Ph, X = CH3 (9); M = Rh, R = iPr, X = CH3 (10); M = Rh, R Ph, X = CH3 (11)]. The treatment of complexes 1 and 2 with HCl, allyl chloride or acyl chloride results, in most cases, in the stereoselective formation of the iridium((III)) complexes [IrHC1(CO)(kappa(3)-N,N,N-R-pybox)][PF6] [R = iPr (12), Ph (13)], [IrCI(eta(1)-CH2CH=CH2)(CO)(kappa(3)-N,N,N-R-pybox)][PF6] [R = iPr (14), Ph (15)] or [IrCl{eta(1)-C(O)CH3}(CO)(kappa(3)-N,N,N-R-pybox)][PF6] [R = iPr (16), Ph (17)], respectively. The structures of derivatives 10 and 15 have been determined by single-crystal X-ray diffraction analysis. The catalytic activity of monocarbonylrhodium(i) and -iridium(i) complexes 1 and 3 in the hydrosilylation and dehydrosilylation of acetophenone with diphenylsilane has also been examined.