Mild Oxidative Addition of C–H Bonds to a Hydrido‐Bridged Dinuclear Complex of Iridium(II) Induced by the Coordination of Heteroatomic Ligands

The oxidative addition of C–H bonds to a dinuclear complex of divalent iridium, [Cp*Ir(μ‐H)] 2 ( 1 ), has been investigated. Reactions of 1 with phosphorus compounds containing a phenyl ring (PR 1 R 2 Ph) at ambient temperature gave novel five‐membered diiridacyclic [(Cp*IrH) 2 (μ‐H)(μ‐R 1 R 2 PC 6 H 4 )] [R 1 = R 2 = Me ( 2a ); R 1 = Me, R 2 = Ph ( 2b ); R 1 = R 2 = Ph ( 2c ); R 1 = R 2 = OEt ( 2d ); and R 1 = OEt, R 2 = Ph ( 2e )] complexes through ortho ‐C–H activation of the phenyl ring bound to the phosphorus atom. The reaction of 1 with tripropylphosphane gave a new four‐membered diiridacyclic [(Cp*IrH) 2 (μ‐H)(μ‐Pr 2 PCHCH 2 CH 3 )] ( 3 ) complex in a similar manner. On the other hand, the reaction of 1 with triethyl phosphite gave a Cp*‐metalated product, [Ir(H)(P(OEt) 3 )(μ,η 5 ,η 1 ‐C 5 Me 4 CH 2 )(μ‐H)Ir(H)(Cp*)] ( 4 ), through C–H activation of a methyl group on one of the Cp* ligands. Furthermore, similar mild C–H activation reactions of 1 with sulfoxides have also been revealed. Thus, reactions of 1 with dimethyl sulfoxide and a couple of sulfoxides containing phenyl groups brought about the activation of the C–H bonds of a methyl group and a phenyl group to give [(Cp*IrH) 2 (μ‐H)(μ‐MeS(=O)CH 2 )] ( 5 ) and [(Cp*IrH) 2 (μ‐H)(μ‐RS(=O)C 6 H 4 )] [R = Me ( 6a ) and R = Ph ( 6b )], respectively. The structures of 2a , 4 , 5 , and 6a have been confirmed by X‐ray analysis. A plausible reaction pathway for these C–H activation reactions has been proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)