Cationic half-sandwich C-N chelating Ir and Rh complexes [Cp*M(NCCH3){kappa(2)(N,C)-NH2CR2-2-C6H4}]+SbF6- (1a, M = Ir, R = CH3; 1b, M = Ir, R = C6H5; 2a, M = Rh, R = CH3; 2b, M = Rh, R = C6H5) are synthesized by AgSbF6-mediated halide abstraction from neutral azametallacycles derived from tritylamine or cumylamine and are fully characterized by NMR spectroscopy and X-ray crystallography. The treatment of the cationic complex 1b with H-2 gas under ambient conditions in the presence of triethylamine in THF-d(8) quantitatively yielded hydrido(amine) complex [Cp*Ir(H){kappa(2)(N,C)-NH2C(C6H5)(2)-2-C6H4}] (4). The C-N chelating Ir complex shows a higher catalytic activity than an N-N chelating complex, [Cp*Ir(NCCH3)(Tscydn)+SbF6- (3; Tscydn = N-(p-toluenesulfonyl)-1,2-cyclohexanediamime), that has been previously used for the asymmetric hydrogenation of acyclic imines. For example, the cationic Ir complex la promoted the hydrogenation of N-(1-phenylethylidene)benzylamine under 30 atm at 30 degrees C in the presence of excess AgSbF6 to produce the corresponding amine in 97% yield within 2 h. The cationic Rh complexes 2 serve as efficient catalysts for hydrogenative condensation of nitriles in the presence of AgSbF6, producing dibenzylamines selectively even at 60 degrees C.
herein an unprecedented highly efficient Guerbet‐type reaction at room temperature (catalytic TON up to >6000). This β‐alkylation of secondary methyl carbinols with primary alcohols has significant advantage of delivering higher‐order secondary alcohols in an economical, redox‐neutral fashion. In addition, the first enantioselective Guerbet reaction has also been achieved using a commercially available