Abstract
Abstract The diphenylphosphinoacetic acid Ph 2 PCH 2 COOH was readily converted to its silver salt [Ag(Ph 2 PCH 2 COO)] ( 1 ), and subsequent reactions of 1 with [Rh(cod)Cl] 2 (cod=1,5-cyclooctadiene) and [Rh(CO) 2 Cl] 2 gave [Rh(cod)(Ph 2 PCH 2 COO)] ( 2 ) and [Rh(CO) 2 (Ph 2 PCH 2 COO)] ( 3 ), respectively. Spectroscopic data and some physical properties of these new compounds are described. The complexes 2 and 3 at 50 °C showed catalytic hydrogenation activities towards benzene and a variety of substituted benzenes. The turn-over number ( TN ) for the arene hydrogenations with 2 under 5 kg/cm 2 of H 2 , decreased with the following sequence: benzene>; toluene>;anisole>;ethylbenzene>; p - and m -xylenes>;methyl benzoate. Benzonitrile and nitrobenzene did not yield any products with hydrogenated benzene-ring moieties, and the latter substrate gave only aniline. The activity sequence observed for the arene hydrogenation resulted from steric and electron-withdrawing effects of the substituents of the benzene rings. In benzene hydrogenation with 2 under 50 kg/cm 2 of H 2 at 50 °C for 36 h, the TN value was found to be about 5800. Complex 2 also showed similar hydrogenation activities towards 1,2,3,4-tetrahydronaphthalene and furan.
Published Version
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