1 Studies on Ruthenium and Rhodium Complexes Containing 1,2- bis (N-Methylbenzimidazolyl)Benzene and Catalytic Transfer Hydrogenation

Abstract

Reactions of ruthenium(III) chloride and rhodium(III) halides with 1,2-bis(N-methylbenzimidazolyl)benzene (N-N) in stoicheiometric amounts in methanol produced binuclear complexes of the compositions [RuCl2(- Cl) (N-N)]2 and [RhX3(N-N)]2. nH2O ( n = 0, X = Br ; n = 1, X = Cl). [RhI3(N-N)]2 was prepared by stirring a mixture of rhodium trichloride with fifteen fold excess of sodium iodide and the N-heterocycle, N-N in methanol. Ruthenium chloride and rhodium halides in 2-methoxyethanol/alcohol reacted with N-N in presence of CO to produce complexes of the types [RuCl2(CO)2(N-N)], [Rh2Cl2(CO)2(N-N)] and [Rh(CO)2(N-N)]Br. The complexes were characterized by elemental analyses, molar conductivity measurements, IR, electronic, 1H- and 13C- NMR spectral studies and by mass spectra. Probable structures have been proposed for the complexes. The complex [RuCl2(-Cl)(N-N)]2 in DMF was found to reduce nitro compounds to corresponding amines using formic acid as the hydrogen donor. Keywords: 1,2-bis(N-methylbenzimidazolyl) benzene, ruthenium and rhodium complexes, carbonyl.