Studies on ruthenium and rhodium complexes containing 6-pyridyl-5,6-dihydrobenzo[4,5]-imidazo[1,2-c]quinazoline and catalytic transfer hydrogenation

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Reactions of ruthenium(III) chloride and rhodium(III) halides with 6-pyridyl-5,6-dihydrobenzo[4,5]-imidazo[1,2-C]quinazoline in stoichiometric amounts in methanol produced binuclear complexes of the compositions [RuCl2(μ− Cl) (N-N)]2 and [RhX3(N-N)]2. nH2O ( n = 0, X = Br or I; 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 in methanol. Rhodium halides in 2-methoxyethanol/alcohol reacted with (N-N) in presence of CO to produce complexes of the types [Rh(CO)2(N-N)]Cl and [Rh2Br2(CO)2(N-N)]. 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(μ− Cl)(N-N)]2 in DMF was found to reduce nitrocompouds to corresponding amines using formic acid as hydrogen donor.