多芽1,8-萘啶配基及其雙金屬錯合物與催化應用

Abstract

Abstract We have successfully prepared a multidentate ligand 2,7-di(2,2′-dipyridylamino) -1,8-naphthyridine (4), and its ruthenium dinuclear complexes. The use of the prepared ruthenium complex as the catalyst for the cycloaddition of o-phenylenediamine with ethyleneglycol was investigated. For the ligand synthesis, the coupling reaction of C-N bond between 2,7-di- chloro-1,8-naphthyridine (3) and 2,2′-dipyridylamine yielded 4, which has six coordination sites for the metal. Coordination of 4 with [(η6-p-cymene)RuCl2]2、[Cu(CH3CN)4PF6]、 CuI and CuBr resulted in a dinuclear ruthenium and dicopper complexes [(4)Ru2(η6-p-cymene)2(Cl)2(PF6)2] (5a)、[(4)2Cu2(THF)2(PF6)4] (5b)、 [(4)Cu2I2] (5c) and [(4)Cu2Br2] (5d), respectively. Complexes of 5a and 5b were characterized by X-ray crystals. We had found that 5a is a hexa-coordination complex, and 5b is a five-coordination complex. Complex 5c and 5d were characterized by ESI-MASS. Complexes 5c and 5d are four-coordination complexes with iodine and bromine as the bridging ligand, respectively. In the catalytic application, tests of the dinuclear ruthenium complex (5a) as catalyst for the cycloaddition reaction of o-phenylenediamine with ethyleneglycol were performed. With oxygen as the oxidant, reaction of o-phenylenediamine with ethylene glycol and ethanolamine with the use of 5a as the catalyst afforded the corresponding quinoxaline in good yields.