Active Copper-Species in Oxidative Coupling of Diphenylmethanimine and their Complexes of the Imine

Abstract

For oxidative coupling of diphenylmethanimine (Im) in excess pyridine, copper (I) bromide and copper 10 halide methoxide were found to be effective catalysts. This showed that the coupling was not specific for copper (I) chloride. The order of the catalyst activity was as follows: Cu (0Cl18)Cl>CuCl>Cu(OCHB)Br>CuBr. Copper (IC) chloride hydroxide Cu (OH) Cl 6 and copper chloride methoxide Cu (OCH9)Cl 7 gave quite analogous spectra in far- infrared region. The former [ 6] did not form complexes with pyridine and diphenylmethanimine, and was inactive, whereas the latter [ 7 ] was highly active. The active catalyst (7) acted on pyridine and the imine at room temperature in such a way that pyCu (OCHE) Cl C, 83 and ImCu(OCH8)Cl [9] were formed, respectively. Complex(9) gave azine in the presence of oxygen. Therefore, E 7 might catalyze the oxidation of imine in the form of C in pyridine, and azine should be formed through 9 by the ligand exchange with imine. Complex 8 was shown to be of a chlorine-bridged, binuclear structure at the cocentration of the reaction, mononuclear py, Cu (OCHE) Cl in infinite dilution and of a polymeric form of binuclear unit in crystalline solid. The strucure of related copper-complexes, CuX L, CuX2.14, CuX2.2 L, Cu (OR)X and LCu (OR)X (L=py, Im; X=Cl, Br; R CH.) in solid and the structural unit in solution were also discussed on the basis of far-infrared spectra, magnetic moments, and molecular weights.