SYNTHESIS, STRUCTURE, AND MAGNETISM OF BINUCLEAR CU(II)CU(II), CU(II)NI(II), AND NI(II)NI(II) COMPLEXES DOUBLY BRIDGED BY OXYMATE GROUPS

Binuclear complexes, [Cu(L)Cu(L')(H2O)2]X2 (H2L=3,3'-trimethylenedinitrilobis(2-butanoneoxime) (H2dopn) or 3,3'-ethylenedinitrilobis(2-butanoneoxime) (H2doen); L'=2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen); X=ClO4 or NO3), [Ni(dopn)Cu(bpy)(H2O)](C1O4)2, and [Ni(dopn)Ni(bpy)2](C1O4)2, have been prepared and characterized. The structure of [Cu(dopn)Cu(phen)(CH3OH)2](ClO4)2 (di-methanol adduct) has been determined by single crystal X-ray method. The Cu(dopn) molecule coordinates to the second copper(II) ion through the deprotonated oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. The binuclear cation is bent at the oxymate oxygens with a dihedral angle of 26.7(2)°. The binuclear copper(II) complexes show a characteristic visible band of significant intensity (ε 2700-2900 dm3 mol-1 cm-1) near 22000 cm-1 and a strong intramolecular antiferromagnetic spin-exchange interaction. The exchange integrals (J) are evaluated to be -413.3-433.0 cm-1. The magnetic moment (per molecule) of the nickel(II)-copper(II) complex is 1.80 μb at room temperature and the moment of the binuclear nickel(II) complex is 2.94 μb, demonstrating that the Ni(dopn) entity of these complexes is diamagnetic. © 1990 The Chemical Society of Japan.