STRUCTURE AND MAGNETIC-PROPERTIES OF NEW DINUCLEAR COPPER(II) COMPLEXES BRIDGED BY CHLORANILATE OR BROMANILATE DIANIONS

Dinuclear copper(II) complexes bridged by chloranilate (ClDHBQ2-) or b romanilate (BrDHBQ2-) dianions and end-capped with 2,2'-dipyridyl (bpy ) or 1,10-phenanthroline (phen), [Cu2(L)2(XDHBQ)]Y2 (L = bpy or phen; X = Cl or Br; Y = ClO4- or PF6-), were prepared as solvated (H2O or CH 3OH) or unsolvated forms. The complex [Cu2(bpy)2(ClDHBQ)](PF6)2 . 2CH3 OH has been characterized by X-ray crystallography. The crystal consis ts of a dinuclear cation {Cu2(bpy)2(ClDHBQ)(CH3OH)2}2+ and hexafluorop hosphate ions. The two copper(II) ions are bridged by ClDHBQ2- with a Cu---Cu separation of 7.661 angstrom. The configuration about each cop per atom is square pyramidal, with two oxygens of ClDHBQ2- and two nit rogens of bpy at the basal plane and the methanol oxygen at the apex. Magnetic studies of the complexes in the temperature range 4.2-300 K r eveal a significant antiferromagnetic spin-exchange through the XDHBQ bridge. The exchange integrals are evaluated as -J = 11.7-16.3 cm-1 ba sed on H = -2JS(1)S(2).