Synthesis and crystal structure of oxalato-bridged dicopper(II) complex with hydrogen bonds [Cu2(μ-C2O4) (bpy)2(H2O)2(NO3)2]

A new dicopper(II) complex [Cu-2(mu-C2O4)(bpy)(2)(H2O)(2)(NO3)(2)] (1) has been synthesized and its structure determined (bpy = 2,2'-bipyridine). The structure consists of centrosymmetric [Cu-2(mu-C2O4)(bpy)(2)(H2O)(2)(NO3)(2)] molecules with each Cu(ll) ion in a distorted octahedral environment: two nitrogen atoms from bpy, two oxygen atoms from the oxalate ion in the basal piano and two oxygen atoms from H2O and the nitrate group in the two axial positions. The unusual ligand arrangement in (1) and the packing of molecules are attributed to intermolecular and intramolecular hydrogen bonding. The intermolecular and intramolecular hydrogen bonding formed a hydrogen bond plane and the intermolecular hydrogen bonding gave rise to a zigzag chain structure. The e.p.r, study of the polycrystalline powder at 110 K gives g(perpendicular to) = 2.04 and g(parallel to) = 2.20, typical of axially elongated copper(II) systems, and the appearance of the half-field signals suggests a magnetic interaction between the two Cu(II) ions. (C) 2000 Elsevier Science B.V. All rights reserved.