Oxamido-bridged heterobinuclear copper(II)-nickel(II) complex and homotrinuclear nickel(II) complex with 2D supramolecular structure: synthesis, crystal structure, magnetic and spectroscopic properties

The oxamido-bridged heterobinuclear copper(II)-nickel(II) complex, [Cu(oxbe)Ni(phen)(2)]ClO4.3H(2)O (1) and homotrinuclear nickel(11) complex {[Ni(oxbe)](2)Ni(H2O)(2)}.2.5DMF (2) have been synthesized and characterized by means of elemental analysis, IR, EPR. and electronic spectra and magnetic susceptibility, where H(3)oxbe is dissymmetrical ligand N-benzoato-N'-(2-aminoethyl)ox-amido, phen = 1.10-phenanthroline, DMF = dimethylformamide. Complex I has an extended oxamido-bridged structure consisting of planar copper(II) and octahedral nickel(II) ions. The chi(M) and mu(eff) versus T plots of 1 is typical of an antiferromagnetically coupled Cu(II)-Ni(II,) pair with a spin-doublet ground state, and magnetic analysis leads to J = -57.1 cm(-1). The molecular structure of 2 is centrosymmetrical, with one octahedral nickel atom lying at an inversion center and two terminal Ni(II) atoms in approximately square planar environment. Through the hydrogen bonds and pi- pi stacking interactions, a 2D supramolecular structure is formed. (C) 2003 Elsevier Ltd. All rights reserved.