Structural, magnetic and spectroscopic characterization of two unusual end-on bis(μ-acetato/μ-nitrato) bridged copper(II) complexes with N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide and (2 E,4 Z)- N,2-dimethylhepta-2,4,6-trienamide-1-phenyl-1-pyridin-2-ylmethanimine (1:1) as capping ligands

Abstract

Two new binuclear end-on bis(μ-acetato/μ-nitrato) bridged complexes with two NNO donor ligands, viz., [(L 1)Cu(μ-CH 3COO) 2Cu(L 1)]·4,4-bipy 1 and [(L 2)Cu(μ-NO 3) 2Cu(L 2)] 2 where [L 1 = N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide, L 2 = (2 E,4 Z)- N,2-dimethylhepta-2,4,6-trienamide-1-phenyl-1-pyridin-2-ylmethanimine (1:1) μ-CH 3COO − = μ-acetato and μ-NO 3 − = μ-nitrato) have been prepared and physiochemically characterized. These complexes are structurally characterized by X-ray crystallography. In both complexes, the two copper centers are linked by two acetate or two nitrate groups in end-on bonding fashion. The copper–copper separation is 3.279 Å for 1 and 3.459 Å for 2. The copper ions are pentacoordinated in both complexes. The coordination geometry may be described as close to square pyramidal (SP) stereochemistry with slight distortion to trigonal bipyramidal (TBP) stereochemistry. The polycrystalline epr spectra of these two complexes exhibit the properties commensurate with S = 1 systems. The magnetic moment ( μ eff) for these complexes are below the theoretical value suggesting antiferromagnetic exchange between the copper(II) ions. The cyclic voltammograms (CV) of the two complexes have been investigated. Superoxide dismutase (SOD) activity of these complexes has also been measured. These complexes can catalyze the dismutation of superoxide.