Copper(II) complexes of N-(2-{[(2E)-2-(2-Hydroxy-(5-substituted)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide ligands and heterocyclic coligands

Abstract

Some copper(II) complexes of the type [Cu(L1–3)(phen]⋅CH2Cl2 (1a–3a) and [Cu(L1–3) (bipy)]⋅CH2Cl2 (1b–3b) (where L1=N-(2-{[(2E)-2-(2-Hydroxy-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L2=N-(2-{[(2E)-2-(2-Hydroxy-(5-bromo)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L3=N-(2-{[(2E)-2-(2-Hydroxy-(5-methoxy)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide; phen=1,10-phenanthroline, bipy=2,2′-bipyridine) have been prepared and characterized on the basis of elemental analyses, IR, UV–Vis and EPR spectral studies. IR spectra indicate that the ligand L1–3 exists in the keto form in the solid state, while at the time of complexation, it tautomerises into enol form. The single crystal X-ray diffraction study of the representative complex [Cu(L1) (phen)]⋅CH2Cl2 (1a) reveals the distorted square pyramidal geometry around copper(II). Crystal data of (1a): space group=P21/n, a=11.5691(16)Å, b=11.0885(15)Å, c=24.890(4)Å, V=3166.2(8)Å3, Z=4. The electrochemical behavior of all the complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its stronger π acidic character. All the complexes exhibit blue–green emission as a result of the fluorescence from the intra-ligand (π→π∗) emission excited state.