Coordination behaviour and DFT studies of copper(II) complexes of a novel chromone derived tetradentate Schiff base

Abstract

New Schiff base chelates of Copper(II) derived from the Schiff base ligand ethylenediaminobi(chromone-3-carbaldehyde) (FCED), viz., [Cu(FCED)Cl]Cl (1), [Cu(FCED)Br]Br (2), [Cu(FCED)(NO₃)](NO₃)  (3) and [Cu(FCED)](ClO₄)₂ (4) have been synthesized and characterized. Microanalytical data, molar conductance and magnetic susceptibility values have been obtained and IR, UV-Visible, EPR spectral studies, TG/DTA, and DFT studies have been carried out to suggest the tentative structures of the complexes. The ligand acts as a neutral tetradentate ONNO donor ligand and the bonding sites are Nitrogen atoms of azomethine groups and Oxygen atoms of carbonyl groups. A square pyramidal geometry is suggested for complexes 1, 2 and 3 and a square planar geometry is suggested for 4. The crystal data indicate that the complex 3 crystallizes in monoclinic P21/n space group with a distorted square pyramidal structure and the π-π stacking interactions results in polymeric chains in unit cell of the complex.