Two copper (II) complexes derived from anthranilic acid and 4-iodo-anthranilic acid Schiff bases: Structural elucidation, halogen bonding interactions and catalytic study using 3,5-DTBC

Abstract

Two monomeric copper complexes [Cu(Pymab)(CCl3COO)(H2O)].H2O (1) and [Cu(Pymaib)(H2O)Cl]2 (2) were synthesized by reacting copper (II) trichloroacetate and copper(II) chloride with the monobasic tridentate Schiff-Base ligands (HPymab = (E)-2-((pyridine-2-yl)methyleneamino)benzoic acid and HPymaib = 4-iodo-2-{(E)-[(pyridin-2-yl) methyleneamino}benzoic acid) and characterized by elemental analysis, IR, UV–Vis, mass spectrometry, CV and single crystal XRD analysis. Both complexes are monomeric in the solid state and in the solution as well. For both complexes, single crystal XRD indicates a distorted square pyramidal coordination geometry of the metal atoms. Both 1 and 2 behave as effective catalysts towards the oxidation of 3,5-di-tert-butyl catechol to the corresponding quinone derivative in aerial oxygen. The reactions follow the Michaelis-Menten enzymatic reaction kinetics with (kcat) values of 1452 h−1 and 1458 h−1 respectively in DMSO and 1590 h−1 and 1636 h−1 in THF respectively. In the solid state both compounds participate in halogen bonding interactions that have been studied using DFT calculations and the molecular electrostatic potential (MEP) and the noncovalent interaction plot index (NCI plot) computational tools.