Novel copper(II), cobalt(II) and nickel(II) complexes with 5-(4-oxo-4H-chromen-3-yl)-4,5-dihydro-1,3,4-thiadiazole-2-carboxamide: Synthesis, structure, spectroscopic studies

Abstract A series of novel organic ligands, 5-(4-oxo-4H-chromen-3-yl)-4,5-dihydro-1,3,4-thiadiazole-2-carboxamide, which are the tautomeric forms of 2-oxo-2-(arylamino)-(2 E )-2- [(4-hydroxy-2-oxo-2H-1-benzopyran-3-yl)-methyledene]ethanethioic acid hydrazides, have been synthesized from 3-formylchromone and oxamic acid thiohydrazides. Copper(II), cobalt(II) and nickel(II) complexes with 2-oxo-2-(arylamino)-(2 E )-2-[(4-hydroxy-2-oxo-2H-1-benzopyran-3-yl)methyledene]ethanethioic acid hydrazides have been synthesized by the interaction of corresponding organic ligands with MCl 2 (M = Cu, Co, Ni). The crystal structure of a copper(II) complex with 5-(4-oxo-4H-chromen-3-yl)-N-phenyl-4,5-dihydro-1,3,4-thiadiazole-2-carboxamide has been solved by a single-crystal X-ray diffraction method. The copper(II) ions in complex molecule are coordinated by aldimine nitrogen atom, thiolate sulfur atom and the oxygen atom the pyrone ring keto-group as well as two bridged chloride anions in a distorted triangular bipyramidal geometry. The electrochemical investigations of synthesized ligands and complexes have been performed by cyclic voltammetry technique.