Synthesis, spectral and single crystal X-ray characterization of 5-(2-(2,3-dimethyl-5-oxo-1-phenyl-2,5-dihydro-1H-pyrazol-4-yl)hydrazono)pyrimidine-2,4,6(1H,3H,5H)-trione and its copper(II) complexes

A novel aryl hydrazone was synthesized via Japp-Klingemann reaction between diazotized 4-aminoantipyrine and barbituric acid. It has characterized by various spectroscopic methods and X-ray single crystal analysis. The effect of pH on the azo-hydrazone tautomerism of the ligand has been studied with UV-Vis spectroscopy. Two types of copper complexes were obtained by the reaction of the ligand with copper sulphate pentahydrate in methanol under different experimental conditions. In one complex, sulfate ion acts only as the counter anion and in the other complex it is coordinated unidentately to the metal ion in the form of bisulphate anion. The complexes were also characterized spectroscopically and by single crystal X-ray analysis. The complexes exhibited distorted square pyramidal geometry. The ESR spectrum of one of the complex was also discussed. (C) 2018 Elsevier Ltd. All rights reserved.