Synthesis and crystal structure of the zinc(II) complex of 5-(2,3-dimethyl-1-phenyl-3-pyrazolin-5-one-4-ylhydrazono) hexahydropyrimidine -2-thioxo-4,5,6-trione

Abstract

Arylazo barbituric acid prepared by coupling diazotized 4-aminoantipyrine with 2-thiobarbituric acid is tautomerised to its hydrazone form, 5-(2,3-dimethyl-1-phenyl-3-pyrazolin-5-one-4-ylhydrazono)hexahydropyrimidine-2-thioxo-4, 5, 6-trione [HTB-AAP] and acts as a tridentate monovalent ligand towards zinc(II) as evidenced by IR, ₁H-NMR and electronic spectra. The single crystal X-ray study of [Zn(TBAAP)(H₂O)₂]NO₃.DMSO reveals that the coordinating sites are the azomethine nitrogen and the two carbonyl oxygen atoms on the pyrazolone and the thiobarbituric acid rings. The zinc(II) ion is five coordinated and nitrate is in the ionic state. Thermal studies support the presence of two coordinated water molecules. XRD investigations confirm the presence of one molecule DMSO as solvate in the complex.