SYNTHESIS AND CHARACTERIZATION OF OXOVANADIUM(IV) AND DICHLOROVANADIUM(IV) COMPLEXES OF BIOLOGICALLY-ACTIVE 4-AMINOANTIPYRINE DERIVATIVES

A new series of oxovanadyl complexes of the Schiff base ligands 4-(2-p yrrolyl methylideneamino)antipyrine (PyAAP), 4-(2-thienylmethylideneam ino)antipyrine (TAAP), 4-furfurylideneaminoantipyrine (FAAP) and 4-(2- hydroxybenzylideneamino)antipyrine (SAAP), have been synthesized and c haracterized by different physical techniques. The spectral and magnet ic data indicate a distorted square pyramidal structure for all comple xes. The selective deoxygenation of the oxovanadyl complexes [(PyAAP-H )(2)(VO)(2)SO4] and [(SAAP-H)(2)VO], which gave a good yield of the co rresponding dichloro compounds [L(2)VCl(2)], L = PyAAP-H or SAAP-H, is made by using different deoxygenating agents in different solvents an d at various temperatures. The purity and the percentage yield of the products are found to be solvent, temperature and deoxygenating agent dependent. Spectral and magnetic studies are used to elucidate the str ucture of the dichloro derivatives. The solvent effects upon the elect ronic spectra of the oxovanadyl complexes and the corresponding dichlo ro derivatives are ascertained. Copyright (C) 1997 Elsevier Science Lt d.