Versatile ligational behavior of azopyrazolone derived from hydralazine

Five complexes of 3-methyl-4 -(phenylhydrazono)-1-phthalazinyl-2-pyrazolin-5-one (LH) were synthesized. The ligand and complexes were characterized using elemental analyses and various analytical techniques such as IR, UV, NMR, mass spectra, magnetic susceptibility measurements, and thermal decomposition studies such as TG/DTG. The geometries of the complexes with special emphasis on the versatile ligational behavior of LH are discussed. All five complexes have octahedral geometry. In four of the complexes [M(LH)Cl-3] where M = Fe(III)/Cr(III) and [M(LH)(OAc)(2)H2O] and M = Cu(II)/Ni(II), the ligand was neutral and tridentate. Another copper complex [CuL(OAc)(H2O)(2)] in which the ligand is tridentate, mono-anionic one was also obtained in an excess of aqueous solution. Antifungal studies of the compounds are also carried out.