Synthesis and structure of Co(II) and Ni(II) complexes with bis(phthalazine-1-hzdrazone)-2,6-diacetylpyridine

Abstract

Hydralazine (1-Hydrazinophthalazine) is a potent arterial vasodilatator. It is used as antihypertension agent. Due to its hydrazinic N atom 1-hydrazinophthalazine can react with carbonile compounds giving Schiff bases (hydrazones). Despite the wide applicability in medicine of 1-hydrazinophthalazine and its derivatives, the coordination ability of these compounds to transition metals are less investigated. Accordingly our aim was to synthetize and characterize a new potentially polydentate ligand and its complexes with Co(II) and Ni(II). The new ligand, bis(phthalazine-1-hzdrazone)-2,6-diacetylpyridine (Hz2DAP) reacted with cobalt(II) acetate tetrahydrate and nickel(II) acetate tetrahydrate. Dark brown single crystals of complexes [Co(Hz2DAP-H)Cl2] and [Ni(Hz2DAP-H)]Cl, where Hz2DAP-H is the monodeprotonated form of Hz2DAP, were precipitated from methanolic solution in reaction of dihydrochloride salt of Hz2DAP and metal acetates in a mole ratio 1:1. Cobalt complex has an octahedral geometry, realized by coordination of Hz2DAP-H in the equatorial plane and with axially chloro ligands. Nickel complex has a square pyramidal geometry. The complexes are characterized by X-ray diffraction, conductometric measurements and thermal analysis.