Synthesis, characterization and magnetochemical studies of some imidazole and imidazolate copper(II) ternary complexes derived from N-salicylidenearoylhydrazines. X-ray crystal and molecular structures of [( N-salicylidene- p-chlorobenzoylhydrazine) ONO(−2)imidazole]copper(II) monohydrate and dimeric [( N-salicylidene- p-methylbenzoylhydrazine) ONO(−2)imidazole]copper(II) hemihydrate

Abstract

The reactions of imidazole (Him) with N-salicylidenearoylhydrazine copper(II) complexes have been studied and a number of ternary copper(II) complexes, [Cu(L)Him]· nH 2O, [Cu(HL)X·Him]· nH 2O and [{Cu(L)} 2Im]· nH 2O, have been prepared and characterized (HL and L refer, respectively, to mono- and dinegative N-salicylidenearoylhydrazine anions and X is a mononegative monodentate ligand). The X-ray crystal and molecular structure of [( N-salicylidene- p-chlorobenzoylhydrazine)imidazole]copper(II) monohydrate, [Cu(Sp-ClBzh)Him]·H 2O, and [( N-salicylidene- p-methylbenzoylhydrazine)imidazole]copper(II) hemihydrate, [Cu(Sp-CH 3Bzh)Him]·1/2H 2O, were measured. The p-chloro complex [Cu(Sp-ClBzh)Him]·H 2O is monomeric with the Cu(II) in a distorted square planar environment and is coordinated to the tridentate hydrazone via phenoxy oxygen, azomethine nitrogen and enolimide oxygen, the fourth coordination site is occupied by the imidazole nitrogen. The p-methyl complex [Cu(Sp-CH 3Bzh)Him]·1/2H 2O was found to be a centrosymmetric dimer, the monomeric unit being bridged through the phenoxy oxygen. The Cu(II) is in a square pyramidal environment and is bounded in the equatorial plane with the enolimide oxygen, azomethine nitrogen and phenoxy oxygen of the hydrazone ligand while the fourth site is occupied by the symmetry related phenoxy oxygen of the other unit; the axial fifth coordination site is occupied by the imidazole nitrogen. The magnetic susceptibility measurements at different temperatures (5–298 K) have been recorded and are discussed. The binuclear imidazolate complexes show antiferromagnetic exchange coupling interactions, the measured − J values are within the range 17.0–20.0 cm −1, while the imidazole complexes do not show any appreciable exchange interactions.