Mono- and di-nuclear nickel(II) complexes with Schiff bases derived from 4-substituted 2,6-diformylphenol and 7-amino-4-methyl-5-azahept-3-en-2-one; crystal and molecular structure of [4-chloro-2,6-bis(4-methyl-2-oxo-5,8-diazanona-3,8-dienyl)phenolato(3–)]dinickel(II) bromide hemihydrate

Abstract

The reaction of 4-chloro- or 4-methyl-2,6-diformylphenol with 7-amino-4-methyl-5-azahept-3-en-2-one leads to either quadridentate mononucleating or heptadentate binucleating Schiff-base ligands, depending on the reaction conditions. Nickel complexes with both types of ligands have been obtained and characterized by i.r., u.v.–visible, n.m.r., and mass spectrometry. An interesting example of impeded pseudo-rotation of a five-membered chelate ring in dinuclear nickel complexes is observed. The single-crystal X-ray structure of [4-chloro-2,6-bis(4-methyl-2-oxo-5,8-diazanona-3,8-dienyl)phenolato(3–)]dinickel(II) bromide hemihydrate has been determined. It consists of a dinuclear complex cation of twisted bifurcated shape and a bromide anion, with a half-equivalent of water incorporated into the crystal lattice. Crystallographic data: space group C2/c(no. 15), a= 22.082(4), b= 11.5, c= 22.368(4)Å, β= 118.61 (1)°, R and R′ 0.0380 and 0.0318, respectively.