ω-Nitroacetophenone as a chelating agent. Part IV. Axial and equatorial ligation in several adducts of bis(ω-nitroacetophenonato)copper(II) with heterocyclic and other N-bases

Abstract

Stable 1:1 adducts with α,α′-bipyridyl, o-phenanthroline, and 2-methylpyridine, and 2:1 adducts with pyridine, 4-methylpyridine, benzylamine, and aniline have been prepared from bis(ω-nitroacetophenonato)copper(II), Cu(ω-nap)₂. Adducts have also been obtained from Ni(ω-nap)₂ with α,α′-bipyridyl (1:1) and 2- and 4-methylpyridine (2:1). X-Ray data, magnetic moments, and optical spectra in the region 6·0–25·0 kk have been mainly used for the determination of the stereochemistry and electronic structure of all the above adducts. Whereas Cu(ω-nap)₂(α-pic) is five-co-ordinate, as previously shown by X-ray analysis, all the other adducts are six-coordinate and pseudo-octahedral with co-ordination of the N-bases either along the axial direction or the equatorial plane. The bispyridine derivative gives two different crystalline forms which are a rare example of cis–trans isomerism in a discrete six-co-ordinate copper(II) complex.