Crystal and molecular structure of a nickel(II) macrocyclic di-imine–diamine complex : rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradeca-4,11-dienenickel(II) perchlorate

Abstract

The crystal structure of the title compound has been solved from photographic data by Patterson and Fourier methods and refined by least-squares techniques to R 0·12 for 2048 reflections. The crystals are orthorhombic, space-group Pbca, with a= 19·73, b= 17·01, and c= 13·69 Å, Z= 8, and consist of perchlorate ions plus a racemate of the optically active form of the trans-positional isomer (identified by a trans-arrangement of the two imine groups) of this approximately planar complex cation. The nickel and four donor nitrogen atoms deviate slightly from square-planar co-ordination, and further strain is evidenced by considerable deviations from the values expected for bond angles, bond lengths, and torsion angles in the complex. The ring conformations in this complex cation are compared with those in [Ni(rac-cisdiene)]²⁺ and [Co(meso-cisdiene)(CN)₂]⁺.