Steric effects in the reversible oxygenation of cobalt–Schiff-base-complexes. Part I. Crystal and molecular structure of the optically active and meso-forms of NN′-butylenebis(salicylideneiminato)cobalt(II)

Abstract

The crystal structures of the title compounds have been determined from three-dimensional X-ray data by conventional Fourier methods. The crystals of the optically active form are orthorhombic, space group P2₁2₁2₁. With Z= 4 and cell parameters a= 10·577, b= 16·725, and c= 9·603 Å, whereas those of the meso-form are monoclinic, space group P2₁/c, with Z= 4 and cell parameters a= 10·566, b= 13·449, c= 12·300 Å, and β= 108·2°. The structures were refined by least-squares methods to R 0·050 [(+)-form, 1226 observed reflections] and 0·033 (meso-form, 2301 observed reflections). The molecules of both compounds are similar, the cobalt atom having a square planar stereochemistry slightly tetrahedrally distorted. The main difference is found in the butylene bridge, the methyl groups being both pseudo-axial in the optically active form, but one pseudo-equatorial and the other pseudo-axial in the meso-form.