Structural aspects of the synthetic oxygen-carrier NN′-ethylenebis-(salicylideneiminato)cobalt(<scp>II</scp>). Part II. Crystal and molecular structure of the monopyridine complex

Abstract

The crystal structure of the monopyridine complex of NN′-ethylenebis(salicylideneiminato)cobalt(II), [Co(salen)-(py)], has been determined by a three-dimensional X-ray analysis. The crystals are orthorhombic, space group Cmc21, with a= 20·22, b= 12·44, c= 7·23 Å, Z= 4. The structure was solved by the heavy-atom method and refined by the anisotropic least-squares method to an R of 0·071 using 539 independent reflexions. The crystals consist of [Co(salen)(py)] molecules in which the cobalt atom has a pyramidal co-ordination polyhedron. The apical position is occupied by a pyridine molecule parallel to the CH2–CH2 bond. The two chemically equivalent halves of the ‘salen’ ligand and half of the pyridine molecule are related by a crystallographic mirror plane. The inactivity of this compound towards oxygen absorption in the solid state is discussed on the basis of the crystal packing.