Crystal and molecular structure of NN′-ethylenebis(salicylideneiminato)-ethylcobalt(III)

The crystal and molecular structure of NN′-ethylenebis(salicylideneiminato)ethylcobalt(III), [EtCo(salen)], has been determined from three-dimensional X-ray data by the heavy-atom method. The crystals are monoclinic with a= 13·97, b= 7·39, c= 18·96 A, β= 127·2°, Z= 4, space group P21/c. Anisotropic least-squares refinement gave R 0·085 for 1762 independent reflexions. The crystals are built up by centrosymmetric dimeric units, dimerisation being achieved through the co-ordination of the cobalt atoms by an oxygen atom of the other [EtCo(salen)] unit (Co–O 2·342 ± 0·003 A).The co-ordination polyhedron of the cobalt atoms is represented by a distorted octahedron. The axial positions are occupied by an oxygen atom of the other Co(salen) unit and by the σ-bonded ethyl group (Co–C 1·990 ± 0·007 A); the four equatorial positions are occupied by the quadridentate salen ligand with Co–O 1·901 ± 0·005 and 1·935 ± 0·004 A and Co–N 1·886 and 1·880 ± 0·006 A. Some properties of salen-type ligands and the trans-influence in the octahedral cobalt complexes are discussed.