Crystal and molecular structure of dimethyl-[3,3′-(trimethylenedinitrilo)bis(butan-2-one oximato)]cobalt(III)

Abstract

The crystal and molecular structure of the title compound, (I), has been determined from three-dimensional X-ray data by conventional Fourier methods. Crystals are monoclinic with a= 7·600(8), b= 8·301 (8), c= 13·675(6)Å, β= 113·5(3)°, Z= 2, space group Pc. The structure was refined by least-squares techniques to R 0·034 for 1342 independent reflexions. The co-ordination polyhedron of the cobalt atom is well represented as a distorted octahedron, the axial positions being occupied by two methyl groups [Co–C 2·045(8) and 2·049(8)Å] whereas the quadridentate {(doh)(do)pn} ligand occupies the four equatorial positions. The propylenediamine bridge has the expected GG′ conformation [torsion angles around the C–C bonds: 62·9 and –67·6°]. Neglecting the central carbon atom of the propylene group, the equatorial ligand is nearly planar with two sets of Co–N distances [1·898(5) and 1·859(5)Å]. The values of the equatorial ligand bond lengths indicate π-electron delocalization in the five-membered rings. The trans-influence of methyl groups is discussed in relation to Co–C distances in the present and analogous compounds.