THE CRYSTAL-STRUCTURES OF BIS[4-(2'-HYDROXYSTYRYL)-2,2,5,5-TETRAMETHYL-3-IMIDAZOLIN-1-OXYLO]COBALT(II) AND NICKEL(II), M(C15H18N2O2)2 (M = CO(II) AND NI(II))

An x-ray diffraction structural analysis was carried out for isostructural Co(II) and Ni(II) complexes with spin-labelled imidazolines with the general formula M(C9H13N2O2)2 (M = C6H5). The central ion has a coordination number of 4 (2N + 20). The ligand donor atoms form a distorted tetrahedron. The "trans" OMO angles are 123.2(3) and 130.5(3)-degrees, while the "trans" NMN angles are 124.4(3) and 123.5(3)-degrees. The mean M-O bond lengths are 1.928 and 1.913 angstrom, while the mean M-N bond lengths are 1.971 and 1.943 angstrom. The OMN chelate bond angles are 95.9 and 93.2-degrees in the Co(II) and Ni(II) complexes, respectively. The structures are molecular in nature. The ligands in the complexes with the exception of the methyl groups are virtually planar. The oxygen atom of the paramagnetic fragment of the ligand lies in the plane of the imidazoline rings. The mean N-O bond length is 1.65 angstrom in the Co(II) complex and 1.272 angstrom in the Ni(II) complex.