PYRIDINE-TYPE COMPLEXES OF TRANSITION-METAL HALIDES .8. PREPARATION, CHARACTERIZATION AND SINGLE-CRYSTAL STRUCTURE OF DIFLUOROTETRAKIS(3,5-DIMETHYLPYRIDINE)-COBALT(II) IN HYDRATE [N-APPROXIMATE-TO-2.6(3)]

A pyridine-type cobalt(II) complex containing fluoro ligands has been prepared from solution. The compound crystallizes in the tetragonal sp ace group P 4/mcc, with a = b = 9.352(2), c = 17.264(4) angstrom and Z = 2. Refinement of its crystal structure against 1065 single-crystal X-ray diffraction data gave a final Rw = 0.056. The octahedral coordin ation around the Co is tetragonally distorted, Co-N = 2.186(4) angstro m and Co-F = 2.016(3) angstrom. The distorted D4h symmetry is also app arent from the far-infrared spectrum. The observed effective magnetic moment (4.368 BM) is slightly lower than in the case of high-spin octa hedral Co(II) complexes (5.2 BM at 300 K) because the ligand field dep arts from the octahedral. Thermal stability of the complex in a nitrog en atmosphere has also been studied.