| Abstrakt: |
The title compound, [Co(NCS)2(C6H7N)4] or Co(NCS)2(4-methylpyridine)4, was prepared by the reaction of Co(NCS)2 with 4-methylpyridine in water and is isotypic to one of the polymorphs of Ni(NCS)2(4-methylpyridine)4 [Kerr & Williams (1977[Kerr, I. S. & Williams, D. J. (1977). Acta Cryst. B33, 3589-3592.]). Acta Cryst. B33, 3589–3592 and Soldatov et al. (2004[Soldatov, D. V., Enright, G. D. & Ripmeester, J. A. (2004). Cryst. Growth Des. 4, 1185-1194.]). Cryst. Growth Des. 4, 1185–1194]. Comparison of the experimental X-ray powder pattern with that calculated from the single-crystal data proves that a pure phase has been obtained. The asymmetric unit consists of one CoII cation, two crystallographically independent thiocyanate anions and four independent 4-methylpyridine ligands, all located in general positions. The CoII cations are sixfold coordinated to two terminally N-bonded thiocyanate anions and four 4-methylpyridine coligands within slightly distorted octahedra. Between the complexes, a number of weak C—H⋯N and C—H⋯S contacts are found. This structure represent a polymorphic modification of Co(NCS)2(4-methylpyridine)4 already reported in the CCD [Harris et al. (2003[Harris, J. D., Eckles, W. E., Hepp, A. F., Duraj, S. A., Hehemann, D. G., Fanwick, P. E. & Richardson, J. (2003). NASA Technical Reports, 211890.]). NASA Technical Reports, 211890]. In contrast to this form, the crystal structure of the new polymorph shows a denser packing, indicating that it is thermodynamically stable at least at low temperatures. Thermogravimetric and differential thermoanalysis reveal that the title compound starts to decomposes at about 100°C and that the coligands are removed in separate steps without any sign of a polymorphic transition before decomposition. [ABSTRACT FROM AUTHOR] |
