Synthesis, crystal structure and thermal reactivity of di-aqua-dithio-cyanato-bis-(pyridine-4-carbo-nitrile)cobalt(II).

The title compound, [Co(NCS)2(C6H4N2)2(H2O)2], is isotypic to its Ni analog and to one of the two modifications of Mn(NCS)2(4-cyano-pyridine)(H2O)2 reported recently [Näther (2026 ▸). Acta Cryst. E82, 441-445 and Wellm et al. (2020 ▸). Cryst. Growth Des. 20, 3374-3385]. Its asymmetric unit is built up of one cobalt cation that occupies a center of inversion, one thio-cyanate anion, one neutral 4-cyano-pyridine coligand and one water mol-ecule that are located in general positions. The metal cations are sixfold coordinated by two terminally N-bonding thio-cyanate anions, two water mol-ecules and two 4-cyano-pyridine coligands within a slightly distorted octa-hedral geometry. The discrete complexes are linked by inter-molecular O-H⋯S hydrogen bonding into layers that condense into a three-dimensional network via weak C-H⋯N inter-actions. Powder X-ray diffraction (PXRD) proves that a pure sample has been obtained. Thermogravimetric measurements reveal that the title compound decomposes in different steps, in which compounds with the composition Co(NCS)2(4-cyano-pyridine)2 and Co(NCS)2(4-cyano-pyridine) are formed as inter-mediates, which are not isotypic to the corresponding Mn compounds already reported in the literature [Wellm et al. (2020 ▸). Cryst. Growth Des. 20, 3374-3385].