Synthesis, crystal structure and thermal properties of bis(acetonitrile-κN)bis(3-bromopyridine-κN)bis(thiocyanato-κN)cobalt(II)

Single crystals of the title compound, [Co(NCS)(2)(C5H4BrN)(2)(C2H3N)(2)], were obtained by the reaction of Co( NCS)(2) with 3-bromopyridine in acetonitrile. The CoII cations lie on crystallographic inversion centers and are coordinated by two N-bonded thiocyanate anions, two 3-bromopyridine and two acetonitrile ligands thereby forming slightly distorted CoN6 octahedra. In the crystal, these complexes are linked by C-H. . .S and C-H. . .N hydrogen bonds into a threedimensional network. In the direction of the crystallographic b-axis, the complexes are arranged into columns with neighboring 3-bromopyridine ligands stacked onto each other, indicating pi-pi interactions. The CN stretching vibration of the thiocyanate anions is observed at 2066 cm(-1), in agreement with the presence of only N-bonded anionic ligands. TG-DTA measurements reveal that in the first mass loss the acetonitrile ligands are removed and that in the second step, half of a 3-bromopyridine ligand is lost, leading to the formation of a polymeric compound with the composition [(Co(NCS) (2))(2)(C5H4BrN)(3)](n) already reported in the literature.