Die Kristallstruktur von H 3 Co(CN) 6

The crystal structure of the hexagonal H 3 Co(CN) 6 ( a = 6.43 Å, c = 5.70 Å, Z = 1) has been determined by X‐ray powder methods. The space group is D   3d 1(at least pseudo), the cobalt atoms being in (0, 0, 0). Structure factor calculations lead to a final R ‐value of 13.2%, based on F 2 ‐sums of coinciding reflections. The carbon and nitrogen atoms are located at the vertices of a slightly distorted octahedron around the cobalt atom; the angle CoCN is 177°. The interatomic distances are: CoC = 1.89 Å, CoN = 2,98 Å, CN = 1.09 Å. The pseudo‐octahedral units of Co(CN) 6 are linked together by NHN bridges. Infrared spectra show that the most probable linkage is the one with a NHN‐bond length of 2.7 Å.