Zusammensetzung und strukturelle Eigenschaften des „zweiwertigen”︁ Kobaltcyanids

The products obtained by mixing aqueous solutions of cobalt (II) chloride and potassium or hydrogen cyanide are nonstoichiometric compounds Co(CN)_x, yH₂O whith x between 2.2 and 2.4 and y between 1.75 and 2.15. They have a cubic face-centered unit cell with a = 10.20 ± 0.02 Å and Z between 6.8 and 7.1 (Z = number of units Co (CN)_x yH₂O per cell). Infrared spectra show that there is zeolitic as well as coordinated water present. The coordination units derived from reflectance spectra in the ultraviolet and visible region are (Co^III)C₆ and Co^IIN_6-xO_x. There exists a close structural relationship between Co(CN)_x, yH₂O and the stoichiometric compound Co₃[Co(CN)₆]₂, zH₂O. Comparison of calculated with experimental density shows that there must be holes in the threedimensional Co? C? N? Co-framework, which can be occupied by water molecules.