Prepn: Ray, Sahu, J. Indian Chem. Soc. 23, 161 (1946); Gmelins, Cobalt (8th ed.) 58, (part A), 364 (1932) and supplement, 712 (1961). Structure reported as Co3[Co(CN)6]2: P. S. Poskozim et al., J. Inorg. Nucl. Chem. 35, 687 (1973). Prepn and structure as Co(CN)2: D. M. S. Mosha, D. Nicholls, Inorg. Chim. Acta 38, 127 (1980).