2304. MOND, L., HIRTZ, H., AND COWAP, M. D. Note on a Volatile Compound of Cobalt With Carbon Monoxide. Chem. News, vol. 98, 1908, p. 165; Chem. Abs., vol. 2, 1908, p. 3315.
Finely divided Co and CO at 150° and under 50 atm. yielded small quantities of Co carbonyl; at 200° under 100 atm. the yield was higher. The Co was prepared by converting CoC2O3, free from Ni and Fe, to oxide, and reducing the latter to metal with H2 in the retort used for the production of the carbonyl. The carbonyl was obtained in large orange crystals, agreeing in composition with the formula Co(CO)4. It decomposes in air to a violet substance, as yet uninvestigated, and is best preserved by sealing up in H2 or CO. It is but slowly attacked by nonoxidizing acids but very readily by oxidizing agents, for example, Co(CO)4+Br2→CoBr2+4CO. It is insoluble in N2O but more or less soluble in CS2, ether, naphtha, alcohol, and Ni carbonyl. If these solutions stand for some time or are warmed, decomposition sets in, D181.827; vapor tension at 15°, 11 mm. Both of these values, however, are affected by the ease with which the carbonyl decomposes and are not to be regarded as final. In an atmosphere of CO2, the decomposition begins at 40°-45° and is complete at 130°-135°, leaving metallic Co. The melting point is 42°-46°.