3656a.     WENDER, I., STERNBERG, H. W., AND ORCHIN, M.  Chemistry of the Metal Carbonyls.  I.  New Concepts Applied to Carbonyls of Cobalt.  Jour. Am. Chem. Soc., vol. 74, 1952, pp. 1216-1219.

          Reactions of a variety of organic compounds with dicobalt octacarbonyl, previously assumed to proceed by displacement of 1 or more mols of CO by the entering organic molecule, are explicable on a common basis:  The entering organic group, which always has an available pair of electrons, effects a homomolecular disproportionation of the dicobalt octacarbonyl into catalyst (II) ion and Co carbonyl anion according to the generalized equation:  12 B+3[Co(CO)₄]₂→2[Co(B)₄][Co(CO)₄]₂+8 CO, where B is a base in the Lewis sense.  The electrons necessary for the formation of the anion are secured at the expense of some of the Co.  Situations are also described in which these electrons are furnished by an external source.  The tendency to form the stable (rare-gas structure) Co carbonyl anion is probably the driving force for the reactions.