Experiments in Bioinorganic Chemistry Current interest in the chemistry of vitamin BIZis high. We have developed two experiments involving a simple BIZ analogue that serve to illustrate the vitamin's reactivity. Potassium pentacyano cabalt(I1) is a five coordinate complex that catalyzes a variety of reactions,' including reductions, oxidations and group transfers. Two of these that are the same as ones in which vitamin B12 participates in biological systems are the oxidation of thiols to disulfides and the transfer of methyl groups t o metal ions.2 2R-S-H (CN),Co3-
+ Me1
-
(CN)8c~ LO1
R-S-S-R
(CN)&o-Me
+ HgCI,
-
MeHgCl
As the complex is easily made and oxygen can serve as the oxidizing agent, the first reaction can be readily demonstrated. The second reaction involves the synthesis of an intermediate followed hy product isolation by tlc, and should take two lab periods. This reaction offers an excellent opportunity to introduce radiochemical analysis into a lab program, as C-14 labeled methyl iodide is readily available. Detailed procedures for these experiments are available on request. 'Kwiatek, Jack, Catalysis Reuiews, I, 37 (1967). 2Halpern, J., and Mayer, J., J. Amer. Chem. Sac., 86,2311 (1964). Colgate University Hamilton, New York 13346
736 / Journal of Chemical Education
Walter A. Wolf
