Cobalt-containing compounds

Cyanide s binding to metallic ions is also employed in a reaction with cobalt-containing compounds that yields cyanocobalamin (see Section 2.6). Cobalt compounds generally are not used because of their toxicity however, Co2EDTA (Klimmek et al. 1983) and hydroxocobalamin (Benabid et al. 1987 Mengel et al. 1989 Mushett et al. 1952) have been used as antidotes both in clinical and laboratory trials. Cardiac toxicity from Co2EDTA use under clinical conditions has raised caution in its clinical use, as the cardiac... 

Vitamin B]2 is a red crystalline, cobalt-containing compound that can be isolated from the liver. It has a functional role in preventing pernicious anaemia and also serves as a coenzyme in hydrogen and methyl transfer reactions (Co appears to be the only metal in vivo catalyzing C transfer reactions O and N transfers are more common). Vitamin B12 is also a growth-promoting factor for several microorganisms. 

It is apparent from most of the examples previously described that the most common formal oxidation state found for the Group 14 element is E(IV) (E = Ge, Sn, Pb). Relatively few examples of divalent germanium, tin, or lead complexes have been described, and of these, many are not well characterized. Cobalt-containing compounds are no exception in this regard and there appears to be only one report in the literature that describes a species of this type, viz. [Ge Co(CO)4 2], 67, although the precise structure of this complex is unknown (77). Two main synthetic routes are described, Eqs. (4) and (S), the starting complex in the latter reaction being... 

Vitamin B12 is a biologically active corrinoid, a group of cobalt-containing compounds with macrocyclic pyrrol rings. Vitamin B12 functions as a cofactor for two enzymes, methionine synthase and L-methylmalonyl coenzyme A (CoA) mutase. Methionine synthase requires methylcobalamin for the methyl transfer from methyltetrahydrofolate to homocysteine to form methionine tetrahy-drofolate. L-methylmalonyl-CoA mutase requires adenosylcobalamin to convert L-methylmalonyl-CoA to succinyl-CoA in an isomerization reaction. An inadequate supply of vitamin B12 results in neuropathy, megaloblastic anemia, and gastrointestinal symptoms (Baik and Russell, 1999). 

The cobalt ion, which forms a stable metal complex with cyanide, is an effective therapeutic agent against cyanide poisoning (Evans, 1964 Hillman et al, 1974 Linell, 1987). Various cobalt-containing compounds known to antagonize cyanide poisoning are discussed below. 

Nitrite administration has been augmented by thiosulfate administration (intravenously) in the treatment of cyanide poisoning. Cobalt-containing compounds (e.g., cobalt chloride and cobalt ethylenediaminetetraacetate) have also been used to form complexes with cyanide, in... 

Here we report a eomparative study of catalytic properties of different type cobalt-containing compounds in alkene epoxidation by dioxygen in the presence of o-butyraldehyde (IBA) and provide some data, which allow us to clarify the reaction mechanism and the nature of the cafeilytic aetion of cobalt compounds. 

We examined catalytic properties of cobalt-containing compounds having different nature, namely, the simple salt, Co(N03)2-6H20, tetra-n-butylammonium salts of PWnCoO ... 

There is substantial literature on cobalt-containing compounds in which a carbon-cobalt bond is in an axial position trans to usually an N-donor ligand, with the four equatorial positions occupied by N-donors too. This coordination arrangement is present in adenosylcobalamin (AdoCbl, coenzyme B12) and in cyanocobalamin (CNCbl, vitamin B12). The trans N-donor is dimethylbenzimidazole (DMBz) attached to a nucleotide (Scheme 2). 

Snyder RD, Lachmann PJ (1989) Thiol involvement in the inhibition of DNA repair by metals in mammalian cells. Mol Toxicol 2 117-128 Steinhoff D, Mohr D (1991) On the question of a carcinogenic action of cobalt-containing compounds. Exp Pahtol 41 169-174 Stevens RG, Jones DY, Micozzi MS, Taylor PR (1988) Body iron stores and the risk of cancer. N Engl J Med 319 1047-1052... 

Values in parentheses are magnetie moments of the lanthanoid atoms in cobalt-containing compounds. These were ealculated on the assumption that the cobalt atoms in these compounds have the same /r p(Co) as in LujCoijP, U p(Co) = U4 tB. 

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