Organocobalt complexes corrinoids

Only one optically active simple organocobalt complex has so far been reported, namely [RCo(DMG)2py], where R is the optically active 1-methylheptyl ligand 55). All cobalt corrinoids, where the ring has been... 

Certain groups of organocobalt(III) complexes have been dealt with in previous reviews. The organo-corrinoids have been mentioned in all reviews on vitamin B, 2 since 1961, when the coenzyme form was identified as an organometallic compound [see, for example, (79, 178) and references therein]. The literature on the corrinoids is too extensive to be treated comprehensively here and for details and references readers are referred to the book on The Inorganic Chemistry of Vitamin B,2 (136)certain other aspects of the organometallic chemistry of cobalt corrinoids are treated elsewhere (137). The pentacyanides were reviewed in 1967 (105), the DMG complexes (cobaloximes) in 1968 (145), and some aspects of salen, BAE, and related complexes in 1970 (17). 

The organo-corrinoids show similar behavior, but also additional complications. Rate constants have been determined 84) for the attack of mercury(II) acetate on various organocobalt cobinamides (X = H2O or absent) and cobalamins (X = 5,6-dimethylbenziminazole). The first complication, which has to be born in mind when comparing the cobinamides with the cobalamins or DMG complexes, is that the organocobin-amides are partly (R = vinyl and methyl) or wholly (R = Et, -Pr, t-Pr,... 

Although the cobalt corrinoids have been studied extensively in. the last two decades (J), the significance of corrin as an equatorial ligand is not well understood. To characterize coenzyme B12 as an organocobalt derivative, a search for model cobalt complexes that can form a Co-C bond axial to a planar equatorial ligand has been stimulated. Studies on model systems (2-13), particularly on the cobaloxime derivatives (2-7), characterized their respective chemistry, but it is still not easy to establish a general correlation between the structure of an equatorial ligand and the properties of cobalt complex... 

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