Structural studies organocobalt complexes

Since the butenylcobalt complex was too unstable, the PMR spectrum of the allylcobalt complex was studied 21, 22) to obtain information on the structure of the organocobalt intermediates in these stereoselective reductions (20). This investigation indicated that a-bonded allylic complexes are in equilibrium with 7r-allylic complexes and cyanide ion, thus providing a rationale for the stereoselectivities observed in the reduction of butadiene and butenyl chlorides. 

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... 

Several nominally Co0 complexes containing chelated arsines are known and a recent study of the coordination of (174) to [Co2 C2 CF3 )2 (CO)6] resulting in structure (175)599 typifies organocobalt work in this area. 

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