Aqua cobaloxime

In the yS-CyD complex with platinum phosphine [220], the trimethylphosphine ligand is bound at the primary hydroxyl side of the fi-CyD cavity. On the other hand, alkyl ligands, i-butyl, -butyl, -hexyl, and cyclohexyl groups of alkyl(aqua)-cobaloximes are inserted into the cavity from the secondary hydroxyl side [221-224]. The channel cavity formed by fi-CyD dimers includes diaqua(benzoate)-hydroxydioxouranium(VI). Two benzoate moieties are inserted into the dimer cavity and the U(VI) atom is located at the primary hydroxyl side without direct contact with the host molecule [225]. 

A spectrophotometric study of the substitution of the aqua ligand in aqua-cobaloximes, shown in equation (45) (where DH = dimethylglyoxime), yields... 

Recrystallization from water/acetone (even at a basic pH) causes some hydrolysis of the acetal. (2,2-Diethoxyethyl)cobalamin, like all alkyl cobalamins, is light sensitive in solution in addition, and unlike most other alkylcobalamins, it is add sensitive, decomposing to both (formylmethyl)cobalamin and aqua-cobalamin.2 The formation of other alkylcobalamins and cobaloximes by reaction with enol ethers has been described.2... 

Fig. 7.23. Structure of the -CyD complex with aqua(n-butyl)cobaloxime.

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