Cobalt II cobaloximes

Much of the recent literature relates to BF2-bridged Co cobaloximes based on dimethyl (89) or diphenyl glyoxime (104). ° The BF2-bridged cobaloximes (e.g. 89) show greater stability to hydrolysis than analogous H-bridged species e.g. 88). The diphenylglyoxime complexes (104) show enhanced air and hydrolytic stability 

The activity in MMA polymerization can be dramatically affected by the apical ligands. Apical aquo or alcohol ligands are labile and rapidly exchange with the polymerization medium. Lewis base ligands (e.g. pyridine, triphenyl phosphine) are comparatively stable. In MMA polymeri/ation, it is found that activity increases with the basicity of the ligand. With alkyl Co complexes, a different order is found possibly because the type of apical ligand also controls the rate of initial generation of the active Co complex. 

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