Mechanistic differences between 'reductive' and 'oxidative'heterolysis of metal-carbon #sigma# bonds

摘要

Volumes of activation, #DELTA#V, for the heterolysis reactions of copper complexes with metal-carbon #sigma# bonds, viz, [(H_2O)_5Cu~(III)-R]~(2-) (R == CH_2CO_2~- or CHCl_2~-) and [Lcu~(II)-R]~- (L = 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane; R = CH_2CO_2~-), were determined using high pressure pulse-radiolysis techniques. In addition, the volume of activation for the bimolecular decomposition of [Lcu~(II)-CH_3]~+ was determined. The results reveal the different roles of the solvent (water) in the transition states for oxidative and reductive heterolysis reactions.