Effect of solvent on the reactions of coordination complexes .22. Kinetics of base hydrolysis of some (aminomonocarboxylato)(tetraethylenepentamine)cobalt(III) complexes in acetonitrile-water media: The role of solvent basicity and solvent structure

The base of hydrolysis of [(tetren)CoO2CR](2+) {R = NH2CH2-, NH2[CH2](2), pyridine-2-(alpha beta S isomer), NH2CH(CH3)-(alpha beta S and alpha beta R isomers); tetren =tetraethylenepentamine} is accelerated by acetonitrile+water media (0 less than or equal to X(AN)less than or equal to 0.578 X-AN = mole fraction of acetonitrile) owing to the combined effects of destabLIisation of OH-, relatively greater destabilisation of the transition state of the amido conjugate base [((tetren)-H)Co2+...-O,CR](++) as compared to that of the initial state [(tetren)CoO2CR](2+), and solvent structure; the activation enthalpies and entropies are also sensitive to solvent structure and conformational arrangement of the tetren ligand.