Kinetics of the solvolysis of chloropenta-amminecobalt(III) ions in mixtures of water witht-butyl alcohol or with 2-methoxyethanol

✍ Scribed by Kamal H. Halawani; Cecil F. Wells

• Publisher: Springer
• Year: 1994
• Tongue: English
• Weight: 516 KB
• Volume: 19
• Category: Article
• ISSN: 0340-4285
• DOI: 10.1007/bf00139115

✦ Synopsis

As the transition state for the solvolysis of [Co(NH3)sC1] z + ions is known to have C1 ions in a situation closely similar to that in the bulk solvent, the kinetics of this solvolysis have been investigated for comparison in H20 with added cosolvents of low and high hydrophobicities. A linear variation of log(rate constant) with the reciprocal of the dielectric constant is found with the former, but not with the latter cosolvent. Maxima in the enthalpies and entropies of activation found using the more hydrophobic cosolvent appear at solvent compositions where extrema occur in the physical properties influenced by structural changes in the solvent. The application of a free energy cycle to the solvolysis in HeO and in the mixtures shows that the emergent solvated cobalt(III) ion in the transition state is more stabilised in the latter than [Co(NH3)sC1] z + with both cosolvents. The application of such a cycle to cases where the initial state is destabilised in the mixture is discussed.