Influence of solvent structure on the aquation of K-chloro(diethylenetriamine)(ethylenediamine) cobalt(III) ion in water and mixed aqueous solvents

✍ Scribed by Gehan M. El-Subruiti; Aziza K. Chehata; Salah S. Massoud

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 146 KB
• Volume: 34
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.1056

✦ Synopsis

Abstract

The aquation of K‐[Co(dien)(en)Cl]^2+^ was followed spectrophotometrically within the temperature range (40–60°C) in water, water–isopropyl alcohol, and water–tert‐butyl alcohol media of varying solvent composition up to 50 and 60 vol% of the organic solvent component respectively. The nonlinear plot of log k vs. D^−1^~s~ was attributed to the differential solvation of the initial and transition states. The variation of Δ__H__^≠^, Δ__S__^≠^, and Δ__G__^≠^ with the mole fraction of the organic component was analyzed and discussed. The isokinetic temperatures were found to be 330 and 317 K for water–isopropyl alcohol and water–tert‐butly alcohol mixtures respectively, indicating that the aquation reaction is entropy controlled. The application of free energy cycle at 25°C for the aquation reaction in both co‐solvents suggests that the transition state is more stable than the initial one. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 1–6, 2002