Kinetics and mechanism of the interaction of adenosine with cis-diaqua(cis-1,2-diaminocyclohexane)platinum(II) perchlorate in aqueous medium

✍ Scribed by Parnajyoti Karmakar; Subhasis Mallick; Subala Mondal; Biplab K. Bera; Arup Mandal; Sudip K. Mukhopadhyay; Alak K. Ghosh

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 228 KB
• Volume: 43
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20549

✦ Synopsis

Abstract

The kinetics of the interaction of adenosine with cis‐[Pt(cis‐dach)(OH~2~)~2~]^2+^ (dach = diaminocyclohexane) was studied spectrophotometrically as a function of [cis‐[Pt(cis‐dach)(OH~2~)~2~]^2+^], [adenosine], and temperature at a particular pH (4.0), where the substrate complex exists predominantly as the diaqua species and the ligand adenosine exists as a neutral molecule. The substitution reaction shows two consecutive steps: the first is the ligand‐assisted anation followed by a chelation step. The activation parameters for both the steps have been evaluated using Eyring equation. The low negative value of Δ__H__^≠^~1~ (43.1 ± 1.3 kJ mol^−1^) and the large negative value of Δ__S__^≠^~1~ (−177 ± 4 J K^−1^ mol^−1^) along with Δ__H__^≠^~2~ (47.9 ± 1.8 kJ mol^−1^) and Δ__S__^≠^~2~ (−181 ± 6 J K^−1^ mol^−1^) indicate an associative mode of activation for both the aqua ligand substitution processes. The kinetic study was substantiated by infrared and electrospray ionization mass spectroscopic analysis. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 219–229, 2011