Kinetics and mechanism of the interaction of adenosine with cis‐diaqua(cis‐1,2‐diaminocyclohexane)platinum(II) perchlorate in aqueous medium |
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| Authors: | Parnajyoti Karmakar Subhasis Mallick Subala Mondal Biplab K Bera Arup Mandal Sudip K Mukhopadhyay Alak K Ghosh |
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| Institution: | 1. Department of Chemistry, The University of Burdwan, Burdwan 713 104, West Bengal, India;2. Department of Chemistry, Asansol B.B.College, Asansol 713 303, West Bengal, India |
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| Abstract: | The kinetics of the interaction of adenosine with cis‐Pt(cis‐dach)(OH2)2]2+ (dach = diaminocyclohexane) was studied spectrophotometrically as a function of cis‐Pt(cis‐dach)(OH2)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 ΔH≠1 (43.1 ± 1.3 kJ mol?1) and the large negative value of ΔS≠1 (?177 ± 4 J K?1 mol?1) along with ΔH≠2 (47.9 ± 1.8 kJ mol?1) and ΔS≠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 |
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