Kinetics of substitution of aqua ligands from cis-diaqua (ethylenediamine)platinum(II) perchlorate by L-asparagine in aqueous medium

✍ Scribed by Sujit K. Bera; Swapan K. Chandra; Gauri S. De

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 116 KB
• Volume: 35
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.10114

✦ Synopsis

The kinetics of the interaction of L-asparagine with [Pt(ethylenediamine)(H 2 O) 2 ] 2+ have been studied spectrophotometrically as a function of [Pt(ethylenediamine)(H 2 O) 2 2+ ], [L-asparagine], and temperature at pH 4.0, where the substrate complex exists predominantly as the diaqua species and L-asparagine as the zwitterion. The substitution reaction shows two consecutive steps: the first step is the ligand-assisted anation and the second one is the chelation step. Activation parameters for both the steps have been calculated using Eyring equation. The low H 1 = (43.59 ± 0.96 kJ mol -1 ) and large negative values of S 1 = (-116.98 ± 2.9 J K -1 mol -1 ) as well as H 2 = (33.78 ± 0.51 kJ mol -1 ) and S 2 = (-221.43 ± 1.57 J K -1 mol -1 ) indicate an associative mode of activation for both the aqua ligand substitution processes.