| Abstract: | The kinetics of the interaction of L ‐asparagine with Pt(ethylenediamine)(H2O)2]2+ have been studied spectrophotometrically as a function of Pt(ethylenediamine)(H2O)22+], 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 ΔH1≠ (43.59 ± 0.96 kJ mol?1) and large negative values of ΔS1≠ (?116.98 ± 2.9 J K?1 mol?1) as well as ΔH2≠ (33.78 ± 0.51 kJ mol?1) and ΔS2≠ (?221.43 ± 1.57 J K?1 mol?1) indicate an associative mode of activation for both the aqua ligand substitution processes. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 252–259, 2003 |
