Kinetic and Mechanistic Studies on the Interaction of Adenosine with Diaquaethylenediamineplatinum(II) Ion

Abstract The kinetics of the interaction of adenosine with [Pt(en)(H2O)2]2+ has been studied spectrophotometrically as a function of [Pt(en)(H2O)2+], [Adenosine] and temperature at a particular pH (4.0) where the substrate complex exists predominantly as the diaqua species and the ligand adenosine as a neutral molecule. The interaction reaction shows distinct two step consecutive process; the first step is the ligand assisted anation and the second step is the chelation step. The activation parameters for both the steps are calculated (Δ H≠1 = 63.7 ± 1.6 kJ mol-1 ΔS1≠ = - 58± 5 JK -1 mol -1 and Δ H2≠ = 41.0 ± 0.5 kj mol -1 ΔS2≠ = 197 ± 1.5 JK1 mol-1 ).