Kinetic and Mechanistic Studies on the Reaction of DL-Methionine with [(H2O)(tap)2RuORu(tap)2(H2O)]2

The reaction has been studied spectrophotometrically; the reaction shows two steps, both of which are dependent on ligand concentration and show a limiting nature. An associative interchange mechanism is proposed. Kinetic and activation parameters (k1∼10−3s−1 and k2∼10−5s−1) and (ΔH≠1=13.8±1.3kJmol−1, ΔS≠1=−250±4JK−1mol−1, ΔH≠2=55.53±1.5kJmol−1, and ΔS≠2=−143±5JK−1mol−1) have been calculated. From the temperature dependence of the outer sphere association equilibrium constant, thermodynamic parameters (ΔH∘1=16.6±2.3kJmol−1 and ΔS∘1=95±7JK−1mol−1; ΔH∘2=29.4±3.2kJmol−1 and ΔS∘2=128±10JK−1mol−1) have also been calculated.