76514-88-0Relevant academic research and scientific papers
Oxygen transfer in the oxidation of triphenylphosphine by (bpy)2pyRuO2+
Moyer, Bruce A.,Sipe, B. Keith,Meyer, Thomas J.
, p. 1475 - 1480 (1981)
The oxidation of PPh3 by (bpy)2pyRuO2+ (bpy is 2,2′-bipyridine) has been studied in acetonitrile solution. The observation of (bpy)2pyRuIIO=PPh32+ as an intermediate demonstrates that the reaction proceeds via an initial redox step (bpy)2pyRuO2+ + PPh3 → (bpy)2pyRuIIO=PPh32+ which is followed by relatively slow (k(25°C) = 1.15 (±0.10) × 10-4 s-1) solvolysis: CH3CN + (bpy)2pyRuIIO=PPh32+ → (bpy)2pyRuCH3CN2+ + O=PPh3. From the results of an 18O-labeling experiment, oxygen transfer from RuIV=O to PPh3 is quantitative within experimental error. The kinetics of the redox step were studied by stopped-flow spectrometry. The reaction is first order in both reactants with k(26.6°C) = 1.75 ± 0.10 × 105 M-1 s-1. Activation parameters were calculated from the temperature dependence of the rate constant, an analysis of which gave ΔH? = 4.7 ± 0.5 kcal/mol and ΔS? = -19 ± 3 eu. The probable microscopic details of the reaction are discussed in terms of a 2-equiv step with strong electronic-vibrational coupling between the electron-donor (P) and -acceptor (Ru) sites through Ru-O and O-P stretching vibrations. The possible role of the spin change which occurs in the net reaction is discussed.
