Structure and Reactivity of (PPh₄)₃[W(CN)₅O] ？ 7H₂O. Kinetics and Mechanism of the Reaction with Molecular Oxygen

Sa？etak The (PPh4)3[W(CN)5O] ？ 7H2O has been synthesised and structurally characterised by X-ray diffraction. In the solid state and in ethanol-acetone mixture, the salt reacts with molecular oxygen giving (PPh4)2[W(CN)4O(O2)]. The progress of the solid state reaction was followed by measuring infrared spectra. The integrated intensities of the W=O, O？O and C≡N bands changed with time according to the pseudo first-order kinetics. In solution, the kinetic measurements indicate that the rate law is of the form -d[complex]/dt = k[complex][O2]. The k value is equal to 5.78 (±0.26) mol-1 dm3 s-1 at 298 K. The activation parameters, ΔH？(k) and ΔS？(k), are 55 (±3) kJ mol-1 and -46 (±8) J K-1 mol-1, respectively. A reaction mechanism is proposed