Structure and Reactivity of (PPh 4 ) 3 [W(CN) 5 O] ⋅ 7H 2 O. Kinetics and Mechanism of the Reaction with Molecular Oxygen
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, H‡ (k) and S‡ (k), are 55 ( 3) kJ mol–1 and –46 ( 8) J K–1 mol–1, respectively. A reaction mechanism is proposed.