Reaction Rates of Xenon Fluorides with Oxides of Nitrogen

The rate of reaction of XeF4 and XeF2 with NO and with NO2 has been studied between 300° and 350°K at pressures between 0.1 and 30 mm. The second‐order rate constant at 300°K and the activation energies are, respectively: XeF4+NO, 3 liters/mole sec, 7 kcal/mole; XeF2+NO, 0.3 liters/mole sec, 10 kcal/mole. The rate of NO2 with XeF4 and XeF2 was too slow to observe, k<0.01 liter/mole sec. The fluorides of xenon react with the oxides of nitrogen much more slowly than F2 reacts with NO or NO2. By means of a Polanyi—Semenov plot, the reactions of XeF4, XeF2, and F2 with oxides of nitrogen were combined to give an estimate of the successive dissociation energies of XeF4, which are (kcal/mole): XeF4→XeF3+F, 48; XeF3→XeF2+F, 15; XeF2→XeF+F, 54; XeF→Xe+F, 11. From these kinetic and thermochemical data a strong case can be made for the stepwise reduction of XeF4.