Experimental Evidence for the Existence of the HO₂−H₂O Complex

Complex formation in the interaction of HO 2 with H 2 O was studied using Fourier transform infrared absorption spectroscopy. Studies were carried out between 230 and 298 K in the presence of excess H 2 O. On the basis of measurements of HO 2 disappearance, equilibrium constants ( K c ) for the formation of the complex were determined to be 1.7 × 10 -16, 4.1 × 10 -17, and ≤4 × 10 -18 cm 3 molecule -1 at 230, 250, and 298 K, respectively. The enthalpy for the reaction forming the complex was determined to be −36 ± 16 kJ mol -1 . This is in good agreement with previous estimates made from kinetic measurements and theoretical calculations.