Complexes of hydroxyl and hydroperoxyl radical with formaldehyde, acetaldehyde, and acetone

We have calculated structures and energetics of complexes of HOx (OH and HO 2)with formaldehyde, acetaldehyde, and acetone. These open shell systems fo rm more strongly bound complexes than their counterpart closed shell water complexes. Binding energies (D-0) for these complexes were as high as 8.9 k cal mol(-1) (HO2-CH3COCH3). The hydroperoxyl radical forms more strongly bo und complexes than the hydroxyl radical. Likewise, for the organic molecule s studied, the strength of binding energies is consistently acetone > aceta ldehyde > formaldehyde. Vibrational frequencies are also calculated and som e relationships between these and binding energies and geometries are discu ssed. These data may be useful when laboratory data is present for these co mplexes. Equilibrium constants for the formation of these complexes are als o calculated. As a result of this, it is predicted that the strongest of th ese complexes, the hydroperoxyl radical-acetone complex, will exist in the atmosphere under certain conditions.