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

We have calculated structures and energetics of complexes of HOx (OH and HO2)with formaldehyde, acetaldehyde, and acetone. These open shell systems form more strongly bound complexes than their counterpart closed shell water complexes. Binding energies (D-0) for these complexes were as high as 8.9 kcal mol(-1) (HO2-CH3COCH3). The hydroperoxyl radical forms more strongly bound complexes than the hydroxyl radical. Likewise, for the organic molecules studied, the strength of binding energies is consistently acetone > acetaldehyde > formaldehyde. Vibrational frequencies are also calculated and some relationships between these and binding energies and geometries are discussed. These data may be useful when laboratory data is present for these complexes. Equilibrium constants for the formation of these complexes are also calculated. As a result of this, it is predicted that the strongest of these complexes, the hydroperoxyl radical-acetone complex, will exist in the atmosphere under certain conditions.