Ab initio characterization of ClOOH: Implications for atmospheric chemistry

The equilibrium structure, dipole moment, harmonic vibrational frequencies, and infrared intensities of ClOOH are determined using the CCSD(T) (singles and doubles coupled-cluster theory plus a perturbational estimate of the effects of connected triple excitations) electronic structure method in conjunction with a TZ2P (triple ζ plus double polarization) basis set. The heat of formation of ClOOH is determined (using two different isodesmic reactions) to be +1.5 ± 1 kcal/mol at 0 K or +0.2 ± 1 kcal/mol at 298.15 K. Using the computed heat of formation, we examined the stability of ClOOH with respect to the ClO + OH, ClOO + H, and HOO + Cl dissociation limits. Since ClOOH is found to be quite stable, it is argued that the chemistry of ClOOH should be included in any accurate modeling of the stratosphere.