Reactivity properties of the HOSO and HSO2 isomers in liquid medium: a sequential Monte Carlo/quantum mechanics study

Context The rationalization of acid rain formation steps is fundamental for mitigating its effects. It is believed the hydroxysulfinyl radical is an intermediate species for the production of atmospheric sulfuric acid. Two stable configurations HOSO and HSO2 have been reported for such a radical in the gas phase. This work aims at studying these isomers in the aqueous medium. The electrical and reactivity quantities- electronic chemical potential (mu), chemical hardness (eta), and electrophilicity (epsilon)are here calculated and compared. Considering first solvation shells (15H(2)O for HSO2 and 23H(2)O for HOSO), an increase of 25% in the dipole moment of HSO2 was obtained, while the dipole moment of HOSO decreases in 11%. Both solvated isomers grow softer (eta decreases) contrasted to the gas phase. Methods HOSO and HSO2 are studied through a sequential Monte Carlo/quantum mechanics approach. Lennard-Jones plus the Coulomb potentials were used to represent intermolecular potential interaction in the frame of the DICE package. Molecular structure calculations were performed at CASPT2/aug - cc - pV(T + d)Z level of theory using theMOLPRO suite of programs.