Ab initio and DFT Study of the Structural Properties and Thermochemistry of CH3S(O)2OONO2 Atmospheric Molecule and CH3S(O)2OO·Radical

摘要

The conformational properties of methanesulfonyl peroxynitrate,CH3S(O)2OONO2 (MSPN),and its radical decomposition products CH3S(O)2OO·and CH3S(O)2O·were studied by ab initio and density functional methods.The dihedral angle around the S-O and the O-O single bond are calculated to be -70.5° and -97.8°(B3LYP/6-311++G(3df,3pd)),respectively.The principal unimolecular dissociation pathways for MSPN were studied using complete basis set (CBS) methods.The reaction enthalpies for the channels CH3S(O)2OONO2→CH3S(O)2OO·+NO2 and CH3S(O)2OONO2→CH3S(O)2O·+NO3 were computed to be 111.0 and 140.9 kJ/mol,respectively.The enthalpies of formation at 298 K for MSPN and CH3S(O)2OO radical were predicted to be -358.2and -281.3 kJ/mol,respectively.