S-OO bond dissociation energies and enthalpies of formation of the thiomethyl peroxyl radicals CH3S(O)nOO (n=0,1,2)

Abstract

Optimized geometries, S-OO bond dissociation energies and enthalpies of formation for a series of thiomethyl peroxyl radicals are investigated using high level ab initio and density functional theory methods. The results show that the S-OO bond dissociation energy is largest in the methylsulfonyl peroxyl radical, CH 3 S(O) 2 OO, which contains two sulfonic type oxygen atoms followed by the methylthiyl peroxyl radical, CH 3 SOO. The methylsulfinyl peroxyl radical, CH 3 S(O)OO, which contains only one sulfonic type oxygen shows the least stability with regard to dissociation to CH 3 S(O)+O 2 . This stabilization trend is nicely reflected in the variations of the S-OO bond distance which is found to be shortest in CH 3 S(O) 2 OO and longest in CH 3 S(O)OO.