Energetics of the lighter chalcogen analogues of carboxylic acid esters

In the current paper we present the results of our quantum chemical (G2, G2(MP2), and G3) study of the structure and energetics of carboxylic acids and their chalcogen analogues. In the particular, calculations and accompanying natural bond orbital (NBO) and atoms in molecules (AIM) analyses were performed on all species with the generic formula RC(═X)YR' (X, Y = O, S, Se and R = R' = CH(3)). Energies, enthalpies, and free energies of formation, resonance energies, interchalcogen methyl transfer energies and their energies of activation, and heavy atom bond lengths and angles are all discussed. A comparison of the calculated results with the sparse experimentally available data shows good agreement. Trends are also presented.