Theoretical study of the HXYH dimers (X, Y = O, S, Se). Hydrogen bonding and chalcogen-chalcogen interactions

A theoretical study of the HXYH (X, Y = O, S and Se) monomers and dimers has been carried out by means of MP2 computational methods. For the monomers, isomerization (H2X = Y//HXYH) and rotational transition state barriers have been calculated. Additionally, the molecular electrostatic potential of the isolated monomers has also been analysed. Due to the chiral nature of these compounds, homo and heterochiral dimers have been explored. The number of minima found for the dimers range between 13 and 22. The electron density of the complexes has been characterized with the Atoms in Molecules (AIM) methodology finding a large variety of interactions. The DFT-SAPT method has been used to analyse the components of the interaction energies. Concerning chalcogen-chalcogen interactions, although the most stable minima are formed through hydrogen bonds (especially if OH groups are present in the molecules) as the size of the atoms involved in the interaction increase, the chalcogen-chalcogen contacts become more important.