A theoretical study of the hydrogen bonding properties of H2BNH2: Some considerations on the basis set superposition error issue

The HB complexes formed by H2BNH2 with five small molecules that can act as hydrogen bond acceptors and donors have been theoretically studied. Three different kinds of complexes have been found to be minima: conventional hydrogen bonds, dihydrogen bonds and those with the π system of H2BNH2. The geometric, electronic and spectroscopic properties of these complexes have been characterized at the MP2/aug-cc-pVDZ computational level. Special attention has been taken on the Basis Set Superposition Error (BSSE) issue using the full counterpoise (CP) method. The interaction energies have been calculated at MP2/aug-cc-pVXZ (X = D, T, Q, and 5) levels with and without BSSE counterpoise correction. These values have been used to extrapolate to the Complete Basis Set (CBS) energy. The results indicate that for the MP2/aug-cc-pVDZ calculations, the smallest errors in the interaction energy are obtained by correcting the interaction energy with the corresponding half of the BSSE correction. For the remaining cases, the CP corrected interaction energies are closer to the CBS ones than to those without correction.