Energy Analysis of Competing Non-Covalent Interaction in 1: 1 and 1: 2 Adducts of Collidine with Benzoic Acids by Means of X-Ray Diffraction

The hydrogen bond pattern and the types of non-covalent interactions in the crystals of the 1: 1 and 1: 2 adducts of 2,4,6-trimethylpyridine and benzoic acids are studied using high-resolution X-ray diffraction. The geometries of the hydrogen bonds are estimated using a combined XRD/DFT approach that provides the geometrical parameters within the margin of error of neutron diffraction studies. The energies of the non-covalent interactions are estimated on the base of the experimental electron density distribution function. It is shown that the structures of the adducts are governed by the NOH and OHO hydrogen bonds. In turn, C H...O contacts and stacking interactions define the packing of the adducts in the crystal. On the other hand, it is important to note that the latter interactions affect the competition of the former hydrogen bonds in some 1: 2 adducts.