Competition and interplay between the lithium bonding and hydrogen bonding: R₃C···HY···LiY and R₃C···LiY···HY triads as a working model (R=H, CH₃; Y=CN, NC).

UMP2 calculations with aug-cc-pVDZ basis set were used to analyze intermolecular interactions in R3C···HY···LiY and R3C···LiY···HY triads (R=H, CH3; Y=CN, NC), which are connected via lithium and hydrogen bonds. To better understand the properties of these systems, the corresponding dyads were also studied. Molecular geometries and binding energies of dyads, and triads were investigated at the UMP2/aug-cc-pVDZ computational level. Particular attention was paid to parameters such as cooperative energies, and many-body interaction energies. All studied complexes, with the simultaneous presence of a lithium bond and a hydrogen bond, showed cooperativity with energy values ranging between −1.71 and −9.03 kJ mol−1. The electronic properties of the complexes were analyzed using parameters derived from atoms in molecules (AIM) methodology. Energy decomposition analysis revealed that the electrostatic interactions are the major source of the attraction in the title complexes.