Theoretical study of diminutive and cooperative effects in triad C4B2H6(HF)2 complexes

Noncovalent dimer and trimer adducts obtained from interaction of nido-C4B2H6 with one and two HF molecules were investigated at MP2/aug-cc-pVTZ computational method. In the trimer adducts, two types of geometrical structures were observed. In one kind, no interaction occurred among HF molecules, while in the other ones HF molecules affected the cluster’s stabilities through their hydrogen bonding. The most stable dimer and trimer complexes were related to those structures in which HF molecules had interaction with C4B2H6 from its basal plane. In the trimer complexes, structure, energy, and the spectral characteristics of C4B2H6–HF dimers were significantly influenced by type of its interaction with secondary HF molecule. The interaction energies illustrated weak diminutive and cooperative effects repeatedly. The most stable complexes displayed cooperative effects, while the most unstable ones displayed diminutive effects. Quantum Theory of Atoms in Molecules (QTAIM) was used to investigate and analyze the essence and types of intermolecular interaction in optimized complexes.