The Electronic Mechanism Ruling the Dihydrogen Bonds and Halogen Bonds in Weakly Bound Systems of H3SiH···HOX and H 3SiH···XOH (X = F, Cl, and Br)

The dihydrogen bond complexes (H3SiH∙∙∙HOX) and halogen bond complexes (H3SiH∙∙∙XOH) formed between SiH4 and hypohalous acids HOX (X = F, Cl, and Br) have been studied at the MP2/6-311++G(2d,2p) computational level. The analyses of structure and infrared vibration frequencies have revealed tendencies in the red shifts and blue shifts of the stretch frequencies of the Si-H, H-O, and O-X bonds. Besides the computation of the interaction energies, punctual atomic charges and charge transference amounts were determined at light of the Natural Bond Orbital (NBO) approach, by which the quantifications of the s- and p-characters of hydrogen, oxygen, and silicon also were useful to unveil the frequency shifts aforementioned. With the purpose to elucidate the donor/acceptor interface along the charge transfer mechanism between the dihydrogen bonds and halogen bonds, the application of the hierarchical cluster analysis (HCA) and principal component analysis (PCA) chemometric techniques were useful in this regard. Moreover, the interaction strengths of the H3SiH∙∙∙HOX and H3SiH∙∙∙XOH complexes was computed through a model that embodies the frequency shifts and topological parameters derived from quantum theory of atoms in molecules (QTAIM).