Enhancing effects of π-hole tetrel bonds on the σ-hole interactions in complexes involving F2TO (T = Si, Ge, Sn)

Abstract

The bimolecular and termolecular complexes involving F2TO (T = Si, Ge, Sn) and XCN/BrY (X = H, Br, CH3, and PH2; Y = F, CN, OH, and H) were designed to form the π-hole tetrel bonds and different sorts of σ-hole interactions, to investigate the influence of π-hole tetrel bonds on the σ-hole interactions. The effect of π-hole tetrel bonds on the σ-hole interactions in three series HCN···F2TO···HCN, HCN···F2SiO···XCN, and HCN···F2SiO···BrY is reflected by the changes in geometry, interaction energy, and charge transfer. With the formation of π-hole tetrel bond, the VS, min value outside the oxygen atom of F2TO becomes more negative, resulting in a stronger σ-hole interaction. Comparing with the bimolecular complex, the σ-hole binding distance and binding angle in the corresponding termolecular complex changes a lot, with the formation of another tetrel bond. The σ-hole interaction energy is enhanced more than 100% in most of the complexes with the exception of HCN···F2SiO···BrCN. The enhancing effect is related to the strength of π-hole tetrel bond, but has no relationship with the strength of σ-hole interactions. In particular, the σ-hole tetrel bond between F2SiO and CH3CN varies from a weak tetrel bond in the bimolecular complex F2SiO···CH3CN to a moderate hydrogen bond in the termolecular complex HCN···F2SiO···CH3CN.