Comparison of tetrel bonds and halogen bonds in complexes of DMSO with ZF3X (Z = C and Si; X = halogen)

Abstract

A theoretical study of the complexes formed by dimethylsulfoxide (DMSO) with ZF₃X (Z = C and Si; X = halogen) has been performed at the MP2/aug-cc-pVTZ level. Three local minima were found on the potential surface of complex DMSO–ZF₃X, forming tetrel bonds and halogen bonds with O⋯Z and O⋯X contacts, respectively. The halogen-bonded complexes are more stable for CF₃X than for SiF₃X with an exception of CF₄, on the contrary, the tetrel-bonded complexes DMSO–SiF₃X are more stable than the analogues DMSO–CF₃X. The strength of the tetrel bonds in DMSO–CF₃X has a small dependence on the nature of the halogen atom, and DMSO–SiF₃X has an abnormal dependence on it. Surprisingly, the tetrel bond in DMSO–SiF₃X is stronger than that with an anion as the electron donor, exhibiting a partially covalent bond nature. A red shift was observed for the SO stretch vibration in most complexes, particularly in the tetrel-bonded complexes of DMSO–SiF₃X. The Z–X stretch vibration exhibits a red shift in the tetrel bond but an irregular shift in the halogen bond.