Sulfonium Cation [SF3]+ Complexes with Noble Gases

Abstract

Chalconium cations are powerful Lewis acids containing a hypervalent chalcogen atom.They are utilized in the field of organocatalysis and crystal engineering. In the current work the electrophilic force of these species has been examined under unfavorable conditions. A relatively weaker chalconium cation - the [SF₃]⁺ sulfonium species - from the [SF₃(NCCH₃)₂][SbF₆] fragment of the crystal structure, where it is partially neutralized by one anionic and two neutral entities, was selected, and its complexes with noble gas atoms, known for their poor reactivity, were modeled. In this manner, the set of three [SF₃(NCCH₃)₂Ng]⁺ and [SF₃(Ng)₂][SbF₆] complexes (Ng= Ar, Kr, Xe) was computed. The Ng atom was positioned in the place of anion (in [SF₃(NCCH₃)₂Ng]⁺) or neutral ligands (in [SF₃(Ng)₂][SbF₆]). The computations were performed in the simulation of solvent presence using the polarizable continuum model. The obtained tetramers were stable, true minima characterized by weak interaction energies between -2 and -1 kcal/mol. What is interesting, when the [SbF₆]^- anion was substituted by the noble gas atom, the interaction energy was significantly weakened compared to the full [SF₃(NCCH₃)₂][SbF₆] system and its nature changed from electrostatic to dispersive. A comparable scenario was observed when the NCCH₃ ligands were replaced with two noble gas atoms.