Crystal structures of three salts of the tri-phenylsulfonium ion.

The reactions of tri-phenyl-sulfonium chloride ([TPS][Cl]) with various acids in methanol yield the corresponding salts tri-phenyl-sulfonium triiodide, C18H15S+·I3 - or [TPS][I3] (I), tri-phenyl-sulfonium perchlorate, C18H15S+·ClO4 - or [TPS][ClO4] (II), and tri-phenyl-sulfonium hexa-fluoro-phosphate, C18H15S+·PF6 - or [TPS][PF6] (III), as crystalline products. These crystals were structurally characterized by single-crystal X-ray diffraction. In all three compounds, the sulfur atom in the tri-phenyl-sulfonium cation adopts a distorted trigonal-pyramidal geometry. [TPS][I3] (I) and [TPS][PF6] (III) both crystallize in the space group P21/n, while [TPS][ClO4] (II) crystallizes in P21. The S-C bond lengths are comparable across the three salts, and the S-C-S bond angles are consistently between 102 and 106°. Hirshfeld surface analyses reveal that each structure is dominated by hydrogen-based inter-molecular contacts, supplemented by anion-specific inter-actions such as I⋯H in (I), O⋯H in (II), and F⋯H in (III). These contacts organize the ions into mono-periodic ribbon- or chain-like arrangements. No significant π-π stacking is observed.