Syntheses and crystal structures of three tri­phenyl­sulfonium halometallate salts of zinc, cadmium and mercury

The crystal structures of three salts of the C₁₈H₁₅S⁺ tri­phenyl­sulfonium ion are reported, namely, bis­(tri­phenyl­sulfonium) tetra­chloro­zinc(II), bis­(tri­phenyl­sulfonium) tetra­chloro­cadmium(II) and bis­(tri­phenyl­sulfonium) tetra­chloro­mercury(II) methanol monosolvate.

Bis(tri­phenyl­sulfonium) tetra­chlorido­zinc(II), (C₁₈H₁₅S)₂[ZnCl₄] (I), bis­(tri­phenyl­sulfonium) tetra­chlorido­cadmium(II), (C₁₈H₁₅S)₂[CdCl₄] (II), and bis­(tri­phenyl­sulfonium) tetra­chlorido­mercury(II) methanol monosolvate, (C₁₈H₁₅S)₂[HgCl₄]·CH₃OH (III), each crystallize in the monoclinic space group P2₁/n. In all three structures, there are two crystallographically independent tri­phenyl­sulfonium (TPS) cations per asymmetric unit, each adopting a distorted trigonal–pyramidal geometry about the S atom (S—C bond lengths in the 1.77–1.80 Å range and C—S—C angles of 100–107°). The [MCl₄]^2– anions (M = Zn²⁺, Cd²⁺, Hg²⁺) are tetra­hedral; their M—Cl bond lengths systematically increase from Zn²⁺ to Hg²⁺, consistent with the larger ionic radius of the heavier metal. Hirshfeld surface analyses show that H⋯H and H⋯C contacts dominate the TPS cation environments, whereas H⋯Cl and S⋯M inter­actions anchor each [MCl₄]^2– anion to two surrounding TPS cations. Weak C—H⋯Cl hydrogen bonds, as well as inversion-centered π–π stacking, generate layers in (I) and (II) and dimeric [(TPS)₂–HgCl₄]₂ assemblies in (III).