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

Bis(tri-phenyl-sulfonium) tetra-chlorido-zinc(II), (C₁₈H₁₅S)₂[ZnCl₄] (<b>I</b>), bis-(tri-phenyl-sulfonium) tetra-chlorido-cadmium(II), (C₁₈H₁₅S)₂[CdCl₄] (<b>II</b>), and bis-(tri-phenyl-sulfonium) tetra-chlorido-mercury(II) methanol monosolvate, (C₁₈H₁₅S)₂[HgCl₄]·CH₃OH (<b>III</b>), each crystallize in the monoclinic space group <i>P</i>2₁/<i>n</i>. In all three structures, there are two crystallographically independent tri-phenyl-sulfonium (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 [<i>M</i>Cl₄]^2- anions (<i>M</i> = Zn²⁺, Cd²⁺, Hg²⁺) are tetra-hedral; 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⋯<i>M</i> inter-actions anchor each [<i>M</i>Cl₄]^2- anion to two surrounding TPS cations. Weak C-H⋯Cl hydrogen bonds, as well as inversion-centered π-π stacking, generate layers in (<b>I</b>) and (<b>II</b>) and dimeric [(TPS)₂-HgCl₄]₂ assemblies in (<b>III</b>).