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

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 1.77-1.80Å 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).