Complexes of heterocyclic thiones and Group 12 metals: Part four. Preparation and characterisation of 1:1 complexes of mercury(II) halides with 1,3-thiazolidine-2-thione and 1,3-benzothiazoline-2-thione. Crystal structure of the discrete trans dimer [(μ-d

The addition of 1,3-thiazolidine-2-thione (tzdSH) or 1,3-benzothiazoline-2-thione (bztzSH) to mercury(II) halides in equimolar quantities in ethanolic solutions resulted in the formation of the 1:1 complexes LHgX2 (L=tzdSH, bztzSH; X=Cl, Br, I) which were characterised by elemental analysis. Spectroscopic evidence confirmed the exocyclic sulphur to be the donor atom in the thione form of the ligand and that the complexes were halogen bridged dimers. The X-ray structure of [(tzdSH)HgBr2]2 shows the molecule to be a centrosymmetric double halogen bridged dimer with distorted tetrahedral coordination geometry for Hg; secondary Hg⋯Br interactions link the molecules together into chains, and there are intramolecular N–H⋯Br hydrogen bonds between the heterocyclic ligands and the bridging bromides.