Complexes of heterocyclic thiones and Group 12 metals: Part 3. Preparation and characterisation of 1:2 complexes of mercury(II) halides with 1-methylimidazoline-2(3H)-thione: the crystal structures of [(HgX2)(1-methylimidazoline-2(3H)-thione)2] (X=Cl, Br,

The stoichiometric addition (1:2 metal–ligand) of aqueous alcoholic solutions of the metal salts to similar solutions of 1-methyl-imidazoline-2(3H)-thione (1-meimz2SH) generated crystalline complexes of general formula, [HgX2(1-meimz2SH)2] (X=Cl, Br, I), in good yield. The chemical formulae of the complexes have been characterised by elemental chemical analysis. Infrared and 13C NMR spectra indicated the presence of the thione form of the heterocyclic ligands in the complexes, as well as their thione–sulfur ligating character. X-ray crystal structure analyses have been performed on the three complexes. The metal in the chloro complex occupies a crystallographic two-fold axis which bisects the SHgS angle. The bromo and iodo complexes occupy general positions, but one of the ligands is disordered in the bromo complex. All of the complexes are mononuclear with the four-coordinate metals possessing distorted tetrahedral geometry. The extent of the distortion is indicated by the angles at the metal which range from 93.71(7) to 127.73(7)°. Metal–sulfur distances range from 2.4514(14) to 2.571(3) Å. Metal–halogen distances range from 2.5984(13) Å (chloro) through 2.641(3) and 2.647(3) Å (bromo) to 2.7866(11) and 2.8047(9) Å (iodo). Hydrogen bonds, involving the thioamide hydrogen (NH) and halogen atoms are exclusively intramolecular in the chloro complex, but both intramolecular and intermolecular in the bromo and iodo complexes.