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, I) at 160 K

The stoichiometric addition (1:2 metal-ligand) of aqueous alcoholic solutio ns of the metal salts to similar solutions of 1-methyl-imidazoline-2(3H)-th ione (1-meimz2SH) generated crystalline complexes of general formula, [HgX2 (1-meimz2SH)(2)] (X = Cl, Br, I), in good yield. The chemical formulae of t he complexes have been characterised by elemental chemical analysis. Infrar ed and C-13 NMR spectra indicated the presence of the thione form of the he terocyclic ligands in the complexes, as well as their thione-sulfur ligatin g character. X-ray crystal structure analyses have been performed on the th ree 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 met als possessing distorted tetrahedral geometry. The extent of the distortion is indicated by the angles at the metal which range from 93.71(7) to 127.7 3(7)degrees. Metal-sulfur distances range from 2.4514(14) to 2.571(3) Angst rom. Metal-halogen distances range from 2.5984(13) Angstrom (chloro) throug h 2.641(3) and 2.647(3) Angstrom (bromo) to 2.7866(11) and 2.8047(9) Angstr om (iodo). Hydrogen bonds, involving the thioamide hydrogen (NH) and haloge n atoms are exclusively intramolecular in the chloro complex, but both intr amolecular and intermolecular in the bromo and iodo complexes. (C) 2000 Els evier Science S.A. All rights reserved.