Mercury(II) compounds with 1,3-imidazole-2-thione and its 1-methyl analogue. Preparative and NMR spectroscopic studies. The crystal structures of di-mu-iodo-bis[iodo(1,3-imidazolium-2-thiolato-S)mercury(II)], bis[bromo(1,3-imidazolium-2-thiolato-S)]mercury(II) and bis[mu-(1-N-methyl-1,3-imidazole-2-thiolato-S)]mercury(II)

A series of mercury(II) compounds of the empirical formulae HgX2L, and HgX2 L2 (X = Cl-, Br-, I-, SCN-; L = imtH(2), meimtH; imtH(2) = 1,3-imidazole-2- thione, meimtH = 1-methyl-1,3-imidazole-2-thione) has been obtained by the reaction of mercury(II) salts and 1,3-imidazole-2-thione and 1-methyl-1,3-i midazole-2-thione, respectively. Mercury(II) acetate yields HgL2 complexes where L = imtH(-), meimt(-). The isolated compounds have been characterised by elemental chemical analysis, IR and H-1 and C-13 NMR spectroscopy. Comp lexation effects on chemical shifts in H-1 and C-13 spectra were shown to b e a reliable probe for distinguishing HgX2L and HgX2L2 complexes. In the fo rmer molecules the thione carbon (C-2) is shielded up to 3.0 ppm and the th ioamide protons (NH) are deshielded up to 0.5 ppm, as compared to the corre sponding atoms in the latter molecules. In all complexes the C-13 complexat ion shift at C-2 decreases with decreasing electronegativity of the halogen atom (X), indicating the corresponding increase in pi-character of the C-2 -S bond. The crystal structures of HgI2(imtH(2)), HgBr2(imtH(2))(2) and Hg( meimt)(2) have been determined by X-ray diffractometry and revealed S-bound imtH(2) in the iodo and bromo complex, while in Hg(meimt)(2) the ligand ac ts as bridging with stronger S and weaker N bonds. (C) 1999 Elsevier Scienc e S.A. All rights reserved.