STRUCTURAL CHARACTERIZATION OF MERCURY(II) COMPOUNDS WITH HETEROCYCLIC 2-THIONE DONORS
Zora Popovic, Zeljka Zugaj, Dubravka Matkovic-Calogovic and Gordana Pavlovic
Laboratory of General and Inorganic
Chemistry, Chemistry Department, Faculty of Science, University
of Zagreb, Ulica kralja Zvonimira 8, HR-10000 Zagreb, Croatia
Keywords:Crystal structures; Mercury(II)
compounds; 1,3-Imidazoline-2-thione;
1-Methyl-1,3-imidazoline-2-thione.
Mercury(II) ion is highly toxic to many organisms due to high affinity of this ion for thiols in a variety of proteins and enzymes. The adducts formed inactivate these essential thiols in many biological processes.1,2 Furthermore, many species resulting from metabolic processes react with Hg(II) ion giving adducts which are also toxic. Detoxyfication mechanisms of the last species in bacterial systems imply the use of enzymes that catalyze hydrolytic reactions of metal ion-molecules bonds.1 In order to a good understanding of the nature of these hydrolytic processes, the research of the reactivity of Hg(II) with biological analogue molecules, including the nature of the bonds formed, the stability of the adducts and their structure seems to be very ineteresting.
Concerning that we have prepared the series of compounds HgX2L and HgX2L2 (X = Cl-, Br-, I-, SCN-; L = imtH2, meimtH; imtH2 = 1,3-imidazoline-2-thione; meimtH = 1-methyl-1,3-imidazoline-2-thione) . Mercury(II) acetate forms HgL'2 (L' = imtH-, meimt-). By the X-ray diffractometry the crystal structures of the HgBr2(meimtH) (1), HgBr2(meimtH)2 (2) and Hg(meimt)2 (3)3 were determined.
Crystal Data for: HgBr2(meimtH) (1), Mr = 474.57, monoclinic,, space group P 21/c, a = 7.708(3), b = 14.584(1), c = 8.814(2) A, b = 101.78(3), Z = 4, V = 969.9(4) A3, Dcalc. = 3.25 gcm-3 , m = 245.5 cm-1, l(MoK) = 0.7107 A, R1 = 0.50, wR = 0.098 for 1125 reflections with (Inet) >= 2s (Inet). HgBr2(meimtH)2 (2), Mr = 588.73, orthorombic, space group P bcn, a = 26.879(3), b = 11.645(1), c = 9.811(1) A, Z = 8, V = 3070.9(5) A3 , Dcalc. = 2.55 gcm-3, m = 15.4 mm-1, l(MoK) = 0.7107 A, R = 0.11, RW = 0.156, S = 1.11 for 989 reflections with (Inet) >= 2s (Inet)
The dimeric nature of the molecule 1 is established by X-ray crystal structure determination. Two mercury atoms bridged over two bromide ions at the slightly different distances Hg-(-Br) of 2.801(2) and 2.843(2) A. In theirs seemingly tetrahedral coordination with bond angles about mercury being in the range 90.35(5) - 139.1(8)o there are also two terminal atoms i.e. a bromide ion and sulfur atom. Terminal Hg-Br bond length of 2.488(2) A as well as Hg-S distance of 2.408(9) A are in agreement with the values previously observed in analogous compounds. The C-N distances in the thioamido moiety are characteristically shorter (1.30(2), 1.35(2) A).The preliminary crystallographic investigations on 2 shows that the crystal structure is built up of discrete molecules. Mercury atom is tetrahedrally surrounded with two bromine atoms with Hg-Br distances of 2.651(5) and 2.634(7) A, and two sulfur atoms at the distances of 2.544(12) and 2.480(13) A with angles from 105.7(3) - 111.5(4)o. Crystal structure analysis is still in progress.
HgBr2(meimtH)