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The Hg atom in the title monomeric complex, di­chloro­bis(3-imidazolium-2-thiol­ato-S)­mercury(II), [HgCl2(C3H4N2S)2], is four-coordinate having an irregular tetrahedral geometry composed of two Cl atoms [Hg—Cl 2.622 (2) and 2.663 (2) Å] and two thione S atoms [Hg—S 2.445 (2) and 2.462 (2) Å]. The monodentate thione ligand adopts a zwitterionic form and exists as the 3-imidazolium-2-thiol­ate ion. The bond angle S1—Hg—S2 of 130.87 (8)° has the greatest deviation from ideal tetrahedral geometry. Intermolecular hydrogen bonds between two of the four N—H groups and one of the Cl atoms [3.232 (8) and 3.238 (7) Å] stabilize the crystal structure, while the other two N—H groups contribute through the formation of N—H...Cl intramolecular hydrogen bonds with the other Cl atom [3.121 (7) and 3.188 (7) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199013736/na1432sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270199013736/na1432Isup2.hkl
Contains datablock I

CCDC reference: 140945

Comment top

The current interest in the coordination chemistry of mercury(II) complexes containing an exocyclic thione (thioketo) group on a heterocyclic molecule which may contain nitrogen, oxygen or sulfur or a combination of these is related to mercury–cysteine thionate interactions in the toxicological behaviour of mercury (Cheesman et al., 1988), in detoxification of the mercury by metallothioneins (Nielsen et al., 1985), in a DNA-binding protein (Dance, 1986), and in mercury reductase and related proteins (Blower & Dillworth, 1987). Deprotonated heterocyclic thiones, i.e. heterocyclic thionates, are ambidentate ligands with exocyclic S or thioamido N donating atoms. The coordination mode depends on the nature of the metal centre, hence N-donor atoms are found in Zn complexes, while in mercury(II) complexes, the S atom is undoubtedly the expected ligating site for Hg2+ (Raper, 1996; Popović, Matković-Čalogović, Hasić & Vikić-Topić, 1999; Popović, Matković-Čalogović, Soldin et al., 1999). The structural identification of mercury(II) complexes with thione ligands has, in the past, relied largely on spectroscopic methods such as IR and 13C NMR (Shunmugam & Sathyanarayana, 1983). The crystal structure of the free ligand is not known, but its hemihydrate (Raper et al., 1984), as well as its alkyl and aryl derivatives (Form et al., 1976; Raper et al., 1983; Ansell, 1972) or even its saturated analogoue imidazolidine-2-thione (Wheatley, 1953), have been examined. Mercury(II) complexes with 1,3-imidazole-2-thione derivatives and corresponding halides show different HgX2 and L ratios that can be deduced as: HgX2.L and HgX2.L2 [X = halide or pseudo-halide ions; L = imtH2 (1,3-imidazole-2-thione) or meimtH (1-methyl-1,3-imidazole-2-thione)] or HgL2 (L = imtH or meimt), depending dominantly on the stoichiometry of the reactants, pH and the coordination ability of the ligand. The structural diversity is present too, i.e. the complexes may be discrete (Popović, Matković-Čalogović, Soldin et al., 1999), dimeric (Raper et al., 1998; Popović, Matković-Čalogović, Soldin et al., 1999) or polymeric (Popović, Matković-Čalogović, Soldin et al., 1999), reflecting the character of Hg—L and Hg—X interactions. In the context of our previous work on mercury(II) complexes with heterocyclic thiones (Popović, Matković-Čalogović, Hasić & Vikić-Topić, 1999; Popović, Matković-Čalogović, Soldin et al., 1999), the crystal and molecular structure of [HgCl2(imtH2)2], (I), is reported here.

The molecule (Fig. 1) is built up of a monomeric HgCl2 unit [Hg—Cl1 2.622 (2) Å and Hg—Cl2 2.663 (2) Å], with two thione ligands coordinated to the Hg atom via the S atom [Hg—S1 2.445 (2) Å and Hg—S2 2.462 (2) Å] in a distorted tetrahedral environment. The smallest and largest bond angles around the Hg atom are S2—Hg—Cl2 101.07 (7)° and S1—Hg—S2 130.87 (8)°. The Hg—Cl distances are longer than the sum of the covalent radii for Cl and tetrahedrally coordinated Hg atoms (0.99 and 1.48 Å, respectively; Pauling, 1960; Grdenić, 1965). The contribution of the Cl atoms in intramolecular and intermolecular hydrogen-bond formation makes the Hg—Cl bond lengths elongated to some extent. A similar value is found in the structure of dichlorobis(6-merkaptopurine)mercury(II) [2.622 (3) Å; Lavertue et al., 1976]. The reason for such elongation is probably also the existence of N—H···Cl hydrogen bonds. The Hg—S distances are shorter than the sum of the covalent radii of S and tetrahedral Hg (2.52 Å; Pauling, 1960; Grdenić, 1965), indicating that the thione ligand forms a strong covalent bond to Hg. The structural comparison with other analogous mercury(II) complexes is quite difficult due to possible secondary interactions between Hg and halogen atoms. Despite this, there are a few monomeric tetrahedral mercury(II)–chloride complexes that contain sulfur bound to mercury. The S atom in those complexes exists in chemically different environments. The Hg—S values vary between 2.417 (3) Å in the structure of dichlorobis(thiosemicarbazide)mercury(II) (Chieh, 1977) and 2.536 (6) Å in bis(N,N'-dimethylthioformamide)mercury(II) (Stålhandske et al., 1997). Similar S—Hg distances to those in (I) are found in mercury(II) chloride complexes of the N,N'-diethyl and N-ethyl imidazolidine-2-thione derivatives (Hg—S 2.42–2.50 Å; Cannas et al., 1981), while in the [(µ2-dibromo)bis(trans{(bromo)(1-methyl-imidazoline-2(3H)-thione)}- mercury(II))] complex (Raper et al., 1998), the Hg—S values are slightly shorter [range 2.405 (4)–2.419 (4) Å]. The S—C bond distances, retaining appreciable double-bond character [S1—C11 1.709 (8) Å and S2—C21 1.717 (9) Å], suggest, along with endocyclic bond-distance values, the zwitterionic nature of the ligand (Allen et al., 1987). The dihedral angle between the two imidazole ring planes amounts to 12.5 (3)°. Such spatial orientation of the imidazole rings is a consequence of the crystal packing of the complex molecules. There are two intramolecular N—H···Cl hydrogen bonds of 3.121 (7) and 3.188 (7) Å (Table 2). Discrete title complex molecules, held together by intermolecular N—H···Cl hydrogen bonds form infinite puckered sheets perpendicular to the z axis (Fig. 2 and Table 2). The shortest intermolecular mercury-to-halogen distance of 3.581 (2) Å exists between the Hg and Cl1 atoms, and is longer than the sum of the van der Waals radii for Hg and Cl (3.20–3.36 Å; Matković-Čalogović, 1994; Nyburg & Faerman, 1985).

Experimental top

The title compound was prepared as described elsewhere (Popović, Matković-Čalogović, Soldin et al., 1999). Crystals suitable for X-ray analysis were formed from a dilute ethanol solution of mercury(II) chloride and the thione ligand in a 1:2 molar ratio at room temperature after standing for several days (yield: 89%). The title compound was characterized by IR spectroscopy and elemental analysis (calculated for C6H8Cl2HgN4S2: C 15.28, H 1.71, Hg 42.54, N 11.88, S 13.57%; found: C 15.89, H 2.44, Hg 42.65, N 11.92, S 13.59%; m.p. 478 K). IR (cm−1): 3298 (s), 3250 (s), 3190 (s), 3131 (s, sh), 2981 (m), 2859 (m), 2625 (m), 1583 (versus), 1477 (versus), 1430 (sh), 1404 (s), 1282 (m), 1227 (m), 1122 (m), 1104 (w), 1077 (s), 955 (m), 918 (m), 746 (s), 739 (s), 683 (s), 666 (versus), 491 (m). The IR spectrum in the region of 4000–450 cm−1 was recorded on a Perkin-Elmer FT—IR spectrophotometer Model 1600 using a KBr disk.

Refinement top

The number of Friedel pairs measured (579) corresponds only to a 0.313 fraction of the measured symmetry-unique reflections, nevertheless there is no reason for rejecting the absolute structure indicated by the Flack (1983) parameter.

Computing details top

Data collection: STADI4 (Stoe & Cie, 1995b); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1995a); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: PLATON98 (Spek, 1998); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure and the atom-numbering scheme of the title complex. Displacement ellipsoids are shown at the 50% probability level. The H atoms are drawn as small circles of arbitary radii.
[Figure 2] Fig. 2. The crystal-packing arrangement of (I) showing the infinite two-dimensional network spreading in the ab plane. The intramolecular (N—H···Cl1) and intermolecular (N—H···Cl2) hydrogen bonds are indicated with dashed lines.
bis[chloro(1,3-imidazolium-2-thiolato-S)]mercury(II) top
Crystal data top
[HgCl2(C3H4N2S)2]Dx = 2.579 Mg m3
Mr = 471.77Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21Cell parameters from 56 reflections
a = 7.5296 (11) Åθ = 9.0–15.4°
b = 13.7209 (19) ŵ = 13.43 mm1
c = 11.7587 (16) ÅT = 293 K
V = 1214.8 (3) Å3Prism, colourless
Z = 40.44 × 0.12 × 0.03 mm
F(000) = 872
Data collection top
Philips PW1100
diffractometer updated by Stoe
1545 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.029
Graphite monochromatorθmax = 29.9°, θmin = 3.0°
ω scansh = 210
Absorption correction: numerical
(X-RED; Stoe & Cie, 1995a)
k = 019
Tmin = 0.158, Tmax = 0.668l = 416
3067 measured reflections5 standard reflections every 90 min
2426 independent reflections intensity decay: 3.3%
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.030Calculated w = 1/[σ2(Fo2) + (0.0278P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.064(Δ/σ)max < 0.001
S = 0.90Δρmax = 0.79 e Å3
2426 reflectionsΔρmin = 0.90 e Å3
137 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.00034 (9)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983)
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.022 (10)
Crystal data top
[HgCl2(C3H4N2S)2]V = 1214.8 (3) Å3
Mr = 471.77Z = 4
Orthorhombic, Pca21Mo Kα radiation
a = 7.5296 (11) ŵ = 13.43 mm1
b = 13.7209 (19) ÅT = 293 K
c = 11.7587 (16) Å0.44 × 0.12 × 0.03 mm
Data collection top
Philips PW1100
diffractometer updated by Stoe
1545 reflections with I > 2σ(I)
Absorption correction: numerical
(X-RED; Stoe & Cie, 1995a)
Rint = 0.029
Tmin = 0.158, Tmax = 0.6685 standard reflections every 90 min
3067 measured reflections intensity decay: 3.3%
2426 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.064Δρmax = 0.79 e Å3
S = 0.90Δρmin = 0.90 e Å3
2426 reflectionsAbsolute structure: Flack (1983)
137 parametersAbsolute structure parameter: 0.022 (10)
1 restraint
Special details top

Refinement. The structure was solved from diffractometer data by direct methods and subsequent difference syntheses and refined by the full-matrix least squares procedure on F2 with anisotropic temperature factors for all non-hydrogen atoms.

The H atoms belonging to C atoms of the imidazole ring were generated geometrically using a riding model with the isotropic displacement parameter set at 1.2Ueq of the carrier C atom. Those on the N atoms were located in the difference Fourier map, but were not well defined and were therefore generated and refined applying the riding model.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Hg0.26266 (4)0.277323 (18)0.31937 (7)0.03887 (10)
Cl10.3805 (3)0.28374 (15)0.10969 (19)0.0384 (5)
Cl20.5592 (3)0.21051 (15)0.41497 (19)0.0369 (5)
S10.2352 (3)0.44395 (15)0.39103 (19)0.0365 (5)
C110.2971 (10)0.5213 (5)0.2842 (7)0.031 (2)
N110.3781 (10)0.5020 (5)0.1843 (6)0.0335 (16)
H110.40590.44480.16020.040*
C120.4092 (13)0.5859 (7)0.1279 (8)0.043 (2)
H120.46380.59160.05720.051*
C130.3478 (12)0.6592 (6)0.1911 (8)0.042 (2)
H130.35190.72520.17330.051*
N120.2777 (8)0.6182 (5)0.2872 (6)0.0380 (19)
H12N0.22840.65010.34170.046*
S20.0653 (3)0.13537 (16)0.3401 (2)0.0430 (6)
C210.1217 (10)0.0596 (5)0.2297 (8)0.0311 (19)
N210.1117 (9)0.0374 (5)0.2318 (7)0.0355 (18)
H210.08100.07090.29040.043*
C220.1565 (14)0.0770 (7)0.1287 (10)0.050 (3)
H220.16000.14280.10990.060*
C230.1943 (12)0.0017 (7)0.0606 (11)0.052 (3)
H230.22960.00530.01500.062*
N220.1715 (11)0.0820 (6)0.1231 (6)0.0430 (19)
H22N0.18690.14020.09770.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg0.05281 (17)0.02776 (11)0.03603 (15)0.00145 (15)0.0001 (3)0.0009 (3)
Cl10.0574 (12)0.0268 (8)0.0309 (10)0.0012 (10)0.0050 (11)0.0000 (10)
Cl20.0451 (10)0.0316 (11)0.0339 (12)0.0029 (9)0.0006 (10)0.0017 (10)
S10.0508 (12)0.0309 (9)0.0279 (10)0.0018 (10)0.0043 (12)0.0027 (9)
C110.035 (4)0.024 (3)0.035 (5)0.002 (3)0.007 (3)0.003 (3)
N110.045 (4)0.025 (3)0.030 (4)0.003 (3)0.002 (4)0.003 (4)
C120.064 (6)0.042 (5)0.022 (5)0.014 (5)0.006 (5)0.007 (4)
C130.050 (5)0.028 (4)0.049 (6)0.007 (4)0.010 (5)0.002 (5)
N120.045 (4)0.029 (3)0.040 (5)0.000 (3)0.004 (4)0.005 (3)
S20.0544 (11)0.0351 (9)0.0395 (17)0.0067 (9)0.0099 (12)0.0038 (11)
C210.033 (4)0.022 (4)0.038 (5)0.002 (3)0.005 (4)0.007 (4)
N210.046 (4)0.027 (3)0.033 (4)0.007 (3)0.002 (4)0.019 (3)
C220.064 (6)0.030 (5)0.056 (7)0.001 (5)0.003 (6)0.004 (5)
C230.067 (7)0.042 (4)0.047 (6)0.006 (4)0.003 (8)0.027 (7)
N220.075 (5)0.030 (4)0.024 (4)0.014 (4)0.004 (4)0.004 (3)
Geometric parameters (Å, º) top
Hg—S12.445 (2)C12—C131.333 (12)
Hg—S22.462 (2)C13—N121.369 (11)
Hg—Cl12.622 (2)S2—C211.717 (9)
Hg—Cl22.663 (2)C21—N211.333 (9)
S1—C111.709 (8)C21—N221.344 (11)
C11—N121.339 (9)N21—C221.370 (13)
C11—N111.350 (10)C22—C231.337 (14)
N11—C121.348 (11)C23—N221.373 (11)
S1—Hg—S2130.87 (8)C13—C12—N11108.0 (8)
S1—Hg—Cl1108.74 (7)C12—C13—N12106.5 (8)
S2—Hg—Cl1108.91 (8)C11—N12—C13110.1 (7)
S1—Hg—Cl2104.32 (7)C21—S2—Hg104.8 (3)
S2—Hg—Cl2101.07 (7)N21—C21—N22105.2 (8)
Cl1—Hg—Cl297.17 (7)N21—C21—S2125.2 (7)
C11—S1—Hg107.7 (3)N22—C21—S2129.5 (6)
N12—C11—N11105.5 (7)C21—N21—C22111.4 (8)
N12—C11—S1124.6 (7)C23—C22—N21106.0 (9)
N11—C11—S1129.9 (6)C22—C23—N22107.4 (10)
C12—N11—C11109.9 (7)C21—N22—C23110.0 (8)
S2—Hg—S1—C11137.3 (3)S1—Hg—S2—C21158.7 (3)
Cl1—Hg—S1—C110.9 (3)Cl1—Hg—S2—C2120.5 (3)
Cl2—Hg—S1—C11103.8 (3)Cl2—Hg—S2—C2181.2 (3)
Hg—S1—C11—N12171.1 (6)Hg—S2—C21—N21149.2 (7)
Hg—S1—C11—N1111.6 (8)Hg—S2—C21—N2236.0 (9)
N12—C11—N11—C120.5 (9)N22—C21—N21—C220.8 (10)
S1—C11—N11—C12177.2 (7)S2—C21—N21—C22176.6 (7)
C11—N11—C12—C130.1 (10)C21—N21—C22—C230.4 (11)
N11—C12—C13—N120.3 (10)N21—C22—C23—N220.2 (11)
N11—C11—N12—C130.7 (9)N21—C21—N22—C230.8 (10)
S1—C11—N12—C13177.2 (6)S2—C21—N22—C23176.5 (7)
C12—C13—N12—C110.7 (10)C22—C23—N22—C210.6 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N11—H11···Cl10.862.303.121 (7)160
N22—H22N···Cl10.862.463.188 (7)144
N12—H12N···Cl2i0.862.453.238 (7)152
N21—H21···Cl2ii0.862.423.232 (8)158
Symmetry codes: (i) x1/2, y+1, z; (ii) x1/2, y, z.

Experimental details

Crystal data
Chemical formula[HgCl2(C3H4N2S)2]
Mr471.77
Crystal system, space groupOrthorhombic, Pca21
Temperature (K)293
a, b, c (Å)7.5296 (11), 13.7209 (19), 11.7587 (16)
V3)1214.8 (3)
Z4
Radiation typeMo Kα
µ (mm1)13.43
Crystal size (mm)0.44 × 0.12 × 0.03
Data collection
DiffractometerPhilips PW1100
diffractometer updated by Stoe
Absorption correctionNumerical
(X-RED; Stoe & Cie, 1995a)
Tmin, Tmax0.158, 0.668
No. of measured, independent and
observed [I > 2σ(I)] reflections
3067, 2426, 1545
Rint0.029
(sin θ/λ)max1)0.701
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.064, 0.90
No. of reflections2426
No. of parameters137
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.79, 0.90
Absolute structureFlack (1983)
Absolute structure parameter0.022 (10)

Computer programs: STADI4 (Stoe & Cie, 1995b), STADI4, X-RED (Stoe & Cie, 1995a), SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997b), PLATON98 (Spek, 1998), SHELXL97.

Selected geometric parameters (Å, º) top
Hg—S12.445 (2)Hg—Cl22.663 (2)
Hg—S22.462 (2)S1—C111.709 (8)
Hg—Cl12.622 (2)S2—C211.717 (9)
S1—Hg—S2130.87 (8)S2—Hg—Cl2101.07 (7)
S1—Hg—Cl1108.74 (7)Cl1—Hg—Cl297.17 (7)
S2—Hg—Cl1108.91 (8)C11—S1—Hg107.7 (3)
S1—Hg—Cl2104.32 (7)C21—S2—Hg104.8 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N11—H11···Cl10.862.303.121 (7)160
N22—H22N···Cl10.862.463.188 (7)144
N12—H12N···Cl2i0.862.453.238 (7)152
N21—H21···Cl2ii0.862.423.232 (8)158
Symmetry codes: (i) x1/2, y+1, z; (ii) x1/2, y, z.
 

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