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Di­chloro­bis­[1-methyl­imidazoline-2(3H)-thione]cadmium(II)

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aDepartment of Chemistry, Faculty of Sciences, Shahid Chamran University, Ahvaz, Iran, and bSchool of Natural Sciences (Chemistry), University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, England
*Correspondence e-mail: beheshti_a@hotmail.com, w.clegg@ncl.ac.uk

(Received 15 June 2005; accepted 16 June 2005; online 24 June 2005)

In the title complex, [CdCl2(C4H6N2S)2], the Cd atom has a distorted tetra­hedral coordination geometry, with two Cl and two monodentate neutral thione ligands bonded through S. There are intra­molecular N—H⋯Cl and inter­molecular N—H⋯S hydrogen bonds, generating centrosymmetric dimers.

Comment

Due to their relevance in biological systems, the use of heterocyclic thio­nes as ligands in transition metal complexes has attracted much attention in the recent past (Raper, 1994[Raper, E. S. (1994). Coord. Chem. Rev. 129, 91-156.], 1997[Raper, E. S. (1997). Coord. Chem. Rev. 165, 475-567.]), because of the search for simple model compounds for metalloproteins. In view of this, CuI, AgI, AuI, HgII and CdII complexes with thio­nes have been widely studied (Isab et al., 2002[Isab, A. A., Ahmad, S. & Arab, M. (2002). Polyhedron, 21, 1267-1271.], and references therein; Beheshti et al., 2005[Beheshti, A., Clegg, W., Brooks, N. R. & Sharafi, F. (2005). Polyhedron, 24, 435-441.]).

[Scheme 1]

The title compound, (I)[link], is an unexpected product, obtained in an attempt to prepare a WS4(CdCl)2(Hmimt)n complex [Hmimt = 1-methyl­imidazoline-2(3H)-thione]. The mol­ecular structure of (I)[link] is shown in Fig. 1[link], and selected bond lengths and angles are listed in Table 1[link]. The CdII ion is coordinated by two Cl and two S-bonded monodentate Hmimt ligands, to give a distorted tetra­hedral S2Cl2 donor set. The major distortions from regular tetra­hedral geometry are an enlarged S—Cd—S angle and considerable variation in the four S—Cd—Cl angles. These are probably a result mainly of steric inter­actions.

The essentially planar Hmimt ligands are in their neutral thione form. Their geometry is typical of this ligand attached in a monodentate fashion through S to metal ions; the mean C=S bond length for almost 100 occurrences of this ligand in 39 crystal structures in the Cambridge Structural Database (version 5.26 with two updates, May 2005; Allen, 2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]) is 1.718 Å, over a range of 1.684–1.750 Å with the omission of a few outliers, and compares with C=S bond lengths of 1.729 (3) and 1.733 (3) Å in (I)[link]. These bonds are thus lengthened and weakened on coordination, as expected, compared with their greater double-bond character in the uncomplexed ligand, which has a C=S bond length of 1.685 (2) Å (Raper et al., 1983[Raper, E. S., Creighton, J. R., Oughtred, R. E. & Nowell, I. W. (1983). Acta Cryst. B39, 355-360.]; Vampa et al., 1995[Vampa, G., Benvenuti, S., Severi, F., Malmusi, L. & Antolini, L. (1995). J. Heterocycl. Chem. 32, 227-234.]). The geometric results are in agreement with spectroscopic observations (see Experimental section).

The structure of (I)[link] may be compared with those of other [MX2(Hmimt)2] complexes (M = Cd or Hg, and X = Cl, Br or I). All of these have monomeric mol­ecules with a distorted tetra­hedral coordination geometry about the metal atom, and the variations in bond lengths and angles can be readily understood in terms of the sizes of the metal and halogen atoms. None of the other complexes is isomorphous with (I)[link]. Indeed, all five known structures have different space groups and packing arrangements (Bell et al., 2000[Bell, N. A., Branston, T. N., Clegg, W., Creighton, J. R., Cucurull-Sanchez, L., Elsegood, M. R. J. & Raper, E. S. (2000). Inorg. Chim. Acta, 303, 220-227.], 2004[Bell, N. A., Clegg, W., Coles, S. J., Constable, C. P., Harrington, R. W., Hursthouse, M. B., Light, M. E., Raper, E. S., Sammon, C. & Walker, M. R. (2004). Inorg. Chim. Acta, 357, 2091-2099.]; Pavlović et al., 2000[Pavlović, G., Popović, Z., Soldin, Ž. & Matković-Čalogović, D. (2000). Acta Cryst. C56, 801-803.]). The bromo analogue of (I)[link] has an unusual structure, with six mol­ecules in the asymmetric unit and a high degree of pseudo-symmetry (Bell et al., 2004[Bell, N. A., Clegg, W., Coles, S. J., Constable, C. P., Harrington, R. W., Hursthouse, M. B., Light, M. E., Raper, E. S., Sammon, C. & Walker, M. R. (2004). Inorg. Chim. Acta, 357, 2091-2099.]).

The N—H groups of the two Hmimt ligands in (I)[link] engage in hydrogen bonds. One of these is intra­molecular, to atom Cl2, and presumably contributes to the lengthening of this Cd—Cl bond relative to the other. The other hydrogen bond is inter­molecular, to the S atom of an adjacent Hmimt ligand, and generates centrosymmetric dimers (Fig. 2[link] and Table 2[link]).

[Figure 1]
Figure 1
The mol­ecular structure of (I)[link], with 50% probability displacement ellipsoids.
[Figure 2]
Figure 2
A centrosymmetric dimer in (I)[link], formed by a pair of inter­molecular N—H⋯S hydrogen bonds. All hydrogen bonds are shown as dashed lines. Unlabelled atoms are generated by the symmetry operation (−x, 1 − y, 1 − z).

Experimental

CdCl2·H2O (1.12 g, 5.56 mmol) was added to a suspension of (NH4)2[WS4] (0.967 g, 2.78 mmol) in acetone (70 ml) and the mixture was stirred for 1 h. Hmimt (0.71 g, 6.22 mmol) was added to this solution and the mixture was stirred for another 4 h at room temperature. The mixture was centrifuged and the yellow supernatant liquid was deca­nted and evaporated to dryness in a vacuum. The residue was washed with dieth­yl ether (2 × 5 ml) and n-penta­ne (2 × 5 ml) to remove any unreacted Hmimt, and dried in a vacuum to give an orange–yellow powder. Both IR [ν(W—S) = 441 cm−1, ν(C=S) = 506 cm−1 and ν(N—H) = 3133 cm−1] and UV–vis λmax = 430, 374, 315 and 273 nm) spectra of the product confirmed the presence of WS4 and S-bonded Hmimt ligands. In the solid state, the complex is air-stable and can be stored for months in a desiccator, but it decomposed slowly when dieth­yl ether was diffused slowly into an acetone solution of the product over 3 d at room temperature, resulting in the formation of pale-yellow crystals with an empirical formula C8H12CdCl2N4S2, as confirmed by X-ray crystallography. The air-stable crystals of this compound are insoluble in common organic solvents, but soluble in solvents with pronounced donor properties, such as dimeth­yl sulfoxide and dimethyl­formamide. 1H NMR (DMSO-d6, 298 K, δ, p.p.m.): 12.01 (s, NH), 6.98 (s, CH), 6.80 (s, CH), 3.32 (s, NCH3); 13C NMR (DMSO-d6, 298 K, δ, p.p.m.): 160.52 (C1/5), 120.05 and 114.62 (C2/6 and C3/7), 33.99 (C4/8) (see Fig. 1[link] for atom numbering). In the NMR spectra of the complex, the ligand signals are shifted down-field from their positions in the spectra of the free ligand (Casa et al., 1996[Casa, J. S., Martinez, E. G., Sánchez, A., González, A. S., Sordo, J., Casellato, U. & Graziani, R. (1996). Inorg. Chim. Acta, 241, 117-123.]), suggesting that, in DMSO-d6, the ligand remains coordinated to the metal. The absence of a weak S—H signal of the thiol form of the ligand in the 1H NMR spectrum of the complex confirms that coordination of Hmimt in DMSO-d6 solution, as in the solid state, takes place only through the S atom, the Hmimt ligands being in the neutral thione form.

Crystal data
  • [CdCl2(C4H6N2S)2]

  • Mr = 411.64

  • Monoclinic, P 21 /c

  • a = 9.6464 (8) Å

  • b = 7.6262 (8) Å

  • c = 19.7151 (8) Å

  • β = 96.485 (6)°

  • V = 1441.1 (2) Å3

  • Z = 4

  • Dx = 1.897 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 22587 reflections

  • θ = 2.5–25.0°

  • μ = 2.16 mm−1

  • T = 150 (2) K

  • Block, pale yellow

  • 0.36 × 0.32 × 0.28 mm

Data collection
  • Nonius KappaCCD area-detector diffractometer

  • φ and ω scans

  • Absorption correction: multi-scan(SADABS; Sheldrick, 2002[Sheldrick, G. M. (2002). SADABS. Version 2.06. University of Göttingen, Germany.])Tmin = 0.481, Tmax = 0.549

  • 22587 measured reflections

  • 2518 independent reflections

  • 2115 reflections with I > 2σ(I)

  • Rint = 0.058

  • θmax = 25.0°

  • h = −11 → 11

  • k = −9 → 9

  • l = −23 → 23

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.023

  • wR(F2) = 0.046

  • S = 1.05

  • 2518 reflections

  • 163 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • w = 1/[σ2(Fo2) + (0.016P)2 + 0.9012P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 0.36 e Å−3

  • Δρmin = −0.32 e Å−3

  • Extinction correction: SHELXTL (Sheldrick, 2001[Sheldrick, G. M. (2001). SHELXTL. Version 6.10. Bruker AXS Inc., Madison, Wisconsin, USA.])

  • Extinction coefficient: 0.0027 (3)

Table 1
Selected geometric parameters (Å, °)[link]

Cd—Cl1 2.4410 (7)
Cd—Cl2 2.5175 (7)
Cd—S1 2.5392 (7)
Cd—S2 2.5663 (7)
S1—C1 1.729 (3)
S2—C5 1.733 (3)
Cl1—Cd—Cl2 104.43 (2)
Cl1—Cd—S1 111.60 (2)
Cl1—Cd—S2 116.52 (2)
Cl2—Cd—S1 106.84 (2)
Cl2—Cd—S2 97.66 (2)
S1—Cd—S2 117.32 (2)
Cd—S1—C1 107.78 (9)
Cd—S2—C5 102.85 (9)

Table 2
Hydrogen-bond geometry (Å, °)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯Cl2 0.80 (3) 2.41 (3) 3.204 (3) 168 (3)
N3—H3⋯S2i 0.88 (3) 2.49 (3) 3.358 (3) 173 (3)
Symmetry codes: (i) -x, -y+1, -z+1.

All H atoms were located in a difference map. Those bonded to N were refined with unconstrained coordinates and Uiso(H) = 1.2Ueq(N). Other H atoms were refined as riding with idealized geometries, including free rotation of meth­yl groups about the C—C bonds (C—H = 0.95–0.98 Å), with the constraint Uiso(H) = 1.2Ueq(C) or 1.5Ueq(meth­yl C) applied.

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: EVALCCD (Duisenberg et al., 2003[Duisenberg, A. J. M., Kroon-Batenburg, L. M. J. & Schreurs, A. M. M. (2003). J. Appl. Cryst. 36, 220-229.]); data reduction: EVALCCD; program(s) used to solve structure: SHELXTL (Sheldrick, 2001[Sheldrick, G. M. (2001). SHELXTL. Version 6.10. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Supporting information


Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: EVALCCD (Duisenberg et al., 2003); data reduction: EVALCCD; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Dichlorobis[1-methylimidazoline-2(3H)-thione]cadmium(II) top
Crystal data top
[CdCl2(C4H6N2S)2]F(000) = 808
Mr = 411.64Dx = 1.897 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 23643 reflections
a = 9.6464 (8) Åθ = 2.5–25.0°
b = 7.6262 (8) ŵ = 2.16 mm1
c = 19.7151 (8) ÅT = 150 K
β = 96.485 (6)°Block, pale yellow
V = 1441.1 (2) Å30.36 × 0.32 × 0.28 mm
Z = 4
Data collection top
Nonius KappaCCD area-detector
diffractometer
2518 independent reflections
Radiation source: sealed tube2115 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.058
φ and ω scansθmax = 25.0°, θmin = 4.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2002)
h = 1111
Tmin = 0.481, Tmax = 0.549k = 99
22587 measured reflectionsl = 2323
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.023H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.046 w = 1/[σ2(Fo2) + (0.016P)2 + 0.9012P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
2518 reflectionsΔρmax = 0.36 e Å3
163 parametersΔρmin = 0.32 e Å3
0 restraintsExtinction correction: SHELXTL (Sheldrick, 2001), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0027 (3)
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cd0.305327 (19)0.40552 (3)0.413963 (10)0.01882 (9)
Cl10.41103 (7)0.42594 (9)0.30744 (3)0.02480 (17)
Cl20.11347 (7)0.18284 (9)0.38971 (3)0.02436 (17)
S10.47501 (7)0.28210 (9)0.50996 (3)0.02039 (17)
C10.3861 (3)0.1299 (3)0.55362 (13)0.0159 (6)
N10.2581 (2)0.0623 (3)0.53657 (12)0.0206 (6)
H10.211 (3)0.084 (4)0.5012 (16)0.025*
N20.4360 (2)0.0558 (3)0.61350 (11)0.0165 (5)
C20.2271 (3)0.0553 (4)0.58620 (14)0.0246 (7)
H20.14340.12100.58630.030*
C30.3374 (3)0.0588 (3)0.63401 (14)0.0216 (6)
H3A0.34630.12720.67450.026*
C40.5738 (3)0.0896 (4)0.65069 (14)0.0216 (6)
H4A0.64550.07660.61960.032*
H4B0.59140.00560.68830.032*
H4C0.57660.20910.66900.032*
S20.15259 (7)0.66470 (9)0.44266 (3)0.01838 (17)
C50.0033 (3)0.6253 (3)0.39218 (13)0.0165 (6)
N30.1171 (2)0.5455 (3)0.41061 (12)0.0205 (5)
H30.119 (3)0.495 (4)0.4504 (16)0.025*
N40.0372 (2)0.6812 (3)0.32768 (11)0.0202 (5)
C60.2242 (3)0.5515 (4)0.35804 (15)0.0255 (7)
H60.31540.50450.35830.031*
C70.1741 (3)0.6372 (4)0.30602 (15)0.0257 (7)
H70.22360.66240.26270.031*
C80.0581 (3)0.7743 (4)0.28699 (15)0.0351 (8)
H8A0.08660.88540.30930.053*
H8B0.01050.79780.24130.053*
H8C0.14070.70170.28320.053*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd0.01600 (12)0.02447 (13)0.01584 (13)0.00119 (9)0.00109 (8)0.00265 (9)
Cl10.0252 (4)0.0334 (4)0.0164 (4)0.0041 (3)0.0050 (3)0.0002 (3)
Cl20.0185 (4)0.0279 (4)0.0256 (4)0.0043 (3)0.0022 (3)0.0001 (3)
S10.0164 (3)0.0233 (4)0.0205 (4)0.0050 (3)0.0019 (3)0.0071 (3)
C10.0173 (14)0.0131 (15)0.0177 (15)0.0013 (11)0.0031 (11)0.0008 (11)
N10.0180 (13)0.0261 (15)0.0164 (13)0.0042 (10)0.0041 (10)0.0018 (10)
N20.0173 (12)0.0156 (12)0.0166 (13)0.0011 (9)0.0021 (10)0.0010 (9)
C20.0217 (16)0.0268 (17)0.0263 (17)0.0099 (12)0.0067 (13)0.0010 (13)
C30.0258 (16)0.0209 (16)0.0189 (15)0.0055 (12)0.0056 (13)0.0015 (12)
C40.0195 (15)0.0253 (16)0.0194 (15)0.0028 (13)0.0009 (12)0.0026 (12)
S20.0159 (3)0.0204 (4)0.0182 (4)0.0020 (3)0.0012 (3)0.0011 (3)
C50.0183 (14)0.0138 (15)0.0173 (15)0.0018 (11)0.0014 (11)0.0024 (11)
N30.0170 (13)0.0255 (14)0.0192 (13)0.0018 (10)0.0022 (11)0.0028 (10)
N40.0234 (13)0.0196 (13)0.0165 (13)0.0046 (10)0.0026 (10)0.0011 (10)
C60.0154 (15)0.0305 (18)0.0291 (17)0.0025 (12)0.0037 (13)0.0036 (13)
C70.0272 (16)0.0229 (17)0.0241 (16)0.0031 (13)0.0098 (13)0.0002 (13)
C80.0445 (19)0.041 (2)0.0185 (17)0.0199 (16)0.0006 (14)0.0072 (14)
Geometric parameters (Å, º) top
Cd—Cl12.4410 (7)C4—H4B0.980
Cd—Cl22.5175 (7)C4—H4C0.980
Cd—S12.5392 (7)S2—C51.733 (3)
Cd—S22.5663 (7)C5—N31.341 (3)
S1—C11.729 (3)C5—N41.346 (3)
C1—N11.345 (3)N3—H30.88 (3)
C1—N21.348 (3)N3—C61.379 (4)
N1—H10.80 (3)N4—C71.383 (4)
N1—C21.385 (4)N4—C81.469 (4)
N2—C31.386 (3)C6—H60.950
N2—C41.466 (3)C6—C71.351 (4)
C2—H20.950C7—H70.950
C2—C31.340 (4)C8—H8A0.980
C3—H3A0.950C8—H8B0.980
C4—H4A0.980C8—H8C0.980
Cl1—Cd—Cl2104.43 (2)H4A—C4—H4B109.5
Cl1—Cd—S1111.60 (2)H4A—C4—H4C109.5
Cl1—Cd—S2116.52 (2)H4B—C4—H4C109.5
Cl2—Cd—S1106.84 (2)Cd—S2—C5102.85 (9)
Cl2—Cd—S297.66 (2)S2—C5—N3127.4 (2)
S1—Cd—S2117.32 (2)S2—C5—N4126.1 (2)
Cd—S1—C1107.78 (9)N3—C5—N4106.3 (2)
S1—C1—N1128.8 (2)C5—N3—H3123.1 (19)
S1—C1—N2124.7 (2)C5—N3—C6110.4 (2)
N1—C1—N2106.6 (2)H3—N3—C6126.5 (19)
C1—N1—H1123 (2)C5—N4—C7109.6 (2)
C1—N1—C2109.7 (2)C5—N4—C8124.7 (2)
H1—N1—C2127 (2)C7—N4—C8125.7 (2)
C1—N2—C3109.3 (2)N3—C6—H6126.7
C1—N2—C4125.3 (2)N3—C6—C7106.5 (3)
C3—N2—C4125.3 (2)H6—C6—C7126.7
N1—C2—H2126.5N4—C7—C6107.1 (3)
N1—C2—C3107.0 (2)N4—C7—H7126.4
H2—C2—C3126.5C6—C7—H7126.4
N2—C3—C2107.4 (2)N4—C8—H8A109.5
N2—C3—H3A126.3N4—C8—H8B109.5
C2—C3—H3A126.3N4—C8—H8C109.5
N2—C4—H4A109.5H8A—C8—H8B109.5
N2—C4—H4B109.5H8A—C8—H8C109.5
N2—C4—H4C109.5H8B—C8—H8C109.5
Cl1—Cd—S1—C1136.06 (9)Cl1—Cd—S2—C579.26 (10)
Cl2—Cd—S1—C122.49 (10)Cl2—Cd—S2—C531.11 (9)
S2—Cd—S1—C185.76 (10)S1—Cd—S2—C5144.60 (9)
Cd—S1—C1—N110.0 (3)Cd—S2—C5—N396.2 (2)
Cd—S1—C1—N2169.9 (2)Cd—S2—C5—N489.2 (2)
S1—C1—N1—C2179.8 (2)S2—C5—N3—C6175.1 (2)
N2—C1—N1—C20.1 (3)N4—C5—N3—C60.4 (3)
S1—C1—N2—C3179.65 (19)S2—C5—N4—C7175.0 (2)
S1—C1—N2—C41.0 (4)S2—C5—N4—C85.2 (4)
N1—C1—N2—C30.3 (3)N3—C5—N4—C70.6 (3)
N1—C1—N2—C4179.0 (2)N3—C5—N4—C8179.2 (3)
C1—N1—C2—C30.1 (3)C5—N3—C6—C70.1 (3)
N1—C2—C3—N20.3 (3)N3—C6—C7—N40.3 (3)
C1—N2—C3—C20.4 (3)C5—N4—C7—C60.5 (3)
C4—N2—C3—C2179.0 (2)C8—N4—C7—C6179.3 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Cl20.80 (3)2.41 (3)3.204 (3)168 (3)
N3—H3···S2i0.88 (3)2.49 (3)3.358 (3)173 (3)
Symmetry code: (i) x, y+1, z+1.
 

Acknowledgements

The authors thank the EPSRC (UK) and Shahid Chamran University for financial support.

References

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