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

Beheshti, A.; Brooks, N.R.; Clegg, W.; Hyvadi, R.

doi:10.1107/S1600536805019203

metal-organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 61| Part 7| July 2005| Pages m1383-m1385

https://doi.org/10.1107/S1600536805019203

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

Azizolla Beheshti,^a ^* Neil R. Brooks,^b William Clegg ^b ^* and Reza Hyvadi ^a

^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 , 1997 ), because of the search for simple model compounds for metalloproteins. In view of this, Cu^I, Ag^I, Au^I, Hg^II and Cd^II complexes with thiones have been widely studied (Isab et al., 2002 , and references therein; Beheshti et al., 2005 ).

The title compound, (I), 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) is shown in Fig. 1, and selected bond lengths and angles are listed in Table 1. The Cd^II 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 ) 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). 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 ; Vampa et al., 1995 ). The geometric results are in agreement with spectroscopic observations (see Experimental section).

The structure of (I) 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). Indeed, all five known structures have different space groups and packing arrangements (Bell et al., 2000 , 2004 ; Pavlović et al., 2000 ). The bromo analogue of (I) has an unusual structure, with six molecules in the asymmetric unit and a high degree of pseudo-symmetry (Bell et al., 2004).

The N—H groups of the two Hmimt ligands in (I) 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 and Table 2).

Figure 1
The molecular structure of (I)

, with 50% probability displacement ellipsoids.

Figure 2
A centrosymmetric dimer in (I)

, 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 λ_max = 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 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 ), 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]
M_r = 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
D_x = 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 )T_min = 0.481, T_max = 0.549
22587 measured reflections
2518 independent reflections
2115 reflections with I > 2σ(I)
R_int = 0.058
θ_max = 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(F_o²) + (0.016P)² + 0.9012P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.32 e Å⁻³
Extinction correction: SHELXTL (Sheldrick, 2001 )
Extinction coefficient: 0.0027 (3)

Table 1
Selected geometric parameters (Å, °)

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, °)

D—H⋯A	D—H	H⋯A	D⋯A	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 U_iso(H) = 1.2U_eq(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 U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C) applied.

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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536805019203/hb6226sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536805019203/hb6226Isup2.hkl

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
M_r = 411.64	D_x = 1.897 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 23643 reflections
a = 9.6464 (8) Å	θ = 2.5–25.0°
b = 7.6262 (8) Å	µ = 2.16 mm⁻¹
c = 19.7151 (8) Å	T = 150 K
β = 96.485 (6)°	Block, pale yellow
V = 1441.1 (2) Å³	0.36 × 0.32 × 0.28 mm
Z = 4

Data collection top

Nonius KappaCCD area-detector diffractometer	2518 independent reflections
Radiation source: sealed tube	2115 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.058
φ and ω scans	θ_max = 25.0°, θ_min = 4.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	h = −11→11
T_min = 0.481, T_max = 0.549	k = −9→9
22587 measured reflections	l = −23→23

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.023	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.046	w = 1/[σ²(F_o²) + (0.016P)² + 0.9012P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max = 0.001
2518 reflections	Δρ_max = 0.36 e Å⁻³
163 parameters	Δρ_min = −0.32 e Å⁻³
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2001), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0027 (3)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cd	0.305327 (19)	0.40552 (3)	0.413963 (10)	0.01882 (9)
Cl1	0.41103 (7)	0.42594 (9)	0.30744 (3)	0.02480 (17)
Cl2	0.11347 (7)	0.18284 (9)	0.38971 (3)	0.02436 (17)
S1	0.47501 (7)	0.28210 (9)	0.50996 (3)	0.02039 (17)
C1	0.3861 (3)	0.1299 (3)	0.55362 (13)	0.0159 (6)
N1	0.2581 (2)	0.0623 (3)	0.53657 (12)	0.0206 (6)
H1	0.211 (3)	0.084 (4)	0.5012 (16)	0.025*
N2	0.4360 (2)	0.0558 (3)	0.61350 (11)	0.0165 (5)
C2	0.2271 (3)	−0.0553 (4)	0.58620 (14)	0.0246 (7)
H2	0.1434	−0.1210	0.5863	0.030*
C3	0.3374 (3)	−0.0588 (3)	0.63401 (14)	0.0216 (6)
H3A	0.3463	−0.1272	0.6745	0.026*
C4	0.5738 (3)	0.0896 (4)	0.65069 (14)	0.0216 (6)
H4A	0.6455	0.0766	0.6196	0.032*
H4B	0.5914	0.0056	0.6883	0.032*
H4C	0.5766	0.2091	0.6690	0.032*
S2	0.15259 (7)	0.66470 (9)	0.44266 (3)	0.01838 (17)
C5	−0.0033 (3)	0.6253 (3)	0.39218 (13)	0.0165 (6)
N3	−0.1171 (2)	0.5455 (3)	0.41061 (12)	0.0205 (5)
H3	−0.119 (3)	0.495 (4)	0.4504 (16)	0.025*
N4	−0.0372 (2)	0.6812 (3)	0.32768 (11)	0.0202 (5)
C6	−0.2242 (3)	0.5515 (4)	0.35804 (15)	0.0255 (7)
H6	−0.3154	0.5045	0.3583	0.031*
C7	−0.1741 (3)	0.6372 (4)	0.30602 (15)	0.0257 (7)
H7	−0.2236	0.6624	0.2627	0.031*
C8	0.0581 (3)	0.7743 (4)	0.28699 (15)	0.0351 (8)
H8A	0.0866	0.8854	0.3093	0.053*
H8B	0.0105	0.7978	0.2413	0.053*
H8C	0.1407	0.7017	0.2832	0.053*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cd	0.01600 (12)	0.02447 (13)	0.01584 (13)	0.00119 (9)	0.00109 (8)	0.00265 (9)
Cl1	0.0252 (4)	0.0334 (4)	0.0164 (4)	−0.0041 (3)	0.0050 (3)	0.0002 (3)
Cl2	0.0185 (4)	0.0279 (4)	0.0256 (4)	−0.0043 (3)	−0.0022 (3)	0.0001 (3)
S1	0.0164 (3)	0.0233 (4)	0.0205 (4)	−0.0050 (3)	−0.0019 (3)	0.0071 (3)
C1	0.0173 (14)	0.0131 (15)	0.0177 (15)	0.0013 (11)	0.0031 (11)	−0.0008 (11)
N1	0.0180 (13)	0.0261 (15)	0.0164 (13)	−0.0042 (10)	−0.0041 (10)	0.0018 (10)
N2	0.0173 (12)	0.0156 (12)	0.0166 (13)	−0.0011 (9)	0.0021 (10)	0.0010 (9)
C2	0.0217 (16)	0.0268 (17)	0.0263 (17)	−0.0099 (12)	0.0067 (13)	−0.0010 (13)
C3	0.0258 (16)	0.0209 (16)	0.0189 (15)	−0.0055 (12)	0.0056 (13)	0.0015 (12)
C4	0.0195 (15)	0.0253 (16)	0.0194 (15)	−0.0028 (13)	−0.0009 (12)	0.0026 (12)
S2	0.0159 (3)	0.0204 (4)	0.0182 (4)	−0.0020 (3)	−0.0012 (3)	−0.0011 (3)
C5	0.0183 (14)	0.0138 (15)	0.0173 (15)	0.0018 (11)	0.0014 (11)	−0.0024 (11)
N3	0.0170 (13)	0.0255 (14)	0.0192 (13)	0.0018 (10)	0.0022 (11)	0.0028 (10)
N4	0.0234 (13)	0.0196 (13)	0.0165 (13)	−0.0046 (10)	−0.0026 (10)	−0.0011 (10)
C6	0.0154 (15)	0.0305 (18)	0.0291 (17)	0.0025 (12)	−0.0037 (13)	−0.0036 (13)
C7	0.0272 (16)	0.0229 (17)	0.0241 (16)	0.0031 (13)	−0.0098 (13)	0.0002 (13)
C8	0.0445 (19)	0.041 (2)	0.0185 (17)	−0.0199 (16)	−0.0006 (14)	0.0072 (14)

Geometric parameters (Å, º) top

Cd—Cl1	2.4410 (7)	C4—H4B	0.980
Cd—Cl2	2.5175 (7)	C4—H4C	0.980
Cd—S1	2.5392 (7)	S2—C5	1.733 (3)
Cd—S2	2.5663 (7)	C5—N3	1.341 (3)
S1—C1	1.729 (3)	C5—N4	1.346 (3)
C1—N1	1.345 (3)	N3—H3	0.88 (3)
C1—N2	1.348 (3)	N3—C6	1.379 (4)
N1—H1	0.80 (3)	N4—C7	1.383 (4)
N1—C2	1.385 (4)	N4—C8	1.469 (4)
N2—C3	1.386 (3)	C6—H6	0.950
N2—C4	1.466 (3)	C6—C7	1.351 (4)
C2—H2	0.950	C7—H7	0.950
C2—C3	1.340 (4)	C8—H8A	0.980
C3—H3A	0.950	C8—H8B	0.980
C4—H4A	0.980	C8—H8C	0.980

Cl1—Cd—Cl2	104.43 (2)	H4A—C4—H4B	109.5
Cl1—Cd—S1	111.60 (2)	H4A—C4—H4C	109.5
Cl1—Cd—S2	116.52 (2)	H4B—C4—H4C	109.5
Cl2—Cd—S1	106.84 (2)	Cd—S2—C5	102.85 (9)
Cl2—Cd—S2	97.66 (2)	S2—C5—N3	127.4 (2)
S1—Cd—S2	117.32 (2)	S2—C5—N4	126.1 (2)
Cd—S1—C1	107.78 (9)	N3—C5—N4	106.3 (2)
S1—C1—N1	128.8 (2)	C5—N3—H3	123.1 (19)
S1—C1—N2	124.7 (2)	C5—N3—C6	110.4 (2)
N1—C1—N2	106.6 (2)	H3—N3—C6	126.5 (19)
C1—N1—H1	123 (2)	C5—N4—C7	109.6 (2)
C1—N1—C2	109.7 (2)	C5—N4—C8	124.7 (2)
H1—N1—C2	127 (2)	C7—N4—C8	125.7 (2)
C1—N2—C3	109.3 (2)	N3—C6—H6	126.7
C1—N2—C4	125.3 (2)	N3—C6—C7	106.5 (3)
C3—N2—C4	125.3 (2)	H6—C6—C7	126.7
N1—C2—H2	126.5	N4—C7—C6	107.1 (3)
N1—C2—C3	107.0 (2)	N4—C7—H7	126.4
H2—C2—C3	126.5	C6—C7—H7	126.4
N2—C3—C2	107.4 (2)	N4—C8—H8A	109.5
N2—C3—H3A	126.3	N4—C8—H8B	109.5
C2—C3—H3A	126.3	N4—C8—H8C	109.5
N2—C4—H4A	109.5	H8A—C8—H8B	109.5
N2—C4—H4B	109.5	H8A—C8—H8C	109.5
N2—C4—H4C	109.5	H8B—C8—H8C	109.5

Cl1—Cd—S1—C1	−136.06 (9)	Cl1—Cd—S2—C5	79.26 (10)
Cl2—Cd—S1—C1	−22.49 (10)	Cl2—Cd—S2—C5	−31.11 (9)
S2—Cd—S1—C1	85.76 (10)	S1—Cd—S2—C5	−144.60 (9)
Cd—S1—C1—N1	10.0 (3)	Cd—S2—C5—N3	96.2 (2)
Cd—S1—C1—N2	−169.9 (2)	Cd—S2—C5—N4	−89.2 (2)
S1—C1—N1—C2	−179.8 (2)	S2—C5—N3—C6	175.1 (2)
N2—C1—N1—C2	0.1 (3)	N4—C5—N3—C6	−0.4 (3)
S1—C1—N2—C3	179.65 (19)	S2—C5—N4—C7	−175.0 (2)
S1—C1—N2—C4	−1.0 (4)	S2—C5—N4—C8	5.2 (4)
N1—C1—N2—C3	−0.3 (3)	N3—C5—N4—C7	0.6 (3)
N1—C1—N2—C4	179.0 (2)	N3—C5—N4—C8	−179.2 (3)
C1—N1—C2—C3	0.1 (3)	C5—N3—C6—C7	0.1 (3)
N1—C2—C3—N2	−0.3 (3)	N3—C6—C7—N4	0.3 (3)
C1—N2—C3—C2	0.4 (3)	C5—N4—C7—C6	−0.5 (3)
C4—N2—C3—C2	−179.0 (2)	C8—N4—C7—C6	179.3 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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 code: (i) −x, −y+1, −z+1.

Acknowledgements

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

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