A tri­methyl­sulfonium salt with a novel polymeric cadmate anion

The title salt, catena-poly[tri­methyl­sulfonium [[mu]₂-chlorido-di-[mu]₂-thio­cyanato-cadmate(II)]] {(C₃H₉S)[CdCl(NCS)₂]}_n, con­sists of tri­methyl­sulfonium cations sandwiched between layers of a two-dimensional polyanion. The Cd^II centre displays a distorted octa­hedral environment coordinated by two bridging Cl atoms, two thio­cyanate N atoms and two thio­cyanate S atoms. The thio­cyanate groups adopt the [mu]-1,3-coordination mode and bridge the Cd^II centres into a one-dimensional zigzag chain extended along the [110] direction. The Cd^II centres of the zigzag chains are crosslinked by bridging Cl atoms, forming a two-dimensional polyanion. The two-dimensional anions are linked to layers of tri­methyl­sulfonium cations by weak inter­molecular C-H...Cl hydrogen bonds, forming the three-dimensional structure.

S1. Introduction

The design and construction of novel organically templated halometallates have attracted much attention due to their intriguing architectures and topologies (Wu et al., 2009; Arnby et al., 2004; Corradi et al., 1998; Subramanian & Hoffmann, 1992; Costin-Hogan et al., 2008) and their potential applications in many fields, including ferroelectricity, optics, magnetism, electrical conductivity and catalysis (Zhang & Xiong, 2012; Corradi et al., 1993, 2001; Martin & Greenwood, 1997; Willett et al., 2004; Yu et al., 2003). Based on the strategy of employing various organic N-heterocyclic/amine molecules as the templating agents, a large number of halometallates with inter­esting structures and useful properties have been obtained in acidic solutions under ambient/hydro­(solvo)thermal conditions in the past two decades. It is known that the size, charge and form of the organic N-heterocyclic/amine molecules has a significant impact on the halometallate frameworks. Although some significant conclusions about the structures have been drawn (Thorn et al., 2005, 2006), it is still difficult to predict the structure of the obtained halometallate when a new organic N-heterocyclic/amine molecule is used, because the anionic halometallate framework may be modified. To introduce another kind of potential bridging inorganic anionic group into the halometallate framework is a useful strategy. In consideration of the potential diversity of coordination modes for the thio­cyanate (SCN^-) group, we focused on the structural characterization of organically templated halocadmates containing the SCN^- group. Recently, several examples of organically templated halocadmates modified with SCN^- groups have been obtained, including the chains [H₂bp][CdCl₂(SCN)₂], [H₂bp][Cd(SCN)₄] (H₂bp is ????), [H₂bpp][Cd₃Br(SCN)₇] (H₂bpp is ????), [H₂bpy][CdBr₂(SCN)₂] (H₂bpy is ?,?'-bi­pyridine­diium), [H₂bpe][Cd(SCN)₄] (H₂bpe is ????) and [H₂dach][CdCl₄] (H₂dach is ????) (Jia et al., 2012) and tubes [H₂pip]₄[Cd₃Br₈(SCN)₂(SO₄)₂(H₂O)].4H₂O (H₂pip is piperidine­diium) (Jin, Jia, Peng et al., 2011). Compared with the above-mentioned cases, two-dimensional organically templated halocadmates modified with SCN^- groups are rare. We report here the synthesis and crystal structure of a two-dimensional tri­methyl­sulfonium-templated chloro­cadmate, (I), containing the SCN^- group.

S2. Experimental

S2.1. Synthesis and crystallization

A mixture of tri­methyl­sulfonium iodide (1.02 g, 5 mmol) and silver carbonate (0.69 g, 2.5 mmol) were added to water (30 ml) and stirred for 30 min at room temperture. After filtering the mixtures, CdCl₂ (0.92 g, 5 mmol) and NH₄SCN (0.38 g, 5 mmol) were added to the filtrate and stirring continued for 2 min. Hydro­chloric acid (0.97 g, 5 mmol, 37% solution in water) was added to the above solution until all the precipitates dissolved. The solution was left to evaporate at room temperature in air for 4 d and afforded colourless crystals suitable for single-crystal X-ray diffraction. IR spectra (4000–400 cm^-1) were recorded on a Shimadzu IR Prestige-21 spectrophotometer with KBr pellets. IR (KBr pellet, ν, cm^-1): 3015 (m), 2927 (m), 2852 (w), 2106 (s), 1625 (s), 1414 (m), 1340 (w), 1039 (m), 938 (w), 755 (w), 462 (m).

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms on C atoms were included in calculated positions and were refined using a riding model, with C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C).

S3. Results and discussion

The title salt, catena-poly[tri­methyl­sulfonium [µ₂-chlorido-di-µ₂-thio­cyanato-cadmate(II)]], (I), has an asymmetric unit consisting of a tri­methyl­sulphonium cation with an anion consisting of a Cd^II cation, two coordinated iso­thio­cyanates and a chloride ligand. Both thio­cyanate ligands and the chloride ligand bridge to inversion-related Cd^II centres resulting in a cadmium complex which has a distorted o­cta­hedral geometry, with two N-coordinated NCS^- ligands, two S-coordinated NCS^- ligands and two chloride ligands (Fig. 1). IR spectroscopic analysis of (I) revealed a strong peak at 2106 cm^-1 that is consistent with the presence of SCN^- groups. As is shown in Fig. 1, the local coordination environment around the crystallographically unique Cd1 cation can be best described as a distorted o­cta­hedron with coordination from two thio­cyanate N atoms (N1 and N2), two thio­cyanate S atoms (S2 and S3ⁱⁱⁱ; symmetry codes as in Fig. 1) and two bridging Cl atoms (Cl1 and Cl1ⁱⁱ). The equatorial plane for the Cd o­cta­hedron is occupied by one µ₂-Cl1 ion, one SCN^- S atom (Sⁱⁱⁱ) and two SCN^- N atoms (N1 and N2), whereas the axis is occupied by the µ₂-Cl1ⁱⁱ ion and the SCN^- S atom (S2) (symmetry codes as in Fig. 1). Note that the same atoms adopt the trans arrangement. The Cd1—N distances of 2.311 (5) and 2.286 (5) Å the Cd1—S distances of 2.7334 (18) and 2.765 (2) Å are comparable with those observed in previously reported compounds (Yu et al., 2008; Jin, Jia, Wang et al., 2011), however, the bridged Cd1—Cl distances of 2.6204 (16) and 2.6440 (16) Å are shorter than distances observed in other reported compounds (Jin, Jia, Wang et al., 2011) which are 2.7636 (9) and 2.7347 (9) Å. The µ₂-SCN^- groups bridge the Cd^II centres into a one-dimensional zigzag chain extended along the [110] direction consisting of eight-membered Cd₂(SCN)₂ loops (Fig. 2). The atoms of the resulting eight-membered Cd₂(SCN)₂ ring are nearly coplanar (mean deviation = 0.0060 Å); this is similar to the Cd₂(SCN)₂ ring in [Cd(SCN)₂(dach)] (Jin, Jia, Wang et al., 2011), but is different to the chair-like conformation exhibited by many other Cd₂(SCN)₂ rings whose mean deviations from the least-squares plane are generally larger (ca 0.7 Å) (Yu et al., 2008; Vujovic et al., 2004; Bose et al., 2004; Jia et al., 2012). Between the zigzag chains, the Cl/Clⁱⁱ and Cl^v/Cl^vi atoms bridge the Cd1/Cd1ⁱⁱ and Cd^v/Cd^vi atoms (symmetry codes as in Fig. 3), respectively, forming a two-dimensional layer structure extending along the ab plane. Thus, two Cl atoms, six Cd^II atoms and four SCN^- groups form a 20-membered ring, as shown in Fig. 3. The two-dimensional structure is also stabilized by weak Cl···S inter­actions with distances of 3.517 (3) Å. The Cd···Cd distance bridged by Cl atoms is 3.9110 (12) Å, while the Cd···Cd distances in the Cd₂(SCN)₂ rings are 5.9848 (19) and 6.1697 (17) Å. The C₃H₉S⁺ cations are located in the inter-layer space and the charges of the cations are balanced by the anionic layers. The bond lengths and angles of the C₃H₉S⁺ cations are in agreement with those reported in the literature (Hess et al., 2007). The anionic layers are linked by tri­methyl­sulfonium cations by weak inter­molecular C1—H1C···Cl1(x-1, y, z-1) hydrogen bonds, forming a three-dimensional structure (Table 2 and Fig. 4).

In the Cambridge Structural Database (CSD; Version 5.33; Allen 2002), the reported two-dimensional organically templated halocadmates with an introduced SCN^-group, can be divided as two types: (a) salt complexes containing organic cations and polymeric anions, with the polymeric anions constructed from Cd atoms and SCN^- groups only without halogen atoms, for example, [BMIM]₂[Cd₂(SCN)₆] (BMIM = 1-butyl-3-methyl­imidazolium; Gao et al., 2008); (b) two-dimensional layered cadmium–thio­cyanate coordination polymers, where the organic templating agents are coordinated to the Cd atoms, for example, [Cd(SCN)₂(dach)] (Jin, Jia, Peng et al., 2011; OR Jin, Jia, Wang et al., 2011). But the title salt does not fit into either of these types and contains organic cations and novel polymeric anions constructed by Cd atoms, µ₂-SCN^- groups and bridging Cl atoms, which means that halogen atoms have been incorporated successfully into the anionic layers of the two-dimensional organically templated halocadmates.

In summary, a rare two-dimensional organically templated halocadmate with a novel polymeric anion has been synthetized and characterized. There are no complex with such an anion in the CSD.

Related literature

For related literature, see: Allen (2002); Arnby et al. (2004); Bose et al. (2004); Corradi et al. (1993, 1998, 2001); Costin-Hogan, Chen, Hughes, Pickett, Valencia, Rath & Beatty (2008); Gao et al. (2008); Hess et al. (2007); Jia et al. (2012); Jin, Jia, Peng, Yu & Xu (2011); Jin, Jia, Wang, Yu, Yang & Xu (2011); Martin & Greenwood (1997); Subramanian & Hoffmann (1992); Thorn et al. (2005, 2006); Vujovic et al. (2004); Willett et al. (2004); Wu et al. (2009); Yu et al. (2003, 2008); Zhang & Xiong (2012).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) -x+1, -y, -z+1; (ii) -x+2, -y, -z+1; (iii) -x+2, -y+1, -z+1; (iv) x, y-1, z.]
	Fig. 2. Zigzag chains constructed from {Cd2(SCN)2} loops.
	Fig. 3. Diagram of the two-dimensional polymeric polyanion. [Symmetry codes: (ii) -x+2, -y, -z+1; (v) -x+1, -y-1, -z+1; (vi) x-1, y-1, z.]
	Fig. 4. Packing diagram of (I), with the weak C—H···Cl hydrogen-bond interactions shown as dashed lines.

catena-poly[trimethylsulfonium [µ₂-chlorido-di-µ₂-thiocyanato-cadmate(II)]]

Crystal data

(C3H9S)[CdCl(NCS)2]	V = 586.1 (2) Å^3
Mr = 341.17	Z = 2
Triclinic, P1	F(000) = 332
Hall symbol: -P 1	Dx = 1.933 Mg m^−3
a = 8.0676 (16) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.8427 (18) Å	µ = 2.58 mm^−1
c = 9.0977 (18) Å	T = 293 K
α = 105.64 (3)°	Block, colourless
β = 105.18 (3)°	0.2 × 0.2 × 0.2 mm
γ = 98.56 (3)°

Data collection

Rigaku Mercury2 diffractometer	2251 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.037
Graphite monochromator	θmax = 27.5°, θmin = 3.0°
CCD_Profile_fitting scans	h = −10→10
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −11→11
Tmin = 0.599, Tmax = 0.602	l = −11→11
6135 measured reflections	3 standard reflections every 180 reflections
2689 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.115	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0488P)^2 + 1.3869P] where P = (Fo^2 + 2Fc^2)/3
2689 reflections	(Δ/σ)max = 0.001
112 parameters	Δρmax = 2.43 e Å^−3
0 restraints	Δρmin = −0.81 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.86066 (5)	0.16318 (5)	0.51766 (5)	0.03287 (15)
Cl1	0.9935 (2)	−0.01563 (17)	0.68752 (17)	0.0396 (3)
S3	0.8315 (2)	0.6143 (2)	0.2782 (2)	0.0525 (5)
S2	0.6964 (2)	0.27693 (18)	0.7376 (2)	0.0450 (4)
N2	0.8133 (7)	0.3471 (6)	0.3859 (7)	0.0466 (13)
N1	0.5958 (7)	−0.0174 (6)	0.3573 (7)	0.0489 (14)
C5	0.8253 (7)	0.4587 (7)	0.3425 (7)	0.0342 (12)
C4	0.5235 (8)	0.1251 (7)	0.6802 (6)	0.0354 (12)
S1	0.2606 (2)	0.1828 (2)	0.14064 (19)	0.0457 (4)
C1	0.0818 (9)	0.2742 (8)	0.0798 (8)	0.0480 (15)
H1A	0.1280	0.3858	0.0952	0.072*
H1B	0.0049	0.2665	0.1434	0.072*
H1C	0.0167	0.2191	−0.0318	0.072*
C2	0.4073 (10)	0.2480 (13)	0.0441 (9)	0.077 (3)
H2A	0.4274	0.3631	0.0684	0.116*
H2B	0.3568	0.1964	−0.0702	0.116*
H2C	0.5175	0.2198	0.0814	0.116*
C3	0.3675 (9)	0.3103 (9)	0.3439 (7)	0.0518 (17)
H3A	0.4792	0.2860	0.3847	0.078*
H3B	0.2945	0.2921	0.4085	0.078*
H3C	0.3862	0.4213	0.3480	0.078*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0327 (2)	0.0279 (2)	0.0392 (2)	0.00456 (15)	0.01092 (17)	0.01454 (17)
Cl1	0.0512 (8)	0.0372 (7)	0.0403 (7)	0.0134 (6)	0.0212 (6)	0.0201 (6)
S3	0.0507 (9)	0.0420 (9)	0.0542 (10)	−0.0053 (7)	−0.0063 (8)	0.0295 (8)
S2	0.0393 (8)	0.0330 (8)	0.0515 (9)	−0.0021 (6)	0.0151 (7)	0.0010 (7)
N2	0.035 (3)	0.038 (3)	0.061 (3)	−0.001 (2)	0.001 (2)	0.025 (3)
N1	0.042 (3)	0.042 (3)	0.051 (3)	−0.012 (2)	0.021 (2)	0.001 (2)
C5	0.028 (3)	0.035 (3)	0.033 (3)	0.004 (2)	0.001 (2)	0.011 (2)
C4	0.040 (3)	0.037 (3)	0.030 (3)	0.011 (2)	0.012 (2)	0.009 (2)
S1	0.0481 (9)	0.0432 (9)	0.0422 (9)	0.0075 (7)	0.0139 (7)	0.0103 (7)
C1	0.047 (4)	0.053 (4)	0.043 (3)	0.015 (3)	0.011 (3)	0.015 (3)
C2	0.051 (4)	0.127 (8)	0.055 (5)	0.008 (5)	0.023 (4)	0.032 (5)
C3	0.050 (4)	0.068 (5)	0.029 (3)	0.011 (3)	0.004 (3)	0.013 (3)

Geometric parameters (Å, º)

Cd1—N2	2.286 (5)	S1—C2	1.766 (7)
Cd1—N1	2.311 (5)	S1—C3	1.785 (6)
Cd1—Cl1^i	2.6204 (16)	S1—C1	1.791 (7)
Cd1—Cl1	2.6440 (16)	C1—H1A	0.9600
Cd1—S2	2.7334 (18)	C1—H1B	0.9600
Cd1—S3^ii	2.765 (2)	C1—H1C	0.9600
Cl1—Cd1^i	2.6204 (16)	C2—H2A	0.9600
S3—C5	1.633 (6)	C2—H2B	0.9600
S3—Cd1^ii	2.765 (2)	C2—H2C	0.9600
S2—C4	1.644 (6)	C3—H3A	0.9600
N2—C5	1.158 (7)	C3—H3B	0.9600
N1—C4^iii	1.153 (7)	C3—H3C	0.9600
C4—N1^iii	1.153 (7)
N2—Cd1—N1	93.2 (2)	C2—S1—C3	101.4 (4)
N2—Cd1—Cl1^i	91.08 (15)	C2—S1—C1	102.0 (4)
N1—Cd1—Cl1^i	87.67 (14)	C3—S1—C1	101.3 (3)
N2—Cd1—Cl1	166.65 (13)	S1—C1—H1A	109.5
N1—Cd1—Cl1	98.94 (16)	S1—C1—H1B	109.5
Cl1^i—Cd1—Cl1	84.04 (5)	H1A—C1—H1B	109.5
N2—Cd1—S2	95.95 (15)	S1—C1—H1C	109.5
N1—Cd1—S2	88.36 (14)	H1A—C1—H1C	109.5
Cl1^i—Cd1—S2	172.11 (5)	H1B—C1—H1C	109.5
Cl1—Cd1—S2	89.86 (5)	S1—C2—H2A	109.5
N2—Cd1—S3^ii	87.08 (13)	S1—C2—H2B	109.5
N1—Cd1—S3^ii	176.85 (14)	H2A—C2—H2B	109.5
Cl1^i—Cd1—S3^ii	95.46 (6)	S1—C2—H2C	109.5
Cl1—Cd1—S3^ii	81.05 (5)	H2A—C2—H2C	109.5
S2—Cd1—S3^ii	88.49 (6)	H2B—C2—H2C	109.5
Cd1^i—Cl1—Cd1	95.96 (5)	S1—C3—H3A	109.5
C5—S3—Cd1^ii	105.4 (2)	S1—C3—H3B	109.5
C4—S2—Cd1	100.4 (2)	H3A—C3—H3B	109.5
C5—N2—Cd1	165.0 (5)	S1—C3—H3C	109.5
C4^iii—N1—Cd1	157.6 (5)	H3A—C3—H3C	109.5
N2—C5—S3	177.2 (5)	H3B—C3—H3C	109.5
N1^iii—C4—S2	178.4 (6)
N2—Cd1—Cl1—Cd1^i	−69.0 (6)	N1—Cd1—N2—C5	−178 (2)
N1—Cd1—Cl1—Cd1^i	86.69 (14)	Cl1^i—Cd1—N2—C5	−91 (2)
Cl1^i—Cd1—Cl1—Cd1^i	0.0	Cl1—Cd1—N2—C5	−23 (3)
S2—Cd1—Cl1—Cd1^i	175.00 (5)	S2—Cd1—N2—C5	93 (2)
S3^ii—Cd1—Cl1—Cd1^i	−96.50 (7)	S3^ii—Cd1—N2—C5	5 (2)
N2—Cd1—S2—C4	112.2 (2)	N2—Cd1—N1—C4^iii	−161.2 (13)
N1—Cd1—S2—C4	19.1 (3)	Cl1^i—Cd1—N1—C4^iii	107.8 (13)
Cl1—Cd1—S2—C4	−79.9 (2)	Cl1—Cd1—N1—C4^iii	24.2 (13)
S3^ii—Cd1—S2—C4	−160.9 (2)	S2—Cd1—N1—C4^iii	−65.4 (13)

Symmetry codes: (i) −x+2, −y, −z+1; (ii) −x+2, −y+1, −z+1; (iii) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1C···Cl1^iv	0.96	2.76	3.606 (7)	147

Symmetry code: (iv) x−1, y, z−1.