A one-dimensional ABX₃-type coordination polymer: catena-poly[benzyl­tri­methyl­ammonium [tri-[mu]-chlorido-cadmium(II)]]

The crystal structure of the title novel one-dimensional ABX₃-type organic-inorganic hybrid complex {(C₁₀H₁₆N)[CdCl₃]}_n, (I), consists of benzyl­tri­methyl­ammonium (Me₃BzN⁺) cations and one-dimensional anionic {[Cd([mu]-Cl)₃]^-}_[infinity] chains. Each Cd^II centre is hexacoordinated by bridging chloride ligands, giving a slightly distorted octa­hedral Cd([mu]-Cl)₆ arrangement. The octa­hedra are linked by two opposite shared faces, giving rise to an almost perfectly linear anionic {[Cd([mu]-Cl)₃]^-}_[infinity] chain in the a-axis direction. Me₃BzN⁺ cations located in the inter-chain spaces balance the charge. Noncovalent static attracting forces (Coulombic and van der Waals forces) and nonclassical C-H...Cl hydrogen-bond inter­actions stabilize the crystal structure.

S1. Comment

The understanding of ABX₃-type perovskites remains one of the most challenging topics at the boundary between solid-state physics and solid-state chemistry. Perovskite materials exhibit many interesting and intriguing properties, from both the theoretical and application points of view. These compounds are used as sensors and catalyst electrodes in certain types of fuel cells and are candidates for memory devices and spintronics applications (Coey et al., 1999). It should be noted that a columnar arrangement is found frequently in ABX₃-type compounds, which have been extensively studied because numerous crystal structures containing the methylammonium cation exhibit phase transitions related to the dynamics of the organic cations and inorganic anions (Doudin & Chapuis, 1992; Morosin, 1972; Puget et al., 1991; Waśkowska et al., 1990). Layered A₂MX₄ perovskites have attracted sustained interest because of their magnetic, electronic and other physical properties and the possibility of tuning both geometries and properties by variation of the organic cations (Gillon et al., 1999). Although perovskites have been known for a long time, new and intriguing physical effects are periodically discovered and their understanding remains an internationally highly competitive area. With these considerations in mind, we have used the benzyltrimethylammonium (Me₃BzN⁺) cation to replace the N(CH₃)₄⁺ cation and have synthesized the title new one-dimensional ABX₃-type organic–inorganic coordination polymer, (I).

The asymmetric unit of (I) consists of a trichlorocadmiate(II) anion and a Me₃BzN⁺ cation, as shown in Fig. 1. The other three Cl anions (Cl1ⁱ, Cl2ⁱ and Cl3ⁱ) are produced by the corresponding Cl anions through the (1/2 + x, - y + 1/2, z) a-glide plane operation (Fig. 2). The Cd^II centres are hexacoordinated by chloride anions, giving a slightly distorted octahedral Cd(µ-Cl)₆ arrangement. The Cd—Cl bond distances are in the range 2.6271 (12)–2.6685 (13) Å and the Cl—Cd—Cl bond angles are in the range 82.72 (4)–175.25 (7)°, deviating slightly from ideal octahedral angle values (90 and 180°). The octahedra are linked by two opposite shared faces, giving rise to infinite [Cd(µ-Cl)₃^-]_∞ chains parallel to the a axis, with a Cd1···Cd1ⁱ distance of 3.3769 (7) Å and a Cd1ⁱ···Cd1···Cd1ⁱⁱ angle of 179.436 (14)° [symmetry codes: (i) x - 1/2, -y + 1/2, z; (ii) x + 1/2, -y + 1/2, z], indicating that the polymer is perfectly linear (Fig. 2). Thus, all halogen atoms act as bridges between two consecutive Cd atoms, and each pair of consecutive Cd atoms is linked by three corner-shared bridging chlorides. It should be noted that this columnar arrangement is found frequently in ABX₃ compounds (Corradi et al., 1997; Costin-Hogan et al., 2008; Jian et al., 2006; López-Garzón et al., 1995; Ma et al., 2006; Maldonado et al., 2008). For example, the {[Cd₃Cl₉]^3-}_∞ anion reported by Jian et al. (2006) was also a one-dimensional inorganic chain, in which each Cd^II cation is octahedrally surrounded by six bridging Cl atoms, giving rise to polymeric chains. In the [NH(CH₃)₃]CdCl₃ (TrMCd) compound reported by Chapuis & Zuniga (1980), the Cd atoms are located at the centres of face-sharing CdCl₆ octahedra, forming infinite one-dimensional chains perpendicular to a hexagonal or nearly hexagonal net. The interchain distances are determined by the size of the organic cation which occupies the space between the octahedra, with a hydrogen bond between the alkylammonium cation and a Cl^- anion.

There are thus three features in the structure of (I). Firstly, all the Cd^II cations are collinear. Secondly, the Cd1···Cd1 distance is much shorter than those reported in other one-dimensional cadmium polymers bridged by Cl atoms (average ca 4.14 Å) (Huang et al., 1998; Hu et al., 2003; Laskar et al., 2002). Although the Cd···Cd distance in complex (I) is larger than the interatomic distance in bulk Cd (2.98 Å; Stuhlmann et al., 1998), it is still shorter than the 115% total sum of Cd metal radii (3.427 Å; Standard reference?). There seems to be no good theoretically supported argument for the existence of a Cd—Cd metal bond in (I) (Bender et al., 1985). Finally, the Me₃BzN⁺ cations on each side of the inorganic chain are arranged in a zigzag configuration. The charges of the cations are balanced by the polymeric [Cd(µ-Cl)₃^-]_∞ anion. The Me₃BzN⁺ cations are located in the inter-chain space with non-covalent static attracting forces (Coulomb and van der Waals forces) and non-classical C—H···Cl hydrogen-bond interactions with the anionic chains to stabilize the crystal structure (Table 1, Fig. 2). The bond lengths and angles of the Me₃BzN⁺ cations are in agreement with those reported in the literature (Müller et al., 1994; Hauge & Maroy, 1996).

Our interest in one-dimensional ABX₃-type organic–inorganic hybrid complexes is based mainly on their potential uses in molecular dielectrics and ferroelectrics. The variable-temperature dielectric response, especially in the relatively high-frequency range, is very useful in the search for phase transitions (Wu et al., 2011; Wu & Jin, 2012). However, we were unable to detect any dielectric anomalies within the temperature range 93–460 K when we measured the dielectric properties of (I) with temperature, implying that there are no structural phase transitions within that temperature range and that (I) may not have ferroelectric properties (Ye et al., 2009; Fu et al., 2007). Further ABX₃-type ferroelectrics still need to be sought and studied.

Related literature

For related literature, see: Bender et al. (1985); Chapuis & Zuniga (1980); Coey et al. (1999); Corradi et al. (1997); Costin-Hogan, Chen, Hughes, Pickett, Valencia, Rath & Beatty (2008); Doudin & Chapuis (1992); Flack (1983); Fu et al. (2007); Gillon et al. (1999); Hauge & Maroy (1996); Hu et al. (2003); Huang et al. (1998); Jian et al. (2006); López-Garzón, Godino-Salido, Gutiérrez-Valero, Moreno & Odedra (1995); Laskar et al. (2002); Müller et al. (1994); Ma et al. (2006); Maldonado et al. (2008); Morosin (1972); Puget et al. (1991); Stuhlmann et al. (1998); Waśkowska et al. (1990); Wu & Jin (2012); Wu et al. (2011); Ye et al. (2009).

S2. Experimental

Benzyltrimethylammonium chloride (97%, Alfa Aesar) and CdCl₂.2.5H₂O (Sinopharm) were used as commercial products without further purification. ¹H NMR and ¹³C NMR spectra were measured on a Bruker Biospin AG Magnet System 300 MHz NMR instrument in D₂O solution with trimethylsulfoxane as internal standard. IR spectra (4000–400 cm^-1) were recorded on a Shimadzu IR Prestige-21 spectrophotometer with KBr pellets. The melting point was determined using an uncorrected X-4 melting-point apparatus (Beijing Kaifu Company).

Compound (I) was prepared by dissolving equimolar amounts of benzyltrimethylammonium chloride and CdCl₂.2.5H₂O in a mixture of water and methanol (1/1 v/v) to afford a colourless solution. This solution was left to evaporate at room temperature in air for two weeks to afford colourless plate-like crystals of (I) suitable for single-crystal X-ray diffraction (yield 90%; m.p. 471–472 K with decomposition). ¹H NMR (D₂O, δ, p.p.m.): 2.91 (s, 9H, CH₃), 4.30 (s, 2H, CH₂), 7.20–7.37 (5H in phenyl ring); ¹³C NMR (D₂O, δ, p.p.m.): 52.43 (CH₃), 69.57 (CH₂), 127.38, 129.21, 130.85, 132.85 (C in phenyl ring); IR (KBr pellet, ν, cm^-1): 3022, 2986, 2955. 1498, 1471, 1450, 973.

S3. Refinement

H atoms were placed in calculated positions, with Csp²—H = 0.93 Å, and Csp³—H = 0.96 and 0.97 Å, and treated as riding, with U_iso(H) = 1.2U_eq(Csp²) or 1.5U_eq(Csp³). The refinement of the Flack (1983) parameter [x = -0.07 (4)] clearly indicates the polar space group.

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: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The asymmetric unit of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Fig. 2. A view of the one-dimensional triple-stranded braid of [Cd(µ-Cl)3^-]∞ hydrogen-bonded interactions with the cations, along the a axis. Dashed lines indicate hydrogen bonds. [Symmetry codes: (i) x+1/2, -y+1/2, z; (ii) x-1/2, -y+1/2, z; (iii) x, y, z-1; (iv) x+1, y, z-1; (v) x+1, y, z; (vi) x+3/2, -y+1/2, z; (vii) x+2, y, z-1; (viii) x+2, y, z. [Resolution poor - please revise. Please also complete the labelling of the molecule at symmetry position (iii) - two atoms affected]

catena-Poly[benzyltrimethylammonium [tri-µ-chlorido-cadmium(II)]]

Crystal data

(C10H16N)[CdCl3]	Dx = 1.773 Mg m^−3
Mr = 368.99	Melting point = 471–472 K
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 12682 reflections
a = 6.7538 (14) Å	θ = 3.0–27.5°
b = 22.852 (5) Å	µ = 2.13 mm^−1
c = 8.9590 (18) Å	T = 291 K
V = 1382.7 (5) Å^3	Plate, colourless
Z = 4	0.24 × 0.22 × 0.20 mm
F(000) = 728

Data collection

Rigaku Mercury2 diffractometer	3167 independent reflections
Radiation source: fine-focus sealed tube	2743 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.044
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 3.2°
CCD profile fitting scans	h = −8→8
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −29→29
Tmin = 0.590, Tmax = 0.650	l = −11→11
13516 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.027	w = 1/[σ^2(Fo^2) + (0.0132P)^2 + 0.2094P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.056	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.26 e Å^−3
3167 reflections	Δρmin = −0.41 e Å^−3
140 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.0246 (5)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), with 1482 Bijvoet Pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.07 (4)

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
C1	0.4914 (11)	0.1034 (3)	0.8740 (5)	0.092 (2)
H1A	0.4935	0.1313	0.9540	0.137*
H1B	0.6216	0.0874	0.8606	0.137*
H1C	0.4005	0.0725	0.8979	0.137*
C2	0.5601 (6)	0.18467 (17)	0.7107 (7)	0.0743 (13)
H2A	0.5121	0.2076	0.6285	0.111*
H2B	0.6919	0.1713	0.6893	0.111*
H2C	0.5615	0.2081	0.7995	0.111*
C3	0.2256 (5)	0.1557 (2)	0.7500 (12)	0.116 (3)
H3A	0.2067	0.1879	0.6828	0.174*
H3B	0.2062	0.1688	0.8508	0.174*
H3C	0.1320	0.1254	0.7274	0.174*
C4	0.4414 (8)	0.0915 (2)	0.6028 (5)	0.0588 (13)
H4A	0.4182	0.1135	0.5119	0.071*
H4B	0.5756	0.0764	0.5983	0.071*
C5	0.3023 (7)	0.04091 (17)	0.6056 (4)	0.0487 (10)
C6	0.3486 (5)	−0.01128 (18)	0.6770 (4)	0.0517 (11)
H6	0.4710	−0.0155	0.7233	0.062*
C7	0.2155 (6)	−0.05671 (16)	0.6798 (5)	0.0625 (13)
H7	0.2488	−0.0916	0.7272	0.075*
C8	0.0355 (7)	−0.0510 (2)	0.6138 (6)	0.0732 (14)
H8	−0.0556	−0.0815	0.6183	0.088*
C9	−0.0116 (10)	−0.0001 (3)	0.5405 (7)	0.100 (2)
H9	−0.1341	0.0036	0.4941	0.120*
C10	0.1216 (7)	0.0453 (2)	0.5354 (5)	0.0750 (16)
H10	0.0893	0.0794	0.4841	0.090*
Cd1	0.63883 (2)	0.249637 (8)	0.22732 (13)	0.03124 (8)
Cl1	0.38657 (14)	0.28920 (5)	0.02411 (8)	0.0366 (3)
Cl2	0.39437 (15)	0.29886 (5)	0.41788 (9)	0.0390 (3)
Cl3	0.38566 (8)	0.16118 (3)	0.23929 (13)	0.0364 (2)
N1	0.4268 (3)	0.13288 (10)	0.7335 (5)	0.0368 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.146 (6)	0.087 (4)	0.042 (3)	−0.036 (4)	−0.024 (3)	0.016 (3)
C2	0.096 (3)	0.067 (3)	0.060 (3)	−0.043 (2)	0.012 (3)	−0.008 (3)
C3	0.051 (2)	0.077 (3)	0.220 (8)	0.013 (2)	0.018 (5)	−0.058 (6)
C4	0.097 (4)	0.048 (3)	0.031 (2)	−0.007 (3)	0.015 (2)	−0.001 (2)
C5	0.073 (3)	0.035 (2)	0.037 (2)	−0.003 (2)	−0.002 (2)	−0.0065 (17)
C6	0.061 (2)	0.040 (2)	0.054 (3)	0.0121 (19)	0.0014 (17)	−0.0043 (18)
C7	0.080 (3)	0.027 (2)	0.080 (4)	0.008 (2)	0.011 (2)	0.0008 (19)
C8	0.077 (3)	0.043 (3)	0.099 (4)	−0.013 (2)	0.002 (3)	−0.015 (3)
C9	0.094 (4)	0.059 (3)	0.148 (6)	−0.012 (3)	−0.059 (5)	−0.009 (5)
C10	0.107 (4)	0.045 (3)	0.074 (3)	−0.010 (3)	−0.050 (3)	0.007 (2)
Cd1	0.01888 (11)	0.04055 (14)	0.03429 (13)	−0.00048 (8)	0.0028 (3)	−0.00021 (14)
Cl1	0.0284 (5)	0.0486 (7)	0.0328 (5)	0.0003 (4)	0.0029 (5)	0.0073 (5)
Cl2	0.0300 (6)	0.0498 (7)	0.0372 (6)	−0.0024 (4)	0.0063 (5)	−0.0122 (5)
Cl3	0.0291 (3)	0.0340 (4)	0.0461 (5)	0.0009 (3)	0.0050 (6)	0.0031 (6)
N1	0.0426 (12)	0.0387 (14)	0.0291 (13)	−0.0064 (11)	0.007 (2)	−0.006 (2)

Geometric parameters (Å, º)

C1—N1	1.493 (6)	C6—H6	0.9300
C1—H1A	0.9600	C7—C8	1.358 (6)
C1—H1B	0.9600	C7—H7	0.9300
C1—H1C	0.9600	C8—C9	1.373 (7)
C2—N1	1.501 (4)	C8—H8	0.9300
C2—H2A	0.9600	C9—C10	1.374 (7)
C2—H2B	0.9600	C9—H9	0.9300
C2—H2C	0.9600	C10—H10	0.9300
C3—N1	1.463 (4)	Cd1—Cl1^i	2.6271 (12)
C3—H3A	0.9600	Cd1—Cl2	2.6279 (13)
C3—H3B	0.9600	Cd1—Cl3^i	2.6351 (8)
C3—H3C	0.9600	Cd1—Cl3	2.6497 (8)
C4—C5	1.489 (6)	Cd1—Cl1	2.6523 (13)
C4—N1	1.509 (5)	Cd1—Cl2^i	2.6685 (13)
C4—H4A	0.9700	Cd1—Cd1^i	3.3769 (7)
C4—H4B	0.9700	Cl1—Cd1^ii	2.6271 (12)
C5—C10	1.377 (6)	Cl2—Cd1^ii	2.6686 (13)
C5—C6	1.389 (5)	Cl3—Cd1^ii	2.6351 (8)
C6—C7	1.373 (5)
N1—C1—H1A	109.5	C9—C10—H10	119.7
N1—C1—H1B	109.5	C5—C10—H10	119.7
H1A—C1—H1B	109.5	Cl1^i—Cd1—Cl2	174.25 (5)
N1—C1—H1C	109.5	Cl1^i—Cd1—Cl3^i	83.49 (4)
H1A—C1—H1C	109.5	Cl2—Cd1—Cl3^i	92.29 (4)
H1B—C1—H1C	109.5	Cl1^i—Cd1—Cl3	100.45 (4)
N1—C2—H2A	109.5	Cl2—Cd1—Cl3	83.96 (4)
N1—C2—H2B	109.5	Cl3^i—Cd1—Cl3	175.25 (7)
H2A—C2—H2B	109.5	Cl1^i—Cd1—Cl1	92.79 (5)
N1—C2—H2C	109.5	Cl2—Cd1—Cl1	84.05 (3)
H2A—C2—H2C	109.5	Cl3^i—Cd1—Cl1	99.83 (4)
H2B—C2—H2C	109.5	Cl3—Cd1—Cl1	82.72 (4)
N1—C3—H3A	109.5	Cl1^i—Cd1—Cl2^i	83.75 (3)
N1—C3—H3B	109.5	Cl2—Cd1—Cl2^i	99.70 (6)
H3A—C3—H3B	109.5	Cl3^i—Cd1—Cl2^i	83.45 (4)
N1—C3—H3C	109.5	Cl3—Cd1—Cl2^i	94.28 (4)
H3A—C3—H3C	109.5	Cl1—Cd1—Cl2^i	174.96 (5)
H3B—C3—H3C	109.5	Cl1^i—Cd1—Cd1^i	50.56 (3)
C5—C4—N1	115.6 (3)	Cl2—Cd1—Cd1^i	128.77 (3)
C5—C4—H4A	108.4	Cl3^i—Cd1—Cd1^i	50.474 (17)
N1—C4—H4A	108.4	Cl3—Cd1—Cd1^i	130.470 (19)
C5—C4—H4B	108.4	Cl1—Cd1—Cd1^i	129.84 (3)
N1—C4—H4B	108.4	Cl2^i—Cd1—Cd1^i	49.86 (3)
H4A—C4—H4B	107.4	Cl1^i—Cd1—Cd1^ii	129.68 (3)
C10—C5—C6	118.2 (4)	Cl2—Cd1—Cd1^ii	50.92 (3)
C10—C5—C4	119.6 (4)	Cl3^i—Cd1—Cd1^ii	128.963 (19)
C6—C5—C4	122.2 (4)	Cl3—Cd1—Cd1^ii	50.092 (17)
C7—C6—C5	120.7 (4)	Cl1—Cd1—Cd1^ii	49.91 (3)
C7—C6—H6	119.6	Cl2^i—Cd1—Cd1^ii	130.45 (3)
C5—C6—H6	119.6	Cd1^i—Cd1—Cd1^ii	179.436 (13)
C8—C7—C6	120.3 (4)	Cd1^ii—Cl1—Cd1	79.53 (4)
C8—C7—H7	119.8	Cd1—Cl2—Cd1^ii	79.22 (4)
C6—C7—H7	119.8	Cd1^ii—Cl3—Cd1	79.43 (3)
C7—C8—C9	119.8 (5)	C3—N1—C1	110.3 (5)
C7—C8—H8	120.1	C3—N1—C2	106.8 (3)
C9—C8—H8	120.1	C1—N1—C2	107.2 (4)
C8—C9—C10	120.2 (5)	C3—N1—C4	111.3 (5)
C8—C9—H9	119.9	C1—N1—C4	110.6 (3)
C10—C9—H9	119.9	C2—N1—C4	110.5 (4)
C9—C10—C5	120.7 (5)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···Cl3^iii	0.96	2.74	3.600 (6)	149
C3—H3B···Cl1^iv	0.96	2.83	3.586 (7)	137
C4—H4A···Cl3	0.97	2.68	3.645 (5)	171

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