Acta Cryst. (2007). E63, m1780 [ doi:10.1107/S1600536807025585 ]
The Cd atom in the title compound, (C12H14N2)[CdBr2Cl2], is coordinated by four halogen atoms in a tetrahedral geometry. The cation lies on a centre of inversion and the anion about a mirror plane. The halogen atoms on the mirror plane are both disordered between Br and Cl in a ratio of 0.75:0.25. The halogen atom in the general position is disordered between Br and Cl in a ratio of 0.25:0.75.
The salt was synthesized from the reaction of ethane-1,2-dipyridinium dibromide (0.035 g, 0.1 mmol) in methanol (5 ml) and cadmium dichloride (0.037 g, 0.2 mmol) in DMF (10 ml). The mixture was set aside for the formation of colourless block-shaped crystals in 40% yield after several days. CH&N elemental analysis: Calc. C 27.22, H 2.67, N 5.29%. Found C 27.89, H 2.49, N 5.36%.
Of the three halogens in the asymmetric unit, one lies in a general position and the other two on a mirror plane. Initial attempts to refine the structure with either three chlorines or three bromines gave unacceptably high R-indices (and large peaks/holes). The three halogen atoms were then refined as three (Br+Cl) mixtures; in one attempt the components had only the same displacement parameters. A second attempt allowed the mixtures to have the same displacement parameters as well as sharing the same site. The second led to a formulation consisting of approximately two Br and two Cl atoms. The use of a special restraint command that fixed the number of Br and Cl atoms as both being exactly two led to the occupancy of Br1 as nearly 0.25 and that of Br2 and Br3 as both nearly 0.75. In the best disorder model, the halogen in the general position was set to (0.25Br + 0.75 C l); those in the special position were both set to (0.75Br + 0.25 C l)·The anion is [CdBr2Cl2]2−, a formulation that is supported by CH&N elemental analysis. Other formulations led to much larger peaks/holes.
Disorder also affected the cation; the pyridyl ring was refined as a rigid hexagon of 1.39 Å sides. The C—C distance was restrained to 1.50±0.01 Å, and the N···C distance to 2.45±0.01 Å. The displacement parameters of atoms of the cation were restrained to be nearly isotropic. Carbon-bound H atoms were positioned geometrically (C–H 0.93 and 0.97 Å), and were included in the refinement in the riding model approximation, with Uiso(H) = 1.2Ueq(C).
In the final difference Fourier map the largest peak was 0.9 Å from C6 and the deepest hole at 0.6 Å from Cl3.
Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2007).
![[Figure 1]](./wn2141fig1thm.gif)
| Fig. 1. The structure of [C12H14N2][CdBr2Cl2], with displacement ellipsoids drawn at the 50% probability level. The bromine and chlorine atoms are disordered; the halogen atom on the general position is labelled X1 (and the symmetry-related X1i); those on the special position are labelled X2 and X3. Hydrogen atoms are drawn as spheres of arbitrary radius. [Symmetry code: i = x, 3/2 – y, z.] Unlabelled atoms in the cation are related to labelled atoms by (1 – x, 1 – y, 1 – z). |
| (C12H14N2)[CdBr2Cl2] | F000 = 1008 |
| Mr = 529.37 | Dx = 2.056 Mg m−3 |
| Orthorhombic, Pnma | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -P 2ac 2n | Cell parameters from 4134 reflections |
| a = 17.955 (2) Å | θ = 2.3–27.4º |
| b = 14.338 (1) Å | µ = 6.25 mm−1 |
| c = 6.6437 (6) Å | T = 295 (2) K |
| V = 1710.4 (3) Å3 | Block, colourless |
| Z = 4 | 0.20 × 0.20 × 0.10 mm |
| Bruker APEX area-detector diffractometer | 1564 independent reflections |
| Radiation source: fine-focus sealed tube | 1415 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.025 |
| T = 298(2) K | θmax = 25.0º |
| φ and ω scans | θmin = 2.3º |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −17→21 |
| Tmin = 0.147, Tmax = 0.574 | k = −15→17 |
| 8939 measured reflections | l = −7→7 |
| 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)] = 0.057 | H-atom parameters constrained |
| wR(F2) = 0.179 | w = 1/[σ2(Fo2) + (0.1162P)2 + 9.0378P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.06 | (Δ/σ)max = 0.001 |
| 1564 reflections | Δρmax = 1.77 e Å−3 |
| 79 parameters | Δρmin = −1.30 e Å−3 |
| 44 restraints | Extinction correction: none |
| Primary atom site location: structure-invariant direct methods |
| (C12H14N2)[CdBr2Cl2] | V = 1710.4 (3) Å3 |
| Mr = 529.37 | Z = 4 |
| Orthorhombic, Pnma | Mo Kα |
| a = 17.955 (2) Å | µ = 6.25 mm−1 |
| b = 14.338 (1) Å | T = 295 (2) K |
| c = 6.6437 (6) Å | 0.20 × 0.20 × 0.10 mm |
| Bruker APEX area-detector diffractometer | 1564 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1415 reflections with I > 2σ(I) |
| Tmin = 0.147, Tmax = 0.574 | Rint = 0.025 |
| 8939 measured reflections |
| R[F2 > 2σ(F2)] = 0.057 | 44 restraints |
| wR(F2) = 0.179 | H-atom parameters constrained |
| S = 1.06 | Δρmax = 1.77 e Å−3 |
| 1564 reflections | Δρmin = −1.30 e Å−3 |
| 79 parameters |
| x | y | z | Uiso*/Ueq | Occ. (<1) | |
| Cd1 | 0.92879 (4) | 0.7500 | 0.64150 (12) | 0.0371 (3) | |
| Br1 | 0.91363 (10) | 0.60359 (14) | 0.4500 (3) | 0.0702 (6) | 0.25 |
| Br2 | 0.82923 (11) | 0.7500 | 0.9121 (3) | 0.0760 (6) | 0.75 |
| Br3 | 1.06428 (9) | 0.7500 | 0.7605 (3) | 0.0720 (6) | 0.75 |
| Cl1 | 0.91363 (10) | 0.60359 (14) | 0.4500 (3) | 0.0702 (6) | 0.75 |
| Cl2 | 0.82923 (11) | 0.7500 | 0.9121 (3) | 0.0760 (6) | 0.25 |
| Cl3 | 1.06428 (9) | 0.7500 | 0.7605 (3) | 0.0720 (6) | 0.25 |
| N1 | 0.5912 (2) | 0.5361 (5) | 0.4128 (9) | 0.069 (2) | |
| C1 | 0.6503 (3) | 0.5331 (5) | 0.5477 (8) | 0.075 (3) | |
| C2 | 0.7163 (2) | 0.5795 (5) | 0.5034 (8) | 0.056 (2) | |
| C3 | 0.7231 (2) | 0.6288 (4) | 0.3243 (8) | 0.055 (2) | |
| C4 | 0.6640 (3) | 0.6318 (4) | 0.1894 (7) | 0.053 (2) | |
| C5 | 0.5980 (2) | 0.5854 (4) | 0.2336 (7) | 0.055 (2) | |
| C6 | 0.5283 (5) | 0.4733 (7) | 0.4383 (15) | 0.080 (3) | |
| H1 | 0.6457 | 0.5001 | 0.6675 | 0.090* | |
| H2 | 0.7558 | 0.5775 | 0.5937 | 0.067* | |
| H3 | 0.7673 | 0.6599 | 0.2947 | 0.067* | |
| H4 | 0.6686 | 0.6648 | 0.0695 | 0.064* | |
| H5 | 0.5585 | 0.5874 | 0.1434 | 0.066* | |
| H6a | 0.5436 | 0.4170 | 0.5081 | 0.096* | |
| H6b | 0.5076 | 0.4561 | 0.3087 | 0.096* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cd1 | 0.0328 (5) | 0.0379 (5) | 0.0406 (5) | 0.000 | 0.0018 (3) | 0.000 |
| Br1 | 0.0544 (10) | 0.0715 (12) | 0.0846 (13) | −0.0025 (8) | −0.0020 (9) | −0.0256 (10) |
| Br2 | 0.0685 (11) | 0.1012 (14) | 0.0584 (10) | 0.000 | 0.0344 (8) | 0.000 |
| Br3 | 0.0437 (9) | 0.0825 (12) | 0.0897 (14) | 0.000 | −0.0088 (8) | 0.000 |
| Cl1 | 0.0544 (10) | 0.0715 (12) | 0.0846 (13) | −0.0025 (8) | −0.0020 (9) | −0.0256 (10) |
| Cl2 | 0.0685 (11) | 0.1012 (14) | 0.0584 (10) | 0.000 | 0.0344 (8) | 0.000 |
| Cl3 | 0.0437 (9) | 0.0825 (12) | 0.0897 (14) | 0.000 | −0.0088 (8) | 0.000 |
| N1 | 0.033 (3) | 0.105 (6) | 0.069 (4) | −0.018 (4) | −0.009 (3) | 0.033 (4) |
| C1 | 0.057 (5) | 0.100 (7) | 0.069 (5) | −0.008 (5) | −0.006 (4) | 0.034 (5) |
| C2 | 0.025 (3) | 0.070 (5) | 0.072 (5) | −0.002 (3) | −0.008 (3) | 0.018 (4) |
| C3 | 0.032 (4) | 0.061 (5) | 0.073 (5) | −0.010 (4) | 0.005 (4) | 0.011 (4) |
| C4 | 0.050 (4) | 0.054 (4) | 0.055 (4) | −0.010 (4) | 0.006 (4) | 0.009 (4) |
| C5 | 0.036 (4) | 0.069 (5) | 0.059 (5) | −0.011 (4) | −0.002 (4) | 0.013 (4) |
| C6 | 0.100 (7) | 0.066 (5) | 0.074 (6) | 0.021 (5) | −0.016 (5) | −0.011 (5) |
| Cd1—Br1 | 2.470 (2) | C2—H2 | 0.9300 |
| Cd1—Br1i | 2.470 (2) | C3—C4 | 1.3900 |
| Cd1—Br2 | 2.535 (2) | C3—H3 | 0.9300 |
| Cd1—Br3 | 2.558 (2) | C4—C5 | 1.3900 |
| N1—C1 | 1.3900 | C4—H4 | 0.9300 |
| N1—C5 | 1.3900 | C5—H5 | 0.9300 |
| N1—C6 | 1.453 (12) | C6—C6ii | 1.514 (9) |
| C1—C2 | 1.3900 | C6—H6A | 0.9700 |
| C1—H1 | 0.9300 | C6—H6B | 0.9700 |
| C2—C3 | 1.3900 | ||
| Br1—Cd1—Br1i | 116.4 (1) | C4—C3—C2 | 120.0 |
| Br1—Cd1—Br2 | 106.7 (1) | C4—C3—H3 | 120.0 |
| Br1—Cd1—Br3 | 105.3 (1) | C2—C3—H3 | 120.0 |
| Br1i—Cd1—Br2 | 106.7 (1) | C3—C4—C5 | 120.0 |
| Br1i—Cd1—Br3 | 105.3 (1) | C3—C4—H4 | 120.0 |
| Br2—Cd1—Br3 | 116.8 (1) | C5—C4—H4 | 120.0 |
| C1—N1—C5 | 120.0 | C4—C5—N1 | 120.0 |
| C1—N1—C6 | 119.9 (6) | C4—C5—H5 | 120.0 |
| C5—N1—C6 | 118.9 (6) | N1—C5—H5 | 120.0 |
| N1—C1—C2 | 120.0 | N1—C6—C6ii | 105.8 (10) |
| N1—C1—H1 | 120.0 | N1—C6—H6A | 110.6 |
| C2—C1—H1 | 120.0 | C6ii—C6—H6A | 110.6 |
| C1—C2—C3 | 120.0 | N1—C6—H6B | 110.6 |
| C1—C2—H2 | 120.0 | C6ii—C6—H6B | 110.6 |
| C3—C2—H2 | 120.0 | H6A—C6—H6B | 108.7 |
| C5—N1—C1—C2 | 0.0 | C3—C4—C5—N1 | 0.0 |
| C6—N1—C1—C2 | 167.7 (7) | C1—N1—C5—C4 | 0.0 |
| N1—C1—C2—C3 | 0.0 | C6—N1—C5—C4 | −167.8 (6) |
| C1—C2—C3—C4 | 0.0 | C1—N1—C6—C6ii | 93.0 (11) |
| C2—C3—C4—C5 | 0.0 | C5—N1—C6—C6ii | −99.2 (11) |
| Symmetry codes: (i) x, −y+3/2, z; (ii) −x+1, −y+1, −z+1. |
| Cd1—Br1 | 2.470 (2) | Cd1—Br3 | 2.558 (2) |
| Cd1—Br2 | 2.535 (2) | ||
| Br1—Cd1—Br1i | 116.4 (1) | Br1—Cd1—Br3 | 105.3 (1) |
| Br1—Cd1—Br2 | 106.7 (1) | Br2—Cd1—Br3 | 116.8 (1) |
| Symmetry codes: (i) x, −y+3/2, z. |
The authors thank the National Natural Science Foundation of China (grant No. 20671083), the Henan Province Excellent Young Foundation (grant No. 0612002800), Zhengzhou University and the University of Malaya for supporting this work. We thank the Central China Normal University for the diffraction measurements.
Allen, F. H. (2002). Acta Cryst. B58, 380–388.
Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.
Bruker (2004). SAINT (Version 6.45a) and SMART (Version 6.45a). Bruker AXS Inc., Madison, Winconsin, USA. [These programs do not have concurrent version numbers - please check]
Kallel, A., Bats, J. W. & Daoud, A. (1981). Acta Cryst. B37, 676–677.
Sato, S., Ikeda, R. & Nakamura, D. (1986). Bull. Chem. Soc. Jpn, 59, 1981–1989.
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.
Westrip, S. P. (2007). publCIF. In preparation.
The discrete tetrahedral tetrahalidocadmate(II) dianion has been characterized in a number of salts (Cambridge Structural Database, Version 5.28; Allen, 2002); examples of the ammonium salts include, for example, bis(tetramethylammonium) tetrachloridocadmate, bis(tetramethylammonium) tetrabromidomercurate (Sato et al., 1986) and bis(tetramethylammonium) tetraiodidocadmate (Kallel et al., 1981). In the 1,2-ethanedipyridinium salt of the mixed-halogen cadmate, the metal atom is coordinated by four halogen atoms in a tetrahedral geometry; the halogen atoms are disordered (Fig. 1). The cations and anions do not have signification interactions with each other.