Acta Cryst. (2010). E66, o2223 [ doi:10.1107/S1600536810030369 ]
In the title salt, C7H11N2+·Br3-, the essentially planar cation (r.m.s. deviation = 0.006 Å) forms an N-H
Br hydrogen bond to one of the Br atoms of the almost linear anion [Br-Br-Br = 179.31 (2)°]. The crystal studied was found to be a racemic twin. The whole-molecule disorder of the cation and anion about a twofold rotation axis described earlier [Ng (2009). Acta Cryst. E65, o1276] is an artifact of halving one of the axes of the orthorhombic unit cell.
The diffraction measurements were those used in the previous study (Ng, 2009). Measurements on another different specimen gave the same refinement results, especially with respect to the 0.5 Flack parameter.
Carbon-bound H-atoms were placed in calculated positions (C—H 0.95 Å for the aromatic H-atoms and 0.98 Å for the methyl H-atoms) and were included in the refinement in the riding model approximation, with U(H) set to 1.2 to 1.5U(C).
The ammonium H-atom was located in a difference Fourier map, and was refined without a restraint.
The structure is a racemic twin; the Flack parameter was refined on 999 Friedel pairs.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).
![[Figure 1]](./hb5583fig1thm.gif)
| Fig. 1. The molecular structure of (I) at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius. |
| C7H11N2+·Br3− | F(000) = 688 |
| Mr = 362.91 | Dx = 2.222 Mg m−3 |
| Orthorhombic, P21212 | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: P 2 2ab | Cell parameters from 4074 reflections |
| a = 14.7253 (2) Å | θ = 2.7–28.3° |
| b = 17.6696 (3) Å | µ = 11.11 mm−1 |
| c = 4.1689 (1) Å | T = 100 K |
| V = 1084.71 (4) Å3 | Block, colorless |
| Z = 4 | 0.20 × 0.15 × 0.10 mm |
| Bruker SMART APEX CCD diffractometer | 2502 independent reflections |
| Radiation source: fine-focus sealed tube | 2300 reflections with I > 2σ(I) |
| graphite | Rint = 0.029 |
| ω scans | θmax = 27.5°, θmin = 1.8° |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −19→19 |
| Tmin = 0.215, Tmax = 0.403 | k = −22→22 |
| 10364 measured reflections | l = −5→5 |
| 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)] = 0.019 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.040 | w = 1/[σ2(Fo2) + (0.0204P)2] where P = (Fo2 + 2Fc2)/3 |
| S = 0.98 | (Δ/σ)max = 0.001 |
| 2502 reflections | Δρmax = 0.38 e Å−3 |
| 116 parameters | Δρmin = −0.31 e Å−3 |
| 0 restraints | Absolute structure: Flack (1983), 999 Friedel pairs |
| Primary atom site location: structure-invariant direct methods | Flack parameter: 0.51 (2) |
| C7H11N2+·Br3− | V = 1084.71 (4) Å3 |
| Mr = 362.91 | Z = 4 |
| Orthorhombic, P21212 | Mo Kα radiation |
| a = 14.7253 (2) Å | µ = 11.11 mm−1 |
| b = 17.6696 (3) Å | T = 100 K |
| c = 4.1689 (1) Å | 0.20 × 0.15 × 0.10 mm |
| Bruker SMART APEX CCD diffractometer | 2502 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2300 reflections with I > 2σ(I) |
| Tmin = 0.215, Tmax = 0.403 | Rint = 0.029 |
| 10364 measured reflections | θmax = 27.5° |
| R[F2 > 2σ(F2)] = 0.019 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.040 | Δρmax = 0.38 e Å−3 |
| S = 0.98 | Δρmin = −0.31 e Å−3 |
| 2502 reflections | Absolute structure: Flack (1983), 999 Friedel pairs |
| 116 parameters | Flack parameter: 0.51 (2) |
| 0 restraints |
| x | y | z | Uiso*/Ueq | ||
| Br1 | 0.422049 (17) | 0.112471 (15) | 0.72575 (7) | 0.01934 (7) | |
| Br2 | 0.261320 (17) | 0.120225 (14) | 0.47003 (7) | 0.01501 (7) | |
| Br3 | 0.106438 (17) | 0.127359 (14) | 0.23133 (7) | 0.01826 (7) | |
| N1 | 0.60669 (15) | 0.13040 (13) | 0.2738 (6) | 0.0196 (5) | |
| H1 | 0.553 (2) | 0.1299 (18) | 0.387 (8) | 0.038 (10)* | |
| N2 | 0.85347 (15) | 0.12901 (12) | −0.1849 (6) | 0.0162 (5) | |
| C1 | 0.6420 (2) | 0.06411 (16) | 0.1723 (7) | 0.0218 (7) | |
| H1A | 0.6095 | 0.0185 | 0.2093 | 0.026* | |
| C2 | 0.72305 (19) | 0.06148 (15) | 0.0185 (7) | 0.0182 (6) | |
| H2 | 0.7468 | 0.0143 | −0.0520 | 0.022* | |
| C3 | 0.77231 (17) | 0.12906 (14) | −0.0370 (6) | 0.0148 (5) | |
| C4 | 0.73201 (19) | 0.19758 (15) | 0.0729 (7) | 0.0179 (6) | |
| H4 | 0.7621 | 0.2445 | 0.0396 | 0.021* | |
| C5 | 0.65084 (18) | 0.19580 (14) | 0.2248 (8) | 0.0200 (6) | |
| H5 | 0.6246 | 0.2418 | 0.2982 | 0.024* | |
| C6 | 0.89406 (19) | 0.05789 (14) | −0.2953 (8) | 0.0221 (7) | |
| H6A | 0.9021 | 0.0237 | −0.1124 | 0.033* | |
| H6B | 0.9532 | 0.0683 | −0.3936 | 0.033* | |
| H6C | 0.8540 | 0.0341 | −0.4538 | 0.033* | |
| C7 | 0.90234 (17) | 0.19907 (14) | −0.2435 (9) | 0.0215 (6) | |
| H7A | 0.8653 | 0.2324 | −0.3782 | 0.032* | |
| H7B | 0.9597 | 0.1879 | −0.3532 | 0.032* | |
| H7C | 0.9150 | 0.2242 | −0.0387 | 0.032* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Br1 | 0.01273 (13) | 0.02577 (14) | 0.01951 (15) | −0.00074 (11) | 0.00148 (13) | 0.00173 (13) |
| Br2 | 0.01278 (13) | 0.01445 (12) | 0.01779 (13) | −0.00072 (11) | 0.00346 (11) | −0.00043 (11) |
| Br3 | 0.01313 (13) | 0.02064 (13) | 0.02101 (14) | −0.00046 (11) | 0.00112 (13) | −0.00002 (14) |
| N1 | 0.0121 (11) | 0.0263 (12) | 0.0204 (13) | 0.0014 (10) | 0.0026 (12) | 0.0015 (13) |
| N2 | 0.0133 (11) | 0.0125 (10) | 0.0228 (13) | 0.0005 (9) | 0.0026 (10) | 0.0024 (10) |
| C1 | 0.0188 (16) | 0.0211 (15) | 0.0255 (18) | −0.0030 (13) | 0.0007 (14) | 0.0025 (12) |
| C2 | 0.0195 (15) | 0.0157 (13) | 0.0196 (16) | 0.0012 (11) | 0.0001 (15) | −0.0015 (12) |
| C3 | 0.0135 (13) | 0.0170 (12) | 0.0140 (12) | 0.0004 (12) | −0.0034 (12) | 0.0014 (12) |
| C4 | 0.0154 (14) | 0.0157 (13) | 0.0225 (16) | −0.0005 (12) | 0.0018 (14) | −0.0014 (11) |
| C5 | 0.0177 (14) | 0.0186 (13) | 0.0236 (17) | 0.0051 (11) | 0.0038 (17) | −0.0030 (14) |
| C6 | 0.0183 (15) | 0.0178 (13) | 0.0303 (19) | 0.0030 (12) | 0.0047 (18) | 0.0008 (14) |
| C7 | 0.0141 (14) | 0.0179 (13) | 0.0323 (18) | −0.0011 (11) | 0.0072 (18) | 0.0024 (15) |
| Br1—Br2 | 2.5994 (4) | C2—H2 | 0.9500 |
| Br2—Br3 | 2.4915 (4) | C3—C4 | 1.424 (4) |
| N1—C5 | 1.342 (3) | C4—C5 | 1.353 (4) |
| N1—C1 | 1.350 (4) | C4—H4 | 0.9500 |
| N1—H1 | 0.92 (3) | C5—H5 | 0.9500 |
| N2—C3 | 1.345 (3) | C6—H6A | 0.9800 |
| N2—C7 | 1.453 (3) | C6—H6B | 0.9800 |
| N2—C6 | 1.466 (3) | C6—H6C | 0.9800 |
| C1—C2 | 1.356 (4) | C7—H7A | 0.9800 |
| C1—H1A | 0.9500 | C7—H7B | 0.9800 |
| C2—C3 | 1.416 (4) | C7—H7C | 0.9800 |
| Br3—Br2—Br1 | 179.314 (16) | C5—C4—H4 | 120.0 |
| C5—N1—C1 | 120.9 (2) | C3—C4—H4 | 120.0 |
| C5—N1—H1 | 120 (2) | N1—C5—C4 | 121.3 (3) |
| C1—N1—H1 | 119 (2) | N1—C5—H5 | 119.4 |
| C3—N2—C7 | 121.1 (2) | C4—C5—H5 | 119.4 |
| C3—N2—C6 | 120.5 (2) | N2—C6—H6A | 109.5 |
| C7—N2—C6 | 118.4 (2) | N2—C6—H6B | 109.5 |
| N1—C1—C2 | 121.2 (3) | H6A—C6—H6B | 109.5 |
| N1—C1—H1A | 119.4 | N2—C6—H6C | 109.5 |
| C2—C1—H1A | 119.4 | H6A—C6—H6C | 109.5 |
| C1—C2—C3 | 119.9 (3) | H6B—C6—H6C | 109.5 |
| C1—C2—H2 | 120.0 | N2—C7—H7A | 109.5 |
| C3—C2—H2 | 120.0 | N2—C7—H7B | 109.5 |
| N2—C3—C2 | 122.0 (2) | H7A—C7—H7B | 109.5 |
| N2—C3—C4 | 121.2 (2) | N2—C7—H7C | 109.5 |
| C2—C3—C4 | 116.8 (2) | H7A—C7—H7C | 109.5 |
| C5—C4—C3 | 119.9 (3) | H7B—C7—H7C | 109.5 |
| C5—N1—C1—C2 | 0.1 (5) | C1—C2—C3—N2 | 179.1 (3) |
| N1—C1—C2—C3 | 0.2 (4) | C1—C2—C3—C4 | −0.6 (4) |
| C7—N2—C3—C2 | 179.1 (3) | N2—C3—C4—C5 | −179.1 (3) |
| C6—N2—C3—C2 | 0.1 (4) | C2—C3—C4—C5 | 0.6 (4) |
| C7—N2—C3—C4 | −1.2 (4) | C1—N1—C5—C4 | −0.1 (5) |
| C6—N2—C3—C4 | 179.8 (3) | C3—C4—C5—N1 | −0.3 (5) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···Br1 | 0.92 (3) | 2.41 (3) | 3.323 (2) | 171 (3) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···Br1 | 0.92 (3) | 2.41 (3) | 3.323 (2) | 171 (3) |
Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.
Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Flack, H. D. (1983). Acta Cryst. A39, 876–881.
Ng, S. W. (2009). Acta Cryst. E65, o1276.
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
Dimethylaminopyridinium tribromide (I) was refined as a whole-molecule-disordered cation and anion that was disordered about a crystallographic twofold rotation axis (Ng, 2009) in the orthorhombic P2221 space group [unit cell parameters 4.1688 (1), 8.8349 (2), 14.7255 (4) Å]. The automatic cell-searching program had, in fact, missed some weaker reflections, so that the true b-axis should be doubled, so that the space group would be P22121 [4.1689 (1), 17.6696 (3), 14.7253 (2) Å]. In the standard P21212 setting, the structure refines smoothly, without disorder, to a final R index of 0.019 (Fig. 1). The disorder is an artifact of halving one of the axis, and a chemically reasonable model coincidentally arose owing to the nature of both the planar cation and linear anion.