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Acta Crystallogr Sect E Struct Rep Online. 2010 September 1; 66(Pt 9): o2223.
Published online 2010 August 11. doi:  10.1107/S1600536810030369
PMCID: PMC3008028

Redetermination of 4-(dimethyl­amino)­pyridinium tribromide

Abstract

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.

Related literature

For the refinement based on a unit cell half as large, see: Ng (2009 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2223-scheme1.jpg

Experimental

Crystal data

  • C7H11N2 +·Br3
  • M r = 362.91
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2223-efi1.jpg
  • a = 14.7253 (2) Å
  • b = 17.6696 (3) Å
  • c = 4.1689 (1) Å
  • V = 1084.71 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 11.11 mm−1
  • T = 100 K
  • 0.20 × 0.15 × 0.10 mm

Data collection

  • Bruker SMART APEX CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.215, T max = 0.403
  • 10364 measured reflections
  • 2502 independent reflections
  • 2300 reflections with I > 2σ(I)
  • R int = 0.029

Refinement

  • R[F 2 > 2σ(F 2)] = 0.019
  • wR(F 2) = 0.040
  • S = 0.98
  • 2502 reflections
  • 116 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.38 e Å−3
  • Δρmin = −0.31 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 999 Friedel pairs
  • Flack parameter: 0.51 (2)

Data collection: APEX2 (Bruker, 2009 [triangle]); cell refinement: SAINT (Bruker, 2009 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour, 2001 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810030369/hb5583sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810030369/hb5583Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

I thank the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

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.

Experimental

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.

Refinement

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.

Figures

Fig. 1.
The molecular structure of (I) at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.

Crystal data

C7H11N2+·Br3F(000) = 688
Mr = 362.91Dx = 2.222 Mg m3
Orthorhombic, P21212Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2 2abCell parameters from 4074 reflections
a = 14.7253 (2) Åθ = 2.7–28.3°
b = 17.6696 (3) ŵ = 11.11 mm1
c = 4.1689 (1) ÅT = 100 K
V = 1084.71 (4) Å3Block, colorless
Z = 40.20 × 0.15 × 0.10 mm

Data collection

Bruker SMART APEX CCD diffractometer2502 independent reflections
Radiation source: fine-focus sealed tube2300 reflections with I > 2σ(I)
graphiteRint = 0.029
ω scansθmax = 27.5°, θmin = 1.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −19→19
Tmin = 0.215, Tmax = 0.403k = −22→22
10364 measured reflectionsl = −5→5

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.019H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.040w = 1/[σ2(Fo2) + (0.0204P)2] where P = (Fo2 + 2Fc2)/3
S = 0.98(Δ/σ)max = 0.001
2502 reflectionsΔρmax = 0.38 e Å3
116 parametersΔρmin = −0.31 e Å3
0 restraintsAbsolute structure: Flack (1983), 999 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.51 (2)

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

xyzUiso*/Ueq
Br10.422049 (17)0.112471 (15)0.72575 (7)0.01934 (7)
Br20.261320 (17)0.120225 (14)0.47003 (7)0.01501 (7)
Br30.106438 (17)0.127359 (14)0.23133 (7)0.01826 (7)
N10.60669 (15)0.13040 (13)0.2738 (6)0.0196 (5)
H10.553 (2)0.1299 (18)0.387 (8)0.038 (10)*
N20.85347 (15)0.12901 (12)−0.1849 (6)0.0162 (5)
C10.6420 (2)0.06411 (16)0.1723 (7)0.0218 (7)
H1A0.60950.01850.20930.026*
C20.72305 (19)0.06148 (15)0.0185 (7)0.0182 (6)
H20.74680.0143−0.05200.022*
C30.77231 (17)0.12906 (14)−0.0370 (6)0.0148 (5)
C40.73201 (19)0.19758 (15)0.0729 (7)0.0179 (6)
H40.76210.24450.03960.021*
C50.65084 (18)0.19580 (14)0.2248 (8)0.0200 (6)
H50.62460.24180.29820.024*
C60.89406 (19)0.05789 (14)−0.2953 (8)0.0221 (7)
H6A0.90210.0237−0.11240.033*
H6B0.95320.0683−0.39360.033*
H6C0.85400.0341−0.45380.033*
C70.90234 (17)0.19907 (14)−0.2435 (9)0.0215 (6)
H7A0.86530.2324−0.37820.032*
H7B0.95970.1879−0.35320.032*
H7C0.91500.2242−0.03870.032*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Br10.01273 (13)0.02577 (14)0.01951 (15)−0.00074 (11)0.00148 (13)0.00173 (13)
Br20.01278 (13)0.01445 (12)0.01779 (13)−0.00072 (11)0.00346 (11)−0.00043 (11)
Br30.01313 (13)0.02064 (13)0.02101 (14)−0.00046 (11)0.00112 (13)−0.00002 (14)
N10.0121 (11)0.0263 (12)0.0204 (13)0.0014 (10)0.0026 (12)0.0015 (13)
N20.0133 (11)0.0125 (10)0.0228 (13)0.0005 (9)0.0026 (10)0.0024 (10)
C10.0188 (16)0.0211 (15)0.0255 (18)−0.0030 (13)0.0007 (14)0.0025 (12)
C20.0195 (15)0.0157 (13)0.0196 (16)0.0012 (11)0.0001 (15)−0.0015 (12)
C30.0135 (13)0.0170 (12)0.0140 (12)0.0004 (12)−0.0034 (12)0.0014 (12)
C40.0154 (14)0.0157 (13)0.0225 (16)−0.0005 (12)0.0018 (14)−0.0014 (11)
C50.0177 (14)0.0186 (13)0.0236 (17)0.0051 (11)0.0038 (17)−0.0030 (14)
C60.0183 (15)0.0178 (13)0.0303 (19)0.0030 (12)0.0047 (18)0.0008 (14)
C70.0141 (14)0.0179 (13)0.0323 (18)−0.0011 (11)0.0072 (18)0.0024 (15)

Geometric parameters (Å, °)

Br1—Br22.5994 (4)C2—H20.9500
Br2—Br32.4915 (4)C3—C41.424 (4)
N1—C51.342 (3)C4—C51.353 (4)
N1—C11.350 (4)C4—H40.9500
N1—H10.92 (3)C5—H50.9500
N2—C31.345 (3)C6—H6A0.9800
N2—C71.453 (3)C6—H6B0.9800
N2—C61.466 (3)C6—H6C0.9800
C1—C21.356 (4)C7—H7A0.9800
C1—H1A0.9500C7—H7B0.9800
C2—C31.416 (4)C7—H7C0.9800
Br3—Br2—Br1179.314 (16)C5—C4—H4120.0
C5—N1—C1120.9 (2)C3—C4—H4120.0
C5—N1—H1120 (2)N1—C5—C4121.3 (3)
C1—N1—H1119 (2)N1—C5—H5119.4
C3—N2—C7121.1 (2)C4—C5—H5119.4
C3—N2—C6120.5 (2)N2—C6—H6A109.5
C7—N2—C6118.4 (2)N2—C6—H6B109.5
N1—C1—C2121.2 (3)H6A—C6—H6B109.5
N1—C1—H1A119.4N2—C6—H6C109.5
C2—C1—H1A119.4H6A—C6—H6C109.5
C1—C2—C3119.9 (3)H6B—C6—H6C109.5
C1—C2—H2120.0N2—C7—H7A109.5
C3—C2—H2120.0N2—C7—H7B109.5
N2—C3—C2122.0 (2)H7A—C7—H7B109.5
N2—C3—C4121.2 (2)N2—C7—H7C109.5
C2—C3—C4116.8 (2)H7A—C7—H7C109.5
C5—C4—C3119.9 (3)H7B—C7—H7C109.5
C5—N1—C1—C20.1 (5)C1—C2—C3—N2179.1 (3)
N1—C1—C2—C30.2 (4)C1—C2—C3—C4−0.6 (4)
C7—N2—C3—C2179.1 (3)N2—C3—C4—C5−179.1 (3)
C6—N2—C3—C20.1 (4)C2—C3—C4—C50.6 (4)
C7—N2—C3—C4−1.2 (4)C1—N1—C5—C4−0.1 (5)
C6—N2—C3—C4179.8 (3)C3—C4—C5—N1−0.3 (5)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1···Br10.92 (3)2.41 (3)3.323 (2)171 (3)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5583).

References

  • 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. [PMC free article] [PubMed]
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Westrip, S. P. (2010). J. Appl. Cryst.43, 920–925.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography