supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

hb2966 scheme

Acta Cryst. (2009). E65, o1276    [ doi:10.1107/S1600536809017048 ]

4-(Dimethylamino)pyridinium tribromide: whole molecule disorder of cation and anion

S. W. Ng

Abstract top

In the title salt, C7H11N2+·Br3-, the cation and the near-linear anion [Br-Br-Br = 179.41 (8)°] both show whole-molecule disorder about crystallographic twofold rotation axes. The cation is weakly hydrogen-bonded to the anion by an N-H...Br interaction. The crystal studied was found to be a racemic twin, with a twin component of nearly 50%.

Comment top

(type here to add)

Related literature top

The compound is known commercially as 4-(dimethylamino)pyridine hydrobromide perbromide, [C7H10N2].[HBr].[Br2]. The 4-dimethylaminopyridinium cation furnishes a number of salts with organic and inorganic acids. For 4-dimethylaminopyridinium bromide, see: Mayr-Stein & Bolte (2000). For dimethylaminopyridinium chloride and its dihydrate, see: Bryant & King (1992); Chao et al. (1977).

Experimental top

Commercially-available 4-dimethylaminopyridine hydrobromide perbromide was recrystallized from ethanol to give colourless blocks of (I).

Refinement top

The Br3 anion lies on a twofold rotation axis, but it was allowed to refine off this symmetry element as a three-atom species.

The cation is disordered about another twofold rotation axis; this was refined as a cation with its atoms of half occupancies. The pyridyl portion was refined as a rigid hexagon of 1.39 Å sides; the pair of N–Cmethyl distances were restrained to within 0.01 Å of each other. The cation was restrained to be nearly planar, and the anisotropic displacement factors were restrained to be nearly isotropic.

The hydrogen atoms were placed at calculated positions (C–H 0.95, N–H 0.88 Å) and refined as riding with Uiso(H) = 1.2Ueq(C,N).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); 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: pubCIF (Westrip, 2009).

Figures top
[Figure 1] Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of [C7H11N2][Br3] at the 70% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius.
4-(Dimethylamino)pyridinium tribromide top
Crystal data top
C7H11N2+·Br3–F000 = 344
Mr = 362.91Dx = 2.222 Mg m−3
Orthorhombic, P2221Mo Kα radiation
λ = 0.71073 Å
Hall symbol: P 2c 2Cell parameters from 2094 reflections
a = 4.1688 (1) Åθ = 2.7–28.3º
b = 8.8349 (2) ŵ = 11.11 mm−1
c = 14.7255 (4) ÅT = 100 K
V = 542.35 (2) Å3Block, colorless
Z = 20.20 × 0.15 × 0.10 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		1256 independent reflections
Radiation source: fine-focus sealed tube1114 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.025
T = 100 Kθmax = 27.5º
ω scansθmin = 2.3º
Absorption correction: Multi-scan
(SADABS; Sheldrick, 1996)		h = −5→5
Tmin = 0.656, Tmax = 1.000k = −11→11
5156 measured reflectionsl = −19→19
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.021  w = 1/[σ2(Fo2) + (0.0322P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.051(Δ/σ)max = 0.001
S = 0.98Δρmax = 0.42 e Å−3
1256 reflectionsΔρmin = −0.33 e Å−3
100 parametersExtinction correction: none
60 restraintsAbsolute structure: Flack (1983), 480 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.47 (4)
Secondary atom site location: difference Fourier map
Crystal data top
C7H11N2+·Br3–V = 542.35 (2) Å3
Mr = 362.91Z = 2
Orthorhombic, P2221Mo Kα
a = 4.1688 (1) ŵ = 11.11 mm−1
b = 8.8349 (2) ÅT = 100 K
c = 14.7255 (4) Å0.20 × 0.15 × 0.10 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		1256 independent reflections
Absorption correction: Multi-scan
(SADABS; Sheldrick, 1996)		1114 reflections with I > 2σ(I)
Tmin = 0.656, Tmax = 1.000Rint = 0.025
5156 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.021H-atom parameters constrained
wR(F2) = 0.051Δρmax = 0.42 e Å−3
S = 0.98Δρmin = −0.33 e Å−3
1256 reflectionsAbsolute structure: Flack (1983), 480 Friedel pairs
100 parametersFlack parameter: 0.47 (4)
60 restraints
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Br10.5290 (6)0.25953 (5)0.23869 (12)0.0155 (3)0.50
Br20.2738 (3)0.27497 (11)0.07779 (5)0.0196 (2)0.50
Br30.7682 (3)0.24565 (11)0.39355 (5)0.01777 (18)0.50
N21.1882 (7)0.2417 (5)−0.3550 (3)0.0144 (9)0.50
N10.7232 (7)0.2399 (4)−0.10428 (15)0.0209 (11)0.50
H10.62500.2392−0.05140.025*0.50
C10.7724 (9)0.1050 (3)−0.1509 (2)0.0190 (11)0.50
H1A0.70000.0122−0.12570.023*0.50
C20.9276 (8)0.1061 (3)−0.23446 (19)0.0196 (13)0.50
H20.96120.0140−0.26630.024*0.50
C31.0335 (5)0.2420 (3)−0.27138 (13)0.0147 (11)0.50
C40.9844 (9)0.3768 (3)−0.2248 (2)0.0195 (12)0.50
H41.05680.4697−0.25000.023*0.50
C50.8292 (9)0.3757 (3)−0.1412 (2)0.0208 (14)0.50
H50.79560.4679−0.10930.025*0.50
C61.2376 (13)0.1015 (6)−0.4024 (3)0.0226 (13)0.50
H6A1.03140.0498−0.41020.034*0.50
H6B1.38290.0370−0.36720.034*0.50
H6C1.33210.1220−0.46200.034*0.50
C71.2983 (11)0.3839 (6)−0.3936 (4)0.0223 (14)0.50
H7A1.11300.4479−0.40770.033*0.50
H7B1.41960.3638−0.44930.033*0.50
H7C1.43660.4359−0.34970.033*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0195 (8)0.01421 (16)0.0128 (8)−0.0005 (3)0.0021 (5)−0.0007 (2)
Br20.0201 (4)0.0274 (5)0.0112 (4)0.0019 (3)0.0015 (3)−0.0010 (3)
Br30.0210 (4)0.0207 (4)0.0116 (4)−0.0011 (3)0.0007 (3)0.0001 (3)
N20.021 (2)0.0110 (19)0.011 (2)−0.001 (2)−0.0034 (17)0.005 (2)
N10.023 (3)0.032 (3)0.008 (2)0.007 (3)0.0025 (19)−0.001 (2)
C10.019 (3)0.021 (3)0.017 (3)−0.001 (2)−0.003 (3)0.002 (2)
C20.012 (3)0.0175 (19)0.029 (4)−0.0005 (16)0.004 (3)0.003 (2)
C30.019 (2)0.0179 (18)0.008 (3)−0.001 (3)−0.002 (2)0.0001 (17)
C40.020 (2)0.022 (2)0.016 (3)−0.004 (3)−0.005 (4)0.0004 (16)
C50.019 (3)0.023 (3)0.020 (3)0.001 (2)−0.001 (3)0.001 (3)
C60.032 (3)0.019 (2)0.017 (3)0.000 (3)−0.001 (4)0.004 (2)
C70.023 (4)0.023 (3)0.020 (3)0.005 (2)0.008 (3)−0.005 (2)
Geometric parameters (Å, °) top
Br1—Br32.492 (3)C2—H20.9500
Br1—Br22.601 (3)C3—C41.3900
N2—C31.390 (5)C4—C51.3900
N2—C61.436 (7)C4—H40.9500
N2—C71.454 (7)C5—H50.9500
N1—C11.3900C6—H6A0.9800
N1—C51.3900C6—H6B0.9800
N1—H10.8800C6—H6C0.9800
C1—C21.3900C7—H7A0.9800
C1—H1A0.9500C7—H7B0.9800
C2—C31.3900C7—H7C0.9800
Br3—Br1—Br2179.41 (8)C5—C4—H4120.0
C3—N2—C6119.9 (4)C3—C4—H4120.0
C3—N2—C7119.4 (4)C4—C5—N1120.0
C6—N2—C7120.7 (4)C4—C5—H5120.0
C1—N1—C5120.0N1—C5—H5120.0
C1—N1—H1120.0N2—C6—H6A109.5
C5—N1—H1120.0N2—C6—H6B109.5
N1—C1—C2120.0H6A—C6—H6B109.5
N1—C1—H1A120.0N2—C6—H6C109.5
C2—C1—H1A120.0H6A—C6—H6C109.5
C1—C2—C3120.0H6B—C6—H6C109.5
C1—C2—H2120.0N2—C7—H7A109.5
C3—C2—H2120.0N2—C7—H7B109.5
N2—C3—C4120.5 (3)H7A—C7—H7B109.5
N2—C3—C2119.5 (3)N2—C7—H7C109.5
C4—C3—C2120.0H7A—C7—H7C109.5
C5—C4—C3120.0H7B—C7—H7C109.5
C5—N1—C1—C20.0C1—C2—C3—N2−179.96 (9)
N1—C1—C2—C30.0C1—C2—C3—C40.0
C6—N2—C3—C4179.95 (9)N2—C3—C4—C5179.96 (9)
C7—N2—C3—C4−0.07 (11)C2—C3—C4—C50.0
C6—N2—C3—C2−0.08 (13)C3—C4—C5—N10.0
C7—N2—C3—C2179.90 (9)C1—N1—C5—C40.0
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Br20.882.423.286 (2)167
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Br20.882.423.286 (2)167
Acknowledgements top

I thank the University of Malaya for supporting this study.

references
References top

Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191.

Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.

Bryant, G. L. & King, J. A. (1992). Acta Cryst. C48, 2036–2039.

Chao, M., Schempp, E. & Rosenstein, D. (1977). Acta Cryst. B33, 1820–1823.

Flack, H. D. (1983). Acta Cryst. A39, 876–881.

Mayr-Stein, R. & Bolte, M. (2000). Acta Cryst. C56, e19–e20.

Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Westrip, S. P. (2009). publCIF. In preparation.