Redetermination of 4-(dimethyl­amino)­pyridinium tribromide

Ng, S.W.

doi:10.1107/S1600536810030369

organic compounds

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Volume 66| Part 9| September 2010| Page o2223

https://doi.org/10.1107/S1600536810030369

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Redetermination of 4-(dimethylamino)pyridinium tribromide

Seik Weng Ng ^a ^*

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: seikweng@um.edu.my

(Received 28 July 2010; accepted 30 July 2010; online 11 August 2010)

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 ).

Experimental

Crystal data

C₇H₁₁N₂⁺·Br₃⁻
M_r = 362.91
Orthorhombic, P 2₁ 2₁ 2
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 ) 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[F² > 2σ(F²)] = 0.019
wR(F²) = 0.040
S = 0.98
2502 reflections
116 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.31 e Å⁻³
Absolute structure: Flack (1983 ), 999 Friedel pairs
Flack parameter: 0.51 (2)

Table 1
Hydrogen-bond geometry (Å, °)

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)

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

Supporting information

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

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810030369/hb5583Isup2.hkl

checkCIF report

Comment top

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.

Related literature top

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

Experimental top

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.

Structure description top

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

Computing details top

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).

Figures top

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

4-(dimethylamino)pyridinium tribromide top

Crystal data top

C₇H₁₁N₂⁺·Br₃⁻	F(000) = 688
M_r = 362.91	D_x = 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

Data collection top

Bruker SMART APEX CCD diffractometer	2502 independent reflections
Radiation source: fine-focus sealed tube	2300 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
ω scans	θ_max = 27.5°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −19→19
T_min = 0.215, T_max = 0.403	k = −22→22
10364 measured reflections	l = −5→5

Refinement top

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(F_o²) + (0.0204P)²] where P = (F_o² + 2F_c²)/3
S = 0.98	(Δ/σ)_max = 0.001
2502 reflections	Δρ_max = 0.38 e Å⁻³
116 parameters	Δρ_min = −0.31 e Å⁻³
0 restraints	Absolute structure: Flack (1983), 999 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.51 (2)

Crystal data top

C₇H₁₁N₂⁺·Br₃⁻	V = 1084.71 (4) Å³
M_r = 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

Data collection top

Bruker SMART APEX CCD diffractometer	2502 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	2300 reflections with I > 2σ(I)
T_min = 0.215, T_max = 0.403	R_int = 0.029
10364 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.019	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.040	Δρ_max = 0.38 e Å⁻³
S = 0.98	Δρ_min = −0.31 e Å⁻³
2502 reflections	Absolute structure: Flack (1983), 999 Friedel pairs
116 parameters	Absolute structure parameter: 0.51 (2)
0 restraints

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

	x	y	z	U_iso*/U_eq
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*

Atomic displacement parameters (Å²) top

	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)

Geometric parameters (Å, º) top

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)

Hydrogen-bond geometry (Å, º) top

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)

Experimental details

Crystal data
Chemical formula	C₇H₁₁N₂⁺·Br₃⁻
M_r	362.91
Crystal system, space group	Orthorhombic, P2₁2₁2
Temperature (K)	100
a, b, c (Å)	14.7253 (2), 17.6696 (3), 4.1689 (1)
V (Å³)	1084.71 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	11.11
Crystal size (mm)	0.20 × 0.15 × 0.10

Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.215, 0.403
No. of measured, independent and observed [I > 2σ(I)] reflections	10364, 2502, 2300
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.040, 0.98
No. of reflections	2502
No. of parameters	116
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.38, −0.31
Absolute structure	Flack (1983), 999 Friedel pairs
Absolute structure parameter	0.51 (2)

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Selected bond lengths (Å) top

Br1—Br2

2.5994 (4)

Br2—Br3

2.4915 (4)

Hydrogen-bond geometry (Å, º) top

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)

Acknowledgements

I thank the University of Malaya for supporting this study.

References

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