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Acta Cryst. (2008). E64, o1025    [ doi:10.1107/S1600536808012154 ]

(S)-1-(2-Ammonio-3-methylbutyl)-1,2-dihydropyridin-2-iminium dibromide

Y. Wang, J. Zhang, H. Chen and S. Luo

Abstract top

In the title compound, C10H19N32+·2Br-, the plane of the three butyl C atoms nearest to the pyridine ring is almost perpendicular to the ring [dihedral angle = 84.80 (2)°]. The N atom of the ammonium group is displaced by 1.150 (8) Å from the plane of these three C atoms. The iminium N atom lies on the opposite side of this plane. The crystal structure is stabilized by hydrogen bonds between the N and Br atoms, as well as by intermolecular C-H...Br interactions.

Comment top

Ionic liquids, specially functional ionic liquids, have received growing attention recently due to their tuneable features for various chemical tasks. (S. Luo, et al., 2006). The title compound, readily synthesized from commercially available L-valine and 2-aminopyridine, might have potential utilities in some specific chemical tasks, when it is converted into a kind of functional ionic liquid by neutralization with sodium hydroxide. The structure of (S)-1-(2-ammonio-3-methylbutyl)pyridin-2(1H)-iminium dibromide is shown in Fig. 1.

The crystal is built of doubly protonated cations and bromide anions. The protonation of the amines is appropriate like in the scheme, for the C1—N2 bond distance reveals its double bond property. The dihedral angle between the plane of three alkyl carbons C6/C7/C8 and the pyridine ring is 84.80 (2) °, which means the two planes are approximately perpendicular to one another. The atom N3 of the ammonium group bonded to the alkyl chain is displaced from the plane of three carbons C6/C7/C8 by 1.150 (8) Å. The iminium N2 lies on the opposite side of this plane. The crystal structure is stablized by hydrogen-bonds between the atoms N and Br as well as by intermolecular C—H—Br interactions. The molecular packing of the title compound showing H-bridge interactions between cationic-anionic groups is shown in Fig. 2.

Related literature top

For the synthesis of (S)-1-bromo-3-methylbutan-2-amine hydrobromide, see: Xu et al. (2006). For related literature, see: Luo et al. (2006).

Experimental top

The title compound was synthesized by treating 2-aminopyridine (0.94 g,10 mmol) with (S)-1-bromo-3-methylbutan-2-amine hydrobromide (2.47 g,10 mmol) in MeCN (30 ml) under stirring at 353 K for 24 h (yield 81%). The compound (S)-1-bromo-3-methylbutan-2-amine hydrobromide was obtained from commercially available L-valine by reduction with NaBH4 and subsequent bromination with PBr3 (Xu et al., 2006). Suitable crystals of the title compound were obtained by slow evaporation of an ethanol solution at room temperature.

Refinement top

All carbon-bonded H atoms were placed in calculated positions with C—H = 0.93 Å (aromatic), C—H = 0.98 Å (sp), C—H = 0.93 Å (sp2), C—H = 0.96 Å(sp3) and refined using a riding model, with Uiso(H)=1.2eq(C). N-bound H atoms were located in a difference map and refined with an N—H distance restraint of 0.86 (3) Å.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound with the atomic labeling scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. The molecular packing of the title compound showing H-bridge interactions between cationic-anionic groups.
(S)-1-(2-Ammonio-3-methylbutyl)-1,2-dihydropyridin-2-iminium dibromide top
Crystal data top
C10H19N32+·2Br–F000 = 340
Mr = 341.10Dx = 1.607 Mg m−3
Monoclinic, P21Mo Kα radiation
λ = 0.71073 Å
a = 5.9311 (11) ÅCell parameters from 1818 reflections
b = 12.456 (2) Åθ = 5.4–53.4º
c = 9.6807 (18) ŵ = 5.73 mm−1
β = 99.733 (3)ºT = 293 (2) K
V = 704.9 (2) Å3Prismatic, colorless
Z = 20.45 × 0.34 × 0.20 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		2307 independent reflections
Radiation source: fine-focus sealed tube2054 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.038
T = 293(2) Kθmax = 27.0º
φ and ω scansθmin = 2.1º
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −7→7
Tmin = 0.381, Tmax = 1.000k = −12→15
4117 measured reflectionsl = −12→12
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH atoms treated by a mixture of
independent and constrained refinement
R[F2 > 2σ(F2)] = 0.041  w = 1/[σ2(Fo2) + (0.0533P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.092(Δ/σ)max < 0.001
S = 0.99Δρmax = 0.91 e Å−3
2307 reflectionsΔρmin = −0.71 e Å−3
147 parametersExtinction correction: none
3 restraintsAbsolute structure: Flack (1983), 696 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.06 (2)
Secondary atom site location: difference Fourier map
Crystal data top
C10H19N32+·2Br–V = 704.9 (2) Å3
Mr = 341.10Z = 2
Monoclinic, P21Mo Kα
a = 5.9311 (11) ŵ = 5.73 mm−1
b = 12.456 (2) ÅT = 293 (2) K
c = 9.6807 (18) Å0.45 × 0.34 × 0.20 mm
β = 99.733 (3)º
Data collection top
Bruker SMART APEX CCD
diffractometer		2307 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		2054 reflections with I > 2σ(I)
Tmin = 0.381, Tmax = 1.000Rint = 0.038
4117 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.041H atoms treated by a mixture of
independent and constrained refinement
wR(F2) = 0.092Δρmax = 0.91 e Å−3
S = 0.99Δρmin = −0.71 e Å−3
2307 reflectionsAbsolute structure: Flack (1983), 696 Friedel pairs
147 parametersFlack parameter: 0.06 (2)
3 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br11.02019 (11)0.21057 (4)0.84434 (6)0.03666 (18)
Br20.61945 (10)0.78903 (5)0.54550 (7)0.03742 (19)
N10.7631 (8)0.4733 (4)0.2958 (5)0.0269 (11)
N20.4665 (11)0.5923 (5)0.3096 (7)0.0398 (14)
N30.9054 (9)0.3672 (4)0.5746 (5)0.0291 (11)
H3A0.77990.33020.54060.044*
H3B0.94810.35180.66510.044*
H3C1.01720.34960.52800.044*
C10.5506 (11)0.5110 (5)0.2454 (6)0.0295 (14)
C20.4223 (13)0.4609 (6)0.1291 (7)0.0404 (17)
H20.27660.48630.09370.048*
C30.5050 (15)0.3772 (7)0.0677 (7)0.052 (2)
H30.41490.3427−0.00720.062*
C40.7331 (15)0.3408 (7)0.1176 (8)0.052 (2)
H40.79750.28560.07250.062*
C50.8497 (13)0.3880 (6)0.2301 (7)0.0378 (16)
H50.99530.36280.26610.045*
C60.9101 (11)0.5224 (6)0.4176 (7)0.0314 (14)
H6A0.89220.59980.41190.038*
H6B1.06860.50600.41310.038*
C70.8569 (10)0.4843 (5)0.5581 (6)0.0274 (13)
H70.69280.49450.55670.033*
C80.9855 (11)0.5495 (6)0.6818 (7)0.0369 (16)
H80.95490.62560.66050.044*
C90.8975 (15)0.5251 (8)0.8154 (7)0.057 (2)
H9A0.94140.45350.84560.086*
H9B0.73380.53090.79940.086*
H9C0.96140.57530.88670.086*
C101.2447 (12)0.5333 (8)0.6994 (8)0.057 (2)
H10A1.31940.57870.77340.086*
H10B1.29620.55140.61350.086*
H10C1.28090.45960.72240.086*
H2A0.355 (12)0.623 (8)0.260 (9)0.09 (4)*
H2B0.525 (13)0.636 (6)0.371 (7)0.06 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0508 (4)0.0348 (4)0.0231 (3)−0.0033 (3)0.0026 (3)−0.0009 (3)
Br20.0309 (3)0.0355 (4)0.0448 (4)0.0023 (3)0.0033 (3)−0.0065 (3)
N10.033 (3)0.025 (3)0.024 (3)0.001 (2)0.007 (2)0.004 (2)
N20.040 (4)0.035 (4)0.041 (4)0.006 (3)−0.002 (3)−0.003 (3)
N30.032 (3)0.029 (3)0.026 (3)−0.004 (2)0.004 (2)0.003 (2)
C10.041 (4)0.028 (4)0.018 (3)−0.001 (3)0.002 (3)0.006 (3)
C20.042 (4)0.051 (5)0.025 (3)−0.004 (3)−0.005 (3)0.006 (3)
C30.074 (5)0.054 (5)0.025 (4)−0.011 (4)−0.002 (4)−0.012 (4)
C40.077 (6)0.049 (5)0.032 (4)0.006 (4)0.014 (4)−0.010 (3)
C50.051 (4)0.038 (4)0.026 (4)0.009 (3)0.012 (3)0.003 (3)
C60.031 (3)0.032 (4)0.028 (3)−0.003 (3)−0.004 (3)0.001 (3)
C70.021 (3)0.030 (3)0.029 (3)0.001 (2)−0.001 (2)0.003 (3)
C80.046 (4)0.030 (4)0.031 (4)0.002 (3)−0.004 (3)−0.006 (3)
C90.066 (5)0.077 (6)0.025 (4)0.014 (5)−0.003 (4)−0.015 (4)
C100.035 (4)0.088 (7)0.043 (5)−0.016 (4)−0.008 (3)−0.014 (5)
Geometric parameters (Å, °) top
Br1—H3B2.4578C4—C51.325 (10)
Br2—H2B2.55 (7)C4—H40.9300
N1—C11.356 (8)C5—H50.9300
N1—C51.380 (8)C6—C71.523 (9)
N1—C61.476 (8)C6—H6A0.9700
N2—C11.329 (9)C6—H6B0.9700
N2—H2A0.84 (8)C7—C81.538 (9)
N2—H2B0.84 (7)C7—H70.9800
N3—C71.490 (8)C8—C91.506 (11)
N3—H3A0.8900C8—C101.531 (10)
N3—H3B0.8900C8—H80.9800
N3—H3C0.8900C9—H9A0.9600
C1—C21.396 (9)C9—H9B0.9600
C2—C31.334 (11)C9—H9C0.9600
C2—H20.9300C10—H10A0.9600
C3—C41.431 (11)C10—H10B0.9600
C3—H30.9300C10—H10C0.9600
C1—N1—C5119.8 (6)C7—C6—H6A108.8
C1—N1—C6122.1 (5)N1—C6—H6B108.8
C5—N1—C6118.2 (5)C7—C6—H6B108.8
C1—N2—H2A114 (7)H6A—C6—H6B107.7
C1—N2—H2B133 (6)N3—C7—C6109.6 (5)
H2A—N2—H2B107 (9)N3—C7—C8111.9 (5)
C7—N3—H3A109.5C6—C7—C8112.3 (6)
C7—N3—H3B109.5N3—C7—H7107.6
H3A—N3—H3B109.5C6—C7—H7107.6
C7—N3—H3C109.5C8—C7—H7107.6
H3A—N3—H3C109.5C9—C8—C10111.4 (6)
H3B—N3—H3C109.5C9—C8—C7111.3 (6)
N2—C1—N1119.7 (6)C10—C8—C7111.9 (6)
N2—C1—C2121.4 (7)C9—C8—H8107.3
N1—C1—C2118.8 (7)C10—C8—H8107.3
C3—C2—C1121.2 (7)C7—C8—H8107.3
C3—C2—H2119.4C8—C9—H9A109.5
C1—C2—H2119.4C8—C9—H9B109.5
C2—C3—C4119.7 (7)H9A—C9—H9B109.5
C2—C3—H3120.2C8—C9—H9C109.5
C4—C3—H3120.2H9A—C9—H9C109.5
C5—C4—C3117.9 (7)H9B—C9—H9C109.5
C5—C4—H4121.0C8—C10—H10A109.5
C3—C4—H4121.0C8—C10—H10B109.5
C4—C5—N1122.5 (7)H10A—C10—H10B109.5
C4—C5—H5118.7C8—C10—H10C109.5
N1—C5—H5118.7H10A—C10—H10C109.5
N1—C6—C7113.7 (5)H10B—C10—H10C109.5
N1—C6—H6A108.8
C5—N1—C1—N2179.3 (6)C6—N1—C5—C4−178.0 (7)
C6—N1—C1—N2−2.4 (9)C1—N1—C6—C782.3 (7)
C5—N1—C1—C21.2 (8)C5—N1—C6—C7−99.4 (7)
C6—N1—C1—C2179.5 (6)N1—C6—C7—N364.0 (7)
N2—C1—C2—C3−177.9 (7)N1—C6—C7—C8−170.9 (5)
N1—C1—C2—C30.2 (10)N3—C7—C8—C9−67.1 (7)
C1—C2—C3—C4−2.8 (11)C6—C7—C8—C9169.2 (6)
C2—C3—C4—C54.2 (11)N3—C7—C8—C1058.3 (8)
C3—C4—C5—N1−3.0 (11)C6—C7—C8—C10−65.5 (8)
C1—N1—C5—C40.3 (10)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···Br20.84 (7)2.55 (7)3.368 (7)167 (8)
N2—H2A···Br1i0.84 (8)2.53 (8)3.357 (6)168 (10)
N3—H3C···Br2ii0.892.503.369 (5)166
N3—H3B···Br10.892.463.238 (5)147
N3—H3A···Br2iii0.892.433.281 (5)160
C3—H3···Br1iv0.933.023.892 (8)157
C4—H4···Br1v0.932.913.748 (8)150
C6—H6A···Br1vi0.972.963.528 (7)119
C5—H5···Br2ii0.932.833.721 (7)162
C8—H8···Br20.982.933.793 (7)147
Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) −x+2, y−1/2, −z+1; (iii) −x+1, y−1/2, −z+1; (iv) x−1, y, z−1; (v) x, y, z−1; (vi) −x+2, y+1/2, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···Br20.84 (7)2.55 (7)3.368 (7)167 (8)
N2—H2A···Br1i0.84 (8)2.53 (8)3.357 (6)168 (10)
N3—H3C···Br2ii0.892.503.369 (5)166
N3—H3B···Br10.892.463.238 (5)147
N3—H3A···Br2iii0.892.433.281 (5)160
C3—H3···Br1iv0.933.023.892 (8)157
C4—H4···Br1v0.932.913.748 (8)150
C6—H6A···Br1vi0.972.963.528 (7)119
C5—H5···Br2ii0.932.833.721 (7)162
C8—H8···Br20.982.933.793 (7)147
Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) −x+2, y−1/2, −z+1; (iii) −x+1, y−1/2, −z+1; (iv) x−1, y, z−1; (v) x, y, z−1; (vi) −x+2, y+1/2, −z+1.
references
References top

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Bruker (2001). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.

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

Luo, S., Mi, X., Zhang, L., Liu, S., Xu, H. & Cheng, J. (2006). Angew. Chem. Int. Ed. 45, 3093–3097.

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

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

Xu, D. Q., Luo, S. P., Yue, H. D., Wang, L. P., Liu, Y. K. & Xu, Z. Y. (2006). Synlett, 16, 2569–2572.