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Acta Cryst. (2009). E65, o783    [ doi:10.1107/S1600536809008952 ]

Gabapentinium picrate

H. Li, H. S. Yathirajan, L. Mallesha, K. N. Mohana and B. Narayana

Abstract top

The title compound {systematic name: [1-(carboxymethyl)cyclohexyl]methanaminium 2,4,6-trinitrophenolate}, C9H18NO2+·C6H2N3O7-, was synthesized from picric acid and gabapentin. The crystal packing is stabilized by intramolecular N-H...O=N and N-H...O-Ph hydrogen bonds. An O-H...O interaction is also present.

Comment top

Gabapentin, (1-(aminomethyl) cyclohexane acetic acid; Neurontin), is a novel anticonvulsant agent and has therapeutically beneficial effects against chronic pain states and anxiety (Bryans & Wustrow, 1999). Gabapentin is a zwitterion in the solid state (Ibers, 2001). On the other hand, picric acid forms salts or charge-transfer complexes with many organic compounds and we have reported crystal structures of a number of picrate complexes with organic compounds of pharmaceutical importance viz. desipraminium picrate (Swamy et al., 2007). The present paper reports the crystal structure of the title compound, (1-(carboxymethyl)cyclohexyl)methanaminium 2,4,6-trinitrophenolate.

Related literature top

For background, see: Bryans & Wustrow (1999). For related structures, see: Ibers (2001); Swamy et al. (2007) and references cited therein.

Experimental top

The title compound was synthesized by mixing solutions of picric acid (4.59 g, 0.01 mol) in 20 ml of distilled water and gabapentin (1.72 g, 0.01 mol) in 20 ml of distilled water and the resulting solution was stirred well for 10 min. A yellow precipitate of gabapentinium picrate was formed almost instantaneously after stirring. The so formed yellow complex was filtered off, washed with distilled water and dried in vacuo over anhydrous calcium chloride. The compound was purified by successive recrystallization from methanol (yield 92%). Single crystals for X-ray studies were grown by slow evaporation of a methanol solution. Analysis (%) found (calculated) for C15H20N4O9: C: 44.68 (45.00); H: 5.11 (5.04); N: 13.73 (13.99)%.

Refinement top

All H atoms were placed at calculated positions and refined using a riding model approximation, with C—H = 0.93–0.97 Å and with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); 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. A view of the asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. Packing in the crystal structure of the title compound, viewed along the a axis
[1-(Carboxymethyl)cyclohexyl]methanaminium 2,4,6-trinitrophenolate top
Crystal data top
C9H18NO2+·C6H2N3O7−F(000) = 840
Mr = 400.35Dx = 1.488 Mg m−3
Monoclinic, P21/nMelting point = 431–434 K
Hall symbol: -P 2ynMo Kα radiation, λ = 0.71073 Å
a = 11.576 (2) ÅCell parameters from 2666 reflections
b = 7.7312 (16) Åθ = 2.8–25.1°
c = 19.973 (4) ŵ = 0.12 mm−1
β = 91.425 (2)°T = 296 K
V = 1787.0 (6) Å3Block, yellow
Z = 40.25 × 0.25 × 0.20 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer		3150 independent reflections
Radiation source: fine-focus sealed tube2408 reflections with I > 2σ(I)
graphiteRint = 0.034
φ and ω scansθmax = 25.1°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)		h = −12→13
Tmin = 0.970, Tmax = 0.976k = −7→9
8899 measured reflectionsl = −23→23
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.062H-atom parameters constrained
wR(F2) = 0.182 w = 1/[σ2(Fo2) + (0.083P)2 + 1.5949P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
3150 reflectionsΔρmax = 1.06 e Å−3
256 parametersΔρmin = −0.55 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.075 (5)
Crystal data top
C9H18NO2+·C6H2N3O7−V = 1787.0 (6) Å3
Mr = 400.35Z = 4
Monoclinic, P21/nMo Kα radiation
a = 11.576 (2) ŵ = 0.12 mm−1
b = 7.7312 (16) ÅT = 296 K
c = 19.973 (4) Å0.25 × 0.25 × 0.20 mm
β = 91.425 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer		3150 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)		2408 reflections with I > 2σ(I)
Tmin = 0.970, Tmax = 0.976Rint = 0.034
8899 measured reflectionsθmax = 25.1°
Refinement top
R[F2 > 2σ(F2)] = 0.062H-atom parameters constrained
wR(F2) = 0.182Δρmax = 1.06 e Å−3
S = 1.07Δρmin = −0.55 e Å−3
3150 reflectionsAbsolute structure: ?
256 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.2919 (2)0.3970 (4)0.05392 (13)0.0375 (6)
C20.3067 (2)0.5162 (3)0.10930 (13)0.0362 (6)
C30.3639 (2)0.6728 (3)0.08832 (16)0.0432 (7)
C40.3949 (2)0.7066 (4)0.02348 (17)0.0499 (8)
H40.43230.80930.01310.060*
C50.3701 (2)0.5869 (4)−0.02563 (15)0.0466 (8)
C60.3199 (2)0.4315 (4)−0.01060 (14)0.0433 (7)
H60.30520.3503−0.04410.052*
C70.4810 (2)0.6530 (3)0.67642 (12)0.0328 (6)
C80.5192 (2)0.4847 (3)0.71209 (13)0.0372 (6)
H8A0.60300.48110.71440.045*
H8B0.49200.48710.75760.045*
C90.4752 (3)0.3205 (4)0.67810 (17)0.0521 (8)
H9A0.51120.30840.63500.063*
H9B0.49720.22130.70530.063*
C100.3458 (3)0.3223 (5)0.6679 (2)0.0727 (11)
H10A0.30930.32140.71110.087*
H10B0.32160.21920.64370.087*
C110.3074 (3)0.4818 (5)0.6289 (2)0.0664 (10)
H11A0.22370.48330.62470.080*
H11B0.33810.47710.58420.080*
C120.3490 (3)0.6467 (4)0.66370 (16)0.0502 (8)
H12A0.31090.65690.70620.060*
H12B0.32610.74530.63640.060*
C130.5043 (3)0.8069 (4)0.72276 (14)0.0429 (7)
H13A0.48660.91220.69820.051*
H13B0.45170.80030.75970.051*
C140.5472 (2)0.6665 (3)0.61064 (12)0.0354 (6)
H14A0.62900.66690.62220.042*
H14B0.53190.56150.58530.042*
C150.5244 (2)0.8160 (3)0.56474 (13)0.0365 (6)
N10.2450 (3)0.2259 (3)0.06681 (13)0.0530 (7)
N20.3944 (3)0.8022 (3)0.13862 (17)0.0582 (8)
N30.4040 (2)0.6182 (5)−0.09448 (17)0.0633 (9)
N40.6251 (2)0.8199 (3)0.75081 (12)0.0490 (7)
H4A0.64430.72100.77100.074*
H4B0.62920.90600.78030.074*
H4C0.67340.84040.71780.074*
O10.1815 (4)0.1631 (5)0.02309 (16)0.1380 (18)
O20.2579 (2)0.1585 (3)0.11974 (12)0.0681 (8)
O30.2754 (2)0.4861 (3)0.16754 (10)0.0492 (6)
O40.3311 (2)0.8242 (3)0.18624 (13)0.0638 (7)
O50.4804 (3)0.8876 (4)0.1315 (2)0.1066 (12)
O60.4584 (2)0.7510 (5)−0.10551 (16)0.0911 (10)
O70.3773 (3)0.5105 (5)−0.13704 (14)0.0893 (10)
O80.4688 (2)0.9447 (3)0.57786 (10)0.0609 (7)
O90.5759 (2)0.7959 (3)0.50733 (11)0.0616 (7)
H90.55760.87540.48200.092*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0436 (15)0.0344 (14)0.0344 (14)−0.0022 (12)−0.0046 (11)0.0041 (11)
C20.0400 (14)0.0318 (14)0.0364 (15)0.0020 (11)−0.0054 (11)0.0019 (11)
C30.0420 (15)0.0297 (14)0.0575 (18)−0.0008 (12)−0.0075 (13)0.0030 (13)
C40.0384 (16)0.0382 (16)0.073 (2)0.0036 (13)0.0079 (14)0.0239 (16)
C50.0394 (15)0.0549 (19)0.0457 (16)0.0112 (14)0.0059 (12)0.0156 (15)
C60.0428 (16)0.0514 (18)0.0356 (15)0.0031 (13)−0.0026 (12)0.0021 (13)
C70.0415 (14)0.0297 (13)0.0271 (13)0.0035 (11)0.0006 (10)0.0015 (10)
C80.0490 (16)0.0323 (14)0.0301 (14)−0.0001 (12)−0.0014 (11)0.0044 (11)
C90.073 (2)0.0313 (16)0.0520 (18)−0.0097 (15)−0.0040 (15)0.0041 (13)
C100.076 (3)0.058 (2)0.084 (3)−0.031 (2)0.002 (2)0.004 (2)
C110.0460 (19)0.078 (3)0.074 (2)−0.0127 (18)−0.0084 (16)−0.001 (2)
C120.0416 (16)0.059 (2)0.0505 (18)0.0065 (14)0.0054 (13)0.0072 (15)
C130.0624 (19)0.0337 (15)0.0325 (14)0.0073 (13)0.0012 (13)−0.0009 (11)
C140.0466 (15)0.0311 (14)0.0285 (13)0.0016 (11)0.0016 (11)0.0015 (10)
C150.0480 (16)0.0346 (15)0.0268 (13)−0.0010 (12)−0.0009 (11)0.0005 (11)
N10.0781 (19)0.0435 (15)0.0369 (14)−0.0202 (13)−0.0054 (12)−0.0054 (12)
N20.0603 (17)0.0320 (14)0.082 (2)−0.0054 (13)−0.0139 (16)−0.0025 (14)
N30.0510 (16)0.078 (2)0.0612 (19)0.0195 (16)0.0141 (14)0.0320 (18)
N40.0808 (19)0.0321 (13)0.0337 (13)−0.0104 (12)−0.0085 (12)−0.0038 (10)
O10.240 (5)0.111 (3)0.0613 (19)−0.105 (3)−0.031 (2)0.0042 (18)
O20.0992 (19)0.0492 (14)0.0547 (15)−0.0240 (13)−0.0203 (13)0.0170 (11)
O30.0769 (15)0.0367 (11)0.0340 (11)−0.0009 (10)0.0009 (10)0.0000 (8)
O40.0849 (18)0.0401 (13)0.0655 (16)0.0009 (12)−0.0174 (14)−0.0124 (11)
O50.089 (2)0.072 (2)0.159 (3)−0.0438 (18)0.005 (2)−0.029 (2)
O60.0774 (19)0.101 (2)0.096 (2)0.0071 (17)0.0278 (16)0.0562 (19)
O70.106 (2)0.116 (3)0.0471 (15)0.016 (2)0.0227 (15)0.0115 (17)
O80.1037 (19)0.0422 (13)0.0375 (12)0.0242 (13)0.0137 (11)0.0090 (10)
O90.0925 (18)0.0544 (14)0.0389 (12)0.0224 (13)0.0198 (11)0.0148 (10)
Geometric parameters (Å, °) top
C1—C61.363 (4)C10—H10B0.9700
C1—C21.447 (4)C11—C121.524 (5)
C1—N11.455 (4)C11—H11A0.9700
C2—O31.249 (3)C11—H11B0.9700
C2—C31.447 (4)C12—H12A0.9700
C3—C41.377 (4)C12—H12B0.9700
C3—N21.455 (4)C13—N41.497 (4)
C4—C51.374 (5)C13—H13A0.9700
C4—H40.9300C13—H13B0.9700
C5—C61.371 (4)C14—C151.495 (4)
C5—N31.460 (4)C14—H14A0.9700
C6—H60.9300C14—H14B0.9700
C7—C131.527 (4)C15—O81.217 (3)
C7—C141.541 (3)C15—O91.314 (3)
C7—C81.543 (3)N1—O21.185 (3)
C7—C121.544 (4)N1—O11.228 (4)
C8—C91.522 (4)N2—O51.205 (4)
C8—H8A0.9700N2—O41.227 (4)
C8—H8B0.9700N3—O71.225 (4)
C9—C101.506 (5)N3—O61.227 (4)
C9—H9A0.9700N4—H4A0.8900
C9—H9B0.9700N4—H4B0.8900
C10—C111.520 (5)N4—H4C0.8900
C10—H10A0.9700O9—H90.8200
C6—C1—C2124.9 (3)C10—C11—H11A109.4
C6—C1—N1116.3 (3)C12—C11—H11A109.4
C2—C1—N1118.8 (2)C10—C11—H11B109.4
O3—C2—C1124.2 (2)C12—C11—H11B109.4
O3—C2—C3124.8 (3)H11A—C11—H11B108.0
C1—C2—C3111.0 (2)C11—C12—C7113.7 (3)
C4—C3—C2124.2 (3)C11—C12—H12A108.8
C4—C3—N2117.0 (3)C7—C12—H12A108.8
C2—C3—N2118.7 (3)C11—C12—H12B108.8
C5—C4—C3119.3 (3)C7—C12—H12B108.8
C5—C4—H4120.4H12A—C12—H12B107.7
C3—C4—H4120.4N4—C13—C7115.4 (2)
C6—C5—C4121.1 (3)N4—C13—H13A108.4
C6—C5—N3118.5 (3)C7—C13—H13A108.4
C4—C5—N3120.3 (3)N4—C13—H13B108.4
C1—C6—C5119.4 (3)C7—C13—H13B108.4
C1—C6—H6120.3H13A—C13—H13B107.5
C5—C6—H6120.3C15—C14—C7119.4 (2)
C13—C7—C14112.4 (2)C15—C14—H14A107.5
C13—C7—C8109.4 (2)C7—C14—H14A107.5
C14—C7—C8107.9 (2)C15—C14—H14B107.5
C13—C7—C12106.5 (2)C7—C14—H14B107.5
C14—C7—C12111.9 (2)H14A—C14—H14B107.0
C8—C7—C12108.7 (2)O8—C15—O9122.6 (2)
C9—C8—C7114.1 (2)O8—C15—C14125.9 (2)
C9—C8—H8A108.7O9—C15—C14111.5 (2)
C7—C8—H8A108.7O2—N1—O1121.3 (3)
C9—C8—H8B108.7O2—N1—C1121.2 (2)
C7—C8—H8B108.7O1—N1—C1117.0 (3)
H8A—C8—H8B107.6O5—N2—O4121.8 (3)
C10—C9—C8111.9 (3)O5—N2—C3118.9 (3)
C10—C9—H9A109.2O4—N2—C3119.4 (3)
C8—C9—H9A109.2O7—N3—O6124.5 (3)
C10—C9—H9B109.2O7—N3—C5118.1 (3)
C8—C9—H9B109.2O6—N3—C5117.3 (4)
H9A—C9—H9B107.9C13—N4—H4A109.5
C9—C10—C11110.7 (3)C13—N4—H4B109.5
C9—C10—H10A109.5H4A—N4—H4B109.5
C11—C10—H10A109.5C13—N4—H4C109.5
C9—C10—H10B109.5H4A—N4—H4C109.5
C11—C10—H10B109.5H4B—N4—H4C109.5
H10A—C10—H10B108.1C15—O9—H9109.5
C10—C11—C12111.0 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O9—H9···O8i0.821.862.672 (3)174
N4—H4C···O4ii0.892.322.957 (4)128
N4—H4C···O3ii0.892.062.862 (3)149
N4—H4B···O2iii0.892.412.894 (3)114
N4—H4B···O4i0.892.233.063 (3)155
N4—H4A···O3iii0.892.213.081 (3)166
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x+1/2, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O9—H9···O8i0.821.862.672 (3)174
N4—H4C···O4ii0.892.322.957 (4)128
N4—H4C···O3ii0.892.062.862 (3)149
N4—H4B···O2iii0.892.412.894 (3)114
N4—H4B···O4i0.892.233.063 (3)155
N4—H4A···O3iii0.892.213.081 (3)166
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x+1/2, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1.
Acknowledgements top

LM thanks University of Mysore for research facilities.

references
References top

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

Bryans, J. S. & Wustrow, D. J. (1999). Med. Res. Rev. 19, 149–177.

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Sheldrick, G. M. (2004). SADABS. University of Göttingen, Germany.

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Swamy, M. T., Ashok, M. A., Yathirajan, H. S., Narayana, B. & Bolte, M. (2007). Acta Cryst. E63, o4919.