[1-(Carb-oxy-meth-yl)cyclo-hex-yl]methanaminium nitrate.

The title compound, C(9)H(18)NO(2) (+)·NO(3) (-), is an anhydrous nitrate salt of gabapentin, which is formed serendipitously in the presence of selected non-coordinating metals. The crystal structure involves extensive hydrogen bonding between the -NH(3) (+) and -COOH groups and the nitrate anion.

Related literature

For related structures, see: Ibers (2001 ▶); Ananda et al. (2003 ▶); Reece & Levendis (2008 ▶); Braga et al. (2008 ▶); Fabbiani et al. (2010 ▶). For the role of γ-amino­butyric acid (GABA) as an inhibitory neurotransmitter, see: Bowery (1993 ▶). Gabapentin is used as a neuroleptic drug in the treatment of epilepsy (Taylor, 1993 ▶) but its applications have been extended to the treatment of neuropathic pain (Magnus, 1999 ▶).

Experimental

Crystal data

C9H18NO2 +·NO3 −

M = 234.25

Orthorhombic,

a = 8.1743 (8) Å

b = 11.5945 (11) Å

c = 12.0396 (9) Å

V = 1141.08 (18) Å3

Z = 4

Mo Kα radiation

μ = 0.11 mm−1

T = 173 K

0.65 × 0.15 × 0.14 mm

Data collection

Bruker APEXII CCD diffractometer

5654 measured reflections

1448 independent reflections

1278 reflections with I > 2σ(I)

R int = 0.044

Refinement

R[F 2 > 2σ(F 2)] = 0.033

wR(F 2) = 0.084

S = 1.06

1448 reflections

146 parameters

H-atom parameters constrained

Δρmax = 0.22 e Å−3

Δρmin = −0.14 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-NT (Bruker, 2005 ▶); data reduction: SAINT-NT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008) ▶; program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) ▶; molecular graphics: X-SEED (Barbour, 2001 ▶; Atwood & Barbour, 2003 ▶); software used to prepare material for publication: X-SEED.

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811001267/pb2049sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811001267/pb2049Isup2.hkl

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

C9H18NO2+·NO3−	F(000) = 504
Mr = 234.25	Dx = 1.364 Mg m−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 1858 reflections
a = 8.1743 (8) Å	θ = 3.0–25.8°
b = 11.5945 (11) Å	µ = 0.11 mm−1
c = 12.0396 (9) Å	T = 173 K
V = 1141.08 (18) Å3	Plate, colourless
Z = 4	0.65 × 0.15 × 0.14 mm

Bruker APEXII CCD diffractometer	1278 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.044
graphite	θmax = 27.0°, θmin = 2.4°
φ and ω scans	h = −10→8
5654 measured reflections	k = −12→14
1448 independent reflections	l = −13→15

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084	H-atom parameters constrained
S = 1.06	w = 1/[σ2(Fo2) + (0.0451P)2 + 0.0272P] where P = (Fo2 + 2Fc2)/3
1448 reflections	(Δ/σ)max < 0.001
146 parameters	Δρmax = 0.22 e Å−3
0 restraints	Δρmin = −0.14 e Å−3

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

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

	x	y	z	Uiso*/Ueq
C1	0.5335 (2)	0.08869 (17)	0.35572 (15)	0.0209 (4)
C2	0.3870 (2)	0.03596 (17)	0.41650 (16)	0.0221 (4)
H2A	0.4250	0.0031	0.4879	0.026*
H2B	0.3076	0.0979	0.4337	0.026*
C3	0.3003 (3)	−0.0580 (2)	0.35067 (17)	0.0301 (5)
H3B	0.2046	−0.0860	0.3932	0.036*
H3A	0.3756	−0.1238	0.3393	0.036*
C4	0.2437 (3)	−0.0124 (2)	0.23826 (18)	0.0369 (6)
H4B	0.1597	0.0480	0.2497	0.044*
H4A	0.1931	−0.0759	0.1953	0.044*
C5	0.3869 (3)	0.0380 (2)	0.17244 (17)	0.0354 (6)
H5A	0.4643	−0.0246	0.1530	0.042*
H5B	0.3456	0.0721	0.1025	0.042*
C6	0.4764 (3)	0.13032 (18)	0.23945 (16)	0.0272 (5)
H6B	0.4031	0.1975	0.2490	0.033*
H6A	0.5732	0.1564	0.1968	0.033*
C7	0.5943 (3)	0.19806 (17)	0.41759 (16)	0.0255 (5)
H7A	0.6985	0.2230	0.3833	0.031*
H7B	0.5136	0.2605	0.4055	0.031*
C8	0.6213 (3)	0.18538 (18)	0.54059 (17)	0.0243 (5)
C9	0.6729 (3)	0.0019 (2)	0.33743 (16)	0.0273 (5)
H9A	0.6386	−0.0538	0.2797	0.033*
H9B	0.7694	0.0440	0.3086	0.033*
N1	0.7225 (2)	−0.06315 (16)	0.43807 (14)	0.0290 (4)
H1A	0.8126	−0.1063	0.4226	0.043*
H1B	0.6393	−0.1103	0.4596	0.043*
H1C	0.7460	−0.0128	0.4938	0.043*
O1	0.7213 (2)	0.12161 (14)	0.58267 (12)	0.0343 (4)
O2	0.5264 (2)	0.25326 (14)	0.59950 (11)	0.0325 (4)
H2C	0.5456	0.2434	0.6674	0.039*
N2	0.4911 (2)	0.27445 (15)	0.87814 (13)	0.0245 (4)
O3	0.3960 (2)	0.34667 (14)	0.84059 (13)	0.0397 (4)
O4	0.5086 (2)	0.26085 (14)	0.97989 (11)	0.0351 (4)
O5	0.5740 (2)	0.21168 (14)	0.81312 (11)	0.0333 (4)

	U11	U22	U33	U12	U13	U23
C1	0.0231 (11)	0.0206 (10)	0.0191 (9)	−0.0003 (8)	0.0014 (8)	0.0006 (7)
C2	0.0206 (10)	0.0232 (10)	0.0224 (9)	0.0005 (9)	0.0021 (8)	0.0002 (8)
C3	0.0306 (12)	0.0289 (12)	0.0307 (11)	−0.0083 (10)	−0.0026 (10)	0.0029 (9)
C4	0.0397 (14)	0.0353 (13)	0.0358 (13)	−0.0083 (12)	−0.0138 (10)	−0.0028 (10)
C5	0.0492 (15)	0.0355 (13)	0.0215 (10)	−0.0054 (12)	−0.0070 (10)	0.0010 (9)
C6	0.0330 (13)	0.0274 (11)	0.0212 (10)	−0.0035 (10)	−0.0009 (9)	0.0051 (8)
C7	0.0265 (11)	0.0211 (10)	0.0288 (11)	−0.0043 (9)	−0.0007 (9)	0.0025 (8)
C8	0.0220 (11)	0.0213 (10)	0.0297 (11)	−0.0052 (9)	−0.0004 (9)	−0.0016 (8)
C9	0.0294 (11)	0.0283 (12)	0.0241 (10)	0.0030 (10)	0.0062 (9)	0.0031 (9)
N1	0.0279 (10)	0.0273 (10)	0.0318 (10)	0.0078 (8)	0.0056 (8)	0.0008 (8)
O1	0.0364 (10)	0.0356 (9)	0.0307 (8)	0.0084 (8)	−0.0063 (7)	−0.0017 (7)
O2	0.0340 (9)	0.0381 (9)	0.0254 (7)	0.0089 (8)	−0.0028 (6)	−0.0040 (6)
N2	0.0241 (10)	0.0224 (9)	0.0268 (9)	−0.0001 (8)	−0.0017 (7)	0.0001 (7)
O3	0.0399 (10)	0.0424 (10)	0.0369 (9)	0.0201 (9)	−0.0004 (8)	0.0076 (7)
O4	0.0458 (10)	0.0381 (9)	0.0214 (7)	0.0065 (8)	−0.0056 (7)	−0.0010 (7)
O5	0.0353 (9)	0.0357 (9)	0.0288 (8)	0.0143 (8)	−0.0002 (7)	−0.0053 (7)

C1—C2	1.531 (3)	C6—H6A	0.9900
C1—C9	1.536 (3)	C7—C8	1.504 (3)
C1—C7	1.552 (3)	C7—H7A	0.9900
C1—C6	1.552 (3)	C7—H7B	0.9900
C2—C3	1.522 (3)	C8—O1	1.214 (3)
C2—H2A	0.9900	C8—O2	1.313 (3)
C2—H2B	0.9900	C9—N1	1.484 (3)
C3—C4	1.525 (3)	C9—H9A	0.9900
C3—H3B	0.9900	C9—H9B	0.9900
C3—H3A	0.9900	N1—H1A	0.9100
C4—C5	1.530 (3)	N1—H1B	0.9100
C4—H4B	0.9900	N1—H1C	0.9100
C4—H4A	0.9900	O2—H2C	0.8400
C5—C6	1.528 (3)	N2—O3	1.229 (2)
C5—H5A	0.9900	N2—O4	1.243 (2)
C5—H5B	0.9900	N2—O5	1.266 (2)
C6—H6B	0.9900
C2—C1—C9	112.79 (16)	C5—C6—H6B	108.8
C2—C1—C7	110.32 (16)	C1—C6—H6B	108.8
C9—C1—C7	111.50 (17)	C5—C6—H6A	108.8
C2—C1—C6	108.67 (17)	C1—C6—H6A	108.8
C9—C1—C6	107.29 (16)	H6B—C6—H6A	107.7
C7—C1—C6	105.95 (16)	C8—C7—C1	116.07 (16)
C3—C2—C1	113.65 (16)	C8—C7—H7A	108.3
C3—C2—H2A	108.8	C1—C7—H7A	108.3
C1—C2—H2A	108.8	C8—C7—H7B	108.3
C3—C2—H2B	108.8	C1—C7—H7B	108.3
C1—C2—H2B	108.8	H7A—C7—H7B	107.4
H2A—C2—H2B	107.7	O1—C8—O2	122.55 (19)
C2—C3—C4	110.82 (19)	O1—C8—C7	124.7 (2)
C2—C3—H3B	109.5	O2—C8—C7	112.73 (19)
C4—C3—H3B	109.5	N1—C9—C1	114.76 (16)
C2—C3—H3A	109.5	N1—C9—H9A	108.6
C4—C3—H3A	109.5	C1—C9—H9A	108.6
H3B—C3—H3A	108.1	N1—C9—H9B	108.6
C3—C4—C5	111.1 (2)	C1—C9—H9B	108.6
C3—C4—H4B	109.4	H9A—C9—H9B	107.6
C5—C4—H4B	109.4	C9—N1—H1A	109.5
C3—C4—H4A	109.4	C9—N1—H1B	109.5
C5—C4—H4A	109.4	H1A—N1—H1B	109.5
H4B—C4—H4A	108.0	C9—N1—H1C	109.5
C6—C5—C4	111.14 (18)	H1A—N1—H1C	109.5
C6—C5—H5A	109.4	H1B—N1—H1C	109.5
C4—C5—H5A	109.4	C8—O2—H2C	109.5
C6—C5—H5B	109.4	O3—N2—O4	121.46 (18)
C4—C5—H5B	109.4	O3—N2—O5	120.20 (16)
H5A—C5—H5B	108.0	O4—N2—O5	118.34 (18)
C5—C6—C1	113.72 (17)
C9—C1—C2—C3	−65.3 (2)	C7—C1—C6—C5	−170.79 (19)
C7—C1—C2—C3	169.32 (17)	C2—C1—C7—C8	49.5 (2)
C6—C1—C2—C3	53.6 (2)	C9—C1—C7—C8	−76.7 (2)
C1—C2—C3—C4	−56.9 (3)	C6—C1—C7—C8	166.91 (19)
C2—C3—C4—C5	56.0 (3)	C1—C7—C8—O1	63.3 (3)
C3—C4—C5—C6	−54.9 (3)	C1—C7—C8—O2	−118.1 (2)
C4—C5—C6—C1	54.1 (3)	C2—C1—C9—N1	−49.7 (2)
C2—C1—C6—C5	−52.2 (2)	C7—C1—C9—N1	75.1 (2)
C9—C1—C6—C5	70.0 (2)	C6—C1—C9—N1	−169.31 (18)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O5i	0.91	2.02	2.828 (2)	147
N1—H1A···O4i	0.91	2.41	3.215 (2)	147
N1—H1A···N2i	0.91	2.58	3.465 (3)	164
N1—H1B···O4ii	0.91	2.06	2.951 (3)	168
N1—H1B···O3ii	0.91	2.47	3.022 (2)	119
N1—H1B···N2ii	0.91	2.60	3.390 (3)	146
N1—H1C···O1	0.91	1.90	2.760 (2)	157
O2—H2C···O5	0.84	1.81	2.646 (2)	175
O2—H2C···N2	0.84	2.60	3.376 (2)	154

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O5i	0.91	2.02	2.828 (2)	147
N1—H1A⋯O4i	0.91	2.41	3.215 (2)	147
N1—H1A⋯N2i	0.91	2.58	3.465 (3)	164
N1—H1B⋯O4ii	0.91	2.06	2.951 (3)	168
N1—H1B⋯O3ii	0.91	2.47	3.022 (2)	119
N1—H1B⋯N2ii	0.91	2.60	3.390 (3)	146
N1—H1C⋯O1	0.91	1.90	2.760 (2)	157
O2—H2C⋯O5	0.84	1.81	2.646 (2)	175
O2—H2C⋯N2	0.84	2.60	3.376 (2)	154

Symmetry codes: (i) ; (ii) .