rac-2-Amino­pyridinium cis-2-carb­oxy­cyclo­hexane-1-carboxyl­ate

Smith, G.; Wermuth, U.D.

doi:10.1107/S1600536811025256

organic compounds

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ISSN: 2056-9890

Volume 67| Part 8| August 2011| Page o1900

doi:10.1107/S1600536811025256

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rac-2-Aminopyridinium cis-2-carboxycyclohexane-1-carboxylate

Graham Smith ^a ^* and Urs D. Wermuth ^a

^aFaculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
^*Correspondence e-mail: g.smith@qut.edu.au

(Received 24 June 2011; accepted 27 June 2011; online 2 July 2011)

In the structure of the title compound, C₅H₇N₂⁺·C₈H₁₁O₄⁻, the cis anions associate through head-to-tail carboxylic acid–carboxyl O—H⋯O hydrogen bonds [graph set C(7)], forming chains which extend along c and are interlinked through the carboxyl groups, forming cyclic R₂²(8) associations with the pyridinium and an amine H-atom donor of the cation. Further amine–carboxyl N—H⋯O interactions form enlarged centrosymmetric rings [graph set R₄⁴(18)] and extensions down b, giving a three-dimensional structure.

Related literature

For the structure of racemic cis-cyclohexane,1,2-dicarboxylic acid, see: Benedetti et al. (1970 ). For the structure of racemic ammonium cis-2-carboxycyclohexane-1-carboxylate, see: Smith & Wermuth (2011 ) and of brucinium (1R,2S-2-carboxycyclohexane-1-carboxylate dihydrate, see: Smith et al. (2011 ). For the structure of the adduct of cis-cyclohexane-1,2-dicarboxylic acid with 4,4′-bipyridine, see: Bhogala et al. (2005 ). For graph-set analysis, see: Etter et al. (1990).

Experimental

Crystal data

C₅H₇N₂⁺·C₈H₁₁O₄⁻
M_r = 266.29
Monoclinic, P 2₁ /c
a = 12.4709 (5) Å
b = 10.4191 (5) Å
c = 10.6451 (5) Å
β = 101.250 (4)°
V = 1356.60 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 200 K
0.35 × 0.32 × 0.20 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.]$ ) T_min = 0.90, T_max = 0.98
9200 measured reflections
2658 independent reflections
1947 reflections with I > 2σ(I)
R_int = 0.022

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.081
S = 0.99
2658 reflections
188 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1A—H1A⋯O11	0.981 (15)	1.656 (15)	2.6223 (15)	167.7 (14)
N21A—H21A⋯O12	0.911 (18)	2.044 (17)	2.9361 (16)	166.3 (14)
N21A—H22A⋯O22ⁱ	0.873 (16)	2.105 (16)	2.9103 (17)	153.1 (14)
O21—H21⋯O11ⁱⁱ	0.991 (19)	1.595 (19)	2.5806 (13)	172.9 (18)
Symmetry codes: (i) -x+1, -y+1, -z+2; (ii) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: CrysAlis PRO (Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.]$ ); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ) within WinGX (Farrugia, 1999 ); molecular graphics: PLATON (Spek, 2009 ); software used to prepare material for publication: PLATON.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811025256/wn2440sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811025256/wn2440Isup2.hkl

checkCIF report

Comment top

Although the structure of racemic cis-cyclohexane-1,2-dicarboxylic acid (cis-CHDC) is known (Benedetti et al., 1970), together with its 1:1 adduct with 4,4'-bipyridine (Bhogala et al., 2005), there are few examples of salts of this acid in the crystallographic literature. We have now reported the structures of the 1:1 ammonium salt (Smith & Wermuth, 2011) and the 1:1 brucinium salt trihydrate (Smith et al., 2011), in which the 1R,2S enantiomer of cis-CHDC has been resolved. Our 1:1 stoichiometric reaction of cyclohexane-1,2-dicarboxylic anhydride with 2-aminopyridine in 50% ethanol/water solution gave large crystals of the title compound, C₅H₇N₂⁺ C₈H₁₁O₄^- and the structure is reported here.

In the structure (Fig. 1) of the title compound, cisC₅H₇N₂⁺ C₈H₁₁O₄^-, the cis-anions associate through head-to-tail carboxylic acid–carboxyl O—H···O hydrogen-bonds [graph set C(7) (Etter et al., 1990)] and are inter-linked through the carboxyl groups, forming cyclic R²₂(8) associations with the pyridinium and an amine H donor of the cation. Further amine···carboxyl N—H···O interactions (Table 1) form enlarged centrosymmetric rings [graph set R⁴₄(18)] (Fig. 2) and extensions down b (Fig. 3) to give a three-dimensional structure.

Related literature top

For the structure of racemic cis-cyclohexane,1,2-dicarboxylic acid, see: Benedetti et al. (1970). For the structure of racemic ammonium cis-2-carboxycyclohexane-1-carboxylate, see: Smith & Wermuth (2011) and of brucinium (1R,2S-2-carboxycyclohexane-1-carboxylate trihydrate, see: Smith et al. (2011). For the structure of the adduct of cis-cyclohexane-1,2-dicarboxylic acid with 4,4'-bipyridine, see: Bhogala et al. (2005). For graph-set analysis, see: Etter et al. (1990).

Experimental top

The title compound was synthesized by heating a solution of 1 mmol of cyclohexane-1,2-dicarboxylic anhydride and 1 mmol of 2-aminopyridine in 50 ml of 1:1 ethanol–water under reflux for 10 min. After concentration to 30 ml the solution was allowed evaporate to moist dryness at room temperature, giving large colourless plates of the title compound (m.p. 396 K) from which a specimen was cleaved for the X-ray analysis.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top

	Fig. 1. Molecular configuration for the cation and anion species. Inter-species hydrogen bonds are shown as dashed lines and displacement ellipsoids are drawn at the 40% probability level.
	Fig. 2. The inter-associated duplex cis-CHDC anion chains which extend along the c direction in the unit cell, showing hydrogen-bonding interactions as dashed lines. Non-associative H atoms are omitted. For symmetry codes, see Table 1.
	Fig. 3. A view of the hydrogen-bonding extensions in the structure down the b axis.

rac-2-Aminopyridinium cis-2-carboxycyclohexane-1-carboxylate top

Crystal data top

C₅H₇N₂⁺·C₈H₁₁O₄⁻	F(000) = 568
M_r = 266.29	D_x = 1.304 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 396 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 12.4709 (5) Å	Cell parameters from 4347 reflections
b = 10.4191 (5) Å	θ = 3.4–28.7°
c = 10.6451 (5) Å	µ = 0.10 mm⁻¹
β = 101.250 (4)°	T = 200 K
V = 1356.60 (11) Å³	Block, colourless
Z = 4	0.35 × 0.32 × 0.20 mm

Data collection top

Oxford Diffraction Gemini-S CCD-detector diffractometer	2658 independent reflections
Radiation source: Enhance (Mo) X-ray source	1947 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.022
Detector resolution: 16.077 pixels mm^-1	θ_max = 26.0°, θ_min = 3.4°
ω scans	h = −15→15
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)	k = −12→12
T_min = 0.90, T_max = 0.98	l = −13→13
9200 measured reflections

Refinement top

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) = 0.081	H atoms treated by a mixture of independent and constrained refinement
S = 0.99	w = 1/[σ²(F_o²) + (0.0472P)²] where P = (F_o² + 2F_c²)/3
2658 reflections	(Δ/σ)_max = 0.001
188 parameters	Δρ_max = 0.16 e Å⁻³
0 restraints	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₅H₇N₂⁺·C₈H₁₁O₄⁻	V = 1356.60 (11) Å³
M_r = 266.29	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 12.4709 (5) Å	µ = 0.10 mm⁻¹
b = 10.4191 (5) Å	T = 200 K
c = 10.6451 (5) Å	0.35 × 0.32 × 0.20 mm
β = 101.250 (4)°

Data collection top

Oxford Diffraction Gemini-S CCD-detector diffractometer	2658 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)	1947 reflections with I > 2σ(I)
T_min = 0.90, T_max = 0.98	R_int = 0.022
9200 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	0 restraints
wR(F²) = 0.081	H atoms treated by a mixture of independent and constrained refinement
S = 0.99	Δρ_max = 0.16 e Å⁻³
2658 reflections	Δρ_min = −0.15 e Å⁻³
188 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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.

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

	x	y	z	U_iso*/U_eq
O11	0.29045 (7)	0.58197 (9)	0.65073 (8)	0.0412 (3)
O12	0.34131 (6)	0.57102 (9)	0.86187 (8)	0.0405 (3)
O21	0.18216 (7)	0.77924 (9)	0.96839 (9)	0.0411 (3)
O22	0.23826 (8)	0.62543 (10)	1.11054 (8)	0.0494 (3)
C1	0.14901 (9)	0.59059 (12)	0.77138 (11)	0.0310 (4)
C2	0.12817 (9)	0.56727 (12)	0.90706 (12)	0.0327 (4)
C3	0.14384 (10)	0.42684 (13)	0.94720 (14)	0.0426 (4)
C4	0.07163 (11)	0.34055 (14)	0.85100 (16)	0.0529 (5)
C5	0.09356 (11)	0.36091 (14)	0.71709 (16)	0.0521 (5)
C6	0.07708 (10)	0.50055 (13)	0.67677 (13)	0.0422 (4)
C11	0.26966 (10)	0.57955 (11)	0.76400 (12)	0.0308 (4)
C21	0.19003 (9)	0.65774 (13)	1.00503 (12)	0.0341 (4)
N1A	0.49126 (9)	0.62635 (11)	0.62208 (11)	0.0387 (4)
N21A	0.55457 (11)	0.50551 (13)	0.80144 (12)	0.0474 (5)
C2A	0.57435 (10)	0.56346 (12)	0.69688 (13)	0.0356 (4)
C3A	0.67632 (10)	0.56253 (13)	0.65925 (13)	0.0410 (4)
C4A	0.68805 (11)	0.62558 (14)	0.55114 (14)	0.0467 (5)
C5A	0.60091 (12)	0.69282 (14)	0.47783 (14)	0.0509 (5)
C6A	0.50392 (12)	0.69068 (14)	0.51527 (14)	0.0473 (5)
H1	0.12600	0.67860	0.74740	0.0370*
H2	0.05060	0.58600	0.90310	0.0390*
H21	0.2185 (15)	0.8363 (19)	1.0383 (18)	0.089 (6)*
H31	0.21980	0.40290	0.95300	0.0510*
H32	0.12570	0.41550	1.03110	0.0510*
H41	0.08540	0.25150	0.87570	0.0640*
H42	−0.00460	0.35890	0.85140	0.0640*
H51	0.04460	0.30730	0.65710	0.0630*
H52	0.16800	0.33550	0.71500	0.0630*
H61	0.00090	0.52350	0.67120	0.0510*
H62	0.09440	0.51130	0.59240	0.0510*
H1A	0.4183 (12)	0.6177 (14)	0.6427 (14)	0.055 (4)*
H3A	0.73520	0.51910	0.70800	0.0490*
H4A	0.75520	0.62400	0.52550	0.0560*
H5A	0.60970	0.73790	0.40510	0.0610*
H6A	0.44470	0.73400	0.46710	0.0570*
H21A	0.4889 (14)	0.5126 (15)	0.8261 (15)	0.060 (5)*
H22A	0.6077 (13)	0.4646 (15)	0.8509 (15)	0.054 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O11	0.0347 (5)	0.0558 (6)	0.0334 (5)	0.0086 (4)	0.0076 (4)	0.0050 (5)
O12	0.0271 (4)	0.0577 (6)	0.0347 (5)	0.0022 (4)	0.0011 (4)	0.0019 (4)
O21	0.0456 (5)	0.0376 (5)	0.0356 (5)	0.0017 (4)	−0.0031 (4)	−0.0025 (4)
O22	0.0553 (6)	0.0572 (7)	0.0314 (5)	0.0134 (5)	−0.0024 (4)	0.0036 (5)
C1	0.0273 (6)	0.0309 (7)	0.0323 (7)	0.0041 (5)	−0.0002 (5)	0.0005 (5)
C2	0.0222 (6)	0.0373 (7)	0.0380 (7)	0.0045 (5)	0.0044 (5)	0.0027 (6)
C3	0.0362 (7)	0.0406 (8)	0.0515 (8)	0.0003 (6)	0.0101 (6)	0.0107 (7)
C4	0.0414 (8)	0.0384 (8)	0.0781 (11)	−0.0057 (7)	0.0094 (7)	0.0034 (8)
C5	0.0402 (8)	0.0424 (9)	0.0703 (10)	−0.0070 (6)	0.0023 (7)	−0.0179 (8)
C6	0.0309 (6)	0.0505 (9)	0.0418 (8)	−0.0017 (6)	−0.0009 (6)	−0.0083 (7)
C11	0.0307 (6)	0.0280 (7)	0.0327 (7)	0.0026 (5)	0.0034 (5)	0.0007 (5)
C21	0.0262 (6)	0.0429 (8)	0.0332 (7)	0.0082 (5)	0.0061 (5)	0.0022 (6)
N1A	0.0327 (6)	0.0385 (6)	0.0435 (7)	0.0042 (5)	0.0040 (5)	0.0024 (5)
N21A	0.0344 (7)	0.0615 (9)	0.0462 (8)	0.0105 (6)	0.0073 (6)	0.0133 (6)
C2A	0.0319 (6)	0.0336 (7)	0.0392 (7)	0.0008 (5)	0.0018 (6)	−0.0030 (6)
C3A	0.0311 (7)	0.0437 (8)	0.0468 (8)	0.0005 (6)	0.0039 (6)	−0.0004 (7)
C4A	0.0391 (8)	0.0464 (9)	0.0558 (9)	−0.0082 (6)	0.0121 (7)	−0.0023 (7)
C5A	0.0539 (9)	0.0479 (9)	0.0511 (9)	−0.0059 (7)	0.0109 (7)	0.0115 (7)
C6A	0.0473 (8)	0.0414 (8)	0.0498 (9)	0.0045 (7)	0.0009 (7)	0.0083 (7)

Geometric parameters (Å, º) top

O11—C11	1.2821 (15)	C1—H1	0.9800
O12—C11	1.2363 (15)	C2—H2	0.9800
O21—C21	1.3226 (16)	C3—H32	0.9700
O22—C21	1.2137 (15)	C3—H31	0.9700
O21—H21	0.991 (19)	C4—H42	0.9700
N1A—C6A	1.3554 (19)	C4—H41	0.9700
N1A—C2A	1.3473 (17)	C5—H51	0.9700
N21A—C2A	1.3310 (19)	C5—H52	0.9700
N1A—H1A	0.981 (15)	C6—H61	0.9700
N21A—H21A	0.911 (18)	C6—H62	0.9700
N21A—H22A	0.873 (16)	C2A—C3A	1.4059 (18)
C1—C2	1.5359 (17)	C3A—C4A	1.358 (2)
C1—C11	1.5262 (17)	C4A—C5A	1.396 (2)
C1—C6	1.5319 (18)	C5A—C6A	1.346 (2)
C2—C3	1.5261 (19)	C3A—H3A	0.9300
C2—C21	1.5025 (18)	C4A—H4A	0.9300
C3—C4	1.519 (2)	C5A—H5A	0.9300
C4—C5	1.518 (2)	C6A—H6A	0.9300
C5—C6	1.520 (2)

O11···N1A	2.6223 (15)	C11···H21ⁱ	2.520 (19)
O11···C21ⁱ	3.2513 (16)	C11···H52	2.8400
O11···O21ⁱ	2.5806 (13)	C11···H31	2.8800
O11···C4Aⁱⁱ	3.0969 (17)	C21···H42^viii	3.0200
O11···O22ⁱ	3.1292 (14)	C21···H22A^iv	2.972 (16)
O12···C6Aⁱⁱⁱ	3.4134 (17)	H1···O21	2.5500
O12···C3	3.1653 (16)	H1···C4^v	3.0000
O12···O22	3.2105 (12)	H1···H42^v	2.5100
O12···N21A	2.9361 (16)	H1A···C11	2.489 (15)
O12···C21	2.7964 (15)	H1A···O11	1.656 (15)
O21···C11	3.3436 (15)	H1A···O12	2.734 (15)
O21···O11ⁱⁱⁱ	2.5806 (13)	H1A···H21ⁱ	2.57 (2)
O22···O12	3.2105 (12)	H1A···H21A	2.26 (2)
O22···C3A^iv	3.1555 (16)	H2···H61	2.5100
O22···O11ⁱⁱⁱ	3.1292 (14)	H2···H32^viii	2.4300
O22···N21A^iv	2.9103 (17)	H2···H42	2.5000
O22···C2A^iv	3.4158 (16)	H3A···H22A	2.4700
O11···H62	2.5100	H3A···O22^iv	2.4200
O11···H4Aⁱⁱ	2.8300	H4A···H41^vii	2.4500
O11···H21A	2.886 (17)	H4A···O11ⁱⁱ	2.8300
O11···H1A	1.656 (15)	H5A···C2Aⁱ	3.0000
O11···H21ⁱ	1.595 (19)	H5A···N21Aⁱ	2.9200
O12···H31	2.6200	H6A···O12ⁱ	2.5500
O12···H21A	2.044 (17)	H21···O11ⁱⁱⁱ	1.595 (19)
O12···H1A	2.734 (15)	H21···C1ⁱⁱⁱ	2.886 (19)
O12···H6Aⁱⁱⁱ	2.5500	H21···H1Aⁱⁱⁱ	2.57 (2)
O21···H62ⁱⁱⁱ	2.8800	H21···H62ⁱⁱⁱ	2.3700
O21···H1	2.5500	H21···C6ⁱⁱⁱ	3.031 (19)
O21···H51^v	2.9000	H21···C11ⁱⁱⁱ	2.520 (19)
O22···H32	2.6500	H21A···C11	2.774 (18)
O22···H3A^iv	2.4200	H21A···O11	2.886 (17)
O22···H22A^iv	2.105 (16)	H21A···H1A	2.26 (2)
O22···H31	2.8400	H21A···O12	2.044 (17)
N1A···O11	2.6223 (15)	H22A···H3A	2.4700
N1A···C11	3.4331 (17)	H22A···O22^iv	2.105 (16)
N21A···O12	2.9361 (16)	H22A···C21^iv	2.972 (16)
N21A···O22^iv	2.9103 (17)	H31···O12	2.6200
N21A···H5Aⁱⁱⁱ	2.9200	H31···O22	2.8400
C2A···C6Aⁱⁱ	3.494 (2)	H31···H52	2.5900
C2A···O22^iv	3.4158 (16)	H31···C11	2.8800
C3···O12	3.1653 (16)	H32···O22	2.6500
C3A···O22^iv	3.1555 (16)	H32···H2^viii	2.4300
C4A···O11ⁱⁱ	3.0969 (17)	H41···H4A^ix	2.4500
C6A···O12ⁱ	3.4134 (17)	H41···C4A^ix	3.0700
C6A···C2Aⁱⁱ	3.494 (2)	H42···H2	2.5000
C11···N1A	3.4331 (17)	H42···H61	2.5800
C11···O21	3.3436 (15)	H42···C21^viii	3.0200
C21···O12	2.7964 (15)	H42···H1^vi	2.5100
C21···O11ⁱⁱⁱ	3.2513 (16)	H51···O21^vi	2.9000
C1···H21ⁱ	2.886 (19)	H52···H31	2.5900
C2A···H5Aⁱⁱⁱ	3.0000	H52···C11	2.8400
C4···H1^vi	3.0000	H61···H2	2.5100
C4A···H41^vii	3.0700	H61···H42	2.5800
C6···H21ⁱ	3.031 (19)	H62···O21ⁱ	2.8800
C11···H21A	2.774 (18)	H62···H21ⁱ	2.3700
C11···H1A	2.489 (15)	H62···O11	2.5100

C21—O21—H21	110.9 (11)	C2—C3—H31	110.00
C2A—N1A—C6A	122.30 (12)	C2—C3—H32	110.00
C6A—N1A—H1A	119.9 (9)	C5—C4—H41	109.00
C2A—N1A—H1A	117.6 (9)	C5—C4—H42	109.00
H21A—N21A—H22A	119.0 (14)	C3—C4—H42	109.00
C2A—N21A—H21A	121.9 (10)	C3—C4—H41	109.00
C2A—N21A—H22A	118.9 (11)	H41—C4—H42	108.00
C2—C1—C6	109.67 (10)	C6—C5—H51	109.00
C2—C1—C11	112.70 (10)	C4—C5—H52	109.00
C6—C1—C11	112.13 (10)	C6—C5—H52	109.00
C1—C2—C21	113.29 (10)	H51—C5—H52	108.00
C1—C2—C3	112.27 (10)	C4—C5—H51	109.00
C3—C2—C21	112.76 (11)	C5—C6—H62	109.00
C2—C3—C4	110.61 (11)	H61—C6—H62	108.00
C3—C4—C5	111.02 (12)	C1—C6—H61	109.00
C4—C5—C6	111.09 (12)	C1—C6—H62	109.00
C1—C6—C5	111.78 (11)	C5—C6—H61	109.00
O11—C11—C1	115.42 (11)	N1A—C2A—C3A	117.98 (12)
O11—C11—O12	123.26 (12)	N21A—C2A—C3A	124.10 (13)
O12—C11—C1	121.31 (11)	N1A—C2A—N21A	117.92 (12)
O21—C21—C2	113.41 (11)	C2A—C3A—C4A	119.42 (12)
O22—C21—C2	124.26 (12)	C3A—C4A—C5A	121.05 (13)
O21—C21—O22	122.23 (12)	C4A—C5A—C6A	118.21 (14)
C6—C1—H1	107.00	N1A—C6A—C5A	121.01 (14)
C2—C1—H1	107.00	C2A—C3A—H3A	120.00
C11—C1—H1	107.00	C4A—C3A—H3A	120.00
C1—C2—H2	106.00	C3A—C4A—H4A	119.00
C3—C2—H2	106.00	C5A—C4A—H4A	119.00
C21—C2—H2	106.00	C4A—C5A—H5A	121.00
C4—C3—H32	110.00	C6A—C5A—H5A	121.00
H31—C3—H32	108.00	N1A—C6A—H6A	120.00
C4—C3—H31	110.00	C5A—C6A—H6A	119.00

C6A—N1A—C2A—N21A	178.49 (13)	C3—C2—C21—O21	176.42 (10)
C6A—N1A—C2A—C3A	−1.86 (19)	C3—C2—C21—O22	−7.23 (17)
C2A—N1A—C6A—C5A	1.1 (2)	C1—C2—C21—O21	47.52 (14)
C6—C1—C2—C3	54.66 (13)	C1—C2—C21—O22	−136.14 (12)
C11—C1—C2—C21	58.14 (14)	C21—C2—C3—C4	174.78 (11)
C6—C1—C2—C21	−176.19 (10)	C2—C3—C4—C5	56.17 (14)
C2—C1—C11—O11	171.57 (10)	C3—C4—C5—C6	−56.90 (15)
C2—C1—C11—O12	−9.55 (16)	C4—C5—C6—C1	56.70 (14)
C11—C1—C2—C3	−71.01 (13)	N1A—C2A—C3A—C4A	0.9 (2)
C6—C1—C11—O12	−133.87 (12)	N21A—C2A—C3A—C4A	−179.53 (14)
C11—C1—C6—C5	71.16 (13)	C2A—C3A—C4A—C5A	0.9 (2)
C6—C1—C11—O11	47.24 (14)	C3A—C4A—C5A—C6A	−1.8 (2)
C2—C1—C6—C5	−54.84 (14)	C4A—C5A—C6A—N1A	0.8 (2)
C1—C2—C3—C4	−55.80 (14)

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+1, −y+1, −z+1; (iii) x, −y+3/2, z+1/2; (iv) −x+1, −y+1, −z+2; (v) −x, y+1/2, −z+3/2; (vi) −x, y−1/2, −z+3/2; (vii) −x+1, y+1/2, −z+3/2; (viii) −x, −y+1, −z+2; (ix) −x+1, y−1/2, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1A···O11	0.981 (15)	1.656 (15)	2.6223 (15)	167.7 (14)
N21A—H21A···O12	0.911 (18)	2.044 (17)	2.9361 (16)	166.3 (14)
N21A—H22A···O22^iv	0.873 (16)	2.105 (16)	2.9103 (17)	153.1 (14)
O21—H21···O11ⁱⁱⁱ	0.991 (19)	1.595 (19)	2.5806 (13)	172.9 (18)
C3A—H3A···O22^iv	0.93	2.42	3.1555 (16)	136
C6A—H6A···O12ⁱ	0.93	2.55	3.4134 (17)	155
C6—H62···O11	0.97	2.51	2.8574 (16)	101

Symmetry codes: (i) x, −y+3/2, z−1/2; (iii) x, −y+3/2, z+1/2; (iv) −x+1, −y+1, −z+2.

Experimental details

Crystal data
Chemical formula	C₅H₇N₂⁺·C₈H₁₁O₄⁻
M_r	266.29
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	200
a, b, c (Å)	12.4709 (5), 10.4191 (5), 10.6451 (5)
β (°)	101.250 (4)
V (Å³)	1356.60 (11)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.35 × 0.32 × 0.20

Data collection
Diffractometer	Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)
T_min, T_max	0.90, 0.98
No. of measured, independent and observed [I > 2σ(I)] reflections	9200, 2658, 1947
R_int	0.022
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.081, 0.99
No. of reflections	2658
No. of parameters	188
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.15

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999), PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H1A···O11	0.981 (15)	1.656 (15)	2.6223 (15)	167.7 (14)
N21A—H21A···O12	0.911 (18)	2.044 (17)	2.9361 (16)	166.3 (14)
N21A—H22A···O22ⁱ	0.873 (16)	2.105 (16)	2.9103 (17)	153.1 (14)
O21—H21···O11ⁱⁱ	0.991 (19)	1.595 (19)	2.5806 (13)	172.9 (18)

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) x, −y+3/2, z+1/2.

Acknowledgements

The authors acknowledge financial support from the Australian Research Council, the Faculty of Science and Technology and the University Library, Queensland University of Technology.

References

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