Bis(4-methyl­imidazolium) succinate succinic acid solvate

Du, G.; Liu, Z.; Chu, Q.; Li, Z.; Zhang, S.

doi:10.1107/S1600536809006205

organic compounds

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ISSN: 2056-9890

Volume 65| Part 3| March 2009| Pages o607-o608

doi:10.1107/S1600536809006205

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Bis(4-methylimidazolium) succinate succinic acid solvate

Guihuan Du,^a ^* Zuli Liu,^a Qian Chu,^b Zhen Li ^b and Suming Zhang ^b

^aDepartment of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China, and ^bTongji Hospital, Huazhong University of Science and Technology, Wuhan 430070, People's Republic of China
^*Correspondence e-mail: duguihuan@126.com

(Received 15 February 2009; accepted 19 February 2009; online 25 February 2009)

In the title compound, 2C₄H₇N₂⁺·C₄H₄O₄²⁻·C₄H₆O₄, the asymmetric unit consists of two 4-methylimidazolium cations, one succinate dianion and one netrual succinic acid molecule and within the latter components, the C—O, C=O and C O bonds are clearly evidenced from their relative distances. In the crystal structure, the individual components are linked by intermolecular N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds into a two-dimensional network parallel to the (101) plane in which R₃³(9), R₃³(12) and R₄⁴(18) hydrogen-bond motifs are present.

Related literature

For general background on co-crystals, see: Aakeröy & Salmon (2005 ); Aakeröy et al. (2007 ); Childs & Hardcastle (2007 ); Childs et al. (2007 ). For hydrogen-bond motifs, see: Bernstein et al. (1995 ).

Experimental

Crystal data

2C₄H₇N₂⁺·C₄H₄O₄²⁻·C₄H₆O₄
M_r = 400.39
Monoclinic, P 2₁ /c
a = 17.260 (5) Å
b = 14.066 (4) Å
c = 7.761 (2) Å
β = 95.008 (6)°
V = 1877.0 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 296 K
0.30 × 0.10 × 0.04 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.957, T_max = 0.995
20337 measured reflections
4080 independent reflections
2197 reflections with I > 2σ(I)
R_int = 0.063

Refinement

R[F² > 2σ(F²)] = 0.056
wR(F²) = 0.153
S = 0.95
4080 reflections
273 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Selected bond lengths (Å)

C9—O1	1.235 (2)
C9—O2	1.271 (2)
C12—O4	1.228 (3)
C12—O3	1.276 (2)
C13—O6	1.210 (2)
C13—O5	1.298 (3)
C16—O7	1.207 (2)
C16—O8	1.302 (3)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4ⁱ	0.96 (2)	1.74 (2)	2.699 (3)	176 (2)
N2—H2A⋯O3	0.97 (2)	1.78 (2)	2.752 (2)	173.0 (19)
N3—H3A⋯O1	1.07 (2)	1.61 (2)	2.673 (2)	170.6 (19)
N4—H4⋯O2ⁱⁱ	0.98 (2)	1.77 (2)	2.745 (2)	178.8 (19)
O5—H5⋯O3	0.98 (3)	1.53 (3)	2.509 (2)	177 (3)
O8—H8⋯O2ⁱⁱⁱ	1.02 (3)	1.50 (3)	2.518 (2)	176 (3)
C2—H2⋯O6	0.93	2.29	3.024 (3)	136
C3—H3⋯O8^iv	0.93	2.43	3.354 (3)	176
C6—H6⋯O5	0.93	2.43	3.346 (3)	169
C7—H7⋯O7^v	0.93	2.29	3.017 (3)	134
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x, y-1, z; (iv) $[-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (v) $[-x+2, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 2001 ); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009 ); software used to prepare material for publication: PLATON.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809006205/lh2776sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809006205/lh2776Isup2.hkl

checkCIF report

Comment top

In recent years, research on co-crystal or organic salts has been expanded rapidly owing to their potential application in the preparation of active pharmaceutical ingredients (Aakeröy et al., 2007; Childs & Hardcastle, 2007; Childs et al., 2007). In this paper, we report an organic salt formed by 4-methyl-imidazole and succinic acid in 95% methanol solution at room temperature, namely bis(4-methyl-imidazolium) succinicate succinic acid, (I).

In (I), the asymmetric unit is composed of two 4-methylimidazolium cations, one succinicate dianion and one netrual succinic acid molecule. The title compound can be regarded as an organic salt according to the definition of Aakeröy and Salmon (2005). One of the succinnic acid molecules is dually deprotonated, leading to a dianion (Fig. 1) which can be evidenced to an extent by the variations of the carboxyl C-O, C ═O and C ≐O bond distances (Table 1).

In the crystal structure, by a combination of four N-H···O and two O-H···O hydrogen bonds (Table 2) molecules in (I) are linked into a two-dimensional network parallel to the (101) plane (Fig.2) in which R₃³(9), R₃³(12) and R₄⁴(18) hydrogen-bonding motifs are present (Bernstein et al., 1995). Within the network, several weak C-H..O interactions are present. No other interactions, such as C-H···π or π···π are observed in (I).

Related literature top

For general background on co-crystals, see: Aakeröy & Salmon (2005); Aakeröy et al. (2007); Childs & Hardcastle (2007); Childs et al. (2007). For hydrogen-bond motifs, see: Bernstein et al. (1995).

Experimental top

All the reagents and solvents were used as obtained without further purification. A 1:2 molar amounts of succinic acid (0.2 mmol, 23.6 mg) and 4-methyl-imidazole (0.4 mmol, 32.8 mg) were dissolved in 95% methanol (20 ml). The mixture was stirred for half an hour at room temperature and then filtered. The resulting solution was kept in air for one week. Plate crystals of (I) suitable for single-crystal X-ray diffraction analysis were grown by slow evaporation of the solution at the bottom of the vessel.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top

	Fig. 1. The asymmetric unit of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H-bonds are shown in dashed lines.
	Fig. 2. Part of the crystal structure of (I), showing the formation of the two-dimensional network parallel to the (101) plane linked by N-H···O, O-H···O and C-H···O hydrogen-bonds. Hydrogen atoms not involved in the motif have been omitted for clarity.

Bis(4-methylimidazolium) succinate succinic acid solvate top

Crystal data top

2C₄H₇N₂⁺·C₄H₄O₄²⁻·C₄H₆O₄	F(000) = 848
M_r = 400.39	D_x = 1.417 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2035 reflections
a = 17.260 (5) Å	θ = 2.4–21.1°
b = 14.066 (4) Å	µ = 0.12 mm⁻¹
c = 7.761 (2) Å	T = 296 K
β = 95.008 (6)°	Plate, colorless
V = 1877.0 (9) Å³	0.30 × 0.10 × 0.04 mm
Z = 4

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	4080 independent reflections
Radiation source: fine focus sealed Siemens Mo tube	2197 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.063
0.3° wide ω exposures scans	θ_max = 27.0°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −22→22
T_min = 0.957, T_max = 0.995	k = −17→17
20337 measured reflections	l = −8→9

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.153	H atoms treated by a mixture of independent and constrained refinement
S = 0.95	w = 1/[σ²(F_o²) + (0.0817P)²] where P = (F_o² + 2F_c²)/3
4080 reflections	(Δ/σ)_max < 0.001
273 parameters	Δρ_max = 0.28 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Crystal data top

2C₄H₇N₂⁺·C₄H₄O₄²⁻·C₄H₆O₄	V = 1877.0 (9) Å³
M_r = 400.39	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 17.260 (5) Å	µ = 0.12 mm⁻¹
b = 14.066 (4) Å	T = 296 K
c = 7.761 (2) Å	0.30 × 0.10 × 0.04 mm
β = 95.008 (6)°

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	4080 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	2197 reflections with I > 2σ(I)
T_min = 0.957, T_max = 0.995	R_int = 0.063
20337 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.056	0 restraints
wR(F²) = 0.153	H atoms treated by a mixture of independent and constrained refinement
S = 0.95	Δρ_max = 0.28 e Å⁻³
4080 reflections	Δρ_min = −0.25 e Å⁻³
273 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
C1	0.45695 (11)	0.47579 (16)	0.7860 (3)	0.0375 (6)
C2	0.50516 (13)	0.33293 (17)	0.7523 (3)	0.0476 (6)
H2	0.5380	0.2839	0.7247	0.057*
C3	0.40700 (12)	0.41101 (16)	0.8406 (3)	0.0431 (6)
H3	0.3597	0.4241	0.8847	0.052*
C4	0.45464 (13)	0.58059 (16)	0.7747 (3)	0.0498 (7)
H4A	0.4367	0.5993	0.6590	0.075*
H4B	0.5059	0.6057	0.8036	0.075*
H4C	0.4199	0.6050	0.8540	0.075*
C5	0.96099 (11)	0.34301 (16)	0.3015 (3)	0.0342 (5)
C6	0.91078 (12)	0.40732 (16)	0.3567 (3)	0.0404 (6)
H6	0.8665	0.3936	0.4122	0.049*
C7	1.00090 (12)	0.48664 (17)	0.2388 (3)	0.0435 (6)
H7	1.0302	0.5361	0.1986	0.052*
C8	0.96426 (13)	0.23840 (16)	0.3093 (3)	0.0454 (6)
H8A	0.9213	0.2150	0.3676	0.068*
H8B	1.0122	0.2190	0.3714	0.068*
H8C	0.9614	0.2131	0.1941	0.068*
C9	0.83954 (12)	0.73296 (15)	0.4322 (3)	0.0327 (5)
C10	0.76053 (11)	0.71074 (15)	0.4945 (3)	0.0352 (5)
H10A	0.7558	0.7446	0.6020	0.042*
H10B	0.7206	0.7348	0.4101	0.042*
C11	0.74541 (12)	0.60712 (15)	0.5235 (3)	0.0377 (6)
H11A	0.7865	0.5824	0.6046	0.045*
H11B	0.7482	0.5737	0.4150	0.045*
C12	0.66724 (12)	0.58515 (15)	0.5925 (3)	0.0374 (6)
C13	0.70985 (12)	0.28540 (16)	0.5270 (3)	0.0380 (6)
C14	0.76523 (12)	0.20813 (16)	0.4875 (3)	0.0398 (6)
H14A	0.8133	0.2165	0.5604	0.048*
H14B	0.7772	0.2145	0.3682	0.048*
C15	0.73494 (12)	0.10900 (16)	0.5142 (3)	0.0449 (6)
H15A	0.7241	0.1020	0.6341	0.054*
H15B	0.6863	0.1009	0.4431	0.054*
C16	0.79014 (13)	0.03232 (16)	0.4709 (3)	0.0410 (6)
N1	0.43813 (11)	0.32252 (14)	0.8197 (3)	0.0457 (5)
H1	0.4148 (14)	0.2622 (18)	0.842 (3)	0.055*
N2	0.51776 (10)	0.42424 (13)	0.7306 (3)	0.0413 (5)
H2A	0.5629 (13)	0.4491 (16)	0.678 (3)	0.050*
N3	0.93627 (10)	0.49658 (14)	0.3170 (2)	0.0433 (5)
H3A	0.9102 (13)	0.5635 (17)	0.342 (3)	0.052*
N4	1.01708 (10)	0.39539 (13)	0.2269 (2)	0.0386 (5)
H4	1.0622 (13)	0.3685 (15)	0.177 (3)	0.046*
O1	0.88428 (9)	0.66845 (11)	0.3982 (2)	0.0565 (5)
O2	0.85672 (8)	0.82023 (10)	0.4172 (2)	0.0453 (4)
O3	0.65044 (8)	0.49741 (10)	0.6087 (2)	0.0461 (4)
O4	0.62385 (9)	0.64950 (11)	0.6310 (3)	0.0647 (6)
O5	0.73726 (9)	0.37014 (12)	0.5060 (2)	0.0542 (5)
H5	0.7020 (17)	0.419 (2)	0.544 (3)	0.081*
O6	0.64637 (10)	0.27081 (12)	0.5766 (3)	0.0671 (6)
O7	0.84928 (10)	0.04663 (12)	0.4027 (3)	0.0639 (6)
O8	0.76793 (10)	−0.05217 (12)	0.5142 (3)	0.0605 (6)
H8	0.8020 (17)	−0.105 (2)	0.473 (4)	0.091*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0270 (11)	0.0344 (13)	0.0528 (14)	0.0012 (9)	0.0138 (10)	−0.0009 (11)
C2	0.0344 (13)	0.0358 (15)	0.0763 (18)	−0.0018 (11)	0.0253 (12)	−0.0020 (13)
C3	0.0284 (12)	0.0410 (15)	0.0625 (16)	−0.0039 (11)	0.0202 (11)	0.0011 (12)
C4	0.0381 (14)	0.0369 (15)	0.0772 (18)	−0.0010 (11)	0.0215 (13)	0.0039 (13)
C5	0.0255 (10)	0.0325 (13)	0.0465 (14)	−0.0003 (9)	0.0148 (10)	−0.0016 (10)
C6	0.0282 (12)	0.0356 (14)	0.0606 (16)	0.0007 (10)	0.0217 (11)	−0.0004 (11)
C7	0.0356 (13)	0.0347 (15)	0.0629 (16)	−0.0005 (10)	0.0199 (11)	−0.0009 (12)
C8	0.0384 (13)	0.0350 (14)	0.0663 (17)	0.0041 (10)	0.0233 (12)	0.0009 (12)
C9	0.0264 (11)	0.0247 (12)	0.0488 (14)	−0.0004 (9)	0.0130 (10)	−0.0008 (10)
C10	0.0279 (11)	0.0303 (13)	0.0497 (14)	−0.0003 (9)	0.0167 (10)	0.0027 (10)
C11	0.0284 (11)	0.0291 (13)	0.0583 (15)	−0.0022 (9)	0.0186 (11)	0.0014 (11)
C12	0.0307 (12)	0.0264 (13)	0.0573 (16)	0.0006 (10)	0.0162 (11)	−0.0019 (11)
C13	0.0300 (11)	0.0330 (14)	0.0532 (15)	0.0001 (10)	0.0164 (10)	0.0005 (11)
C14	0.0293 (12)	0.0372 (14)	0.0553 (15)	0.0034 (10)	0.0167 (11)	−0.0011 (11)
C15	0.0314 (12)	0.0370 (15)	0.0693 (17)	0.0051 (10)	0.0222 (12)	−0.0016 (12)
C16	0.0322 (12)	0.0341 (14)	0.0594 (15)	0.0004 (10)	0.0184 (11)	−0.0030 (11)
N1	0.0371 (11)	0.0327 (12)	0.0697 (14)	−0.0074 (9)	0.0195 (10)	0.0020 (10)
N2	0.0298 (10)	0.0333 (12)	0.0639 (13)	−0.0044 (8)	0.0223 (9)	0.0000 (10)
N3	0.0353 (10)	0.0325 (12)	0.0645 (14)	0.0056 (9)	0.0183 (9)	−0.0042 (10)
N4	0.0280 (10)	0.0344 (12)	0.0561 (13)	0.0016 (8)	0.0200 (9)	−0.0018 (9)
O1	0.0422 (10)	0.0304 (10)	0.1026 (14)	0.0040 (7)	0.0383 (9)	−0.0027 (9)
O2	0.0326 (9)	0.0257 (9)	0.0821 (12)	−0.0009 (7)	0.0309 (8)	0.0033 (8)
O3	0.0342 (8)	0.0266 (9)	0.0819 (12)	−0.0027 (7)	0.0300 (8)	0.0026 (8)
O4	0.0474 (10)	0.0309 (10)	0.1235 (16)	0.0039 (8)	0.0513 (11)	−0.0015 (10)
O5	0.0409 (9)	0.0291 (10)	0.0980 (15)	0.0005 (7)	0.0368 (10)	−0.0032 (9)
O6	0.0406 (10)	0.0420 (11)	0.1255 (16)	0.0021 (8)	0.0465 (11)	0.0062 (10)
O7	0.0452 (10)	0.0430 (11)	0.1108 (15)	0.0044 (8)	0.0480 (10)	0.0016 (10)
O8	0.0464 (10)	0.0310 (11)	0.1109 (16)	0.0043 (8)	0.0453 (10)	0.0041 (10)

Geometric parameters (Å, º) top

C1—C3	1.348 (3)	C10—C11	1.501 (3)
C1—N2	1.375 (3)	C10—H10A	0.9700
C1—C4	1.477 (3)	C10—H10B	0.9700
C2—N2	1.316 (3)	C11—C12	1.526 (3)
C2—N1	1.319 (3)	C11—H11A	0.9700
C2—H2	0.9300	C11—H11B	0.9700
C3—N1	1.371 (3)	C12—O4	1.228 (3)
C3—H3	0.9300	C12—O3	1.276 (2)
C4—H4A	0.9600	C13—O6	1.210 (2)
C4—H4B	0.9600	C13—O5	1.298 (3)
C4—H4C	0.9600	C13—C14	1.497 (3)
C5—C6	1.348 (3)	C14—C15	1.510 (3)
C5—N4	1.383 (3)	C14—H14A	0.9700
C5—C8	1.474 (3)	C14—H14B	0.9700
C6—N3	1.374 (3)	C15—C16	1.497 (3)
C6—H6	0.9300	C15—H15A	0.9700
C7—N4	1.319 (3)	C15—H15B	0.9700
C7—N3	1.323 (3)	C16—O7	1.207 (2)
C7—H7	0.9300	C16—O8	1.302 (3)
C8—H8A	0.9600	N1—H1	0.96 (2)
C8—H8B	0.9600	N2—H2A	0.97 (2)
C8—H8C	0.9600	N3—H3A	1.07 (2)
C9—O1	1.235 (2)	N4—H4	0.98 (2)
C9—O2	1.271 (2)	O5—H5	0.98 (3)
C9—C10	1.519 (3)	O8—H8	1.02 (3)

C3—C1—N2	105.6 (2)	C10—C11—H11A	108.6
C3—C1—C4	132.7 (2)	C12—C11—H11A	108.6
N2—C1—C4	121.66 (19)	C10—C11—H11B	108.6
N2—C2—N1	108.6 (2)	C12—C11—H11B	108.6
N2—C2—H2	125.7	H11A—C11—H11B	107.5
N1—C2—H2	125.7	O4—C12—O3	122.69 (19)
C1—C3—N1	107.98 (19)	O4—C12—C11	120.84 (19)
C1—C3—H3	126.0	O3—C12—C11	116.47 (18)
N1—C3—H3	126.0	O6—C13—O5	123.1 (2)
C1—C4—H4A	109.5	O6—C13—C14	123.7 (2)
C1—C4—H4B	109.5	O5—C13—C14	113.25 (18)
H4A—C4—H4B	109.5	C13—C14—C15	114.05 (17)
C1—C4—H4C	109.5	C13—C14—H14A	108.7
H4A—C4—H4C	109.5	C15—C14—H14A	108.7
H4B—C4—H4C	109.5	C13—C14—H14B	108.7
C6—C5—N4	105.58 (19)	C15—C14—H14B	108.7
C6—C5—C8	132.85 (19)	H14A—C14—H14B	107.6
N4—C5—C8	121.57 (18)	C16—C15—C14	113.57 (18)
C5—C6—N3	108.32 (18)	C16—C15—H15A	108.9
C5—C6—H6	125.8	C14—C15—H15A	108.9
N3—C6—H6	125.8	C16—C15—H15B	108.9
N4—C7—N3	109.1 (2)	C14—C15—H15B	108.9
N4—C7—H7	125.4	H15A—C15—H15B	107.7
N3—C7—H7	125.4	O7—C16—O8	123.0 (2)
C5—C8—H8A	109.5	O7—C16—C15	123.9 (2)
C5—C8—H8B	109.5	O8—C16—C15	113.10 (19)
H8A—C8—H8B	109.5	C2—N1—C3	108.21 (19)
C5—C8—H8C	109.5	C2—N1—H1	124.3 (15)
H8A—C8—H8C	109.5	C3—N1—H1	127.4 (15)
H8B—C8—H8C	109.5	C2—N2—C1	109.59 (18)
O1—C9—O2	122.35 (18)	C2—N2—H2A	123.4 (13)
O1—C9—C10	120.83 (19)	C1—N2—H2A	126.9 (13)
O2—C9—C10	116.82 (18)	C7—N3—C6	107.79 (19)
C11—C10—C9	114.85 (17)	C7—N3—H3A	124.3 (12)
C11—C10—H10A	108.6	C6—N3—H3A	127.9 (12)
C9—C10—H10A	108.6	C7—N4—C5	109.20 (18)
C11—C10—H10B	108.6	C7—N4—H4	126.0 (13)
C9—C10—H10B	108.6	C5—N4—H4	124.8 (13)
H10A—C10—H10B	107.5	C13—O5—H5	111.4 (16)
C10—C11—C12	114.83 (17)	C16—O8—H8	113.4 (16)

N2—C1—C3—N1	0.7 (3)	C14—C15—C16—O7	−8.0 (4)
C4—C1—C3—N1	179.0 (3)	C14—C15—C16—O8	172.0 (2)
N4—C5—C6—N3	−0.3 (3)	N2—C2—N1—C3	0.3 (3)
C8—C5—C6—N3	179.4 (2)	C1—C3—N1—C2	−0.6 (3)
O1—C9—C10—C11	4.6 (3)	N1—C2—N2—C1	0.1 (3)
O2—C9—C10—C11	−175.4 (2)	C3—C1—N2—C2	−0.5 (3)
C9—C10—C11—C12	177.83 (19)	C4—C1—N2—C2	−179.0 (2)
C10—C11—C12—O4	−4.7 (3)	N4—C7—N3—C6	0.2 (3)
C10—C11—C12—O3	175.8 (2)	C5—C6—N3—C7	0.0 (3)
O6—C13—C14—C15	0.2 (4)	N3—C7—N4—C5	−0.4 (3)
O5—C13—C14—C15	179.0 (2)	C6—C5—N4—C7	0.4 (3)
C13—C14—C15—C16	178.83 (19)	C8—C5—N4—C7	−179.3 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱ	0.96 (2)	1.74 (2)	2.699 (3)	176 (2)
N2—H2A···O3	0.97 (2)	1.78 (2)	2.752 (2)	173.0 (19)
N3—H3A···O1	1.07 (2)	1.61 (2)	2.673 (2)	170.6 (19)
N4—H4···O2ⁱⁱ	0.98 (2)	1.77 (2)	2.745 (2)	178.8 (19)
O5—H5···O3	0.98 (3)	1.53 (3)	2.509 (2)	177 (3)
O8—H8···O2ⁱⁱⁱ	1.02 (3)	1.50 (3)	2.518 (2)	176 (3)
C2—H2···O6	0.93	2.29	3.024 (3)	136
C3—H3···O8^iv	0.93	2.43	3.354 (3)	176
C6—H6···O5	0.93	2.43	3.346 (3)	169
C7—H7···O7^v	0.93	2.29	3.017 (3)	134

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

Experimental details

Crystal data
Chemical formula	2C₄H₇N₂⁺·C₄H₄O₄²⁻·C₄H₆O₄
M_r	400.39
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	17.260 (5), 14.066 (4), 7.761 (2)
β (°)	95.008 (6)
V (Å³)	1877.0 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.30 × 0.10 × 0.04

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.957, 0.995
No. of measured, independent and observed [I > 2σ(I)] reflections	20337, 4080, 2197
R_int	0.063
(sin θ/λ)_max (Å⁻¹)	0.639

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.153, 0.95
No. of reflections	4080
No. of parameters	273
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.25

Computer programs: SMART (Bruker, 2001), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).

Selected bond lengths (Å) top

C9—O1	1.235 (2)	C13—O6	1.210 (2)
C9—O2	1.271 (2)	C13—O5	1.298 (3)
C12—O4	1.228 (3)	C16—O7	1.207 (2)
C12—O3	1.276 (2)	C16—O8	1.302 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱ	0.96 (2)	1.74 (2)	2.699 (3)	176 (2)
N2—H2A···O3	0.97 (2)	1.78 (2)	2.752 (2)	173.0 (19)
N3—H3A···O1	1.07 (2)	1.61 (2)	2.673 (2)	170.6 (19)
N4—H4···O2ⁱⁱ	0.98 (2)	1.77 (2)	2.745 (2)	178.8 (19)
O5—H5···O3	0.98 (3)	1.53 (3)	2.509 (2)	177 (3)
O8—H8···O2ⁱⁱⁱ	1.02 (3)	1.50 (3)	2.518 (2)	176 (3)
C2—H2···O6	0.93	2.29	3.024 (3)	135.9
C3—H3···O8^iv	0.93	2.43	3.354 (3)	175.5
C6—H6···O5	0.93	2.43	3.346 (3)	168.8
C7—H7···O7^v	0.93	2.29	3.017 (3)	134.4

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

Acknowledgements

This work was supported by the National Natural Science Foundation of China under grant Nos. 10574047, 10574048 and 20490210. This work was also supported by the National 973 Project under grant. No. 2006CB921605.

References

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