Bis(dicyclo­hexyl­ammonium 4-hydroxy­benzoate)

Zain, S.M.; Ng, S.W.

doi:10.1107/S1600536807029856

Bis(dicyclohexylammonium 4-hydroxybenzoate)

In the crystal structure of the title compound, 2C₁₂H₂₄N⁺·2C₇H₅O₃^-, the cation is linked to the single-bonded carboxylate O atom of an anion as well as to the double-bonded carbonyl O atom of another anion to form a centrosymmetric hydrogen-bonded ion pair. Adjacent ion pairs are linked through the hydroxy group of the anion to produce a honeycomb-like layer structure.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807029856/tk2167sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807029856/tk2167Isup2.hkl Contains datablock I

CCDC reference: 655025

checkCIF report

Key indicators

Single-crystal X-ray study
T = 173 K
Mean (C-C) = 0.002 Å
R factor = 0.045
wR factor = 0.135
Data-to-parameter ratio = 16.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT222_ALERT_3_B Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       4.05 Ratio

Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.74
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.90 Ratio
PLAT716_ALERT_1_C H...A   Unknown or Inconsistent Label ..........    H1<I>N<
PLAT716_ALERT_1_C H...A   Unknown or Inconsistent Label ..........    H2<I>N<
PLAT716_ALERT_1_C H...A   Unknown or Inconsistent Label ..........    H3<I>O<

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         29

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   8 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   6 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

4-Hydroxybenzoic acid is an excellent counterion for the engineering of ammonium salts that exhibit second-harmonic generation, as noted from the SHG activity of (S)-ethylphenylammonium 4-hydroxybenzoate (Aakeröy et al., 1993). The anion is capable of mutiple hydrogen bonding interactions, this feature is crucial to chemical stability. We have previously used the sterically crowded dicyclohexylammonium cation in the synthesis of monocarboxylates (Ng, 1996; Ng, 1997; Ng, 1998; Ng & Hook, 1999; Ng et al., 1999, 2001; Subramanian et al., 2000) but these monocarboxylates do not have hydrogen-bond donor sites. Our studies are now extended to a study of dicyclohexylammonium 4-hydroxybenzoate, which exists as a hydrogen-bonded dimeric ion-pair that is linked across a center-of-inversion (Fig. 1). The ammonium hydrogen serves as as donor to a single-bond carboxyl oxygen atom of one anion as well as to the double-bond carbonyl oxygen atom of the symmetry-related anion. The carboxylate –CO₂ unit has localized bonds: the hydrogen bond to the negatively-charged oxygen atom is significantly longer than that to the neutral oxygen atom. The hydroxy group engages in linking adjacent dimeric ion-pairs into a layer motif (Table 1, Fig. 2). The layer has a honeycomb-like topology (Fig. 3) but is buckled.

The crystal structures of polymethyleneiminium 4-hydroxybenzoates, [(CH₂)_nNH₂] [C₇H₅O₃] (n = 4, 5 and 6) have been reported; the hexamethyleneiminiums exists in two modifications (Moritani et al., 1987). The compounds, whose carboxylate groups are also localized, adopt chain motif instead, a motif that is also adopted by dicyclohexylammonium trifluoroacetate (Ng et al., 1999).

Related literature top

For crystal structures of dicyclohexylammonium salts of monocarboxylic acids, see Ng (1996, 1997, 1998), Ng et al. (1999, 2001), Ng & Hook (1999), Subramanian et al. (2000). For crystal structures of other ammonium salts of 4-hydroxybenzoic acid, see Moritani et al. (1987). For related literature, see: Aakeröy et al. (1993); Subramanian et al. (2000).

Experimental top

Dicyclohexylamine (0.17 g, 1 mmol) and 4-hydroxybenzoic acid (0.14 g, 1 mmol) were dissolved in ethanol (25 ml). The mixture was heated to dissolve the reactants. Colorless plates of the salt separated from the solution after several days.

Structure description top

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001) and OLEX (Dolomanov et al., 2003); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top

	Fig. 1. Thermal ellipsoid plot of the hydrogen-bonded dimer; displacement ellipsoids are drawn at the 70% probability level. The dashed lines denote hydrogen bonds. [Symmetry code i: 1 – x, 1 – y, 1 – z.]
	Fig. 2. Layer structure; displacement ellipsoids are drawn at the 70% probability level. The dashed lines denote hydrogen bonds, and the atoms constituting the 12-membered O–C=O···H–N–H···O–C=O···H–N–H··· ring are shown with their van der Waals surfaces.
	Fig. 3. OLEX depiction of the (6,3)-honeycomb topology, shown projected against the unit cell.

Bis(dicyclohexylammonium 4-hydroxybenzoate) top

Crystal data top

2C₁₂H₂₄N⁺·2C₇H₅O₃⁻	F(000) = 696
M_r = 638.86	D_x = 1.156 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 9647 reflections
a = 9.4779 (2) Å	θ = 2.4–34.6°
b = 11.0650 (3) Å	µ = 0.08 mm⁻¹
c = 17.5816 (4) Å	T = 173 K
β = 95.431 (1)°	Plate, colorless
V = 1835.56 (8) Å³	0.35 × 0.30 × 0.06 mm
Z = 2

Data collection top

Bruker APEX2 area-detector diffractometer	4227 reflections with I > 2σ(I)
Radiation source: medium-focus sealed tube	R_int = 0.033
Graphite monochromator	θ_max = 30.0°, θ_min = 2.6°
φ and ω scans	h = −13→13
32008 measured reflections	k = −15→15
5346 independent reflections	l = −24→24

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)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.135	All H-atom parameters refined
S = 1.04	w = 1/[σ²(F_o²) + (0.0739P)² + 0.5355P] where P = (F_o² + 2F_c²)/3
5346 reflections	(Δ/σ)_max = 0.001
324 parameters	Δρ_max = 0.52 e Å⁻³
29 restraints	Δρ_min = −0.19 e Å⁻³

Crystal data top

2C₁₂H₂₄N⁺·2C₇H₅O₃⁻	V = 1835.56 (8) Å³
M_r = 638.86	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.4779 (2) Å	µ = 0.08 mm⁻¹
b = 11.0650 (3) Å	T = 173 K
c = 17.5816 (4) Å	0.35 × 0.30 × 0.06 mm
β = 95.431 (1)°

Data collection top

Bruker APEX2 area-detector diffractometer	4227 reflections with I > 2σ(I)
32008 measured reflections	R_int = 0.033
5346 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	29 restraints
wR(F²) = 0.135	All H-atom parameters refined
S = 1.04	Δρ_max = 0.52 e Å⁻³
5346 reflections	Δρ_min = −0.19 e Å⁻³
324 parameters

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

	x	y	z	U_iso*/U_eq
O1	0.3950 (1)	0.6161 (1)	0.3722 (1)	0.0201 (2)
O2	0.2552 (1)	0.6278 (1)	0.4673 (1)	0.0238 (2)
O3	0.0294 (1)	1.0816 (1)	0.2716 (1)	0.0224 (2)
N1	0.6664 (1)	0.5639 (1)	0.4429 (1)	0.0159 (2)
C1	0.7400 (1)	0.5365 (1)	0.3728 (1)	0.0193 (2)
C2	0.9009 (1)	0.5378 (2)	0.3891 (1)	0.0312 (3)
C3	0.9688 (2)	0.5083 (2)	0.3159 (1)	0.0472 (5)
C4	0.9177 (2)	0.3876 (2)	0.2818 (1)	0.0439 (4)
C5	0.7560 (1)	0.3837 (1)	0.2691 (1)	0.0305 (3)
C6	0.6884 (1)	0.4135 (1)	0.3423 (1)	0.0224 (2)
C7	0.7084 (1)	0.6764 (1)	0.4870 (1)	0.0163 (2)
C8	0.6200 (1)	0.6816 (1)	0.5551 (1)	0.0185 (2)
C9	0.6546 (1)	0.7949 (1)	0.6030 (1)	0.0210 (2)
C10	0.6305 (1)	0.9076 (1)	0.5536 (1)	0.0222 (2)
C11	0.7201 (1)	0.9028 (1)	0.4858 (1)	0.0227 (2)
C12	0.6889 (1)	0.7891 (1)	0.4374 (1)	0.0201 (2)
C13	0.2947 (1)	0.6642 (1)	0.4052 (1)	0.0165 (2)
C14	0.2207 (1)	0.7721 (1)	0.3683 (1)	0.0152 (2)
C15	0.2559 (1)	0.8142 (1)	0.2979 (1)	0.0182 (2)
C16	0.1924 (1)	0.9166 (1)	0.2646 (1)	0.0194 (2)
C17	0.0917 (1)	0.9792 (1)	0.3017 (1)	0.0178 (2)
C18	0.0528 (1)	0.9369 (1)	0.3717 (1)	0.0190 (2)
C19	0.1173 (1)	0.8343 (1)	0.4046 (1)	0.0176 (2)
H3o	0.063 (2)	1.096 (2)	0.228 (1)	0.052 (6)*
H1n	0.577 (1)	0.571 (1)	0.428 (1)	0.019 (3)*
H2n	0.680 (2)	0.503 (1)	0.473 (1)	0.036 (4)*
H1	0.709 (2)	0.597 (1)	0.337 (1)	0.022 (4)*
H21	0.929 (2)	0.481 (1)	0.429 (1)	0.036 (4)*
H22	0.933 (2)	0.615 (1)	0.409 (1)	0.038 (5)*
H31	1.069 (1)	0.507 (2)	0.327 (1)	0.061 (6)*
H32	0.949 (3)	0.570 (2)	0.278 (1)	0.077 (8)*
H41	0.946 (2)	0.323 (1)	0.318 (1)	0.049 (6)*
H42	0.959 (2)	0.372 (2)	0.235 (1)	0.054 (6)*
H51	0.727 (2)	0.304 (1)	0.253 (1)	0.044 (5)*
H52	0.728 (2)	0.445 (1)	0.232 (1)	0.029 (4)*
H61	0.587 (1)	0.414 (1)	0.334 (1)	0.024 (4)*
H62	0.713 (2)	0.355 (1)	0.381 (1)	0.034 (4)*
H7	0.807 (1)	0.667 (1)	0.505 (1)	0.020 (3)*
H81	0.635 (2)	0.610 (1)	0.585 (1)	0.023 (4)*
H82	0.522 (1)	0.685 (2)	0.536 (1)	0.030 (4)*
H91	0.753 (1)	0.795 (1)	0.625 (1)	0.026 (4)*
H92	0.595 (1)	0.796 (1)	0.645 (1)	0.024 (4)*
H101	0.651 (2)	0.979 (1)	0.583 (1)	0.028 (4)*
H102	0.532 (1)	0.911 (1)	0.533 (1)	0.022 (4)*
H111	0.818 (1)	0.906 (1)	0.506 (1)	0.026 (4)*
H112	0.706 (2)	0.975 (1)	0.455 (1)	0.028 (4)*
H121	0.594 (1)	0.790 (1)	0.413 (1)	0.024 (4)*
H122	0.751 (1)	0.787 (2)	0.398 (1)	0.028 (4)*
H15	0.324 (1)	0.769 (1)	0.272 (1)	0.026 (4)*
H16	0.218 (2)	0.947 (2)	0.217 (1)	0.028 (4)*
H18	−0.017 (1)	0.981 (1)	0.395 (1)	0.029 (4)*
H19	0.096 (2)	0.807 (1)	0.453 (1)	0.026 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0204 (4)	0.0178 (4)	0.0214 (4)	0.0044 (3)	−0.0021 (3)	−0.0041 (3)
O2	0.0307 (4)	0.0195 (4)	0.0211 (4)	0.0056 (3)	0.0024 (3)	0.0052 (3)
O3	0.0265 (4)	0.0160 (4)	0.0247 (4)	0.0036 (3)	0.0019 (3)	0.0053 (3)
N1	0.0173 (4)	0.0147 (4)	0.0156 (4)	0.0007 (3)	0.0007 (3)	−0.0009 (3)
C1	0.0183 (5)	0.0226 (5)	0.0172 (5)	0.0011 (4)	0.0027 (4)	−0.0052 (4)
C2	0.0187 (5)	0.0415 (8)	0.0334 (7)	−0.0008 (5)	0.0019 (5)	−0.0174 (6)
C3	0.0210 (6)	0.0725 (13)	0.0499 (9)	−0.0063 (7)	0.0127 (6)	−0.0310 (9)
C4	0.0272 (7)	0.0609 (11)	0.0439 (9)	0.0101 (7)	0.0050 (6)	−0.0269 (8)
C5	0.0275 (6)	0.0362 (7)	0.0280 (6)	0.0029 (5)	0.0029 (5)	−0.0136 (6)
C6	0.0225 (5)	0.0226 (6)	0.0216 (5)	0.0022 (4)	0.0001 (4)	−0.0066 (4)
C7	0.0191 (5)	0.0139 (5)	0.0157 (5)	−0.0006 (4)	−0.0001 (4)	−0.0019 (4)
C8	0.0255 (5)	0.0151 (5)	0.0148 (5)	0.0004 (4)	0.0020 (4)	0.0001 (4)
C9	0.0287 (6)	0.0180 (5)	0.0163 (5)	0.0008 (4)	0.0014 (4)	−0.0020 (4)
C10	0.0284 (6)	0.0148 (5)	0.0234 (5)	0.0006 (4)	0.0037 (4)	−0.0017 (4)
C11	0.0290 (6)	0.0153 (5)	0.0242 (6)	−0.0032 (4)	0.0049 (4)	0.0005 (4)
C12	0.0262 (5)	0.0171 (5)	0.0170 (5)	−0.0025 (4)	0.0028 (4)	0.0017 (4)
C13	0.0177 (5)	0.0127 (5)	0.0182 (5)	−0.0005 (4)	−0.0030 (4)	−0.0019 (4)
C14	0.0154 (4)	0.0128 (5)	0.0169 (5)	−0.0005 (4)	−0.0005 (3)	−0.0002 (4)
C15	0.0182 (5)	0.0187 (5)	0.0177 (5)	0.0004 (4)	0.0025 (4)	−0.0010 (4)
C16	0.0216 (5)	0.0201 (5)	0.0166 (5)	−0.0007 (4)	0.0017 (4)	0.0027 (4)
C17	0.0187 (5)	0.0136 (5)	0.0204 (5)	−0.0015 (4)	−0.0019 (4)	0.0013 (4)
C18	0.0188 (5)	0.0160 (5)	0.0227 (5)	0.0018 (4)	0.0045 (4)	−0.0005 (4)
C19	0.0190 (5)	0.0161 (5)	0.0179 (5)	−0.0007 (4)	0.0035 (4)	0.0013 (4)

Geometric parameters (Å, º) top

O1—C13	1.276 (1)	C1—H1	0.95 (1)
O2—C13	1.254 (1)	C2—H21	0.96 (1)
O3—C17	1.362 (1)	C2—H22	0.96 (1)
N1—C1	1.503 (1)	C3—H31	0.95 (1)
N1—C7	1.501 (1)	C3—H32	0.96 (1)
C1—C2	1.525 (2)	C4—H41	0.97 (1)
C1—C6	1.526 (2)	C4—H42	0.96 (1)
C2—C3	1.528 (2)	C5—H51	0.96 (1)
C3—C4	1.524 (2)	C5—H52	0.96 (1)
C4—C5	1.529 (2)	C6—H61	0.96 (1)
C5—C6	1.528 (2)	C6—H62	0.95 (1)
C7—C12	1.523 (2)	C7—H7	0.96 (1)
C7—C8	1.526 (2)	C9—H91	0.97 (1)
C9—C10	1.525 (2)	C9—H92	0.97 (1)
C9—C8	1.528 (2)	C10—H101	0.96 (1)
C10—C11	1.528 (2)	C10—H102	0.97 (1)
C11—C12	1.532 (2)	C11—H111	0.96 (1)
C13—C14	1.500 (2)	C11—H112	0.97 (1)
C14—C15	1.393 (2)	C8—H81	0.95 (1)
C14—C19	1.399 (2)	C8—H82	0.96 (1)
C15—C16	1.386 (2)	C12—H121	0.96 (1)
C16—C17	1.390 (2)	C12—H122	0.96 (1)
C17—C18	1.399 (2)	C15—H15	0.97 (1)
C18—C19	1.390 (2)	C16—H16	0.96 (1)
O3—H3o	0.87 (1)	C18—H18	0.95 (1)
N1—H1n	0.87 (1)	C19—H19	0.95 (1)
N1—H2n	0.86 (1)

C1—N1—C7	118.0 (1)	C5—C4—H41	107 (1)
N1—C1—C2	112.2 (1)	C3—C4—H42	111 (1)
N1—C1—C6	108.0 (1)	C5—C4—H42	111 (1)
C2—C1—C6	110.9 (1)	H41—C4—H42	108 (2)
C1—C2—C3	109.5 (1)	C6—C5—H51	108 (1)
C4—C3—C2	112.0 (2)	C4—C5—H51	109 (1)
C3—C4—C5	111.1 (1)	C6—C5—H52	108 (1)
C6—C5—C4	111.4 (1)	C4—C5—H52	107 (1)
C1—C6—C5	110.1 (1)	H51—C5—H52	114 (2)
N1—C7—C12	111.8 (1)	C1—C6—H61	110 (1)
N1—C7—C8	107.4 (1)	C5—C6—H61	111 (1)
C12—C7—C8	111.9 (1)	C1—C6—H62	108 (1)
C10—C9—C8	110.2 (1)	C5—C6—H62	111 (1)
C9—C10—C11	110.6 (1)	H61—C6—H62	107 (1)
C10—C11—C12	111.6 (1)	N1—C7—H7	106 (1)
C7—C8—C9	111.0 (1)	C12—C7—H7	110 (1)
C7—C12—C11	110.4 (1)	C8—C7—H7	110 (1)
O1—C13—O2	124.0 (1)	C10—C9—H91	108 (1)
O2—C13—C14	117.7 (1)	C8—C9—H91	111 (1)
O1—C13—C14	118.3 (1)	C10—C9—H92	111 (1)
C15—C14—C19	118.5 (1)	C8—C9—H92	109 (1)
C15—C14—C13	120.6 (1)	H91—C9—H92	108 (1)
C19—C14—C13	120.9 (1)	C9—C10—H101	111 (1)
C16—C15—C14	121.2 (1)	C11—C10—H101	111 (1)
C15—C16—C17	119.9 (1)	C9—C10—H102	109 (1)
O3—C17—C16	121.6 (1)	C11—C10—H102	107 (1)
O3—C17—C18	118.6 (1)	H101—C10—H102	108 (1)
C16—C17—C18	119.7 (1)	C10—C11—H111	108 (1)
C19—C18—C17	119.9 (1)	C12—C11—H111	111 (1)
C18—C19—C14	120.8 (1)	C10—C11—H112	110 (1)
C17—O3—H3o	108 (1)	C12—C11—H112	111 (1)
C7—N1—H1n	107 (1)	H111—C11—H112	105 (1)
C1—N1—H1n	106 (1)	C7—C8—H81	109 (1)
C7—N1—H2n	108 (1)	C9—C8—H81	112 (1)
C1—N1—H2n	107 (1)	C7—C8—H82	109 (1)
H1n—N1—H2n	110 (2)	C9—C8—H82	108 (1)
N1—C1—H1	106 (1)	H81—C8—H82	108 (1)
C2—C1—H1	111 (1)	C7—C12—H121	109 (1)
C6—C1—H1	109 (1)	C11—C12—H121	111 (1)
C1—C2—H21	110 (1)	C7—C12—H122	111 (1)
C3—C2—H21	111 (1)	C11—C12—H122	109 (1)
C1—C2—H22	110 (1)	H121—C12—H122	107 (1)
C3—C2—H22	110 (1)	C16—C15—H15	120 (1)
H21—C2—H22	106 (2)	C14—C15—H15	119 (1)
C4—C3—H31	110 (1)	C15—C16—H16	121 (1)
C2—C3—H31	109 (1)	C17—C16—H16	119 (1)
C4—C3—H32	108 (2)	C19—C18—H18	122 (1)
C2—C3—H32	112 (2)	C17—C18—H18	118 (1)
H31—C3—H32	106 (2)	C18—C19—H19	121 (1)
C3—C4—H41	109 (1)	C14—C19—H19	119 (1)

C7—N1—C1—C2	52.8 (1)	N1—C7—C12—C11	175.0 (1)
C7—N1—C1—C6	175.3 (1)	C8—C7—C12—C11	54.5 (1)
N1—C1—C2—C3	179.5 (1)	C10—C11—C12—C7	−55.0 (1)
C6—C1—C2—C3	58.7 (2)	O2—C13—C14—C15	−177.6 (1)
C1—C2—C3—C4	−56.6 (2)	O1—C13—C14—C15	3.4 (2)
C2—C3—C4—C5	54.6 (2)	O2—C13—C14—C19	3.9 (2)
C3—C4—C5—C6	−54.1 (2)	O1—C13—C14—C19	−175.1 (1)
N1—C1—C6—C5	177.8 (1)	C19—C14—C15—C16	1.1 (2)
C2—C1—C6—C5	−58.9 (1)	C13—C14—C15—C16	−177.4 (1)
C4—C5—C6—C1	56.3 (2)	C14—C15—C16—C17	0.0 (2)
C1—N1—C7—C12	57.7 (1)	C15—C16—C17—O3	178.5 (1)
C1—N1—C7—C8	−179.2 (1)	C15—C16—C17—C18	−1.3 (2)
C8—C9—C10—C11	−57.5 (1)	O3—C17—C18—C19	−178.4 (1)
C9—C10—C11—C12	57.0 (1)	C16—C17—C18—C19	1.5 (2)
N1—C7—C8—C9	−179.3 (1)	C17—C18—C19—C14	−0.4 (2)
C12—C7—C8—C9	−56.2 (1)	C15—C14—C19—C18	−1.0 (2)
C10—C9—C8—C7	57.1 (1)	C13—C14—C19—C18	177.6 (1)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1n···O1	0.87 (1)	1.96 (1)	2.808 (1)	164 (1)
N1—H2n···O2ⁱ	0.86 (1)	1.85 (1)	2.706 (1)	169 (2)
O3—H3o···O1ⁱⁱ	0.87 (1)	1.86 (1)	2.719 (1)	170 (2)

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

Experimental details

Crystal data
Chemical formula	2C₁₂H₂₄N⁺·2C₇H₅O₃⁻
M_r	638.86
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	173
a, b, c (Å)	9.4779 (2), 11.0650 (3), 17.5816 (4)
β (°)	95.431 (1)
V (Å³)	1835.56 (8)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.35 × 0.30 × 0.06

Data collection
Diffractometer	Bruker APEX2 area-detector
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	32008, 5346, 4227
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.135, 1.04
No. of reflections	5346
No. of parameters	324
No. of restraints	29
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.52, −0.19

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), X-SEED (Barbour, 2001) and OLEX (Dolomanov et al., 2003), publCIF (Westrip, 2007).