Imidazolium 2,4-dihydroxy­benzoate

The title compound, C₃H₅N₂⁺·C₇H₅O₄⁻, consists of imidazolium cations and 2,4-dihydroxy­benzoate anions that link to each other via hydrogen bonding. Furthermore, π–π stacking is observed between parallel benzene rings and between benzene and imidazole rings.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.038
• wR factor = 0.110
• Data-to-parameter ratio = 16.0

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Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Imidazolium 2,4-dihydroxybenzoate

Crystal data

C3H5N2^+·C7H5O4^−	F(000) = 464
Mr = 222.20	Dx = 1.450 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 8262 reflections
a = 10.172 (6) Å	θ = 3.0–27.0°
b = 9.824 (5) Å	µ = 0.11 mm^−1
c = 11.433 (5) Å	T = 295 K
β = 116.99 (2)°	Prism, pale-brown
V = 1018.1 (9) Å^3	0.12 × 0.10 × 0.10 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID diffractometer	1921 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.038
Graphite monochromator	θmax = 27.5°, θmin = 3.0°
Detector resolution: 10.00 pixels mm^-1	h = −12→13
ω scans	k = −12→12
9806 measured reflections	l = −14→14
2335 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.038	H-atom parameters constrained
wR(F^2) = 0.110	w = 1/[σ^2(Fo^2) + (0.0586P)^2 + 0.1067P] where P = (Fo^2 + 2Fc^2)/3
S = 1.12	(Δ/σ)max = 0.001
2335 reflections	Δρmax = 0.26 e Å^−3
146 parameters	Δρmin = −0.17 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.058 (6)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.72188 (12)	0.43709 (11)	0.36009 (11)	0.0433 (3)
H1	0.6474	0.4728	0.2950	0.052*
N2	0.90500 (12)	0.30800 (11)	0.47154 (10)	0.0398 (3)
H2	0.9706	0.2452	0.4917	0.048*
O1	0.50487 (9)	0.60621 (9)	0.18794 (8)	0.0366 (2)
O2	0.37524 (10)	0.62085 (10)	−0.02807 (9)	0.0444 (3)
O3	0.14957 (11)	0.47260 (11)	−0.15086 (8)	0.0527 (3)
H3A	0.2218	0.5259	−0.1381	0.063*
O4	−0.02492 (11)	0.20167 (11)	0.08552 (9)	0.0544 (3)
H4A	−0.0008	0.1808	0.1699	0.065*
C1	0.39492 (13)	0.57310 (12)	0.08174 (11)	0.0317 (3)
C2	0.28516 (12)	0.47533 (12)	0.08432 (11)	0.0314 (3)
C3	0.16663 (13)	0.42979 (12)	−0.03249 (11)	0.0343 (3)
C4	0.06442 (14)	0.33825 (13)	−0.03009 (12)	0.0390 (3)
H4	−0.0134	0.3090	−0.1082	0.047*
C5	0.07830 (13)	0.29059 (13)	0.08857 (12)	0.0378 (3)
C6	0.19504 (15)	0.33398 (14)	0.20604 (12)	0.0411 (3)
H6	0.2045	0.3016	0.2859	0.049*
C7	0.29558 (14)	0.42478 (13)	0.20263 (11)	0.0375 (3)
H7	0.3729	0.4536	0.2812	0.045*
C8	0.80046 (14)	0.33357 (13)	0.35301 (12)	0.0407 (3)
H8	0.7845	0.2867	0.2770	0.049*
C10	0.77802 (17)	0.47818 (16)	0.48747 (14)	0.0510 (4)
H10	0.7432	0.5491	0.5197	0.061*
C9	0.89286 (17)	0.39703 (15)	0.55744 (13)	0.0491 (4)
H9	0.9529	0.4007	0.6476	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0381 (6)	0.0463 (6)	0.0385 (6)	0.0095 (5)	0.0111 (5)	0.0079 (5)
N2	0.0376 (6)	0.0398 (6)	0.0406 (6)	0.0083 (4)	0.0165 (5)	0.0064 (4)
O1	0.0308 (4)	0.0409 (5)	0.0338 (4)	−0.0028 (3)	0.0108 (3)	−0.0023 (4)
O2	0.0421 (5)	0.0524 (6)	0.0343 (5)	−0.0116 (4)	0.0134 (4)	0.0066 (4)
O3	0.0528 (6)	0.0705 (7)	0.0263 (4)	−0.0231 (5)	0.0106 (4)	0.0041 (4)
O4	0.0530 (6)	0.0625 (6)	0.0428 (5)	−0.0258 (5)	0.0175 (4)	0.0027 (5)
C1	0.0297 (6)	0.0329 (6)	0.0311 (6)	0.0022 (4)	0.0125 (4)	0.0006 (5)
C2	0.0307 (6)	0.0332 (6)	0.0291 (6)	0.0004 (4)	0.0125 (4)	0.0001 (5)
C3	0.0356 (6)	0.0391 (6)	0.0259 (5)	−0.0009 (5)	0.0119 (5)	0.0014 (5)
C4	0.0358 (6)	0.0442 (7)	0.0303 (6)	−0.0088 (5)	0.0090 (5)	−0.0025 (5)
C5	0.0376 (6)	0.0374 (6)	0.0389 (7)	−0.0057 (5)	0.0179 (5)	0.0005 (5)
C6	0.0467 (7)	0.0468 (7)	0.0296 (6)	−0.0072 (6)	0.0171 (5)	0.0025 (5)
C7	0.0372 (6)	0.0430 (7)	0.0277 (6)	−0.0062 (5)	0.0107 (5)	−0.0012 (5)
C8	0.0456 (7)	0.0413 (7)	0.0344 (6)	0.0023 (5)	0.0173 (5)	0.0025 (5)
C10	0.0531 (8)	0.0522 (8)	0.0445 (8)	0.0123 (6)	0.0195 (6)	−0.0056 (6)
C9	0.0476 (8)	0.0582 (9)	0.0334 (7)	0.0048 (6)	0.0112 (6)	−0.0019 (6)

Geometric parameters (Å, º)

N1—C8	1.3186 (18)	C2—C7	1.3990 (17)
N1—C10	1.3620 (19)	C2—C3	1.4058 (17)
N1—H1	0.8600	C3—C4	1.3843 (18)
N2—C8	1.3124 (17)	C4—C5	1.3804 (18)
N2—C9	1.3620 (18)	C4—H4	0.9300
N2—H2	0.8600	C5—C6	1.3958 (18)
O1—C1	1.2643 (15)	C6—C7	1.3710 (18)
O2—C1	1.2680 (15)	C6—H6	0.9300
O3—C3	1.3510 (15)	C7—H7	0.9300
O3—H3A	0.8593	C8—H8	0.9300
O4—C5	1.3542 (16)	C10—C9	1.339 (2)
O4—H4A	0.9044	C10—H10	0.9300
C1—C2	1.4833 (17)	C9—H9	0.9300
C8—N1—C10	108.81 (11)	C3—C4—H4	120.1
C8—N1—H1	125.6	O4—C5—C4	117.47 (11)
C10—N1—H1	125.6	O4—C5—C6	122.20 (11)
C8—N2—C9	108.99 (11)	C4—C5—C6	120.33 (12)
C8—N2—H2	125.5	C7—C6—C5	119.42 (11)
C9—N2—H2	125.5	C7—C6—H6	120.3
C3—O3—H3A	107.9	C5—C6—H6	120.3
C5—O4—H4A	106.7	C6—C7—C2	121.89 (11)
O1—C1—O2	121.94 (11)	C6—C7—H7	119.1
O1—C1—C2	119.56 (11)	C2—C7—H7	119.1
O2—C1—C2	118.50 (10)	N2—C8—N1	108.30 (12)
C7—C2—C3	117.49 (11)	N2—C8—H8	125.8
C7—C2—C1	121.44 (10)	N1—C8—H8	125.8
C3—C2—C1	121.07 (11)	C9—C10—N1	106.93 (13)
O3—C3—C4	117.76 (10)	C9—C10—H10	126.5
O3—C3—C2	121.17 (11)	N1—C10—H10	126.5
C4—C3—C2	121.07 (11)	C10—C9—N2	106.96 (13)
C5—C4—C3	119.80 (11)	C10—C9—H9	126.5
C5—C4—H4	120.1	N2—C9—H9	126.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1	0.86	1.93	2.750 (2)	160
N2—H2···O2^i	0.86	1.88	2.736 (2)	174
O3—H3A···O2	0.86	1.76	2.537 (2)	149
O4—H4A···O1^ii	0.90	1.80	2.674 (2)	162
C9—H9···O3^iii	0.93	2.37	3.254 (3)	158

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