The inner salt 4-carboxy-2-(pyridinium-4-yl)-1H-imidazole-5-carboxylate monohydrate

In the title compound, C₁₀H₇N₃O₄·H₂O, one carboxyl group is deprotonated and the pyridyl group is protonated. The inner salt mol­ecule has a planar structure, apart from the carboxylic acid group, which is tilted from the imidazole plane by a small dihedral angle of 7.3 (3)°.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.051
• wR factor = 0.111
• Data-to-parameter ratio = 11.7

checkCIF/PLATON results

No syntax errors found


No errors found in this datablock

---

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

4-carboxy-2-(pyridinium-4-yl)-1H-imidazole-5-dicarboxylate monohydrate

Crystal data

C10H7N3O4·H2O	F(000) = 520
Mr = 251.20	Dx = 1.627 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1068 reflections
a = 5.6348 (15) Å	θ = 2.6–23.4°
b = 8.457 (2) Å	µ = 0.13 mm^−1
c = 21.605 (6) Å	T = 298 K
β = 94.889 (4)°	Planete, yellow
V = 1025.7 (5) Å^3	0.26 × 0.24 × 0.03 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	1912 independent reflections
Radiation source: fine-focus sealed tube	1541 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
φ and ω scans	θmax = 25.5°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −4→6
Tmin = 0.966, Tmax = 0.990	k = −9→10
5216 measured reflections	l = −26→26

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.051	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.111	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0437P)^2 + 0.2198P] where P = (Fo^2 + 2Fc^2)/3
1912 reflections	(Δ/σ)max = 0.001
163 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.8506 (4)	0.4838 (3)	0.60335 (10)	0.0281 (5)
C2	0.6719 (4)	0.5982 (2)	0.57526 (9)	0.0241 (5)
C3	0.4716 (4)	0.6694 (2)	0.59559 (9)	0.0253 (5)
C4	0.3661 (4)	0.6560 (3)	0.65615 (10)	0.0299 (5)
C5	0.4978 (4)	0.7506 (2)	0.50291 (10)	0.0255 (5)
C6	0.4441 (4)	0.8321 (2)	0.44343 (10)	0.0254 (5)
C7	0.5829 (4)	0.8191 (3)	0.39374 (10)	0.0319 (5)
H7	0.7196	0.7570	0.3971	0.038*
C8	0.5181 (4)	0.8984 (3)	0.33948 (10)	0.0358 (6)
H8	0.6111	0.8898	0.3061	0.043*
C9	0.1834 (4)	1.0036 (3)	0.38145 (11)	0.0372 (6)
H9	0.0489	1.0677	0.3769	0.045*
C10	0.2403 (4)	0.9257 (3)	0.43598 (11)	0.0338 (6)
H10	0.1425	0.9352	0.4683	0.041*
N1	0.3226 (3)	0.9874 (2)	0.33446 (9)	0.0358 (5)
H1N	0.2734	1.0549	0.2985	0.054*
N2	0.3656 (3)	0.7649 (2)	0.55016 (8)	0.0286 (4)
N3	0.6857 (3)	0.6519 (2)	0.51620 (8)	0.0262 (4)
H3N	0.7975	0.6222	0.4881	0.039*
O1	0.2004 (3)	0.7393 (2)	0.66784 (8)	0.0473 (5)
O2	0.4564 (3)	0.55115 (19)	0.69540 (7)	0.0378 (4)
H2A	0.6020	0.5051	0.6838	0.057*
O3	0.8208 (3)	0.43801 (19)	0.65815 (7)	0.0394 (4)
O4	1.0113 (3)	0.43913 (18)	0.57235 (7)	0.0380 (4)
O5	0.8688 (3)	0.79770 (19)	0.75193 (7)	0.0415 (4)
H5A	0.9543	0.8453	0.7821	0.062*
H5B	0.9891	0.7631	0.7311	0.062*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0261 (12)	0.0313 (12)	0.0268 (11)	−0.0032 (10)	0.0024 (10)	−0.0017 (10)
C2	0.0259 (11)	0.0272 (11)	0.0199 (10)	−0.0028 (9)	0.0057 (9)	−0.0020 (9)
C3	0.0243 (12)	0.0283 (11)	0.0235 (11)	−0.0012 (10)	0.0037 (9)	−0.0018 (9)
C4	0.0283 (12)	0.0338 (13)	0.0283 (12)	−0.0042 (11)	0.0060 (10)	−0.0027 (10)
C5	0.0270 (11)	0.0255 (11)	0.0244 (11)	−0.0013 (9)	0.0049 (9)	−0.0022 (9)
C6	0.0277 (12)	0.0248 (11)	0.0236 (11)	−0.0025 (9)	0.0024 (9)	−0.0005 (9)
C7	0.0304 (13)	0.0366 (13)	0.0293 (12)	0.0018 (11)	0.0063 (10)	0.0002 (10)
C8	0.0378 (14)	0.0439 (14)	0.0266 (12)	0.0004 (12)	0.0077 (10)	0.0031 (11)
C9	0.0309 (13)	0.0373 (14)	0.0432 (14)	0.0035 (11)	0.0019 (11)	0.0037 (11)
C10	0.0309 (13)	0.0375 (13)	0.0338 (12)	0.0032 (11)	0.0075 (10)	0.0009 (11)
N1	0.0389 (12)	0.0379 (11)	0.0299 (10)	−0.0025 (10)	−0.0021 (9)	0.0074 (9)
N2	0.0287 (10)	0.0316 (10)	0.0261 (10)	0.0018 (8)	0.0066 (8)	−0.0005 (8)
N3	0.0256 (10)	0.0308 (10)	0.0231 (9)	0.0015 (8)	0.0068 (8)	−0.0022 (8)
O1	0.0483 (11)	0.0546 (11)	0.0426 (10)	0.0186 (9)	0.0238 (9)	0.0048 (9)
O2	0.0370 (9)	0.0514 (10)	0.0264 (8)	0.0069 (8)	0.0104 (7)	0.0064 (8)
O3	0.0384 (10)	0.0527 (11)	0.0277 (8)	0.0089 (8)	0.0071 (7)	0.0111 (8)
O4	0.0356 (9)	0.0461 (10)	0.0338 (9)	0.0133 (8)	0.0116 (8)	0.0023 (8)
O5	0.0374 (10)	0.0567 (11)	0.0306 (9)	0.0021 (9)	0.0043 (7)	−0.0054 (8)

Geometric parameters (Å, º)

C1—O3	1.270 (3)	C7—C8	1.372 (3)
C1—O4	1.230 (3)	C7—H7	0.9300
C1—C2	1.488 (3)	C8—N1	1.331 (3)
C2—N3	1.363 (3)	C8—H8	0.9300
C2—C3	1.383 (3)	C9—N1	1.342 (3)
C3—N2	1.369 (3)	C9—C10	1.364 (3)
C3—C4	1.487 (3)	C9—H9	0.9300
C4—O1	1.213 (3)	C10—H10	0.9300
C4—O2	1.300 (3)	N1—H1N	0.9842
C5—N2	1.319 (3)	N3—H3N	0.9448
C5—N3	1.360 (3)	O2—H2A	0.9605
C5—C6	1.467 (3)	O5—H5A	0.8754
C6—C7	1.386 (3)	O5—H5B	0.8950
C6—C10	1.393 (3)
O4—C1—O3	125.1 (2)	C6—C7—H7	120.1
O4—C1—C2	118.77 (19)	N1—C8—C7	120.3 (2)
O3—C1—C2	116.1 (2)	N1—C8—H8	119.9
N3—C2—C3	105.40 (18)	C7—C8—H8	119.9
N3—C2—C1	120.52 (19)	N1—C9—C10	119.6 (2)
C3—C2—C1	134.07 (19)	N1—C9—H9	120.2
N2—C3—C2	110.31 (18)	C10—C9—H9	120.2
N2—C3—C4	119.56 (19)	C9—C10—C6	120.3 (2)
C2—C3—C4	130.1 (2)	C9—C10—H10	119.8
O1—C4—O2	121.7 (2)	C6—C10—H10	119.8
O1—C4—C3	120.8 (2)	C8—N1—C9	122.0 (2)
O2—C4—C3	117.5 (2)	C8—N1—H1N	124.6
N2—C5—N3	111.94 (19)	C9—N1—H1N	113.2
N2—C5—C6	123.2 (2)	C5—N2—C3	105.09 (18)
N3—C5—C6	124.9 (2)	C5—N3—C2	107.26 (18)
C7—C6—C10	118.0 (2)	C5—N3—H3N	125.3
C7—C6—C5	123.6 (2)	C2—N3—H3N	127.3
C10—C6—C5	118.3 (2)	C4—O2—H2A	113.7
C8—C7—C6	119.8 (2)	H5A—O5—H5B	97.7
C8—C7—H7	120.1
O4—C1—C2—N3	0.2 (3)	C10—C6—C7—C8	0.4 (3)
O3—C1—C2—N3	−178.67 (19)	C5—C6—C7—C8	179.3 (2)
O4—C1—C2—C3	178.7 (2)	C6—C7—C8—N1	0.0 (3)
O3—C1—C2—C3	−0.2 (3)	N1—C9—C10—C6	1.2 (3)
N3—C2—C3—N2	−0.2 (2)	C7—C6—C10—C9	−1.0 (3)
C1—C2—C3—N2	−178.9 (2)	C5—C6—C10—C9	180.0 (2)
N3—C2—C3—C4	179.9 (2)	C7—C8—N1—C9	0.2 (3)
C1—C2—C3—C4	1.3 (4)	C10—C9—N1—C8	−0.8 (3)
N2—C3—C4—O1	−6.7 (3)	N3—C5—N2—C3	−0.8 (2)
C2—C3—C4—O1	173.1 (2)	C6—C5—N2—C3	178.87 (19)
N2—C3—C4—O2	172.59 (18)	C2—C3—N2—C5	0.6 (2)
C2—C3—C4—O2	−7.6 (3)	C4—C3—N2—C5	−179.51 (19)
N2—C5—C6—C7	179.3 (2)	N2—C5—N3—C2	0.7 (2)
N3—C5—C6—C7	−1.0 (3)	C6—C5—N3—C2	−178.98 (19)
N2—C5—C6—C10	−1.7 (3)	C3—C2—N3—C5	−0.3 (2)
N3—C5—C6—C10	177.91 (19)	C1—C2—N3—C5	178.61 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O5^i	0.98	1.80	2.758 (2)	164
N3—H3N···O4^ii	0.94	1.84	2.779 (2)	174
O2—H2A···O3	0.96	1.51	2.462 (2)	173
O5—H5B···O1^iii	0.90	1.90	2.759 (2)	161
O5—H5A···O3^iv	0.88	1.90	2.768 (2)	172

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