2-Ethyl-1H-imidazole-4-carboxyl­ate monohydrate

Abstract

In the title compound, C₇H₈N₂O₄·H₂O, the imidazole N atom is protonated and one of the carboxyl­ate groups is deprontonated, forming a zwitterion. The two carboxyl groups are are approximately coplanar with the imidazole ring [O—C—C—C torsion angles = −176.8 (2) and 2.9 (4)° for one group and −4.6 (3) and 176.4 (2)° for the other] and have an intra­molecular O—H⋯O hydrogen bond between them. The water mol­ecule is linked to the organic mol­ecules via an N—H⋯O hydrogen bonds. Inter­molecular O—H⋯O and N—H⋯O hydrogen bonds are found in the crystal structure.

Related literature

For our past work based on the 2-propyl-1H-imidazole-4,5-carboxyl­ate (H₃pimda) ligand, see: Yan et al. (2010 ▶); Li et al. (2010 ▶); Song et al. (2010 ▶); He et al. (2010 ▶); Fan et al. (2010 ▶). For related coordination polymers based on H₃EIDC (2-ethyl-1H-imidazole-4,5-dicarboxyl­ate), see: Wang et al. (2008 ▶); Zhang et al. (2010 ▶); Li et al. (2011 ▶). For the synthesis of H₃EIDC, see: Sun et al. (2006 ▶).

Experimental

Crystal data

• C₇H₁₀N₂O₅

• M _r = 202.17

• Monoclinic,

• a = 7.6132 (6) Å

• b = 14.3779 (16) Å

• c = 7.9396 (8) Å

• β = 97.799 (1)°

• V = 861.04 (15) ų

• Z = 4

• Mo Kα radiation

• μ = 0.13 mm⁻¹

• T = 298 K

• 0.50 × 0.41 × 0.40 mm

Data collection

• Bruker SMART 1000 CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2007 ▶) T _min = 0.936, T _max = 0.948

• 4224 measured reflections

• 1510 independent reflections

• 1166 reflections with I > 2σ(I)

• R _int = 0.031

Refinement

• R[F ² > 2σ(F ²)] = 0.038

• wR(F ²) = 0.106

• S = 1.05

• 1510 reflections

• 129 parameters

• 3 restraints

• H-atom parameters constrained

• Δρ_max = 0.28 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4i	0.86	1.91	2.754 (2)	168
N2—H2⋯O1Wii	0.86	1.89	2.751 (2)	177
O2—H2A⋯O3	0.82	1.63	2.452 (2)	176
O1W—H1W⋯O2iii	0.85	2.05	2.8863 (19)	169
O1W—H2W⋯O1	0.85	2.03	2.849 (2)	163

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

4,5-imidazoledicarboxylic acid (H₃IDC) ligand posesses great potential for coordination interactions and hydrogen bonding, can be deprotonated to generate H₂IDC^-, HIDC₂^- and IDC₃^- anions at different pH values. Up to date, it has been widely studied. 2-propyl-1H-imidazole-4,5-carboxylate (H₃pimda) ligand as one derivative of H₃IDC with efficient N,O-donors has been used to obtain new metal-organic complexes by our research group(Song et al., 2010; Yan et al., 2010; He et al. 2010; Fan et al. 2010; Li et al. 2010). Recently, an analogue of H₃IDC, 2-ethyl-1H-imidazole-4,5-dicarboxylate (H₃EIDC)ligand has also been used to construct intriguing coordination polymers (Wang et al., 2008; Zhang et al. , 2010; Li et al., 2011;). However, the crystal structure of H₃EIDC ligand has not been determined. Considering that in mind, we focus on obtaining the crystal and its crystal structure will be reported here.

As illustrated in Fig. 1, the title compound, (C₇H₈N₂O₄).H₂O, crystallizes as a zwitterion in which the imidazole N atom is protonated, one of the carboxylate groups is deprontonated. The two carboxyl groups are approximately coplanar with the imidazole ring, as indicated by the fact that the O1—C1—C2—C3 and O2—C1—C2—C3 torsion angles are -176.8 (2) ° and 2.9 (4) °, respectively; the O3—C4—C3—C2 and O4—C4—C3—C2 torsion angles are -4.6 (3) ° and 176.4 (2) °, respectively. The solvent water molecules are linked to the organic ligands via N—H···O and O—H···O hydrogen bonds(Table 1), which stabilize the three-dimensional network(Fig. 2).

Experimental

The organic molecule powder was abtained from 2-ethylbenzimidazole according to a literature procedure (Sun et al. 2006), then the 2-ethyl-1H-imidazole-4,5-dicarboxylate(0.5 mmol, 0.9 g) was disolved in 15 ml of H₂O solution with the pH of 6 adjusted by NaOH, colorless crystals was obtained by slow evaporation of the solvent at room temperature.

Refinement

H atoms of the water molecule were located in a difference Fourier map and refined as riding with an O—H distance restraint of 0.84 (1) Å, with U_iso(H) = 1.5 U_eq. The H···H distances within the water molecules were restraint to 1.39 (1) Å. Carboxyl H atoms were located in a difference map but were refined as riding on the parent O atoms with with O—H = 0.82 Å with U_iso(H) = 1.5 U_eq(O). Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.96 (methyl), 0.97 (methylene) and N—H = 0.86 Å, U_iso(H) = 1.2 or 1.5 U_eq(C, N).

Figures

Fig. 1.

The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids.

Fig. 2.

A view of the three-dimensional network constructed by O—H···O and N—H···O hydrogen bonding interactions

Crystal data

C7H10N2O5	F(000) = 424
Mr = 202.17	Dx = 1.560 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1702 reflections
a = 7.6132 (6) Å	θ = 2.5–25.9°
b = 14.3779 (16) Å	µ = 0.13 mm−1
c = 7.9396 (8) Å	T = 298 K
β = 97.799 (1)°	Block, colorless
V = 861.04 (15) Å3	0.50 × 0.41 × 0.40 mm
Z = 4

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	1510 independent reflections
Radiation source: fine-focus sealed tube	1166 reflections with I > 2σ(I)
graphite	Rint = 0.031
φ and ω scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2007)	h = −9→8
Tmin = 0.936, Tmax = 0.948	k = −17→13
4224 measured reflections	l = −9→7

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038	H-atom parameters constrained
wR(F2) = 0.106	w = 1/[σ2(Fo2) + (0.047P)2 + 0.3916P] where P = (Fo2 + 2Fc2)/3
S = 1.05	(Δ/σ)max < 0.001
1510 reflections	Δρmax = 0.28 e Å−3
129 parameters	Δρmin = −0.21 e Å−3
3 restraints	Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.060 (5)

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
N1	0.4705 (2)	0.42162 (11)	0.2301 (2)	0.0314 (4)
H1	0.4860	0.4805	0.2208	0.038*
N2	0.3607 (2)	0.29056 (11)	0.2927 (2)	0.0305 (4)
H2	0.2932	0.2499	0.3308	0.037*
O1	0.7740 (2)	0.46097 (10)	0.0811 (2)	0.0517 (5)
O2	0.8238 (2)	0.31103 (10)	0.0434 (2)	0.0457 (5)
H2A	0.7770	0.2619	0.0653	0.069*
O3	0.6974 (2)	0.16119 (9)	0.1124 (2)	0.0433 (4)
O4	0.4800 (2)	0.11124 (9)	0.2502 (2)	0.0436 (4)
O1W	0.8455 (2)	0.65550 (10)	0.0862 (2)	0.0501 (5)
H1W	0.9476	0.6582	0.0543	0.075*
H2W	0.8189	0.5995	0.1057	0.075*
C1	0.7364 (3)	0.37964 (14)	0.0950 (3)	0.0356 (5)
C2	0.5789 (3)	0.35434 (13)	0.1777 (2)	0.0295 (5)
C3	0.5090 (3)	0.27125 (13)	0.2173 (2)	0.0282 (5)
C4	0.5648 (3)	0.17372 (13)	0.1935 (3)	0.0314 (5)
C5	0.3383 (3)	0.38238 (13)	0.2972 (3)	0.0310 (5)
C6	0.1908 (3)	0.43371 (15)	0.3579 (3)	0.0466 (6)
H6A	0.1212	0.4632	0.2610	0.056*
H6B	0.2403	0.4827	0.4340	0.056*
C7	0.0694 (3)	0.37559 (17)	0.4485 (3)	0.0528 (7)
H7A	0.0221	0.3257	0.3758	0.079*
H7B	−0.0259	0.4135	0.4773	0.079*
H7C	0.1345	0.3504	0.5503	0.079*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0332 (9)	0.0177 (8)	0.0455 (11)	0.0005 (7)	0.0140 (8)	0.0015 (7)
N2	0.0316 (9)	0.0200 (8)	0.0425 (10)	−0.0005 (6)	0.0145 (8)	0.0011 (7)
O1	0.0503 (10)	0.0288 (9)	0.0821 (13)	−0.0062 (7)	0.0310 (9)	0.0027 (8)
O2	0.0437 (9)	0.0295 (8)	0.0707 (11)	0.0011 (7)	0.0321 (8)	0.0009 (7)
O3	0.0479 (9)	0.0275 (8)	0.0601 (10)	0.0068 (6)	0.0272 (8)	−0.0009 (7)
O4	0.0460 (9)	0.0202 (7)	0.0690 (11)	0.0006 (6)	0.0236 (8)	0.0029 (7)
O1W	0.0479 (10)	0.0283 (8)	0.0813 (12)	−0.0006 (7)	0.0344 (9)	−0.0023 (8)
C1	0.0344 (11)	0.0281 (11)	0.0466 (13)	0.0005 (9)	0.0137 (10)	0.0017 (9)
C2	0.0306 (11)	0.0234 (10)	0.0355 (11)	0.0029 (8)	0.0087 (9)	−0.0001 (8)
C3	0.0296 (10)	0.0222 (10)	0.0340 (11)	0.0015 (8)	0.0090 (9)	−0.0005 (8)
C4	0.0337 (11)	0.0227 (10)	0.0389 (12)	0.0023 (8)	0.0092 (9)	−0.0002 (9)
C5	0.0313 (11)	0.0222 (10)	0.0414 (12)	0.0011 (8)	0.0124 (9)	0.0005 (9)
C6	0.0433 (13)	0.0273 (12)	0.0751 (17)	0.0048 (9)	0.0295 (13)	−0.0017 (11)
C7	0.0468 (14)	0.0451 (14)	0.0734 (17)	0.0080 (11)	0.0334 (13)	0.0037 (13)

Geometric parameters (Å, °)

N1—C5	1.327 (2)	O1W—H2W	0.8501
N1—C2	1.372 (2)	C1—C2	1.488 (3)
N1—H1	0.8600	C2—C3	1.362 (3)
N2—C5	1.332 (3)	C3—C4	1.485 (3)
N2—C3	1.376 (2)	C5—C6	1.478 (3)
N2—H2	0.8600	C6—C7	1.500 (3)
O1—C1	1.212 (2)	C6—H6A	0.9700
O2—C1	1.288 (2)	C6—H6B	0.9700
O2—H2A	0.8200	C7—H7A	0.9600
O3—C4	1.281 (2)	C7—H7B	0.9600
O4—C4	1.227 (2)	C7—H7C	0.9600
O1W—H1W	0.8500
C5—N1—C2	110.02 (16)	O4—C4—C3	118.07 (17)
C5—N1—H1	125.0	O3—C4—C3	117.11 (17)
C2—N1—H1	125.0	N1—C5—N2	107.67 (16)
C5—N2—C3	109.11 (15)	N1—C5—C6	124.74 (17)
C5—N2—H2	125.4	N2—C5—C6	127.55 (17)
C3—N2—H2	125.4	C5—C6—C7	115.01 (18)
C1—O2—H2A	109.5	C5—C6—H6A	108.5
H1W—O1W—H2W	110.3	C7—C6—H6A	108.5
O1—C1—O2	124.86 (19)	C5—C6—H6B	108.5
O1—C1—C2	119.35 (18)	C7—C6—H6B	108.5
O2—C1—C2	115.80 (17)	H6A—C6—H6B	107.5
C3—C2—N1	106.15 (16)	C6—C7—H7A	109.5
C3—C2—C1	132.84 (18)	C6—C7—H7B	109.5
N1—C2—C1	121.01 (17)	H7A—C7—H7B	109.5
C2—C3—N2	107.05 (16)	C6—C7—H7C	109.5
C2—C3—C4	132.14 (17)	H7A—C7—H7C	109.5
N2—C3—C4	120.81 (17)	H7B—C7—H7C	109.5
O4—C4—O3	124.82 (17)
C5—N1—C2—C3	−0.7 (2)	C5—N2—C3—C4	−179.30 (18)
C5—N1—C2—C1	179.02 (18)	C2—C3—C4—O4	176.4 (2)
O1—C1—C2—C3	−176.8 (2)	N2—C3—C4—O4	−3.4 (3)
O2—C1—C2—C3	2.9 (4)	C2—C3—C4—O3	−4.6 (3)
O1—C1—C2—N1	3.5 (3)	N2—C3—C4—O3	175.56 (18)
O2—C1—C2—N1	−176.74 (19)	C2—N1—C5—N2	1.3 (2)
N1—C2—C3—N2	−0.1 (2)	C2—N1—C5—C6	−176.3 (2)
C1—C2—C3—N2	−179.8 (2)	C3—N2—C5—N1	−1.3 (2)
N1—C2—C3—C4	−179.9 (2)	C3—N2—C5—C6	176.2 (2)
C1—C2—C3—C4	0.4 (4)	N1—C5—C6—C7	−172.7 (2)
C5—N2—C3—C2	0.9 (2)	N2—C5—C6—C7	10.2 (4)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4i	0.86	1.91	2.754 (2)	168
N2—H2···O1Wii	0.86	1.89	2.751 (2)	177
O2—H2A···O3	0.82	1.63	2.452 (2)	176
O1W—H1W···O2iii	0.85	2.05	2.8863 (19)	169
O1W—H2W···O1	0.85	2.03	2.849 (2)	163

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