Diaqua­bis­(5-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ato-κ²N³,O⁴)zinc trihydrate

In the crystal structure of the title compound, [Zn(C₇H₇N₂O₄)₂(H₂O)₂]·3H₂O, the Zn^II ion, located an inversion center, is N,O-chelated by two 5-carb­oxy-2-ethyl-1H-imidazole-4-carboxyl­ate anions and further coordinated by two water mol­ecules in a distorted octa­hedral geometry. The carb­oxy group links with the carboxyl­ate group of the same ligand via an intra­molecular O—H...O hydrogen bond. An extensive inter­molecular N—H...O and O—H...O hydrogen-bonded network exists in the crystal structure. One disordered lattice water mol­ecule is half-occupied and is located close to an inversion center.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.006 Å
• Disorder in solvent or counterion
• R factor = 0.041
• wR factor = 0.119
• Data-to-parameter ratio = 11.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT417_ALERT_2_C Short Inter D-H..H-D       H2     ..  H6F     ..       2.14 Ang.
PLAT417_ALERT_2_C Short Inter D-H..H-D       H6F    ..  H7F     ..       2.12 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.594         34

Alert level G
PLAT302_ALERT_4_G Note: Anion/Solvent Disorder ...................         33 Perc.
PLAT710_ALERT_4_G Delete 1-2-3 or 2-3-4 Linear Torsion Angle ... #          1
            N1  -ZN1 -N1  -C5      6.00  0.00   2.666   1.555   1.555   1.555
PLAT710_ALERT_4_G Delete 1-2-3 or 2-3-4 Linear Torsion Angle ... #          6
            N1  -ZN1 -N1  -C2     13.00  0.00   2.666   1.555   1.555   1.555
PLAT710_ALERT_4_G Delete 1-2-3 or 2-3-4 Linear Torsion Angle ... #         15
            O1  -ZN1 -O1  -C1     17.00  0.00   2.666   1.555   1.555   1.555
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          71 Perc.

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   0 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
   4 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Self-assembly of supramolecular architectures based on imidazole carboxylate ligands has draw much attention during recent decades. To the best of our knowledge, coordination polymers based on 2-ethyl-4,5-imidazoledicarboxylate has been rarely reported so far (Wang et al., 2008; Zhang et al., 2010; Li et al., 2011). Herein we report the title compound by the reaction of zinc nitrate with 2-ethyl-4,5-imidazoledicarboxylate (H₃EIDC) in an aqueous solution under hydrothermal condition.

The title compound, [Zn(C₇H₇N₂O₄)₂(H₂O)₂].3H₂O, depicted in Fig. 1, has two symmetrical coordination water molecules, three free water molecules and two 2-ethyl-4,5-imidazoledicarboxylate ligands. the Zn^II ion, lying on a center of inversion, is surrounded by two terminal water molecules, two nitrogen atoms and two oxygen atoms from two different 2-ethyl-4,5-imidazoledicarboxylate ligands in a slightly distorted octahedral coordination environment. Three solvent water molecules exist via hydrogen bonding among the imidazole N atom, the carboxylate O atom and the O atom from water molecule, whose distances and angles are shown in Tab. 1, Each H₂EIDC is bonded to Zn^II ion in a µ₂-mode. A three-dimensional supramolecular structure is consolidated by hydrogen-bonding interactions (N—H···O and O—H···O).

Related literature

For coordination polymers built from 2-ethyl-4,5-imidazoledicarboxylate, see: Li et al. (2011); Wang et al. (2008); Zhang et al. (2010).

S2. Experimental

A mixture of Zn(NO₃)₂ (0.5 mmol, 0.110 g) and 2-ethyl-1H-imidazole-4,5-dicarboxylic acid (0.5 mmol, 0.95 g) in an aqueous solution (15 ml) was placed in a 23 ml Teflon-lined reactor, which was heated at 423 K for 2 d, and then cooled to room temperature at a rate of 10 K h^-1. Crystals of the title compound were obtained by slow evaporation of the solvent at room temperature.

S3. Refinement

Carboxy H atom was located in a difference map and refined with distance constraint of O—H = 0.82 Å, U_iso(H) = 1.5U_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 1.5U_eq(C,N). H atoms of the O6 water molecule were located in a difference Fourier map and refined as riding in as-found relative positions with U_iso(H) = 1.2U_eq(O). The O7 atom is located close to an inversion center and is half-occupied in the crystal structure; its H atoms were placed in calculated positions and refined in a riding mode with U_iso(H) = 1.2U_eq(O).

Computing details

Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The structure of the title compound, showing the atomic numbering scheme with 30% probability displacement ellipsoids [symmetry codes: i: 1 - x, 1 - y, 1 - z.]

Diaquabis(5-carboxy-2-ethyl-1H-imidazole-5-carboxylato- κ²N³,O⁴)zinc trihydrate

Crystal data

[Zn(C7H7N2O4)2(H2O)2]·3H2O	Z = 1
Mr = 521.74	F(000) = 270
Triclinic, P1	Dx = 1.688 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.229 (1) Å	Cell parameters from 1329 reflections
b = 8.8959 (12) Å	θ = 2.4–26.5°
c = 9.3541 (15) Å	µ = 1.27 mm^−1
α = 65.769 (1)°	T = 298 K
β = 88.587 (2)°	Block, colorless
γ = 70.676 (1)°	0.24 × 0.22 × 0.21 mm
V = 513.31 (13) Å^3

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	1774 independent reflections
Radiation source: fine-focus sealed tube	1532 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
φ and ω scans	θmax = 25.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −8→8
Tmin = 0.750, Tmax = 0.776	k = −8→10
2676 measured reflections	l = −10→11

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.119	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0572P)^2 + 0.7163P] where P = (Fo^2 + 2Fc^2)/3
1774 reflections	(Δ/σ)max = 0.001
152 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.71 e Å^−3

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	Occ. (<1)
Zn1	0.5000	0.5000	0.5000	0.0323 (2)
N1	0.3641 (4)	0.6476 (4)	0.6256 (3)	0.0279 (7)
N2	0.2272 (4)	0.7940 (4)	0.7637 (4)	0.0323 (7)
H2	0.1798	0.8155	0.8413	0.039*
O1	0.4472 (4)	0.7653 (3)	0.3230 (3)	0.0387 (6)
O2	0.3323 (5)	1.0446 (4)	0.2846 (3)	0.0471 (8)
O3	0.1810 (4)	1.2103 (3)	0.4395 (3)	0.0459 (7)
H3	0.2405	1.1501	0.3944	0.069*
O4	0.0686 (4)	1.1604 (4)	0.6715 (4)	0.0461 (7)
O5	0.7784 (4)	0.4784 (4)	0.5890 (4)	0.0511 (8)
H5C	0.8109	0.5636	0.5848	0.061*
H5D	0.8821	0.3872	0.6159	0.061*
O6	0.1656 (5)	0.8359 (5)	0.0415 (4)	0.0734 (11)
H6E	0.1063	0.8394	0.1212	0.088*
H6F	0.1745	0.9376	−0.0026	0.088*
O7	0.439 (3)	0.987 (4)	0.987 (3)	0.169 (9)	0.50
H7F	0.4629	0.9037	1.0795	0.202*	0.50
H7G	0.5168	0.9516	0.9288	0.202*	0.50
C1	0.3691 (5)	0.8809 (5)	0.3702 (4)	0.0310 (8)
C2	0.3209 (5)	0.8245 (4)	0.5336 (4)	0.0274 (8)
C3	0.2351 (5)	0.9175 (5)	0.6180 (4)	0.0290 (8)
C4	0.1541 (6)	1.1095 (5)	0.5770 (5)	0.0343 (9)
C5	0.3068 (5)	0.6320 (5)	0.7650 (4)	0.0304 (8)
C6	0.3164 (6)	0.4663 (5)	0.9015 (5)	0.0386 (9)
H6A	0.2978	0.4874	0.9956	0.046*
H6B	0.4466	0.3783	0.9188	0.046*
C7	0.1624 (8)	0.3961 (7)	0.8768 (6)	0.0579 (13)
H7A	0.1874	0.3649	0.7895	0.087*
H7B	0.0336	0.4849	0.8544	0.087*
H7C	0.1681	0.2938	0.9706	0.087*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0374 (4)	0.0234 (3)	0.0368 (4)	−0.0042 (3)	0.0041 (3)	−0.0184 (3)
N1	0.0294 (16)	0.0241 (15)	0.0311 (16)	−0.0060 (12)	0.0031 (12)	−0.0152 (13)
N2	0.0336 (17)	0.0309 (17)	0.0357 (17)	−0.0051 (14)	0.0058 (13)	−0.0222 (14)
O1	0.0490 (17)	0.0309 (14)	0.0351 (15)	−0.0090 (12)	0.0111 (12)	−0.0174 (12)
O2	0.072 (2)	0.0276 (15)	0.0381 (16)	−0.0160 (14)	0.0135 (15)	−0.0120 (13)
O3	0.0598 (19)	0.0240 (14)	0.0548 (19)	−0.0083 (13)	0.0056 (15)	−0.0226 (14)
O4	0.0492 (18)	0.0328 (15)	0.0566 (18)	−0.0010 (13)	0.0059 (14)	−0.0298 (14)
O5	0.0344 (16)	0.0329 (16)	0.090 (2)	−0.0026 (12)	−0.0071 (15)	−0.0364 (17)
O6	0.073 (2)	0.095 (3)	0.055 (2)	−0.014 (2)	0.0122 (18)	−0.047 (2)
O7	0.15 (2)	0.154 (14)	0.125 (11)	−0.022 (16)	0.017 (16)	−0.013 (10)
C1	0.034 (2)	0.0264 (19)	0.034 (2)	−0.0091 (16)	0.0034 (16)	−0.0152 (16)
C2	0.0266 (18)	0.0230 (18)	0.0333 (19)	−0.0067 (14)	−0.0006 (14)	−0.0139 (15)
C3	0.0283 (19)	0.0248 (18)	0.0352 (19)	−0.0064 (15)	0.0006 (15)	−0.0162 (16)
C4	0.032 (2)	0.0264 (19)	0.046 (2)	−0.0056 (16)	−0.0028 (17)	−0.0206 (19)
C5	0.0291 (19)	0.0295 (19)	0.034 (2)	−0.0064 (15)	0.0017 (15)	−0.0170 (16)
C6	0.045 (2)	0.033 (2)	0.033 (2)	−0.0097 (18)	0.0042 (18)	−0.0130 (17)
C7	0.069 (3)	0.058 (3)	0.048 (3)	−0.034 (3)	0.004 (2)	−0.014 (2)

Geometric parameters (Å, º)

Zn1—N1	2.104 (3)	O5—H5D	0.8499
Zn1—N1^i	2.104 (3)	O6—H6E	0.8578
Zn1—O1	2.164 (3)	O6—H6F	0.8502
Zn1—O1^i	2.164 (3)	O7—O7^ii	1.05 (3)
Zn1—O5	2.116 (3)	O7—H7F	0.8500
Zn1—O5^i	2.116 (3)	O7—H7G	0.8500
N1—C5	1.324 (5)	C1—C2	1.473 (5)
N1—C2	1.375 (4)	C2—C3	1.366 (5)
N2—C5	1.358 (5)	C3—C4	1.490 (5)
N2—C3	1.369 (5)	C5—C6	1.483 (5)
N2—H2	0.8600	C6—C7	1.509 (6)
O1—C1	1.243 (4)	C6—H6A	0.9700
O2—C1	1.277 (4)	C6—H6B	0.9700
O3—C4	1.286 (5)	C7—H7A	0.9600
O3—H3	0.8200	C7—H7B	0.9600
O4—C4	1.218 (5)	C7—H7C	0.9600
O5—H5C	0.8501
N1—Zn1—N1^i	180.0	H7F—O7—H7G	108.8
N1—Zn1—O5	88.97 (11)	O1—C1—O2	123.1 (3)
N1^i—Zn1—O5	91.03 (11)	O1—C1—C2	118.0 (3)
N1—Zn1—O5^i	91.03 (11)	O2—C1—C2	118.9 (3)
N1^i—Zn1—O5^i	88.97 (11)	C3—C2—N1	109.7 (3)
O5—Zn1—O5^i	180.00 (16)	C3—C2—C1	131.9 (3)
N1—Zn1—O1	78.99 (10)	N1—C2—C1	118.5 (3)
N1^i—Zn1—O1	101.01 (10)	C2—C3—N2	105.4 (3)
O5—Zn1—O1	91.97 (11)	C2—C3—C4	132.7 (4)
O5^i—Zn1—O1	88.03 (11)	N2—C3—C4	121.8 (3)
N1—Zn1—O1^i	101.01 (10)	O4—C4—O3	124.9 (4)
N1^i—Zn1—O1^i	78.99 (10)	O4—C4—C3	119.8 (4)
O5—Zn1—O1^i	88.03 (11)	O3—C4—C3	115.4 (3)
O5^i—Zn1—O1^i	91.97 (11)	N1—C5—N2	109.7 (3)
O1—Zn1—O1^i	180.00 (11)	N1—C5—C6	126.4 (3)
C5—N1—C2	106.7 (3)	N2—C5—C6	123.8 (3)
C5—N1—Zn1	142.7 (3)	C5—C6—C7	112.4 (3)
C2—N1—Zn1	110.7 (2)	C5—C6—H6A	109.1
C5—N2—C3	108.6 (3)	C7—C6—H6A	109.1
C5—N2—H2	125.7	C5—C6—H6B	109.1
C3—N2—H2	125.7	C7—C6—H6B	109.1
C1—O1—Zn1	113.8 (2)	H6A—C6—H6B	107.9
C4—O3—H3	109.5	C6—C7—H7A	109.5
Zn1—O5—H5C	125.6	C6—C7—H7B	109.5
Zn1—O5—H5D	124.4	H7A—C7—H7B	109.5
H5C—O5—H5D	108.7	C6—C7—H7C	109.5
H6E—O6—H6F	102.5	H7A—C7—H7C	109.5
O7^ii—O7—H7F	88.8	H7B—C7—H7C	109.5
O7^ii—O7—H7G	79.9
N1^i—Zn1—N1—C5	55 (100)	O2—C1—C2—C3	1.8 (6)
O5—Zn1—N1—C5	−87.4 (4)	O1—C1—C2—N1	−0.1 (5)
O5^i—Zn1—N1—C5	92.6 (4)	O2—C1—C2—N1	−178.9 (3)
O1—Zn1—N1—C5	−179.6 (4)	N1—C2—C3—N2	0.2 (4)
O1^i—Zn1—N1—C5	0.4 (4)	C1—C2—C3—N2	179.6 (4)
N1^i—Zn1—N1—C2	−127 (100)	N1—C2—C3—C4	−177.8 (4)
O5—Zn1—N1—C2	90.9 (2)	C1—C2—C3—C4	1.5 (7)
O5^i—Zn1—N1—C2	−89.1 (2)	C5—N2—C3—C2	0.0 (4)
O1—Zn1—N1—C2	−1.3 (2)	C5—N2—C3—C4	178.3 (3)
O1^i—Zn1—N1—C2	178.7 (2)	C2—C3—C4—O4	173.7 (4)
N1—Zn1—O1—C1	1.4 (3)	N2—C3—C4—O4	−4.1 (5)
N1^i—Zn1—O1—C1	−178.6 (3)	C2—C3—C4—O3	−5.9 (6)
O5—Zn1—O1—C1	−87.2 (3)	N2—C3—C4—O3	176.3 (3)
O5^i—Zn1—O1—C1	92.8 (3)	C2—N1—C5—N2	0.4 (4)
O1^i—Zn1—O1—C1	168 (100)	Zn1—N1—C5—N2	178.7 (3)
Zn1—O1—C1—O2	177.7 (3)	C2—N1—C5—C6	177.6 (3)
Zn1—O1—C1—C2	−1.1 (4)	Zn1—N1—C5—C6	−4.1 (6)
C5—N1—C2—C3	−0.4 (4)	C3—N2—C5—N1	−0.3 (4)
Zn1—N1—C2—C3	−179.3 (2)	C3—N2—C5—C6	−177.5 (3)
C5—N1—C2—C1	−179.8 (3)	N1—C5—C6—C7	−73.4 (5)
Zn1—N1—C2—C1	1.3 (4)	N2—C5—C6—C7	103.4 (4)
O1—C1—C2—C3	−179.4 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O6^iii	0.86	1.95	2.778 (4)	161
O3—H3···O2	0.82	1.65	2.465 (4)	172
O5—H5C···O3^iv	0.85	1.95	2.785 (4)	167
O5—H5D···O4^v	0.85	1.88	2.713 (4)	166
O6—H6E···O4^vi	0.86	2.29	3.145 (5)	175
O6—H6F···O7^vii	0.85	2.09	2.664 (17)	125
O7—H7F···O1^iii	0.85	2.12	2.93 (3)	160
O7—H7G···O2^iv	0.85	2.24	3.06 (3)	160

Symmetry codes: (iii) x, y, z+1; (iv) −x+1, −y+2, −z+1; (v) x+1, y−1, z; (vi) −x, −y+2, −z+1; (vii) x, y, z−1.