metal-organic compounds
Poly[[[diaquasodium]-μ3-5-carboxy-2-ethyl-1H-imidazole-4-carboxylato-κ4N3,O4:O5:O5] monohydrate]
aCollege of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, People's Republic of China, bCollege of Science, Guangdong Ocean University, Zhanjiang 524088, People's Republic of China, and cCollege of Agriculture, Guangdong Ocean University, Zhanjiang 524088, People's Republic of China
*Correspondence e-mail: songwd60@163.com
In the title complex, {[Na(C7H7N2O4)(H2O)2]·H2O}n, the NaI atom exhibits a distorted octahedral geometry and is six-coordinated in an NO5 environment. The equatorial plane is defined by three O atoms and one N atom from two distinct 5-carboxy-2-ethyl-1H-imidazole-4-carboxylate (H2EIDC) ligands and one coordinated water molecule, and the apical sites are occupied by one carboxyl O atom from one H2EIDC ligand and one O atom from the other coordinated water molecule. The NaI atoms are linked by H2EIDC ligands, generating an infinite double chain along the a axis. These chains are further connected via O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional supramolecular network.
Related literature
For the rational design of metal coordination complexes, see: Sava et al. (2009); Lu et al. (2010); Xue et al. (2009). For H3IDC complexes with supramolecular architectures, see: Zou et al. (2006); Li et al. (2006); Sun et al. (2005). For related coordination polymers based on H3EIDC, see: Wang et al. (2008); Zhang et al. (2010).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 2007); cell 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.
Supporting information
10.1107/S1600536811002741/zl2345sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811002741/zl2345Isup2.hkl
A mixture of NaOH (0.1 mmol, 0.004 g) and 2-ethyl-1H-imidazole-4,5-dicarboxylic acid (0.5 mmol, 0.9 g) in 10 ml of H2O was sealed in an autoclave equipped with a Teflon liner (20 ml) and then heated to 433 K for 4 days. Colorless crystals were obtained by slow evaporation of the solvent at room temperature with a yield of 42% based on NaOH.
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 Uiso(H) = 1.5 Ueq. 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 O—H = 0.82 Å and Uiso(H) = 1.5 Ueq(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, Uiso(H) = 1.2 or 1.5 Ueq(C, N).
Data collection: SMART (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); 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 (Sheldrick, 2008).Fig. 1. The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids. (symmetry codes: i = 1-x, 1-y, 1-z; ii = 2-x, 1-y, 1-z). | |
Fig. 2. (a) One-dimensional double chain constructed of Na2O2 subunits and H2EIDC ligands propagating along the a axis (H atoms are omitted for clarity); (b) A view of the three-dimensional network constructed by O—H···O and N—H···O hydrogen bonding interactions (H atoms not involved in the hydrogen bonds are omitted for clarity). |
[Na(C7H7N2O4)(H2O)2]·H2O | F(000) = 544 |
Mr = 260.18 | Dx = 1.527 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 1702 reflections |
a = 8.5231 (8) Å | θ = 2.5–25.9° |
b = 7.0598 (7) Å | µ = 0.17 mm−1 |
c = 19.0329 (17) Å | T = 298 K |
β = 98.880 (1)° | Block, colorless |
V = 1131.51 (18) Å3 | 0.49 × 0.48 × 0.34 mm |
Z = 4 |
Bruker SMART 1000 CCD area-detector diffractometer | 1991 independent reflections |
Radiation source: fine-focus sealed tube | 1549 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.043 |
ϕ and ω scans | θmax = 25.0°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −6→10 |
Tmin = 0.923, Tmax = 0.946 | k = −8→8 |
5410 measured reflections | l = −22→21 |
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)] = 0.039 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.109 | w = 1/[σ2(Fo2) + (0.0431P)2 + 0.658P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
1991 reflections | Δρmax = 0.33 e Å−3 |
162 parameters | Δρmin = −0.27 e Å−3 |
9 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.116 (7) |
[Na(C7H7N2O4)(H2O)2]·H2O | V = 1131.51 (18) Å3 |
Mr = 260.18 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 8.5231 (8) Å | µ = 0.17 mm−1 |
b = 7.0598 (7) Å | T = 298 K |
c = 19.0329 (17) Å | 0.49 × 0.48 × 0.34 mm |
β = 98.880 (1)° |
Bruker SMART 1000 CCD area-detector diffractometer | 1991 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 1549 reflections with I > 2σ(I) |
Tmin = 0.923, Tmax = 0.946 | Rint = 0.043 |
5410 measured reflections |
R[F2 > 2σ(F2)] = 0.039 | 9 restraints |
wR(F2) = 0.109 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.33 e Å−3 |
1991 reflections | Δρmin = −0.27 e Å−3 |
162 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Na1 | 0.93820 (11) | 0.32398 (16) | 0.56175 (5) | 0.0388 (4) | |
N1 | 0.3469 (2) | 0.7014 (3) | 0.42293 (10) | 0.0288 (5) | |
N2 | 0.5987 (2) | 0.6488 (3) | 0.41437 (10) | 0.0283 (5) | |
H2 | 0.6816 | 0.6165 | 0.3966 | 0.034* | |
O1 | 0.2192 (2) | 0.8220 (3) | 0.54163 (10) | 0.0413 (5) | |
O2 | 0.4583 (2) | 0.8601 (3) | 0.60539 (9) | 0.0361 (5) | |
O3 | 0.7371 (2) | 0.8029 (3) | 0.59418 (9) | 0.0361 (5) | |
H3 | 0.6453 | 0.8360 | 0.5953 | 0.054* | |
O4 | 0.8713 (2) | 0.6644 (3) | 0.51722 (9) | 0.0374 (5) | |
O1W | 1.1322 (2) | 0.5012 (3) | 0.63961 (10) | 0.0413 (5) | |
H1W | 1.132 (4) | 0.608 (2) | 0.6204 (13) | 0.062* | |
H2W | 1.152 (4) | 0.509 (4) | 0.6843 (6) | 0.062* | |
O2W | 1.0214 (2) | 0.0314 (3) | 0.61812 (10) | 0.0444 (6) | |
H3W | 1.0861 | −0.0263 | 0.5958 | 0.067* | |
H4W | 0.9347 | −0.0303 | 0.6128 | 0.067* | |
O3W | 0.3117 (3) | 0.0343 (4) | 0.71733 (11) | 0.0803 (9) | |
H5W | 0.3704 | −0.0161 | 0.6902 | 0.120* | |
H6W | 0.2135 | 0.0274 | 0.7005 | 0.120* | |
C1 | 0.3656 (3) | 0.8138 (4) | 0.54743 (13) | 0.0292 (6) | |
C2 | 0.4401 (3) | 0.7466 (3) | 0.48677 (12) | 0.0256 (6) | |
C3 | 0.5973 (3) | 0.7131 (3) | 0.48215 (12) | 0.0255 (6) | |
C4 | 0.7464 (3) | 0.7262 (4) | 0.53360 (13) | 0.0277 (6) | |
C5 | 0.4475 (3) | 0.6448 (4) | 0.38032 (13) | 0.0280 (6) | |
C6 | 0.4053 (3) | 0.5841 (5) | 0.30430 (13) | 0.0391 (7) | |
H6A | 0.4522 | 0.4610 | 0.2986 | 0.047* | |
H6B | 0.4512 | 0.6731 | 0.2744 | 0.047* | |
C7 | 0.2284 (3) | 0.5722 (5) | 0.27913 (15) | 0.0472 (8) | |
H7A | 0.1832 | 0.4770 | 0.3059 | 0.071* | |
H7B | 0.2094 | 0.5397 | 0.2296 | 0.071* | |
H7C | 0.1804 | 0.6925 | 0.2859 | 0.071* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Na1 | 0.0261 (6) | 0.0525 (8) | 0.0381 (6) | 0.0021 (5) | 0.0057 (4) | −0.0010 (5) |
N1 | 0.0239 (11) | 0.0336 (12) | 0.0288 (11) | 0.0004 (9) | 0.0038 (9) | 0.0000 (9) |
N2 | 0.0228 (11) | 0.0363 (13) | 0.0270 (11) | 0.0012 (9) | 0.0083 (8) | −0.0012 (9) |
O1 | 0.0241 (10) | 0.0583 (13) | 0.0433 (11) | 0.0016 (9) | 0.0107 (8) | −0.0118 (10) |
O2 | 0.0295 (10) | 0.0503 (12) | 0.0289 (10) | 0.0009 (8) | 0.0057 (7) | −0.0098 (8) |
O3 | 0.0243 (9) | 0.0520 (13) | 0.0319 (10) | 0.0009 (8) | 0.0033 (7) | −0.0077 (9) |
O4 | 0.0229 (10) | 0.0517 (13) | 0.0379 (10) | 0.0049 (8) | 0.0061 (8) | −0.0022 (9) |
O1W | 0.0422 (11) | 0.0494 (13) | 0.0332 (10) | 0.0032 (10) | 0.0086 (9) | −0.0007 (9) |
O2W | 0.0342 (10) | 0.0526 (13) | 0.0464 (12) | 0.0014 (9) | 0.0062 (8) | −0.0099 (10) |
O3W | 0.0568 (15) | 0.148 (3) | 0.0359 (12) | 0.0132 (16) | 0.0053 (10) | −0.0115 (15) |
C1 | 0.0279 (14) | 0.0297 (14) | 0.0312 (14) | −0.0002 (11) | 0.0082 (11) | 0.0000 (11) |
C2 | 0.0246 (12) | 0.0257 (13) | 0.0272 (12) | −0.0007 (10) | 0.0056 (10) | 0.0015 (10) |
C3 | 0.0257 (13) | 0.0260 (13) | 0.0255 (12) | −0.0001 (10) | 0.0060 (10) | 0.0000 (10) |
C4 | 0.0255 (13) | 0.0291 (14) | 0.0293 (13) | −0.0002 (11) | 0.0062 (10) | 0.0011 (11) |
C5 | 0.0266 (13) | 0.0307 (14) | 0.0272 (13) | 0.0003 (10) | 0.0054 (10) | 0.0006 (11) |
C6 | 0.0391 (16) | 0.0506 (19) | 0.0275 (14) | −0.0012 (13) | 0.0048 (11) | −0.0024 (13) |
C7 | 0.0446 (17) | 0.058 (2) | 0.0351 (15) | −0.0049 (15) | −0.0052 (12) | 0.0008 (14) |
Na1—O4i | 2.378 (2) | O4—Na1i | 2.378 (2) |
Na1—O2W | 2.384 (2) | O1W—H1W | 0.840 (11) |
Na1—O1W | 2.396 (2) | O1W—H2W | 0.843 (11) |
Na1—O1ii | 2.433 (2) | O2W—H3W | 0.8500 |
Na1—N1ii | 2.498 (2) | O2W—H4W | 0.8500 |
Na1—O4 | 2.583 (2) | O3W—H5W | 0.8500 |
N1—C5 | 1.329 (3) | O3W—H6W | 0.8499 |
N1—C2 | 1.383 (3) | C1—C2 | 1.480 (3) |
N1—Na1ii | 2.498 (2) | C2—C3 | 1.377 (3) |
N2—C5 | 1.351 (3) | C3—C4 | 1.482 (3) |
N2—C3 | 1.369 (3) | C5—C6 | 1.499 (3) |
N2—H2 | 0.8600 | C6—C7 | 1.512 (4) |
O1—C1 | 1.237 (3) | C6—H6A | 0.9700 |
O1—Na1ii | 2.432 (2) | C6—H6B | 0.9700 |
O2—C1 | 1.296 (3) | C7—H7A | 0.9600 |
O3—C4 | 1.287 (3) | C7—H7B | 0.9600 |
O3—H3 | 0.8200 | C7—H7C | 0.9600 |
O4—C4 | 1.234 (3) | ||
O4i—Na1—O2W | 97.45 (7) | Na1—O1W—H2W | 132 (2) |
O4i—Na1—O1W | 84.24 (7) | H1W—O1W—H2W | 111.4 (15) |
O2W—Na1—O1W | 92.58 (7) | Na1—O2W—H3W | 111.2 |
O4i—Na1—O1ii | 81.27 (7) | Na1—O2W—H4W | 101.4 |
O2W—Na1—O1ii | 94.91 (8) | H3W—O2W—H4W | 108.2 |
O1W—Na1—O1ii | 164.44 (8) | H5W—O3W—H6W | 112.6 |
O4i—Na1—N1ii | 147.95 (8) | O1—C1—O2 | 122.6 (2) |
O2W—Na1—N1ii | 96.45 (8) | O1—C1—C2 | 119.6 (2) |
O1W—Na1—N1ii | 123.79 (8) | O2—C1—C2 | 117.8 (2) |
O1ii—Na1—N1ii | 68.86 (7) | C3—C2—N1 | 109.7 (2) |
O4i—Na1—O4 | 84.16 (7) | C3—C2—C1 | 130.1 (2) |
O2W—Na1—O4 | 171.50 (8) | N1—C2—C1 | 120.1 (2) |
O1W—Na1—O4 | 79.24 (7) | N2—C3—C2 | 105.48 (19) |
O1ii—Na1—O4 | 93.59 (7) | N2—C3—C4 | 120.8 (2) |
N1ii—Na1—O4 | 86.31 (7) | C2—C3—C4 | 133.7 (2) |
O4i—Na1—Na1i | 44.22 (5) | O4—C4—O3 | 123.3 (2) |
O2W—Na1—Na1i | 140.98 (7) | O4—C4—C3 | 119.7 (2) |
O1W—Na1—Na1i | 78.72 (6) | O3—C4—C3 | 116.9 (2) |
O1ii—Na1—Na1i | 86.90 (6) | N1—C5—N2 | 111.0 (2) |
N1ii—Na1—Na1i | 120.13 (7) | N1—C5—C6 | 126.4 (2) |
O4—Na1—Na1i | 39.94 (4) | N2—C5—C6 | 122.6 (2) |
C5—N1—C2 | 105.55 (19) | C5—C6—C7 | 113.6 (2) |
C5—N1—Na1ii | 141.28 (17) | C5—C6—H6A | 108.8 |
C2—N1—Na1ii | 110.58 (15) | C7—C6—H6A | 108.8 |
C5—N2—C3 | 108.2 (2) | C5—C6—H6B | 108.8 |
C5—N2—H2 | 125.9 | C7—C6—H6B | 108.8 |
C3—N2—H2 | 125.9 | H6A—C6—H6B | 107.7 |
C1—O1—Na1ii | 118.37 (16) | C6—C7—H7A | 109.5 |
C4—O3—H3 | 109.5 | C6—C7—H7B | 109.5 |
C4—O4—Na1i | 147.92 (17) | H7A—C7—H7B | 109.5 |
C4—O4—Na1 | 113.65 (16) | C6—C7—H7C | 109.5 |
Na1i—O4—Na1 | 95.84 (7) | H7A—C7—H7C | 109.5 |
Na1—O1W—H1W | 104 (2) | H7B—C7—H7C | 109.5 |
O4i—Na1—O4—C4 | 167.0 (2) | N1—C2—C3—N2 | 0.6 (3) |
O1W—Na1—O4—C4 | −107.73 (17) | C1—C2—C3—N2 | 178.7 (2) |
O1ii—Na1—O4—C4 | 86.20 (17) | N1—C2—C3—C4 | −176.6 (3) |
N1ii—Na1—O4—C4 | 17.68 (17) | C1—C2—C3—C4 | 1.5 (5) |
Na1i—Na1—O4—C4 | 167.0 (2) | Na1i—O4—C4—O3 | −121.0 (3) |
O4i—Na1—O4—Na1i | 0.0 | Na1—O4—C4—O3 | 83.8 (3) |
O1W—Na1—O4—Na1i | 85.23 (7) | Na1i—O4—C4—C3 | 59.2 (4) |
O1ii—Na1—O4—Na1i | −80.84 (7) | Na1—O4—C4—C3 | −96.0 (2) |
N1ii—Na1—O4—Na1i | −149.36 (8) | N2—C3—C4—O4 | −5.9 (4) |
Na1ii—O1—C1—O2 | −168.77 (19) | C2—C3—C4—O4 | 171.0 (3) |
Na1ii—O1—C1—C2 | 10.4 (3) | N2—C3—C4—O3 | 174.3 (2) |
C5—N1—C2—C3 | −1.1 (3) | C2—C3—C4—O3 | −8.9 (4) |
Na1ii—N1—C2—C3 | 164.78 (16) | C2—N1—C5—N2 | 1.1 (3) |
C5—N1—C2—C1 | −179.3 (2) | Na1ii—N1—C5—N2 | −157.43 (19) |
Na1ii—N1—C2—C1 | −13.5 (3) | C2—N1—C5—C6 | −178.6 (3) |
O1—C1—C2—C3 | −175.0 (3) | Na1ii—N1—C5—C6 | 22.8 (5) |
O2—C1—C2—C3 | 4.3 (4) | C3—N2—C5—N1 | −0.7 (3) |
O1—C1—C2—N1 | 2.9 (4) | C3—N2—C5—C6 | 179.0 (2) |
O2—C1—C2—N1 | −177.8 (2) | N1—C5—C6—C7 | −5.9 (4) |
C5—N2—C3—C2 | 0.0 (3) | N2—C5—C6—C7 | 174.4 (2) |
C5—N2—C3—C4 | 177.7 (2) |
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3W—H6W···O2Wiii | 0.85 | 2.09 | 2.872 (3) | 154 |
O3W—H5W···O2iv | 0.85 | 2.07 | 2.904 (3) | 165 |
O2W—H4W···O3iv | 0.85 | 2.04 | 2.888 (3) | 174 |
O2W—H3W···O1v | 0.85 | 1.96 | 2.812 (3) | 174 |
O1W—H2W···O3Wvi | 0.84 (1) | 1.86 (1) | 2.701 (3) | 178 (3) |
O1W—H1W···O1vii | 0.84 (1) | 2.33 (2) | 3.096 (3) | 152 (3) |
O3—H3···O2 | 0.82 | 1.64 | 2.453 (2) | 168 |
N2—H2···O1Wi | 0.86 | 2.01 | 2.857 (3) | 171 |
Symmetry codes: (i) −x+2, −y+1, −z+1; (iii) x−1, y, z; (iv) x, y−1, z; (v) x+1, y−1, z; (vi) −x+3/2, y+1/2, −z+3/2; (vii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | [Na(C7H7N2O4)(H2O)2]·H2O |
Mr | 260.18 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 298 |
a, b, c (Å) | 8.5231 (8), 7.0598 (7), 19.0329 (17) |
β (°) | 98.880 (1) |
V (Å3) | 1131.51 (18) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.17 |
Crystal size (mm) | 0.49 × 0.48 × 0.34 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.923, 0.946 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5410, 1991, 1549 |
Rint | 0.043 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.039, 0.109, 1.04 |
No. of reflections | 1991 |
No. of parameters | 162 |
No. of restraints | 9 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.33, −0.27 |
Computer programs: SMART (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O3W—H6W···O2Wi | 0.85 | 2.09 | 2.872 (3) | 154 |
O3W—H5W···O2ii | 0.85 | 2.07 | 2.904 (3) | 165 |
O2W—H4W···O3ii | 0.85 | 2.04 | 2.888 (3) | 174 |
O2W—H3W···O1iii | 0.85 | 1.96 | 2.812 (3) | 174 |
O1W—H2W···O3Wiv | 0.843 (11) | 1.859 (12) | 2.701 (3) | 178 (3) |
O1W—H1W···O1v | 0.840 (11) | 2.326 (17) | 3.096 (3) | 152 (3) |
O3—H3···O2 | 0.82 | 1.64 | 2.453 (2) | 168 |
N2—H2···O1Wvi | 0.86 | 2.01 | 2.857 (3) | 171 |
Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) x+1, y−1, z; (iv) −x+3/2, y+1/2, −z+3/2; (v) x+1, y, z; (vi) −x+2, −y+1, −z+1. |
Acknowledgements
The work was supported by the Nonprofit Industry Foundation of the National Ocean Administration of China (grant No. 2000905021), the Guangdong Ocean Fisheries Technology Promotion Project [grant No. A2009003–018(c)], the Guangdong Chinese Academy of Science Comprehensive Strategic Cooperation Project (grant No. 2009B091300121), the Guangdong Province Key Project in the Field of Social Development [grant No. A2009011–007(c)], the Science and Technology Department of Guangdong Province Project (grant No. 00087 061110314018) and the Guangdong Natural Science Fundation (No. 9252408801000002).
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The rational design and synthesis of novel metal-coordination complexes via deliberate selection of metal ions and organic ligands has attracted much attention due to the fascinating structures that can be obtained and their potential applications in catalysis, magnetism, photoluminescence and gas storage (Sava et al.,2009; Lu et al., 2010; Xue et al., 2009). The 4,5-imidazoledicarboxylic acid (H3IDC) ligand exhibits flexible multi-functional coordination sites involving two N atoms of the imidazole ring and four carboxyl O atoms, and has been widely used to construct novel supramolecular architectures (Zou et al., 2006; Li et al., 2006; Sun et al., 2005). To augment the data for the well studied H3IDC ligand, we recently chose to study a closely related ligand, 2-ethyl-1H-imidazole-4,5-dicarboxylic acid (H3EIDC) with an ethyl substitutent in the 2-position of the imidazole group, which could be a good candidate for generating intriguing supramolecular networks. To the best of our knowledge, only a few coordination polymers based on the H3EIDC ligand have been reported so far (Wang et al., 2008; Zhang et al., 2010). We report herein the hydrothermal synthesis and crystal structure of a new NaI complex, the title compound.
As illustrated in Fig. 1, the title complex, [Na(C7H7N2O4)2(H2O)2].H2O, comprises one H2EIDC ligand, one NaI ion, two coordinated water molecules and one solvent water molecule. Each NaI cation exhibits a distorted octahedral geometry and is six-coordinated by three oxygen (O4, O1i and O4ii) atoms and one nitrogen (Ni) atom of three distinct H2EIDC ligands and two oxygen atoms (O1W and O2W) from two coordinated water molecules (symmetry codes: i = 1-x, 1-y, 1-z; ii = 2-x, 1-y, 1-z). The equatorial plane is built by the O4, O1i, O1W and N1i atoms and the apical positions are occupied by O2W and O4ii. Two adjacent Na centers are bridged by two carboxyl oxygen atoms to form a Na2O2 subunit with a Na—Na distance of 3.684 (2) Å, and the Na2O2 subunits are linked by H2EIDC ligands to generate a one-dimensional double chain propagating along the a axis (Fig. 2a). The adjacent one-dimensional chains are connected into a three-dimensional supramolecular structure (Fig. 2 b) via N—H···O and O—H···O hydrogen bonds involving the uncoordinated imidazole N atoms, the uncoordinated and coordinated carboxylate O atoms from the H2EIDC ligands and the uncoordinated and coordinated water molecules (Table 1).