Acta Cryst. (2008). E64, m104 [ doi:10.1107/S1600536807064501 ]
![[mu]](/logos/entities/mu_rmgif.gif)
-pyrazine-2,3-dicarboxylato] dihydrate]The crystal structure of the title compound, {[Fe(C6H2N2O4)(H2O)2]·2H2O}n, was synthesized by a diffusion method. It has a one-dimensional polymeric chain structure and the chains are further connected into a three-dimensional structure by hydrogen bonds. The FeII ion has a distorted octahedral coordination environment, with two N and two O atoms from the pyrazine-2,3-dicarboxylate ligands in the equatorial plane and with two water molecules in axial positions. The Fe atom lies on a crystallographic centre of symmetry and a twofold rotation axis passes through the pyrazine ring.
The title compound was obtained by a diffusion method. In one arm of U-tube was placed (C6H2N2O4)Na2 (42 mg, 0.2 mmol) in water/ethanol (1:1; 10 ml) and in the other H12Cl2O14Fe (73 mg, 0.2 mmol) in water/ethanol (1:1; 10 ml). The red crystals were collected by filtration, washed with distilled water, followed by ethanol and dried under reduced pressure for 2 h.
Analysis found: C 24.39, H 3.41, N 9.26%; C6H10N2O8Fe requires: C 24.51, H 3.43, N 9.53%.
The H-atoms were included in the riding-model approximation with C—H = 0.93 - 0.96 Å and O—H = 0.82 Å, and with Uiso(H) = 1.2Ueq(C-aromatic).
Data collection: SMART (Siemens, 1996); cell refinement: SMART (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).
![[Figure 1]](./br2063fig1thm.gif)
| Fig. 1. The structure of (I) showing 30% probability displacement ellipsoids and the atom-numbering scheme. The H atoms are omitted for clarity. |
![[Figure 2]](./br2063fig2thm.gif)
| Fig. 2. three-dimensional supramolecular network of (I). O—H···O hydrogen bonds interactions shown. |
| [Fe(C6H2N2O4)(H2O)2]·2H2O | F000 = 600 |
| Mr = 294.01 | Dx = 1.869 Mg m−3 |
| Monoclinic, C2/c | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -C 2yc | Cell parameters from 3554 reflections |
| a = 12.5650 (2) Å | θ = 3.3–28.2º |
| b = 7.5158 (1) Å | µ = 1.48 mm−1 |
| c = 11.8314 (2) Å | T = 298 (2) K |
| β = 110.759 (1)º | Block, red |
| V = 1044.77 (3) Å3 | 0.23 × 0.20 × 0.18 mm |
| Z = 4 |
| CCD area-detector diffractometer | 1291 independent reflections |
| Radiation source: fine-focus sealed tube | 1219 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.019 |
| T = 298(2) K | θmax = 28.3º |
| φ and ω scans | θmin = 3.2º |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −12→16 |
| Tmin = 0.727, Tmax = 0.777 | k = −10→10 |
| 5477 measured reflections | l = −15→15 |
| Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
| Least-squares matrix: full | H-atom parameters constrained |
| R[F2 > 2σ(F2)] = 0.029 | w = 1/[σ2(Fo2) + (0.0523P)2 + 1.9364P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.088 | (Δ/σ)max < 0.001 |
| S = 1.04 | Δρmax = 0.59 e Å−3 |
| 1291 reflections | Δρmin = −0.70 e Å−3 |
| 80 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.028 (2) |
| Secondary atom site location: difference Fourier map |
| [Fe(C6H2N2O4)(H2O)2]·2H2O | V = 1044.77 (3) Å3 |
| Mr = 294.01 | Z = 4 |
| Monoclinic, C2/c | Mo Kα |
| a = 12.5650 (2) Å | µ = 1.48 mm−1 |
| b = 7.5158 (1) Å | T = 298 (2) K |
| c = 11.8314 (2) Å | 0.23 × 0.20 × 0.18 mm |
| β = 110.759 (1)º |
| CCD area-detector diffractometer | 1291 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1219 reflections with I > 2σ(I) |
| Tmin = 0.727, Tmax = 0.777 | Rint = 0.019 |
| 5477 measured reflections |
| R[F2 > 2σ(F2)] = 0.029 | 80 parameters |
| wR(F2) = 0.088 | H-atom parameters constrained |
| S = 1.04 | Δρmax = 0.59 e Å−3 |
| 1291 reflections | Δρmin = −0.70 e Å−3 |
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 | ||
| Fe1 | 0.2500 | 0.2500 | 0.5000 | 0.01865 (18) | |
| C1 | 0.08321 (16) | −0.0176 (3) | 0.38935 (17) | 0.0225 (4) | |
| C2 | 0.04250 (15) | 0.1436 (3) | 0.30732 (16) | 0.0202 (4) | |
| C3 | 0.04814 (18) | 0.4486 (3) | 0.30161 (19) | 0.0289 (5) | |
| H3 | 0.0840 | 0.5557 | 0.3320 | 0.035* | |
| N1 | 0.09020 (14) | 0.2975 (2) | 0.35810 (15) | 0.0228 (3) | |
| O1 | 0.18127 (13) | −0.0012 (2) | 0.47077 (14) | 0.0283 (3) | |
| O2 | 0.01979 (14) | −0.1458 (2) | 0.37732 (17) | 0.0378 (4) | |
| O3 | 0.32048 (15) | 0.2010 (3) | 0.36718 (16) | 0.0387 (4) | |
| H3A | 0.3336 | 0.0941 | 0.3525 | 0.046* | |
| H3B | 0.3619 | 0.2805 | 0.3524 | 0.046* | |
| O4 | 0.1817 (2) | 0.2742 (3) | 0.14299 (19) | 0.0509 (6) | |
| H4A | 0.1531 | 0.1832 | 0.1004 | 0.061* | |
| H4B | 0.2226 | 0.3406 | 0.1168 | 0.061* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Fe1 | 0.0141 (2) | 0.0209 (3) | 0.0166 (2) | −0.00144 (12) | 0.00016 (15) | −0.00229 (12) |
| C1 | 0.0209 (8) | 0.0219 (9) | 0.0224 (8) | 0.0007 (7) | 0.0047 (7) | 0.0014 (7) |
| C2 | 0.0158 (8) | 0.0194 (9) | 0.0222 (9) | −0.0005 (6) | 0.0030 (7) | 0.0004 (7) |
| C3 | 0.0279 (10) | 0.0193 (9) | 0.0318 (11) | −0.0031 (8) | 0.0010 (9) | −0.0023 (8) |
| N1 | 0.0181 (7) | 0.0223 (8) | 0.0226 (8) | −0.0007 (6) | 0.0005 (5) | −0.0013 (6) |
| O1 | 0.0244 (7) | 0.0240 (6) | 0.0276 (7) | −0.0012 (5) | −0.0018 (6) | 0.0040 (5) |
| O2 | 0.0301 (8) | 0.0273 (8) | 0.0484 (10) | −0.0073 (6) | 0.0047 (7) | 0.0081 (7) |
| O3 | 0.0317 (9) | 0.0544 (11) | 0.0337 (9) | −0.0109 (8) | 0.0160 (7) | −0.0108 (8) |
| O4 | 0.0651 (14) | 0.0589 (13) | 0.0310 (9) | −0.0257 (10) | 0.0200 (10) | −0.0104 (8) |
| Fe1—O1i | 2.0539 (15) | C2—N1 | 1.343 (3) |
| Fe1—O1 | 2.0539 (15) | C2—C2ii | 1.398 (3) |
| Fe1—O3 | 2.0919 (17) | C3—N1 | 1.329 (3) |
| Fe1—O3i | 2.0919 (17) | C3—C3ii | 1.381 (4) |
| Fe1—N1i | 2.1420 (17) | C3—H3 | 0.9300 |
| Fe1—N1 | 2.1420 (17) | O3—H3A | 0.8500 |
| C1—O2 | 1.226 (3) | O3—H3B | 0.8500 |
| C1—O1 | 1.273 (2) | O4—H4A | 0.8500 |
| C1—C2 | 1.523 (3) | O4—H4B | 0.8501 |
| O1i—Fe1—O1 | 180.0 | O2—C1—C2 | 119.56 (17) |
| O1i—Fe1—O3 | 91.35 (7) | O1—C1—C2 | 114.93 (16) |
| O1—Fe1—O3 | 88.65 (7) | N1—C2—C2ii | 120.03 (11) |
| O1i—Fe1—O3i | 88.65 (7) | N1—C2—C1 | 113.86 (16) |
| O1—Fe1—O3i | 91.35 (7) | C2ii—C2—C1 | 125.94 (10) |
| O3—Fe1—O3i | 180.000 (1) | N1—C3—C3ii | 120.82 (11) |
| O1i—Fe1—N1i | 78.46 (6) | N1—C3—H3 | 119.6 |
| O1—Fe1—N1i | 101.54 (6) | C3ii—C3—H3 | 119.6 |
| O3—Fe1—N1i | 91.76 (7) | C3—N1—C2 | 118.46 (17) |
| O3i—Fe1—N1i | 88.24 (7) | C3—N1—Fe1 | 129.20 (14) |
| O1i—Fe1—N1 | 101.54 (6) | C2—N1—Fe1 | 110.65 (13) |
| O1—Fe1—N1 | 78.46 (6) | C1—O1—Fe1 | 116.94 (13) |
| O3—Fe1—N1 | 88.24 (7) | Fe1—O3—H3A | 118.9 |
| O3i—Fe1—N1 | 91.76 (7) | Fe1—O3—H3B | 118.9 |
| N1i—Fe1—N1 | 180.0 | H3A—O3—H3B | 116.4 |
| O2—C1—O1 | 125.39 (19) | H4A—O4—H4B | 116.0 |
| Symmetry codes: (i) −x+1/2, −y+1/2, −z+1; (ii) −x, y, −z+1/2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O4—H4A···O1iii | 0.85 | 2.17 | 2.890 (3) | 142 |
| O4—H4A···O2iii | 0.85 | 2.59 | 3.227 (3) | 133 |
| O4—H4B···O1iv | 0.85 | 2.20 | 3.045 (3) | 174 |
| O3—H3A···O4v | 0.85 | 2.41 | 3.210 (3) | 156 |
| O3—H3B···O2vi | 0.85 | 1.98 | 2.720 (2) | 145 |
| C3—H3···O2vii | 0.93 | 2.51 | 3.232 (3) | 135 |
| Symmetry codes: (iii) x, −y, z−1/2; (iv) −x+1/2, y+1/2, −z+1/2; (v) −x+1/2, y−1/2, −z+1/2; (vi) x+1/2, y+1/2, z; (vii) x, y+1, z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O4—H4A···O1i | 0.85 | 2.17 | 2.890 (3) | 142 |
| O4—H4A···O2i | 0.85 | 2.59 | 3.227 (3) | 133 |
| O4—H4B···O1ii | 0.85 | 2.20 | 3.045 (3) | 174 |
| O3—H3A···O4iii | 0.85 | 2.41 | 3.210 (3) | 156 |
| O3—H3B···O2iv | 0.85 | 1.98 | 2.720 (2) | 145 |
| C3—H3···O2v | 0.93 | 2.51 | 3.232 (3) | 135 |
| Symmetry codes: (i) x, −y, z−1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1/2, y−1/2, −z+1/2; (iv) x+1/2, y+1/2, z; (v) x, y+1, z. |
The authors thank the Natural Science Foundation of Henan Province (grant No. 0511020300) for financial support.
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Recently, the effective combination of coordination bond and hydrogen bond has been applied in the engineering study of inorganic-organic hybrid material and the construction of metal-organic coordination supramolecular complexes. The suitable organic ligand makes the complex not only to possess novel structure but also produces unique optical, electric and magnetic properties. Pyrazine-2,3-dicarboxylic acid (pzdcH2) has proved to be well suited for the construction of multidimensional frameworks, due to the presence of two adjacent carboxylate groups (O donor atoms) as substituents on the N-heterocyclic pyrazine ring (N donor atoms). A series of one-dimensional, two-dimensional and three-dimensional metal-organic coordination supramolecular complexes have been synthesized and characterized. Now, we report the crystal structure of the title compound (I), and the crystal structure is similar to the structures reported by Mao et al. (1996). In compound 1, the iron atom is hexacoordinate where the sphere about any iron atom includes the N1, N1A, O1, O1A, O3 and O3A atoms. The Fe atom lies on a crystallographic center of symmetry and that the ligand lies on a crystallographic twofold axis. Two coordinated water molecules are on the axis. The coordination distances for the Fe—O1 2.054 (1) Å are similar with the usual carboxyl oxygen to iron distance of 2.091 Å. The pzdc dianion ligands bridge Fe ions to form extended linear chains. In this structure, the pzdc dianion ligand coordinates to two metal centers via chelate interactions involving each nitrogen N(1) and oxygen O(1) from the adjacent carboxylate substituent (Fig. 1). As shown in Fig. 2, the chains are linked in a 3-D surpramolecular network by O—H···O hydrogen-bonding interactions.