metal-organic compounds
catena-Poly[iron(II)-bis{μ-5-carboxy-2-[(1H-1,2,4-triazol-1-yl)methyl]-1H-imidazole-4-carboxylato}]
aDepartment of Quality Examination and Management, Zhengzhou College of Animal Husbandry Engineering, Zhengzhou, Henan, 450011, People's Republic of China, and bDepartment of Biological Engineering, Zhengzhou College of Animal Husbandry Engineering, Zhengzhou, Henan, 450011, People's Republic of China
*Correspondence e-mail: tongyan4200@163.com
In the title coordination polymer, [Fe(C8H6N5O4)2]n {or [FeL2]n,where HL = 2-[(1H-1,2,4-triazol-1-yl) methyl]-1H-imidazole-4,5-dicarboxylic acid)}, the FeII ion, located on an inversion centre, is six-coordinated by two O atoms and four N atoms from two L− ligands in a distorted octahedral geometry [Fe—O = 2.1452 (13), Fe—N = 2.1316 (14) and 2.2484 (15) Å]. There is an intramolecular O—H⋯O hydrogen bond in each L− ligand. Being an effective tridentate bridging ligand, the deprotonated L− anions link two FeII atoms, yielding a chain-like polymer propagating along [100]. In the crystal, these polymer chains are linked via N—H⋯N hydrogen bonds, forming a two-dimensional network.
Related literature
For the design and self-assembly of metal-organic coordination polymers (MOCP's), see: Batten & Robson (1998); Eddaoudi et al. (2001). For related structures, see: Wang et al. (2008); Meng et al. (2009); Zhang, Li et al. (2010); Zhang, Ma et al. (2010); Feng et al. 2010); Li et al. (2010); Chen et al. (2010); Jing et al. (2010).
Experimental
Crystal data
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Refinement
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Data collection: CrystalClear (Rigaku, 2000); cell CrystalClear; data reduction: CrystalClear; 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
https://doi.org/10.1107/S1600536811036026/su2292sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811036026/su2292Isup2.hkl
The title coordination polymer was synthesized by adding 1.0 mmol of 2-[(1H-1,2,4-triazol-1-yl) methyl]-1H-imidazole-4,5-dicarboxylic acid, (HL), to 5 mL water. Then FeSO4(0.5 mmol) was added to the above solution, and the mixture was heated to 393 K for 3 days, and then cooled to room temperature. Yellow crystals, suitable for X-ray analysis, were obtained in 46% yield. Anal. Calcd (%) for C16H12FeN10O8: C, 36.38; H, 2.29; N, 26.52. Found (%): C, 36.52; H, 2.45; N, 26.36.
The H atoms were included in calculated positions and treated as riding atoms: C–H = 0.93 Å for the triazole and 0.97 Å for the methylene H atoms with Uiso(H) = 1.2Ueq(C); O–H = 0.82 Å and N–H = 0.86 Å, with Uiso(H) = 1.5Ueq(O) and 1.2Ueq(N).
The design and self-assembly of metal-organic coordination polymers (MOCP's) has received much attention since the early work of (Batten & Robson, 1998) and the group of Yaghi (Eddaoudi et al., 2001). The selection of suitable bi- or multi-dentate bridging ligands plays a crucial role in the construction of MOCP's, through tuning their structural dimensionalities and stereochemistry with different coordination sites. In this work, the semi-rigid ligand, 2-[(1H-1,2,4-triazol-1-yl) methyl]-1H-imidazole-4,5-dicarboxylic acid (HL), was synthesized. Similar ligands, which differ only in the groups on the 2-position of the imidazole ring, such as 2-ethyl-1H-imidazole-4,5-dicarboxylic acid, 2-propyl-1H-imidazole-4,5-dicarboxylic acid (Wang et al., 2008; Meng et al., 2009; Zhang, Li et al., 2010; Zhang, Ma et al., 2010; Feng, et al., 2010), and 2-pyridinyl-1H-imidazole -4,5-dicarboxylic acid (Li et al., 2010; Chen et al., 2010; Jing et al., 2010), have been studied extensively. We report herein on the
of the title one-dimensional coordination polymer.As shown in Fig. 1, the
of the title coordination polymer contains half a FeII ion, located on an inversion centre, and a deprotonated L- ligand. The local coordination geometry around the FeII centre can be described as distorted octahedral. The equatorial plane is formed by two imidazole N atoms (N4 and N4d) and two carboxylate O atoms (O1 and O1d) from two L- ligands, while the axial positions are occupied by two triazolate N atoms (N3b and N3c). The cis bond angles around each FeII centre are in the range 78.11 (5)° to 101.89 (5)°.Two FeII centers are linked together by two identical L- ligands through triazolate N-donors, imidazole N-donors and carboxylate O-donors into a 14-membered box-like macrocycle with the Fe1···Fe1iiseparation being 7.179 Å. The symmetrically related triazolyl rings are parallel to one another, and the shortest distance between atoms is 3.662 Å, indicating a weak π-π interaction. Being an effective tridentate bridging ligand, the deprotonated L- anions link two FeII centers to yield a one-dimensional chain-like polymer propagating along [100].
In the crystal the one-dimensional polymer chains are linked by classical N-H···N hydrogen bonds, involving the uncoordinated triazolate N atoms and the imidazole N atoms, resulting in the formation of a two-dimensional supramolecular network propagating in the bc-plane (Table 1 and Fig. 2).
For the design and self-assembly of metal-organic coordination polymers (MOCP's), see: Batten & Robson (1998); Eddaoudi et al. (2001). For related structures, see: Wang et al. (2008); Meng et al. (2009); Zhang, Li et al. (2010); Zhang, Ma et al. (2010); Feng et al. 2010); Li et al. (2010); Chen et al. (2010); Jing et al. (2010).
Data collection: CrystalClear (Rigaku, 2000); cell
CrystalClear (Rigaku, 2000); data reduction: CrystalClear (Rigaku, 2000); 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).[Fe(C8H6N5O4)2] | F(000) = 536 |
Mr = 528.21 | Dx = 1.811 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3321 reflections |
a = 7.1790 (14) Å | θ = 2.0–31.1° |
b = 13.490 (3) Å | µ = 0.85 mm−1 |
c = 10.129 (2) Å | T = 293 K |
β = 99.11 (3)° | Prism, yellow |
V = 968.6 (3) Å3 | 0.30 × 0.15 × 0.10 mm |
Z = 2 |
Rigaku Mercury CCD diffractometer | 1900 independent reflections |
Radiation source: fine-focus sealed tube | 1847 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
ω scans | θmax = 26.0°, θmin = 2.5° |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000) | h = −8→8 |
Tmin = 0.784, Tmax = 0.919 | k = −16→16 |
10179 measured reflections | l = −12→12 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.073 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0398P)2 + 0.4416P] where P = (Fo2 + 2Fc2)/3 |
1900 reflections | (Δ/σ)max < 0.001 |
160 parameters | Δρmax = 0.25 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
[Fe(C8H6N5O4)2] | V = 968.6 (3) Å3 |
Mr = 528.21 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.1790 (14) Å | µ = 0.85 mm−1 |
b = 13.490 (3) Å | T = 293 K |
c = 10.129 (2) Å | 0.30 × 0.15 × 0.10 mm |
β = 99.11 (3)° |
Rigaku Mercury CCD diffractometer | 1900 independent reflections |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000) | 1847 reflections with I > 2σ(I) |
Tmin = 0.784, Tmax = 0.919 | Rint = 0.020 |
10179 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.073 | H-atom parameters constrained |
S = 1.08 | Δρmax = 0.25 e Å−3 |
1900 reflections | Δρmin = −0.25 e Å−3 |
160 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles |
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 | 0.00000 | 0.00000 | 0.00000 | 0.0218 (1) | |
O1 | 0.06876 (16) | 0.10364 (9) | −0.14553 (12) | 0.0289 (3) | |
O2 | −0.00859 (18) | 0.15001 (9) | −0.35930 (13) | 0.0354 (4) | |
O3 | −0.19925 (18) | 0.08021 (10) | −0.56865 (12) | 0.0349 (4) | |
O4 | −0.38127 (18) | −0.05047 (10) | −0.62554 (12) | 0.0351 (4) | |
N1 | −0.51150 (18) | −0.17230 (10) | −0.08531 (13) | 0.0226 (4) | |
N2 | −0.5674 (2) | −0.23038 (11) | 0.01037 (16) | 0.0345 (5) | |
N3 | −0.75834 (19) | −0.09910 (10) | −0.02990 (14) | 0.0261 (4) | |
N4 | −0.16330 (18) | −0.05447 (9) | −0.17946 (13) | 0.0217 (4) | |
N5 | −0.32936 (18) | −0.11788 (10) | −0.36005 (13) | 0.0235 (4) | |
C1 | −0.7157 (3) | −0.18384 (14) | 0.0396 (2) | 0.0361 (6) | |
C2 | −0.6267 (2) | −0.09475 (12) | −0.10846 (16) | 0.0248 (5) | |
C3 | −0.3469 (2) | −0.20523 (12) | −0.14359 (18) | 0.0272 (5) | |
C4 | −0.2792 (2) | −0.12666 (11) | −0.22693 (16) | 0.0216 (4) | |
C5 | −0.1404 (2) | 0.00355 (11) | −0.28705 (16) | 0.0217 (5) | |
C6 | −0.0165 (2) | 0.09232 (12) | −0.26313 (16) | 0.0245 (4) | |
C7 | −0.2437 (2) | −0.03540 (12) | −0.40038 (16) | 0.0228 (5) | |
C8 | −0.2797 (2) | −0.00276 (12) | −0.54165 (17) | 0.0259 (5) | |
H1A | −0.78580 | −0.20710 | 0.10290 | 0.0430* | |
H2A | −0.61660 | −0.04490 | −0.17040 | 0.0300* | |
H3A | −0.13760 | 0.10250 | −0.50000 | 0.0520* | |
H3B | −0.38060 | −0.26360 | −0.19810 | 0.0330* | |
H3C | −0.24600 | −0.22340 | −0.07230 | 0.0330* | |
H5A | −0.40260 | −0.15730 | −0.41090 | 0.0280* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe1 | 0.0216 (2) | 0.0231 (2) | 0.0203 (2) | 0.0023 (1) | 0.0022 (1) | −0.0003 (1) |
O1 | 0.0284 (6) | 0.0284 (6) | 0.0293 (6) | −0.0064 (5) | 0.0031 (5) | −0.0015 (5) |
O2 | 0.0361 (7) | 0.0321 (7) | 0.0375 (7) | −0.0095 (5) | 0.0041 (5) | 0.0108 (5) |
O3 | 0.0412 (7) | 0.0376 (7) | 0.0263 (6) | −0.0011 (6) | 0.0069 (5) | 0.0070 (5) |
O4 | 0.0399 (7) | 0.0399 (7) | 0.0240 (6) | 0.0047 (6) | 0.0009 (5) | −0.0041 (5) |
N1 | 0.0236 (7) | 0.0206 (7) | 0.0247 (7) | 0.0014 (5) | 0.0070 (5) | 0.0047 (5) |
N2 | 0.0359 (8) | 0.0312 (8) | 0.0406 (9) | 0.0099 (7) | 0.0191 (7) | 0.0174 (7) |
N3 | 0.0258 (7) | 0.0249 (7) | 0.0282 (7) | 0.0049 (5) | 0.0061 (6) | 0.0023 (6) |
N4 | 0.0217 (6) | 0.0217 (7) | 0.0224 (6) | −0.0002 (5) | 0.0053 (5) | 0.0006 (5) |
N5 | 0.0236 (7) | 0.0229 (7) | 0.0241 (7) | −0.0025 (5) | 0.0045 (5) | −0.0039 (5) |
C1 | 0.0365 (10) | 0.0333 (10) | 0.0435 (11) | 0.0095 (8) | 0.0214 (8) | 0.0130 (8) |
C2 | 0.0284 (8) | 0.0225 (8) | 0.0238 (8) | 0.0040 (6) | 0.0051 (6) | 0.0035 (6) |
C3 | 0.0268 (8) | 0.0215 (8) | 0.0360 (9) | 0.0023 (6) | 0.0132 (7) | 0.0023 (7) |
C4 | 0.0204 (7) | 0.0205 (7) | 0.0250 (8) | 0.0016 (6) | 0.0073 (6) | −0.0006 (6) |
C5 | 0.0207 (8) | 0.0229 (8) | 0.0224 (8) | 0.0007 (6) | 0.0062 (6) | 0.0021 (6) |
C6 | 0.0210 (7) | 0.0248 (8) | 0.0289 (8) | 0.0003 (6) | 0.0073 (6) | 0.0010 (6) |
C7 | 0.0214 (8) | 0.0248 (8) | 0.0232 (8) | 0.0014 (6) | 0.0069 (6) | −0.0002 (6) |
C8 | 0.0243 (8) | 0.0310 (9) | 0.0236 (8) | 0.0079 (6) | 0.0077 (7) | 0.0015 (6) |
Fe1—O1 | 2.1452 (13) | N3—C2 | 1.330 (2) |
Fe1—N4 | 2.1316 (14) | N3—C1 | 1.352 (2) |
Fe1—N3i | 2.2484 (15) | N4—C4 | 1.321 (2) |
Fe1—N3ii | 2.2484 (15) | N4—C5 | 1.373 (2) |
Fe1—O1iii | 2.1452 (13) | N5—C7 | 1.365 (2) |
Fe1—N4iii | 2.1316 (14) | N5—C4 | 1.345 (2) |
O1—C6 | 1.259 (2) | N5—H5A | 0.8600 |
O2—C6 | 1.255 (2) | C3—C4 | 1.484 (2) |
O3—C8 | 1.308 (2) | C5—C6 | 1.489 (2) |
O4—C8 | 1.213 (2) | C5—C7 | 1.369 (2) |
O3—H3A | 0.8200 | C7—C8 | 1.480 (2) |
N1—C2 | 1.331 (2) | C1—H1A | 0.9300 |
N1—C3 | 1.471 (2) | C2—H2A | 0.9300 |
N1—N2 | 1.356 (2) | C3—H3B | 0.9700 |
N2—C1 | 1.310 (3) | C3—H3C | 0.9700 |
O1—Fe1—N4 | 78.11 (6) | C7—N5—H5A | 126.00 |
O1—Fe1—N3i | 91.64 (6) | N2—C1—N3 | 114.38 (18) |
O1—Fe1—N3ii | 88.36 (6) | N1—C2—N3 | 109.91 (14) |
O1—Fe1—O1iii | 180.00 | N1—C3—C4 | 111.65 (13) |
O1—Fe1—N4iii | 101.89 (6) | N5—C4—C3 | 125.00 (14) |
N3i—Fe1—N4 | 90.69 (6) | N4—C4—N5 | 110.69 (14) |
N3ii—Fe1—N4 | 89.31 (6) | N4—C4—C3 | 124.31 (15) |
O1iii—Fe1—N4 | 101.89 (6) | N4—C5—C7 | 109.26 (14) |
N4—Fe1—N4iii | 180.00 | N4—C5—C6 | 118.24 (14) |
N3i—Fe1—N3ii | 180.00 | C6—C5—C7 | 132.51 (15) |
O1iii—Fe1—N3i | 88.36 (6) | O1—C6—O2 | 125.73 (15) |
N3i—Fe1—N4iii | 89.31 (6) | O1—C6—C5 | 116.10 (14) |
O1iii—Fe1—N3ii | 91.64 (6) | O2—C6—C5 | 118.15 (15) |
N3ii—Fe1—N4iii | 90.69 (6) | C5—C7—C8 | 133.23 (15) |
O1iii—Fe1—N4iii | 78.11 (6) | N5—C7—C5 | 105.78 (14) |
Fe1—O1—C6 | 116.15 (11) | N5—C7—C8 | 120.92 (14) |
C8—O3—H3A | 109.00 | O3—C8—O4 | 122.94 (16) |
N2—N1—C3 | 117.39 (13) | O3—C8—C7 | 116.19 (14) |
C2—N1—C3 | 133.07 (14) | O4—C8—C7 | 120.86 (15) |
N2—N1—C2 | 109.52 (13) | N2—C1—H1A | 123.00 |
N1—N2—C1 | 103.17 (15) | N3—C1—H1A | 123.00 |
Fe1iv—N3—C1 | 123.27 (13) | N1—C2—H2A | 125.00 |
Fe1iv—N3—C2 | 133.72 (11) | N3—C2—H2A | 125.00 |
C1—N3—C2 | 103.01 (15) | N1—C3—H3B | 109.00 |
Fe1—N4—C5 | 111.20 (10) | N1—C3—H3C | 109.00 |
C4—N4—C5 | 106.21 (13) | C4—C3—H3B | 109.00 |
Fe1—N4—C4 | 142.58 (11) | C4—C3—H3C | 109.00 |
C4—N5—C7 | 108.07 (13) | H3B—C3—H3C | 108.00 |
C4—N5—H5A | 126.00 | ||
N4—Fe1—O1—C6 | 3.33 (11) | Fe1—N4—C4—C3 | 3.5 (3) |
N3i—Fe1—O1—C6 | 93.69 (12) | C5—N4—C4—N5 | 0.72 (17) |
N3ii—Fe1—O1—C6 | −86.31 (12) | C5—N4—C4—C3 | −178.19 (14) |
N4iii—Fe1—O1—C6 | −176.67 (11) | Fe1—N4—C5—C6 | −1.63 (17) |
O1—Fe1—N4—C4 | 177.56 (18) | Fe1—N4—C5—C7 | 178.49 (10) |
O1—Fe1—N4—C5 | −0.67 (10) | C4—N4—C5—C6 | 179.49 (13) |
N3i—Fe1—N4—C4 | 86.04 (18) | C4—N4—C5—C7 | −0.39 (17) |
N3i—Fe1—N4—C5 | −92.20 (11) | C7—N5—C4—N4 | −0.78 (18) |
N3ii—Fe1—N4—C4 | −93.96 (18) | C7—N5—C4—C3 | 178.12 (14) |
N3ii—Fe1—N4—C5 | 87.80 (11) | C4—N5—C7—C5 | 0.50 (17) |
O1iii—Fe1—N4—C4 | −2.44 (18) | C4—N5—C7—C8 | −176.74 (14) |
O1iii—Fe1—N4—C5 | 179.33 (10) | N1—C3—C4—N4 | 84.25 (18) |
Fe1—O1—C6—O2 | 173.29 (13) | N1—C3—C4—N5 | −94.50 (18) |
Fe1—O1—C6—C5 | −5.11 (17) | N4—C5—C6—O1 | 4.6 (2) |
C2—N1—N2—C1 | 0.14 (19) | N4—C5—C6—O2 | −173.91 (14) |
C3—N1—N2—C1 | −178.66 (15) | C7—C5—C6—O1 | −175.54 (16) |
N2—N1—C2—N3 | 0.34 (18) | C7—C5—C6—O2 | 5.9 (3) |
C3—N1—C2—N3 | 178.87 (16) | N4—C5—C7—N5 | −0.07 (17) |
N2—N1—C3—C4 | −169.17 (14) | N4—C5—C7—C8 | 176.68 (16) |
C2—N1—C3—C4 | 12.4 (2) | C6—C5—C7—N5 | −179.92 (15) |
N1—N2—C1—N3 | −0.6 (2) | C6—C5—C7—C8 | −3.2 (3) |
C2—N3—C1—N2 | 0.8 (2) | N5—C7—C8—O3 | 176.25 (14) |
Fe1iv—N3—C1—N2 | −178.52 (12) | N5—C7—C8—O4 | −2.5 (2) |
C1—N3—C2—N1 | −0.64 (18) | C5—C7—C8—O3 | −0.1 (3) |
Fe1iv—N3—C2—N1 | 178.54 (11) | C5—C7—C8—O4 | −178.83 (17) |
Fe1—N4—C4—N5 | −177.57 (13) |
Symmetry codes: (i) x+1, y, z; (ii) −x−1, −y, −z; (iii) −x, −y, −z; (iv) x−1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O2 | 0.82 | 1.70 | 2.5175 (19) | 179 |
N5—H5A···N2v | 0.86 | 2.01 | 2.850 (2) | 166 |
Symmetry code: (v) x, −y−1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | [Fe(C8H6N5O4)2] |
Mr | 528.21 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 7.1790 (14), 13.490 (3), 10.129 (2) |
β (°) | 99.11 (3) |
V (Å3) | 968.6 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.85 |
Crystal size (mm) | 0.30 × 0.15 × 0.10 |
Data collection | |
Diffractometer | Rigaku Mercury CCD |
Absorption correction | Multi-scan (CrystalClear; Rigaku, 2000) |
Tmin, Tmax | 0.784, 0.919 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10179, 1900, 1847 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.073, 1.08 |
No. of reflections | 1900 |
No. of parameters | 160 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.25 |
Computer programs: CrystalClear (Rigaku, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O2 | 0.82 | 1.70 | 2.5175 (19) | 179 |
N5—H5A···N2i | 0.86 | 2.01 | 2.850 (2) | 166 |
Symmetry code: (i) x, −y−1/2, z−1/2. |
Acknowledgements
This work was sponsored by the Natural Science Foundation of Henan Province (No. 200510469005) and the start-up fund for scientific research of Zhengzhou College of Animal Husbandry Engineering.
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The design and self-assembly of metal-organic coordination polymers (MOCP's) has received much attention since the early work of (Batten & Robson, 1998) and the group of Yaghi (Eddaoudi et al., 2001). The selection of suitable bi- or multi-dentate bridging ligands plays a crucial role in the construction of MOCP's, through tuning their structural dimensionalities and stereochemistry with different coordination sites. In this work, the semi-rigid ligand, 2-[(1H-1,2,4-triazol-1-yl) methyl]-1H-imidazole-4,5-dicarboxylic acid (HL), was synthesized. Similar ligands, which differ only in the groups on the 2-position of the imidazole ring, such as 2-ethyl-1H-imidazole-4,5-dicarboxylic acid, 2-propyl-1H-imidazole-4,5-dicarboxylic acid (Wang et al., 2008; Meng et al., 2009; Zhang, Li et al., 2010; Zhang, Ma et al., 2010; Feng, et al., 2010), and 2-pyridinyl-1H-imidazole -4,5-dicarboxylic acid (Li et al., 2010; Chen et al., 2010; Jing et al., 2010), have been studied extensively. We report herein on the crystal structure of the title one-dimensional coordination polymer.
As shown in Fig. 1, the asymmetric unit of the title coordination polymer contains half a FeII ion, located on an inversion centre, and a deprotonated L- ligand. The local coordination geometry around the FeII centre can be described as distorted octahedral. The equatorial plane is formed by two imidazole N atoms (N4 and N4d) and two carboxylate O atoms (O1 and O1d) from two L- ligands, while the axial positions are occupied by two triazolate N atoms (N3b and N3c). The cis bond angles around each FeII centre are in the range 78.11 (5)° to 101.89 (5)°.
Two FeII centers are linked together by two identical L- ligands through triazolate N-donors, imidazole N-donors and carboxylate O-donors into a 14-membered box-like macrocycle with the Fe1···Fe1iiseparation being 7.179 Å. The symmetrically related triazolyl rings are parallel to one another, and the shortest distance between atoms is 3.662 Å, indicating a weak π-π interaction. Being an effective tridentate bridging ligand, the deprotonated L- anions link two FeII centers to yield a one-dimensional chain-like polymer propagating along [100].
In the crystal the one-dimensional polymer chains are linked by classical N-H···N hydrogen bonds, involving the uncoordinated triazolate N atoms and the imidazole N atoms, resulting in the formation of a two-dimensional supramolecular network propagating in the bc-plane (Table 1 and Fig. 2).