Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104009813/ob1176sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104009813/ob1176Isup2.hkl |
CCDC reference: 243589
The title compound, (I), was prepared by the solvothermal reaction of iron(III) chloride (0.008 g, 0.05 mmol) and 4,5-imidazoledicarboxylic acid (0.016 g, 0.1 mmol) in 99.5% ethanol (10 ml). The reaction was performed in a 23 ml Teflon-lined stainless steel Parr bomb under autogeneous pressure. After heating at 433 K for 2 d and cooling to room temperature at 13 K h−1, light-yellow crystals of (I) were obtained. The title compound was the only product (yield 0.4 mg, 2%).
The H atoms were positioned geometrically, with O—H 0.82, N—H 0.86 and C—H 0.93 Å. They were constrained to ride on their parent atoms, with Uiso(H) = 1.5Ueq(O) or 1.2Ueq(C,N).
Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).
[Fe(C5H3N2O4)2] | F(000) = 368 |
Mr = 366.04 | Dx = 1.328 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 6.9909 (14) Å | Cell parameters from 2242 reflections |
b = 11.719 (2) Å | θ = 3.3–25.0° |
c = 11.2519 (16) Å | µ = 0.86 mm−1 |
β = 96.909 (9)° | T = 293 K |
V = 915.2 (3) Å3 | Dipyramid, light yellow |
Z = 2 | 0.30 × 0.18 × 0.10 mm |
MAKE Mercury CCD diffractometer | 1614 independent reflections |
Radiation source: fine-focus sealed tube | 1455 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.031 |
ω scans | θmax = 25.0°, θmin = 3.3° |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000) | h = −5→8 |
Tmin = 0.599, Tmax = 0.917 | k = −13→13 |
5462 measured reflections | l = −12→13 |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.178 | H-atom parameters constrained |
S = 1.18 | w = 1/[σ2(Fo2) + (0.113P)2 + 0.6498P] where P = (Fo2 + 2Fc2)/3 |
1614 reflections | (Δ/σ)max < 0.001 |
106 parameters | Δρmax = 0.83 e Å−3 |
0 restraints | Δρmin = −0.37 e Å−3 |
[Fe(C5H3N2O4)2] | V = 915.2 (3) Å3 |
Mr = 366.04 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.9909 (14) Å | µ = 0.86 mm−1 |
b = 11.719 (2) Å | T = 293 K |
c = 11.2519 (16) Å | 0.30 × 0.18 × 0.10 mm |
β = 96.909 (9)° |
MAKE Mercury CCD diffractometer | 1614 independent reflections |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2000) | 1455 reflections with I > 2σ(I) |
Tmin = 0.599, Tmax = 0.917 | Rint = 0.031 |
5462 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.178 | H-atom parameters constrained |
S = 1.18 | Δρmax = 0.83 e Å−3 |
1614 reflections | Δρmin = −0.37 e Å−3 |
106 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 | ||
Fe | 0.0000 | 0.0000 | 0.0000 | 0.0197 (3) | |
O1 | 0.4420 (4) | 0.3767 (2) | 0.3637 (3) | 0.0347 (7) | |
O2 | 0.1243 (4) | 0.3603 (3) | 0.3564 (3) | 0.0435 (8) | |
H2B | 0.0391 | 0.3216 | 0.3195 | 0.065* | |
O3 | −0.1605 (3) | 0.1017 (2) | 0.1165 (3) | 0.0328 (7) | |
O4 | −0.1370 (4) | 0.2451 (3) | 0.2468 (3) | 0.0462 (8) | |
N1 | 0.2187 (4) | 0.1101 (2) | 0.0891 (3) | 0.0255 (7) | |
N2 | 0.4527 (4) | 0.2107 (3) | 0.1854 (3) | 0.0302 (8) | |
H2A | 0.5669 | 0.2361 | 0.2073 | 0.036* | |
C1 | 0.4055 (5) | 0.1304 (3) | 0.1027 (4) | 0.0295 (9) | |
H1A | 0.4934 | 0.0934 | 0.0601 | 0.035* | |
C2 | 0.2888 (5) | 0.2454 (3) | 0.2291 (3) | 0.0274 (8) | |
C3 | 0.1439 (5) | 0.1812 (3) | 0.1687 (3) | 0.0250 (8) | |
C4 | 0.2876 (6) | 0.3334 (3) | 0.3228 (3) | 0.0305 (9) | |
C5 | −0.0645 (5) | 0.1755 (3) | 0.1777 (3) | 0.0293 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Fe | 0.0167 (5) | 0.0194 (5) | 0.0217 (5) | −0.0003 (2) | −0.0022 (3) | −0.0006 (2) |
O1 | 0.0243 (15) | 0.0381 (15) | 0.0410 (16) | −0.0069 (11) | 0.0006 (12) | −0.0189 (12) |
O2 | 0.0236 (15) | 0.0526 (18) | 0.0544 (19) | −0.0081 (13) | 0.0050 (13) | −0.0324 (15) |
O3 | 0.0166 (13) | 0.0392 (15) | 0.0426 (16) | −0.0048 (11) | 0.0037 (11) | −0.0148 (12) |
O4 | 0.0192 (14) | 0.0575 (19) | 0.063 (2) | −0.0050 (13) | 0.0110 (13) | −0.0361 (16) |
N1 | 0.0160 (15) | 0.0287 (15) | 0.0317 (17) | −0.0017 (12) | 0.0020 (13) | −0.0085 (12) |
N2 | 0.0149 (15) | 0.0374 (18) | 0.0379 (18) | −0.0057 (13) | 0.0011 (13) | −0.0133 (14) |
C1 | 0.0157 (18) | 0.037 (2) | 0.036 (2) | −0.0017 (15) | 0.0044 (15) | −0.0109 (17) |
C2 | 0.0171 (17) | 0.032 (2) | 0.0323 (19) | −0.0028 (15) | 0.0016 (15) | −0.0085 (16) |
C3 | 0.0174 (18) | 0.0287 (18) | 0.0287 (19) | −0.0027 (14) | 0.0019 (14) | −0.0079 (15) |
C4 | 0.024 (2) | 0.033 (2) | 0.034 (2) | −0.0027 (16) | 0.0005 (16) | −0.0109 (16) |
C5 | 0.0186 (19) | 0.036 (2) | 0.034 (2) | −0.0003 (16) | 0.0027 (15) | −0.0097 (16) |
Fe—O1i | 2.111 (2) | O4—C5 | 1.273 (5) |
Fe—O1ii | 2.111 (2) | N1—C1 | 1.318 (5) |
Fe—N1 | 2.154 (3) | N1—C3 | 1.372 (5) |
Fe—N1iii | 2.154 (3) | N2—C1 | 1.337 (5) |
Fe—O3 | 2.180 (3) | N2—C2 | 1.362 (5) |
Fe—O3iii | 2.180 (3) | N2—H2A | 0.8600 |
O1—C4 | 1.231 (5) | C1—H1A | 0.9300 |
O1—Feiv | 2.111 (2) | C2—C3 | 1.374 (5) |
O2—C4 | 1.285 (5) | C2—C4 | 1.476 (5) |
O2—H2B | 0.8200 | C3—C5 | 1.474 (5) |
O3—C5 | 1.250 (5) | ||
O1i—Fe—O1ii | 180.00 (14) | C3—N1—Fe | 111.3 (2) |
O1i—Fe—N1 | 90.50 (11) | C1—N2—C2 | 108.3 (3) |
O1ii—Fe—N1 | 89.50 (11) | C1—N2—H2A | 125.9 |
O1i—Fe—N1iii | 89.50 (11) | C2—N2—H2A | 125.9 |
O1ii—Fe—N1iii | 90.50 (11) | N1—C1—N2 | 111.4 (3) |
N1—Fe—N1iii | 180.00 (18) | N1—C1—H1A | 124.3 |
O1i—Fe—O3 | 90.30 (11) | N2—C1—H1A | 124.3 |
O1ii—Fe—O3 | 89.70 (11) | N2—C2—C3 | 105.1 (3) |
N1—Fe—O3 | 77.32 (10) | N2—C2—C4 | 122.9 (3) |
N1iii—Fe—O3 | 102.68 (10) | C3—C2—C4 | 132.0 (4) |
O1i—Fe—O3iii | 89.70 (11) | N1—C3—C2 | 109.8 (3) |
O1ii—Fe—O3iii | 90.30 (11) | N1—C3—C5 | 118.4 (3) |
N1—Fe—O3iii | 102.68 (10) | C2—C3—C5 | 131.8 (3) |
N1iii—Fe—O3iii | 77.32 (10) | O1—C4—O2 | 124.0 (4) |
O3—Fe—O3iii | 180.00 (18) | O1—C4—C2 | 118.4 (3) |
C4—O1—Feiv | 129.6 (3) | O2—C4—C2 | 117.6 (3) |
C4—O2—H2B | 109.5 | O3—C5—O4 | 123.6 (3) |
C5—O3—Fe | 115.4 (2) | O3—C5—C3 | 117.6 (3) |
C1—N1—C3 | 105.4 (3) | O4—C5—C3 | 118.8 (3) |
C1—N1—Fe | 143.1 (2) |
Symmetry codes: (i) −x+1/2, y−1/2, −z+1/2; (ii) x−1/2, −y+1/2, z−1/2; (iii) −x, −y, −z; (iv) −x+1/2, y+1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2B···O4 | 0.82 | 1.66 | 2.477 (4) | 179 |
N2—H2A···O4v | 0.86 | 2.07 | 2.897 (4) | 162 |
Symmetry code: (v) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | [Fe(C5H3N2O4)2] |
Mr | 366.04 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 6.9909 (14), 11.719 (2), 11.2519 (16) |
β (°) | 96.909 (9) |
V (Å3) | 915.2 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.86 |
Crystal size (mm) | 0.30 × 0.18 × 0.10 |
Data collection | |
Diffractometer | MAKE Mercury CCD diffractometer |
Absorption correction | Multi-scan (CrystalClear; Rigaku, 2000) |
Tmin, Tmax | 0.599, 0.917 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5462, 1614, 1455 |
Rint | 0.031 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.178, 1.18 |
No. of reflections | 1614 |
No. of parameters | 106 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.83, −0.37 |
Computer programs: CrystalClear (Rigaku, 2000), CrystalClear, SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997a), SHELXL97, SHELXTL (Sheldrick, 1997b).
Fe—O1i | 2.111 (2) | N1—C1 | 1.318 (5) |
Fe—N1 | 2.154 (3) | N1—C3 | 1.372 (5) |
Fe—O3 | 2.180 (3) | N2—C1 | 1.337 (5) |
O1—C4 | 1.231 (5) | N2—C2 | 1.362 (5) |
O2—C4 | 1.285 (5) | C2—C3 | 1.374 (5) |
O3—C5 | 1.250 (5) | C2—C4 | 1.476 (5) |
O4—C5 | 1.273 (5) | C3—C5 | 1.474 (5) |
O1i—Fe—N1 | 90.50 (11) | N1—Fe—O3 | 77.32 (10) |
O1i—Fe—O3 | 90.30 (11) |
Symmetry code: (i) −x+1/2, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2B···O4 | 0.82 | 1.66 | 2.477 (4) | 179 |
N2—H2A···O4ii | 0.86 | 2.07 | 2.897 (4) | 162 |
Symmetry code: (ii) x+1, y, z. |
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The structures and properties of metal complexes with biologically relevant ligands are currently attractive, on account of their promising contribution to understanding the active mechanism of metalloproteins by means of modelling their metal binding site (Chauvin et al., 2003; Mukherjee, 2000). However, as a derivative of imidazole which is ubiquitous at the active site of many metalloproteins, 4,5-imidazoledicarboxylic acid (H3IMDC) has been less well studied (Wang et al., 2004; Rajendiran et al., 2003; Huang et al., 2001; Sengupta et al., 2001; Caudle et al., 1997). Here, we report the synthesis and crystal structure of the title compound, [Fe(H2IMDC)2]n, (I). \sch
In compound (I), the Fe atom lies on centre of symmetry and the coordination enviroment is octahedral (Fig. 1 and Table 1). Each Fe atom is hexacoordinated by N2O4, with two chelating rings from H2IMDC− ligands [Fe—N1 2.154 (3) and Fe—O3 2.180 (3) Å] arranged symmetrically in the equatorial plane and two O atoms from H2IMDC− ligands [Fe—O1(1/2 − x, y − 1/2, 1/2 − z) 2.111 (2) Å] completing the apical sites.
Complex (1) displays an extended two-dimensional layer structure constructed of quasi-squares, with four Fe atoms at the corners and H2IMDC− as linkers (Fig. 2). Each H2IMDC− anion is nearly planar and connects two FeII ions in an individual mono- and bidentate mode. The lateral Fe···Fe lengths of the Fe4 square are all 8.572 (1) Å, the diagonal Fe···Fe distances are 11.719 (2) and 12.512 (2) Å, and the vertex angles are 86.25 (1) and 93.75 (1)°, indicating only slight deviations from the ideal square geometry.
Recently, a cobalt complex containing Co4 molecular squares with 4,5-imidazoledicarboxylate bridges has been reported (Wang et al., 2004), in which IMDC3− links two cobalt ions in a bis(bidentate) mode and the two chelating rings of two IMDC3− ligands coordinated to one metal atom are almost perpendicular to each other. Furthermore, 2,2'-bipyridine exists as a terminal ligand, chelating the central atom to prevent the structure expanding in two dimensions. However, in (I), the Fe4 squares are extended by the H2IMDC− ligand and form an infinite layer structure without terminal ligands to end it. It is noted that the H2IMDC− ligand in (I) is less geometrically symmetrical than the IMDC3− in the reported molecular squares, but it provides much smaller deviations from the ideal square geometry.
The layers of complex (I) are connected by N—H···O hydrogen bonds, leading to the formation of a three-dimensional network structure with tunnels along the a axis (Fig. 3). The packing diagram of (I) along the b axis is shown in Fig. 4. It is very interesting that this crystal structure of hydrogen-bonded networks survives with solvent-accessible voids of 180 Å3. The maximum peak in the final difference Fourier map is 0.82 e Å−3 at the Fe atom, and the minimum peak is −0.37 e Å−3, 0.69 Å away from atom H2A.
According to charge-balance requirements, the oxidation state of Fe in (I) is tentatively assigned as +2, since the reaction of aromatic N ligands such as imidazole or pyridine derivatives with transition metal salts can result in spontaneous metal ion reduction (Stupka et al., 2004; Wang et al., 2004; Lu & Babb, 2002; Sugiyama et al., 2002). In addition, we have also recently obtained a type of FeII coordination complex from the reaction of FeCl3 and 2,5-pyridinedicarboxylic acid via the solvothermal method in N,N-dimethylformamide. The mechanism of the redox reactions involving the usual aromatic ligands with N or N2 donors under solvo(hydro)thermal conditions are still under study.