Acta Cryst. (2007). E63, m2008 [ doi:10.1107/S160053680703067X ]
In the title compound, [Cd(C6H6N4)2(H2O)2](C8H4O4), the CdII atom (site symmetry 
) is chelated by two 2,2'-biimidazole (H2biim) ligands in the equatorial plane and two axial water molecules to result in a trans-CdN4O2 octahedral geometry. The complex dication and centrosymmetric benzene-1,4-dicarboxylate (bdc) dianion interact via O-H
O and N-HO hydrogen bonds. Centrosymmetric aromatic ![[pi]](http://journals.iucr.org/logos/entities/pi_rmgif.gif)
- stacking involving one of the C3N2 rings of the H2biim species also occurs with a short centroid-centroid separation of 3.4164 (14) Å.
2,2'-Biimidazole was synthesized according to the literature method (Fieselmann et al., 1978). Benzene-1,4-dicarboxylic acid, 2,2'-biimidazole and cadmium acetate dihydrate were reacted in a molar ratio of 1:2:1. The mixture was stirred for 30 min, then the pH was adjusted to 6.5 with an aqueous solution of NaOH (0.1 M). The mixture with a total volume of 21 ml was heated at 433 K for 5 d in a sealed 25 ml Teflon-lined stainless steel vessel under autogenous pressure. After the reaction mixture was slowly cooled to room temperature at a rate of 5 K h−1, colourless blocks of (I) were obtained.
The water H atoms were located in a difference map and refined as riding in their as-found relative positions with free refinement for their Uiso values. The other H atoms were positioned geometrically (C—H = 0.93 Å, N—H = 0.86 Å) and refined as riding with Uiso(H) = 1.2Ueq(C).
Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXL97 and local programs.
![[Figure 1]](./hb2453fig1thm.gif)
| Fig. 1. The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level (arbitrary spheres for the H atoms). Symmetry codes: (i) 2 − x, −y, 2 − z; (ii) 2 − x, −y, 3 − z. |
![[Figure 2]](./hb2453fig2thm.gif)
| Fig. 2. The packing diagrame for (I). The dotted lines indicate the hydrogen bonds. |
| [Cd(C6H6N4)2(H2O)2](C8H4O4) | F000 = 584 |
| Mr = 580.84 | Dx = 1.660 Mg m−3 |
| Monoclinic, P21/n | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -P 2yn | Cell parameters from 903 reflections |
| a = 8.336 (2) Å | θ = 2.6–25.8º |
| b = 11.009 (3) Å | µ = 0.99 mm−1 |
| c = 12.688 (4) Å | T = 293 (2) K |
| β = 93.674 (3)º | Block, colourless |
| V = 1161.9 (6) Å3 | 0.58 × 0.53 × 0.25 mm |
| Z = 2 |
| Bruker SMART CCD diffractometer | 2294 independent reflections |
| Radiation source: fine-focus sealed tube | 2139 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.014 |
| T = 293(2) K | θmax = 26.1º |
| ω scans | θmin = 2.5º |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) or Bruker (1997)? | h = −10→10 |
| Tmin = 0.596, Tmax = 0.786 | k = −13→13 |
| 9682 measured reflections | l = −15→15 |
| 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)] = 0.018 | H-atom parameters constrained |
| wR(F2) = 0.049 | w = 1/[σ2(Fo2) + (0.0258P)2 + 0.5043P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.04 | (Δ/σ)max = 0.003 |
| 2294 reflections | Δρmax = 0.30 e Å−3 |
| 162 parameters | Δρmin = −0.26 e Å−3 |
| 4 restraints | Extinction correction: none |
| Primary atom site location: structure-invariant direct methods |
| [Cd(C6H6N4)2(H2O)2](C8H4O4) | V = 1161.9 (6) Å3 |
| Mr = 580.84 | Z = 2 |
| Monoclinic, P21/n | Mo Kα |
| a = 8.336 (2) Å | µ = 0.99 mm−1 |
| b = 11.009 (3) Å | T = 293 (2) K |
| c = 12.688 (4) Å | 0.58 × 0.53 × 0.25 mm |
| β = 93.674 (3)º |
| Bruker SMART CCD diffractometer | 2294 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) or Bruker (1997)? | 2139 reflections with I > 2σ(I) |
| Tmin = 0.596, Tmax = 0.786 | Rint = 0.014 |
| 9682 measured reflections |
| R[F2 > 2σ(F2)] = 0.018 | 4 restraints |
| wR(F2) = 0.049 | H-atom parameters constrained |
| S = 1.04 | Δρmax = 0.30 e Å−3 |
| 2294 reflections | Δρmin = −0.26 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 > 2sigma(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 | ||
| Cd1 | 1.0000 | 0.0000 | 1.0000 | 0.02922 (7) | |
| OW1 | 1.08556 (16) | 0.14916 (12) | 0.87749 (10) | 0.0465 (3) | |
| HW1A | 1.1376 | 0.1233 | 0.8272 | 0.058 (7)* | |
| HW1B | 1.1015 | 0.2283 | 0.8870 | 0.061 (7)* | |
| O2 | 0.62681 (16) | 0.09753 (13) | 1.35814 (11) | 0.0526 (4) | |
| O1 | 0.72382 (15) | −0.05438 (15) | 1.26778 (11) | 0.0510 (4) | |
| N1 | 1.25379 (15) | −0.08664 (12) | 1.01642 (10) | 0.0272 (3) | |
| N2 | 1.48489 (15) | −0.08867 (12) | 1.11125 (10) | 0.0289 (3) | |
| H2A | 1.5591 | −0.0698 | 1.1587 | 0.035* | |
| N3 | 1.34980 (16) | 0.12255 (13) | 1.23815 (11) | 0.0352 (3) | |
| H3A | 1.4448 | 0.1088 | 1.2661 | 0.042* | |
| N4 | 1.13014 (16) | 0.10607 (13) | 1.13365 (10) | 0.0321 (3) | |
| C8 | 0.8710 (2) | 0.00788 (13) | 1.42460 (14) | 0.0297 (4) | |
| C7 | 0.7303 (2) | 0.01824 (15) | 1.34368 (14) | 0.0340 (4) | |
| C9 | 1.0192 (2) | −0.03370 (17) | 1.39653 (14) | 0.0342 (4) | |
| H9 | 1.0326 | −0.0567 | 1.3271 | 0.041* | |
| C3 | 1.33955 (18) | −0.03673 (14) | 1.09696 (12) | 0.0249 (3) | |
| C1 | 1.3500 (2) | −0.17504 (15) | 0.97813 (13) | 0.0322 (3) | |
| H1 | 1.3222 | −0.2257 | 0.9212 | 0.039* | |
| C10 | 1.1479 (2) | −0.04125 (17) | 1.47141 (13) | 0.0340 (4) | |
| H10 | 1.2471 | −0.0688 | 1.4518 | 0.041* | |
| C4 | 1.27572 (18) | 0.06208 (14) | 1.15733 (12) | 0.0264 (3) | |
| C2 | 1.4928 (2) | −0.17705 (15) | 1.03637 (14) | 0.0336 (4) | |
| H2 | 1.5791 | −0.2286 | 1.0270 | 0.040* | |
| C6 | 1.1112 (2) | 0.19951 (17) | 1.20294 (15) | 0.0414 (4) | |
| H6 | 1.0202 | 0.2481 | 1.2052 | 0.050* | |
| C5 | 1.2461 (2) | 0.20980 (19) | 1.26767 (15) | 0.0436 (4) | |
| H5 | 1.2644 | 0.2658 | 1.3220 | 0.052* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cd1 | 0.02300 (10) | 0.03417 (11) | 0.02907 (10) | 0.00073 (6) | −0.00917 (7) | −0.00343 (6) |
| OW1 | 0.0536 (8) | 0.0415 (8) | 0.0455 (8) | 0.0030 (6) | 0.0117 (6) | 0.0052 (6) |
| O2 | 0.0464 (8) | 0.0513 (8) | 0.0563 (8) | 0.0186 (7) | −0.0271 (7) | −0.0148 (7) |
| O1 | 0.0353 (7) | 0.0740 (10) | 0.0412 (8) | 0.0118 (7) | −0.0167 (6) | −0.0207 (7) |
| N1 | 0.0257 (6) | 0.0282 (7) | 0.0270 (6) | −0.0006 (5) | −0.0036 (5) | −0.0018 (5) |
| N2 | 0.0227 (6) | 0.0315 (7) | 0.0316 (7) | 0.0014 (5) | −0.0058 (5) | 0.0000 (5) |
| N3 | 0.0281 (7) | 0.0417 (8) | 0.0340 (7) | 0.0040 (6) | −0.0115 (6) | −0.0114 (6) |
| N4 | 0.0261 (7) | 0.0364 (8) | 0.0326 (7) | 0.0045 (6) | −0.0061 (5) | −0.0080 (6) |
| C8 | 0.0278 (8) | 0.0277 (8) | 0.0321 (9) | −0.0017 (6) | −0.0102 (7) | 0.0019 (6) |
| C7 | 0.0297 (9) | 0.0391 (9) | 0.0317 (9) | −0.0003 (7) | −0.0104 (7) | 0.0007 (7) |
| C9 | 0.0327 (9) | 0.0412 (9) | 0.0277 (8) | 0.0006 (7) | −0.0057 (7) | −0.0021 (7) |
| C3 | 0.0231 (7) | 0.0254 (7) | 0.0258 (7) | −0.0006 (6) | −0.0023 (6) | 0.0019 (6) |
| C1 | 0.0343 (8) | 0.0297 (8) | 0.0322 (8) | 0.0014 (7) | −0.0002 (7) | −0.0057 (6) |
| C10 | 0.0265 (8) | 0.0398 (9) | 0.0346 (9) | 0.0031 (7) | −0.0052 (7) | −0.0013 (7) |
| C4 | 0.0244 (7) | 0.0290 (8) | 0.0251 (7) | 0.0000 (6) | −0.0043 (6) | −0.0017 (6) |
| C2 | 0.0315 (8) | 0.0297 (8) | 0.0397 (9) | 0.0055 (6) | 0.0023 (7) | −0.0025 (7) |
| C6 | 0.0348 (9) | 0.0444 (10) | 0.0440 (10) | 0.0117 (8) | −0.0062 (8) | −0.0160 (8) |
| C5 | 0.0415 (10) | 0.0463 (10) | 0.0412 (10) | 0.0083 (8) | −0.0100 (8) | −0.0216 (8) |
| Cd1—N4 | 2.2759 (14) | N3—H3A | 0.8600 |
| Cd1—N4i | 2.2759 (14) | N4—C4 | 1.323 (2) |
| Cd1—N1i | 2.3178 (14) | N4—C6 | 1.369 (2) |
| Cd1—N1 | 2.3178 (14) | C8—C9 | 1.385 (3) |
| Cd1—OW1 | 2.4007 (14) | C8—C10ii | 1.388 (3) |
| Cd1—OW1i | 2.4007 (14) | C8—C7 | 1.513 (2) |
| OW1—HW1A | 0.8438 | C9—C10 | 1.389 (2) |
| OW1—HW1B | 0.8879 | C9—H9 | 0.9300 |
| O2—C7 | 1.249 (2) | C3—C4 | 1.451 (2) |
| O1—C7 | 1.250 (2) | C1—C2 | 1.360 (2) |
| N1—C3 | 1.328 (2) | C1—H1 | 0.9300 |
| N1—C1 | 1.370 (2) | C10—C8ii | 1.388 (3) |
| N2—C3 | 1.341 (2) | C10—H10 | 0.9300 |
| N2—C2 | 1.364 (2) | C2—H2 | 0.9300 |
| N2—H2A | 0.8600 | C6—C5 | 1.354 (2) |
| N3—C4 | 1.340 (2) | C6—H6 | 0.9300 |
| N3—C5 | 1.361 (2) | C5—H5 | 0.9300 |
| N4—Cd1—N4i | 180.0 | C9—C8—C10ii | 119.26 (16) |
| N4—Cd1—N1i | 104.16 (5) | C9—C8—C7 | 121.05 (16) |
| N4i—Cd1—N1i | 75.84 (5) | C10ii—C8—C7 | 119.68 (16) |
| N4—Cd1—N1 | 75.84 (5) | O2—C7—O1 | 124.34 (16) |
| N4i—Cd1—N1 | 104.16 (5) | O2—C7—C8 | 117.75 (16) |
| N1i—Cd1—N1 | 180.0 | O1—C7—C8 | 117.90 (16) |
| N4—Cd1—OW1 | 89.10 (5) | C8—C9—C10 | 120.43 (17) |
| N4i—Cd1—OW1 | 90.90 (5) | C8—C9—H9 | 119.8 |
| N1i—Cd1—OW1 | 88.15 (5) | C10—C9—H9 | 119.8 |
| N1—Cd1—OW1 | 91.85 (5) | N1—C3—N2 | 111.39 (14) |
| N4—Cd1—OW1i | 90.90 (5) | N1—C3—C4 | 121.26 (13) |
| N4i—Cd1—OW1i | 89.10 (5) | N2—C3—C4 | 127.35 (14) |
| N1i—Cd1—OW1i | 91.85 (5) | C2—C1—N1 | 109.33 (14) |
| N1—Cd1—OW1i | 88.15 (5) | C2—C1—H1 | 125.3 |
| OW1—Cd1—OW1i | 180.0 | N1—C1—H1 | 125.3 |
| Cd1—OW1—HW1A | 116.5 | C8ii—C10—C9 | 120.31 (17) |
| Cd1—OW1—HW1B | 129.1 | C8ii—C10—H10 | 119.8 |
| HW1A—OW1—HW1B | 110.8 | C9—C10—H10 | 119.8 |
| C3—N1—C1 | 105.55 (13) | N4—C4—N3 | 111.29 (14) |
| C3—N1—Cd1 | 110.01 (10) | N4—C4—C3 | 121.10 (13) |
| C1—N1—Cd1 | 144.33 (11) | N3—C4—C3 | 127.58 (14) |
| C3—N2—C2 | 107.07 (13) | C1—C2—N2 | 106.66 (14) |
| C3—N2—H2A | 126.5 | C1—C2—H2 | 126.7 |
| C2—N2—H2A | 126.5 | N2—C2—H2 | 126.7 |
| C4—N3—C5 | 106.95 (14) | C5—C6—N4 | 109.06 (15) |
| C4—N3—H3A | 126.5 | C5—C6—H6 | 125.5 |
| C5—N3—H3A | 126.5 | N4—C6—H6 | 125.5 |
| C4—N4—C6 | 105.74 (13) | C6—C5—N3 | 106.96 (15) |
| C4—N4—Cd1 | 111.59 (10) | C6—C5—H5 | 126.5 |
| C6—N4—Cd1 | 142.64 (11) | N3—C5—H5 | 126.5 |
| N4—Cd1—N1—C3 | 3.63 (10) | C1—N1—C3—C4 | 179.68 (14) |
| N4i—Cd1—N1—C3 | −176.37 (10) | Cd1—N1—C3—C4 | −3.15 (18) |
| OW1—Cd1—N1—C3 | 92.23 (11) | C2—N2—C3—N1 | −0.33 (18) |
| OW1i—Cd1—N1—C3 | −87.77 (11) | C2—N2—C3—C4 | −179.77 (16) |
| N4—Cd1—N1—C1 | 178.95 (19) | C3—N1—C1—C2 | 0.00 (19) |
| N4i—Cd1—N1—C1 | −1.05 (19) | Cd1—N1—C1—C2 | −175.44 (13) |
| OW1—Cd1—N1—C1 | −92.45 (19) | C8—C9—C10—C8ii | 0.4 (3) |
| OW1i—Cd1—N1—C1 | 87.55 (19) | C6—N4—C4—N3 | 0.15 (19) |
| N1i—Cd1—N4—C4 | 176.15 (11) | Cd1—N4—C4—N3 | −178.11 (11) |
| N1—Cd1—N4—C4 | −3.85 (11) | C6—N4—C4—C3 | −177.99 (15) |
| OW1—Cd1—N4—C4 | −95.99 (11) | Cd1—N4—C4—C3 | 3.75 (19) |
| OW1i—Cd1—N4—C4 | 84.01 (11) | C5—N3—C4—N4 | 0.0 (2) |
| N1i—Cd1—N4—C6 | −1.1 (2) | C5—N3—C4—C3 | 177.98 (17) |
| N1—Cd1—N4—C6 | 178.9 (2) | N1—C3—C4—N4 | −0.4 (2) |
| OW1—Cd1—N4—C6 | 86.8 (2) | N2—C3—C4—N4 | 179.02 (15) |
| OW1i—Cd1—N4—C6 | −93.2 (2) | N1—C3—C4—N3 | −178.18 (15) |
| C9—C8—C7—O2 | −151.17 (18) | N2—C3—C4—N3 | 1.2 (3) |
| C10ii—C8—C7—O2 | 28.4 (2) | N1—C1—C2—N2 | −0.2 (2) |
| C9—C8—C7—O1 | 30.0 (3) | C3—N2—C2—C1 | 0.31 (18) |
| C10ii—C8—C7—O1 | −150.43 (18) | C4—N4—C6—C5 | −0.2 (2) |
| C10ii—C8—C9—C10 | −0.4 (3) | Cd1—N4—C6—C5 | 177.10 (16) |
| C7—C8—C9—C10 | 179.16 (16) | N4—C6—C5—N3 | 0.2 (2) |
| C1—N1—C3—N2 | 0.21 (18) | C4—N3—C5—C6 | −0.1 (2) |
| Cd1—N1—C3—N2 | 177.38 (10) |
| Symmetry codes: (i) −x+2, −y, −z+2; (ii) −x+2, −y, −z+3. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| OW1—HW1A···O1i | 0.84 | 1.88 | 2.718 (2) | 171 |
| OW1—HW1B···O2iii | 0.89 | 1.97 | 2.822 (2) | 161 |
| N2—H2A···O1iv | 0.86 | 1.89 | 2.7471 (18) | 171 |
| N3—H3A···O2iv | 0.86 | 1.86 | 2.6972 (19) | 165 |
| Symmetry codes: (i) −x+2, −y, −z+2; (iii) x+1/2, −y+1/2, z−1/2; (iv) x+1, y, z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| OW1—HW1A···O1i | 0.84 | 1.88 | 2.718 (2) | 171 |
| OW1—HW1B···O2ii | 0.89 | 1.97 | 2.822 (2) | 161 |
| N2—H2A···O1iii | 0.86 | 1.89 | 2.7471 (18) | 171 |
| N3—H3A···O2iii | 0.86 | 1.86 | 2.6972 (19) | 165 |
| Symmetry codes: (i) −x+2, −y, −z+2; (ii) x+1/2, −y+1/2, z−1/2; (iii) x+1, y, z. |
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As part of the ongoing study of complexes containing 2,2'-biimidazole (H2biim) as a ligand (Ding et al.,2005), we now report the title compound, (I), which contains Cd2+-containing complex ions, charge balanced by benzene-1,4-dicarboxylate dianions.
The Cd atom (site symmetry 1) in (I) is coordinated by four N atoms of two H2biim ligands and two O atoms from two water molecules, in a octahedral geometry (Table 1, Fig. 1). The cation and anion interact by way of N—H···O and O—H···O hydrogen bonds (Table 2).
The plane-to-plane distance of 3.26 Å between the C1 imidazol ring and its symmetry equivalent partner at (3 − x, −y, 2 − z), in an offset fashion (slippage = 1.10 Å) indicates a strong π–π interaction (Fig. 2).