Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110008085/sq3239sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270110008085/sq3239Isup2.hkl |
CCDC reference: 774883
Heating a mixture of CdCl2.2.5H2O (4.6 mg, 0.02 mmol) and H4pdtc (2.6 mg, 0.01 mmol) in water (4.0 ml) at 368 K for 1 d afforded colourless crystals of (I), which were filtered off, washed with water, ethanol and [Diethyl?] ether, and dried at room temperature (yield 78% based on H4pdtc). IR (KBr pellet, ν, cm-1): 1616 s, 1560 s, 1453 m, 1371 s, 1334 m, 1269 w, 1159 m, 837 w.
H atoms on C atoms were positioned geometrically and included in the structure-factor calculations as riding atoms, with C—H = 0.93 Å. The H atoms of the water molecules were clearly visible in difference maps, and these were placed in the difference-map positions and constrained to ride on their parent O atoms, with O—H = 0.82 Å. All H atoms were assigned fixed isotropic displacement parameters, with Uiso(H) = 1.2Ueq(parent atom), in the subsequent refinement.
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXL97 (Sheldrick, 2008); software used to prepare material for publication: PLATON (Spek, 2009).
[Cd2(C9HNO8)(H2O)4]·H2O | Z = 2 |
Mr = 565.99 | F(000) = 544 |
Triclinic, P1 | Dx = 2.680 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.3989 (5) Å | Cell parameters from 4815 reflections |
b = 8.5350 (3) Å | θ = 3.5–25.7° |
c = 11.4883 (5) Å | µ = 3.11 mm−1 |
α = 89.325 (4)° | T = 293 K |
β = 69.014 (5)° | Prism, colourless |
γ = 67.269 (4)° | 0.18 × 0.12 × 0.09 mm |
V = 701.48 (6) Å3 |
Oxford Xcalibur, Atlas, Gemini Ultra diffractometer | 2650 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2181 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
Detector resolution: 10.3592 pixels mm-1 | θmax = 25.7°, θmin = 3.5° |
ω scans | h = −10→8 |
Absorption correction: analytical (CrysAlis PRO; Oxford Diffraction, 2010) | k = −10→9 |
Tmin = 0.645, Tmax = 0.756 | l = −13→10 |
4815 measured reflections |
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)] = 0.023 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.044 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0156P)2] where P = (Fo2 + 2Fc2)/3 |
2650 reflections | (Δ/σ)max < 0.001 |
226 parameters | Δρmax = 0.68 e Å−3 |
0 restraints | Δρmin = −0.87 e Å−3 |
[Cd2(C9HNO8)(H2O)4]·H2O | γ = 67.269 (4)° |
Mr = 565.99 | V = 701.48 (6) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.3989 (5) Å | Mo Kα radiation |
b = 8.5350 (3) Å | µ = 3.11 mm−1 |
c = 11.4883 (5) Å | T = 293 K |
α = 89.325 (4)° | 0.18 × 0.12 × 0.09 mm |
β = 69.014 (5)° |
Oxford Xcalibur, Atlas, Gemini Ultra diffractometer | 2650 independent reflections |
Absorption correction: analytical (CrysAlis PRO; Oxford Diffraction, 2010) | 2181 reflections with I > 2σ(I) |
Tmin = 0.645, Tmax = 0.756 | Rint = 0.018 |
4815 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | 0 restraints |
wR(F2) = 0.044 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.68 e Å−3 |
2650 reflections | Δρmin = −0.87 e Å−3 |
226 parameters |
Experimental. CrysAlisPro, Oxford Diffraction Ltd., Version 1.171.33.52 (release 06-11-2009 CrysAlis171 .NET) (compiled Nov 6 2009,16:24:50) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 | ||
Cd1 | 0.76367 (5) | 0.19923 (5) | 1.11014 (4) | 0.02449 (13) | |
Cd2 | 0.85198 (6) | 0.56158 (5) | 0.40771 (4) | 0.02831 (14) | |
O1 | 0.7284 (6) | 0.1749 (5) | 0.9117 (4) | 0.0321 (10) | |
O2 | 0.7084 (6) | 0.2984 (5) | 0.7422 (4) | 0.0356 (10) | |
O3 | 0.8385 (5) | 0.5752 (5) | 0.6188 (3) | 0.0263 (9) | |
O4 | 0.5287 (5) | 0.6759 (5) | 0.7175 (3) | 0.0273 (9) | |
O5 | 0.9194 (5) | 0.8872 (5) | 1.0181 (4) | 0.0315 (9) | |
O6 | 0.6222 (5) | 0.9917 (5) | 1.1425 (4) | 0.0318 (10) | |
O7 | 0.8382 (6) | 0.6540 (5) | 1.2270 (4) | 0.0320 (10) | |
O8 | 0.8012 (6) | 0.4118 (5) | 1.2286 (4) | 0.0334 (10) | |
O9 | 0.9057 (6) | 0.0580 (5) | 1.2566 (4) | 0.0349 (10) | |
H9A | 1.0146 | −0.0062 | 1.2154 | 0.042* | |
H9B | 0.9134 | 0.1251 | 1.3024 | 0.042* | |
O10 | 0.8699 (6) | 0.8237 (5) | 0.4409 (4) | 0.0404 (11) | |
H10A | 0.8666 | 0.8837 | 0.3847 | 0.049* | |
H10B | 0.7835 | 0.9015 | 0.4959 | 0.049* | |
O11 | 0.5275 (6) | 0.6943 (6) | 0.4842 (4) | 0.0409 (11) | |
H11A | 0.4973 | 0.7833 | 0.4536 | 0.049* | |
H11B | 0.4950 | 0.7216 | 0.5601 | 0.049* | |
O12 | 0.8328 (6) | 0.3056 (5) | 0.4657 (4) | 0.0391 (11) | |
H12A | 0.8878 | 0.2622 | 0.5120 | 0.047* | |
H12B | 0.7226 | 0.3241 | 0.5041 | 0.047* | |
O13 | 0.6272 (6) | 1.0593 (5) | 0.6480 (4) | 0.0409 (11) | |
H13A | 0.5477 | 1.0440 | 0.7080 | 0.049* | |
H13B | 0.6639 | 1.1186 | 0.6776 | 0.049* | |
N1 | 0.7397 (6) | 0.4479 (6) | 1.0143 (4) | 0.0210 (10) | |
C1 | 0.7171 (7) | 0.2970 (7) | 0.8482 (5) | 0.0238 (12) | |
C2 | 0.7202 (7) | 0.4563 (7) | 0.9038 (5) | 0.0219 (12) | |
C3 | 0.7114 (7) | 0.5992 (7) | 0.8421 (5) | 0.0224 (12) | |
C4 | 0.6887 (8) | 0.6156 (7) | 0.7173 (5) | 0.0229 (12) | |
C5 | 0.7237 (7) | 0.7347 (7) | 0.8980 (5) | 0.0251 (13) | |
H5A | 0.7144 | 0.8329 | 0.8600 | 0.030* | |
C6 | 0.7500 (7) | 0.7236 (7) | 1.0111 (5) | 0.0224 (12) | |
C7 | 0.7663 (8) | 0.8755 (7) | 1.0643 (5) | 0.0244 (13) | |
C8 | 0.7591 (7) | 0.5767 (7) | 1.0663 (5) | 0.0230 (13) | |
C9 | 0.8002 (7) | 0.5451 (7) | 1.1830 (5) | 0.0246 (13) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.0271 (2) | 0.0227 (2) | 0.0239 (2) | −0.01080 (19) | −0.00933 (18) | 0.00413 (17) |
Cd2 | 0.0290 (3) | 0.0312 (2) | 0.0259 (3) | −0.0119 (2) | −0.01241 (19) | 0.00600 (18) |
O1 | 0.047 (3) | 0.026 (2) | 0.033 (2) | −0.019 (2) | −0.020 (2) | 0.0080 (18) |
O2 | 0.054 (3) | 0.034 (2) | 0.026 (2) | −0.021 (2) | −0.020 (2) | 0.0053 (18) |
O3 | 0.025 (2) | 0.030 (2) | 0.022 (2) | −0.0096 (18) | −0.0077 (17) | 0.0026 (17) |
O4 | 0.024 (2) | 0.033 (2) | 0.023 (2) | −0.0086 (18) | −0.0099 (17) | 0.0026 (16) |
O5 | 0.031 (2) | 0.033 (2) | 0.034 (2) | −0.0187 (19) | −0.0088 (18) | 0.0037 (18) |
O6 | 0.030 (2) | 0.025 (2) | 0.033 (2) | −0.0074 (19) | −0.0077 (19) | −0.0033 (18) |
O7 | 0.046 (3) | 0.031 (2) | 0.029 (2) | −0.019 (2) | −0.022 (2) | 0.0059 (17) |
O8 | 0.046 (3) | 0.033 (2) | 0.028 (2) | −0.019 (2) | −0.0186 (19) | 0.0117 (18) |
O9 | 0.038 (2) | 0.031 (2) | 0.034 (3) | −0.012 (2) | −0.014 (2) | 0.0011 (19) |
O10 | 0.052 (3) | 0.034 (2) | 0.029 (2) | −0.016 (2) | −0.009 (2) | 0.0044 (19) |
O11 | 0.037 (3) | 0.051 (3) | 0.030 (2) | −0.013 (2) | −0.014 (2) | 0.007 (2) |
O12 | 0.046 (3) | 0.044 (3) | 0.037 (3) | −0.023 (2) | −0.022 (2) | 0.010 (2) |
O13 | 0.046 (3) | 0.045 (3) | 0.034 (3) | −0.026 (2) | −0.009 (2) | 0.002 (2) |
N1 | 0.020 (2) | 0.021 (2) | 0.020 (2) | −0.006 (2) | −0.0075 (19) | 0.0021 (18) |
C1 | 0.022 (3) | 0.022 (3) | 0.027 (3) | −0.007 (2) | −0.011 (2) | 0.001 (2) |
C2 | 0.017 (3) | 0.024 (3) | 0.022 (3) | −0.007 (2) | −0.006 (2) | 0.001 (2) |
C3 | 0.022 (3) | 0.023 (3) | 0.019 (3) | −0.008 (2) | −0.007 (2) | 0.001 (2) |
C4 | 0.030 (3) | 0.020 (3) | 0.021 (3) | −0.011 (3) | −0.011 (3) | 0.005 (2) |
C5 | 0.027 (3) | 0.024 (3) | 0.025 (3) | −0.012 (3) | −0.009 (2) | 0.008 (2) |
C6 | 0.025 (3) | 0.021 (3) | 0.021 (3) | −0.009 (2) | −0.009 (2) | 0.005 (2) |
C7 | 0.031 (3) | 0.028 (3) | 0.020 (3) | −0.014 (3) | −0.015 (3) | 0.010 (2) |
C8 | 0.015 (3) | 0.025 (3) | 0.024 (3) | −0.003 (2) | −0.006 (2) | 0.001 (2) |
C9 | 0.025 (3) | 0.027 (3) | 0.020 (3) | −0.009 (3) | −0.008 (2) | 0.004 (2) |
Cd1—O5i | 2.345 (4) | O7—C9 | 1.256 (7) |
Cd1—N1 | 2.352 (5) | O7—Cd2vii | 2.238 (4) |
Cd1—O4ii | 2.373 (4) | O8—C9 | 1.245 (7) |
Cd1—O1 | 2.423 (4) | O9—H9A | 0.8184 |
Cd1—O6iii | 2.446 (4) | O9—H9B | 0.8182 |
Cd1—O9 | 2.447 (4) | O10—H10A | 0.8210 |
Cd1—O8 | 2.460 (4) | O10—H10B | 0.8221 |
Cd1—O5iii | 2.511 (4) | O11—H11A | 0.8206 |
Cd2—O7iv | 2.238 (4) | O11—H11B | 0.8205 |
Cd2—O3v | 2.304 (4) | O12—H12A | 0.8198 |
Cd2—O11 | 2.325 (4) | O12—H12B | 0.8196 |
Cd2—O12 | 2.325 (4) | O13—H13A | 0.8212 |
Cd2—O10 | 2.344 (4) | O13—H13B | 0.8156 |
Cd2—O3 | 2.389 (4) | N1—C2 | 1.335 (7) |
O1—C1 | 1.258 (7) | N1—C8 | 1.347 (7) |
O2—C1 | 1.246 (7) | C1—C2 | 1.522 (8) |
O3—C4 | 1.279 (6) | C2—C3 | 1.393 (8) |
O3—Cd2v | 2.304 (4) | C3—C5 | 1.384 (8) |
O4—C4 | 1.238 (6) | C3—C4 | 1.511 (7) |
O4—Cd1ii | 2.373 (4) | C5—C6 | 1.390 (8) |
O5—C7 | 1.247 (6) | C5—H5A | 0.9300 |
O5—Cd1i | 2.345 (4) | C6—C8 | 1.386 (8) |
O5—Cd1vi | 2.511 (4) | C6—C7 | 1.513 (8) |
O6—C7 | 1.253 (7) | C8—C9 | 1.497 (8) |
O6—Cd1vi | 2.446 (4) | ||
O5i—Cd1—N1 | 81.77 (14) | C7—O5—Cd1vi | 90.3 (3) |
O5i—Cd1—O4ii | 162.11 (13) | Cd1i—O5—Cd1vi | 112.46 (15) |
N1—Cd1—O4ii | 96.79 (14) | C7—O6—Cd1vi | 93.2 (3) |
O5i—Cd1—O1 | 83.95 (14) | C9—O7—Cd2vii | 101.7 (3) |
N1—Cd1—O1 | 68.07 (14) | C9—O8—Cd1 | 117.7 (3) |
O4ii—Cd1—O1 | 112.19 (13) | Cd1—O9—H9A | 108.1 |
O5i—Cd1—O6iii | 120.12 (13) | Cd1—O9—H9B | 112.7 |
N1—Cd1—O6iii | 138.26 (15) | H9A—O9—H9B | 103.8 |
O4ii—Cd1—O6iii | 72.44 (13) | Cd2—O10—H10A | 116.1 |
O1—Cd1—O6iii | 78.83 (13) | Cd2—O10—H10B | 120.7 |
O5i—Cd1—O9 | 80.08 (14) | H10A—O10—H10B | 93.2 |
N1—Cd1—O9 | 135.63 (15) | Cd2—O11—H11A | 108.3 |
O4ii—Cd1—O9 | 88.89 (13) | Cd2—O11—H11B | 104.7 |
O1—Cd1—O9 | 147.89 (13) | H11A—O11—H11B | 107.4 |
O6iii—Cd1—O9 | 85.37 (14) | Cd2—O12—H12A | 114.3 |
O5i—Cd1—O8 | 86.42 (13) | Cd2—O12—H12B | 108.7 |
N1—Cd1—O8 | 67.71 (14) | H12A—O12—H12B | 106.9 |
O4ii—Cd1—O8 | 76.64 (13) | H13A—O13—H13B | 106.1 |
O1—Cd1—O8 | 135.62 (13) | C2—N1—C8 | 119.9 (5) |
O6iii—Cd1—O8 | 141.20 (13) | C2—N1—Cd1 | 119.9 (3) |
O9—Cd1—O8 | 71.03 (13) | C8—N1—Cd1 | 120.0 (4) |
O5i—Cd1—O5iii | 67.54 (15) | O2—C1—O1 | 126.1 (5) |
N1—Cd1—O5iii | 131.36 (14) | O2—C1—C2 | 116.6 (5) |
O4ii—Cd1—O5iii | 123.59 (13) | O1—C1—C2 | 117.3 (5) |
O1—Cd1—O5iii | 71.84 (13) | N1—C2—C3 | 121.6 (5) |
O6iii—Cd1—O5iii | 52.58 (12) | N1—C2—C1 | 115.4 (5) |
O9—Cd1—O5iii | 76.33 (13) | C3—C2—C1 | 122.9 (5) |
O8—Cd1—O5iii | 141.20 (13) | C5—C3—C2 | 118.5 (5) |
O7iv—Cd2—O3v | 108.53 (14) | C5—C3—C4 | 117.7 (5) |
O7iv—Cd2—O11 | 84.78 (15) | C2—C3—C4 | 123.8 (5) |
O3v—Cd2—O11 | 166.47 (14) | O4—C4—O3 | 124.7 (5) |
O7iv—Cd2—O12 | 123.72 (14) | O4—C4—C3 | 118.6 (5) |
O3v—Cd2—O12 | 85.24 (14) | O3—C4—C3 | 116.5 (5) |
O11—Cd2—O12 | 89.31 (16) | C3—C5—C6 | 119.9 (5) |
O7iv—Cd2—O10 | 82.08 (15) | C3—C5—H5A | 120.1 |
O3v—Cd2—O10 | 88.22 (14) | C6—C5—H5A | 120.0 |
O11—Cd2—O10 | 91.34 (15) | C8—C6—C5 | 118.4 (5) |
O12—Cd2—O10 | 154.12 (15) | C8—C6—C7 | 125.1 (5) |
O7iv—Cd2—O3 | 158.25 (13) | C5—C6—C7 | 116.5 (5) |
O3v—Cd2—O3 | 77.03 (14) | O5—C7—O6 | 122.9 (5) |
O11—Cd2—O3 | 89.69 (14) | O5—C7—C6 | 117.8 (5) |
O12—Cd2—O3 | 77.11 (14) | O6—C7—C6 | 118.9 (5) |
O10—Cd2—O3 | 77.03 (14) | N1—C8—C6 | 121.7 (5) |
C1—O1—Cd1 | 119.3 (3) | N1—C8—C9 | 115.2 (5) |
C4—O3—Cd2v | 130.9 (4) | C6—C8—C9 | 123.1 (5) |
C4—O3—Cd2 | 124.4 (3) | O8—C9—O7 | 123.7 (5) |
Cd2v—O3—Cd2 | 102.97 (14) | O8—C9—C8 | 119.2 (5) |
C4—O4—Cd1ii | 129.4 (3) | O7—C9—C8 | 117.1 (5) |
C7—O5—Cd1i | 156.7 (4) |
Symmetry codes: (i) −x+2, −y+1, −z+2; (ii) −x+1, −y+1, −z+2; (iii) x, y−1, z; (iv) x, y, z−1; (v) −x+2, −y+1, −z+1; (vi) x, y+1, z; (vii) x, y, z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O9—H9B···O12vii | 0.82 | 2.17 | 2.946 (6) | 158.6 |
O9—H9A···O1viii | 0.82 | 2.06 | 2.872 (5) | 169.9 |
O10—H10A···O9ix | 0.82 | 2.11 | 2.912 (6) | 164.3 |
O10—H10B···O13 | 0.82 | 1.91 | 2.707 (6) | 164.3 |
O11—H11A···O13x | 0.82 | 2.00 | 2.765 (6) | 154.1 |
O11—H11B···O4 | 0.82 | 1.94 | 2.686 (6) | 150.6 |
O12—H12A···O10v | 0.82 | 2.14 | 2.892 (6) | 151.7 |
O12—H12A···O2 | 0.82 | 2.48 | 2.975 (6) | 119.7 |
O12—H12B···O11xi | 0.82 | 2.12 | 2.870 (6) | 151.5 |
O13—H13A···O6xii | 0.82 | 1.91 | 2.728 (6) | 174.0 |
O13—H13B···O2vi | 0.82 | 1.93 | 2.730 (6) | 167.9 |
Symmetry codes: (v) −x+2, −y+1, −z+1; (vi) x, y+1, z; (vii) x, y, z+1; (viii) −x+2, −y, −z+2; (ix) x, y+1, z−1; (x) −x+1, −y+2, −z+1; (xi) −x+1, −y+1, −z+1; (xii) −x+1, −y+2, −z+2. |
Experimental details
Crystal data | |
Chemical formula | [Cd2(C9HNO8)(H2O)4]·H2O |
Mr | 565.99 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 8.3989 (5), 8.5350 (3), 11.4883 (5) |
α, β, γ (°) | 89.325 (4), 69.014 (5), 67.269 (4) |
V (Å3) | 701.48 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.11 |
Crystal size (mm) | 0.18 × 0.12 × 0.09 |
Data collection | |
Diffractometer | Oxford Xcalibur, Atlas, Gemini Ultra diffractometer |
Absorption correction | Analytical (CrysAlis PRO; Oxford Diffraction, 2010) |
Tmin, Tmax | 0.645, 0.756 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4815, 2650, 2181 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.609 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.044, 1.07 |
No. of reflections | 2650 |
No. of parameters | 226 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.68, −0.87 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).
Cd1—O5i | 2.345 (4) | Cd1—O5iii | 2.511 (4) |
Cd1—N1 | 2.352 (5) | Cd2—O7iv | 2.238 (4) |
Cd1—O4ii | 2.373 (4) | Cd2—O3v | 2.304 (4) |
Cd1—O1 | 2.423 (4) | Cd2—O11 | 2.325 (4) |
Cd1—O6iii | 2.446 (4) | Cd2—O12 | 2.325 (4) |
Cd1—O9 | 2.447 (4) | Cd2—O10 | 2.344 (4) |
Cd1—O8 | 2.460 (4) | Cd2—O3 | 2.389 (4) |
O5i—Cd1—N1 | 81.77 (14) | O6iii—Cd1—O5iii | 52.58 (12) |
N1—Cd1—O1 | 68.07 (14) | O9—Cd1—O5iii | 76.33 (13) |
O4ii—Cd1—O6iii | 72.44 (13) | O7iv—Cd2—O11 | 84.78 (15) |
O1—Cd1—O6iii | 78.83 (13) | O3v—Cd2—O12 | 85.24 (14) |
N1—Cd1—O8 | 67.71 (14) | O7iv—Cd2—O10 | 82.08 (15) |
O4ii—Cd1—O8 | 76.64 (13) | O3v—Cd2—O3 | 77.03 (14) |
O9—Cd1—O8 | 71.03 (13) | O12—Cd2—O3 | 77.11 (14) |
O5i—Cd1—O5iii | 67.54 (15) | O10—Cd2—O3 | 77.03 (14) |
O1—Cd1—O5iii | 71.84 (13) |
Symmetry codes: (i) −x+2, −y+1, −z+2; (ii) −x+1, −y+1, −z+2; (iii) x, y−1, z; (iv) x, y, z−1; (v) −x+2, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O9—H9B···O12vi | 0.82 | 2.17 | 2.946 (6) | 158.6 |
O9—H9A···O1vii | 0.82 | 2.06 | 2.872 (5) | 169.9 |
O10—H10A···O9viii | 0.82 | 2.11 | 2.912 (6) | 164.3 |
O10—H10B···O13 | 0.82 | 1.91 | 2.707 (6) | 164.3 |
O11—H11A···O13ix | 0.82 | 2.00 | 2.765 (6) | 154.1 |
O11—H11B···O4 | 0.82 | 1.94 | 2.686 (6) | 150.6 |
O12—H12A···O10v | 0.82 | 2.14 | 2.892 (6) | 151.7 |
O12—H12A···O2 | 0.82 | 2.48 | 2.975 (6) | 119.7 |
O12—H12B···O11x | 0.82 | 2.12 | 2.870 (6) | 151.5 |
O13—H13A···O6xi | 0.82 | 1.91 | 2.728 (6) | 174.0 |
O13—H13B···O2xii | 0.82 | 1.93 | 2.730 (6) | 167.9 |
Symmetry codes: (v) −x+2, −y+1, −z+1; (vi) x, y, z+1; (vii) −x+2, −y, −z+2; (viii) x, y+1, z−1; (ix) −x+1, −y+2, −z+1; (x) −x+1, −y+1, −z+1; (xi) −x+1, −y+2, −z+2; (xii) x, y+1, z. |
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In the past few years, crystal engineering of porous metal–organic coordination networks has attracted much attention because of their interesting structural patterns with both aesthetic appeal and special functionalities for potential applications (Czaja et al., 2009; Lee et al., 2009; Li et al., 2009; Ma et al., 2009; Murray et al., 2009; Tranchemontagne et al., 2009; Wang & Cohen, 2009). It has been shown that judicious choice of organic bridging ligands and metal nodes is the key step towards the construction of interesting topological frameworks.
Pyridine-2,3,5,6-tetracarboxylic acid (H4pdtc), which contains one pyridine and four carboxylate potential donor groups, should be an effective ligand for coordinating to transition metal cations to generate some interesting structural networks (Babu & Nangia, 2006). However, only two pdtc ligand coordinated compounds have been reported to date, a tetranuclear zinc(II) compound bridged by two pdtc anions, and a mononuclear nickel(II) compound chelated by pdtc (Yang et al., 2008). In the former case, because the additional coordination sites of the Zn cations are blocked by four chelating 1,10-phenanthroline molecules, the tetranuclear Zn unit cannot be further bridged by additional pdtc ligands to form a polymeric framework. In the latter case, as three water coordination sites of the Ni cation are not replaced by additional pdtc ligands, the pdtc ligand only chelates one Ni cation to form a mononuclear nickel(II) compound.
Because of the relatively large ionic radius of the CdII cation, its coordination numbers in O-donor complexes typically range from 6 to 8, which suggests that cadmium compounds should form some interesting three-dimensional frameworks (Wang et al., 2007). In fact, there are several examples of three-dimensional frameworks of CdII cations bridged by pyridine carboxylates, such as pyridine-3,4-dicarboxylate (Xia et al., 2004), pyridine-2,4-dicarboxylate (Bai et al., 2008), pyridine-2,3-dicarboxylate (Zhang et al., 2005; Han et al., 2006) and pyridine-2,4,6-tricarboxylate (Wang et al., 2007; Zou et al., 2008). Attracted by the interesting structural motifs of these pyridine carboxylate-bridged cadmium compounds, we anticipated that pdtc would be an effective bridging ligand to generate a novel structural network. We report here the first three-dimensional porous polymeric framework compound based on the pdtc ligand, the title compound, [Cd2(pdtc)(H2O)4].H2O, (I).
Compound (I) crystallizes in the triclinic P1 space group with two CdII cations, one fully deprotonated pdtc4- anion, four aqua ligands and one solvent water molecule in the asymmetric unit (Fig. 1). Each pdtc ligand employs its pyridine group and carboxylate groups to chelate and bridge seven CdII cations. Atom Cd1 is chelated by the pyridine group and two neighbouring carboxyl O atoms from the first pdtc ligand, two O atoms of a carboxylate group from a second pdtc ligand, one carboxyl O atom from a third pdtc ligand, a µ2 carboxyl O atom from a fourth pdtc ligand and one aqua ligand, in an octa-coordinated distorted square-antiprismatic coordination environment (Table 1).
The pdtc ligands link the Cd1 cations into an interesting lamellar framework structure in the ab plane (Fig. 2). Atom Cd2 has a hexa-coordinated octahedral geometry, chelated by two O atoms of one pdtc carboxylate group, one µ2 carboxyl O atom of another pdtc ligand and three aqua ligands (Table 1). There is one additional interaction, Cd2–O8v = 2.676 (4) Å [symmetry code: (v) x, y, z - 1], but this is outside the typical range of 2.1–2.4 Å for Cd—O coordination (Standard reference?). The µ2 carboxyl O atom bridges two Cd2 sites into a binuclear unit, which is further doubly bridged by pdtc ligands into a chain network along the c direction (Fig. 3). As the alternating pdtc ligands along c are attributed to different layers of pdtc linking up Cd1 sites, the Cd2 sites serve to join neighbouring lamellar Cd1–pdtc frameworks into a three-dimensional porous network structure (Fig. 4). The cavities are filled with solvent water molecules that interact with the host framework through hydrogen bonding. The hydrogen-bond distances between solvent water molecules and carboxyl O atoms range from 2.728 (6) to 2.730 (6) Å, and those between solvent water molecules and aqua ligands from 2.707 (6) to 2.765 (6) Å. Finally, there are also extensive hydrogen bonds between aqua ligands and carboxyl O atoms [2.686 (6)–2.975 (6) Å] and between aqua ligands themselves [2.870 (6)–2.946 (6) Å].
The framework structure of (I) is quite different from previously reported three-dimensional compounds bridged by pyridine dicarboxylates. For example, pyridine-3,4-dicarboxylate acts a tetradentate ligand to link four octahedrally distorted CdII cations into a three-dimensional architecture with small square channels without guest molecules (Xia et al., 2004). The pyridine-2,4-dicarboxylate ligand acts as a pentadentate ligand to link five octahedral CdII cations into a three-dimensional framework with large channels occupied by the pyridine groups of the ligands (Bai et al., 2008), while pyridine-2,3-dicarboxylate, adopting two different coordination modes, bridges CdII tetramers into a three-dimensional network without guest molecules (Han et al., 2006). The three-dimensional framework of pyridine-2,4,6-tricarboxylate-bridged CdII cations is similar to (I) in that there are two different types of CdII cations in distorted octahedral and pentagonal–bipyramidal coordination environments. Pyridine-2,4,6-tricarboxylate bridges the pentagonal–bipyramidal coordinated CdII cations into a two-dimensional layer structure, which is further extended into a three-dimensional network linked by the octahedrally coordinated CdII cations and carboxyl groups without guest molecules within the cavities thus formed (Wang et al., 2007).
Thermogravimetric analysis (TGA) of (I) indicates that a weight loss of 15.7% occurs between 303 and 433 K, corresponding to the loss of solvent water molecules and aqua ligands (expected 15.9%), without a distinct plateau in the curve. There is almost no further weight loss until 683 K, above which (I) began to lose the coordinated pdtc ligand and to decompose. After a sample of (I) was ground and heated at 368 K for 2 h, a powder X-ray diffraction (PXRD) profile of the resultant powder showed no sharp peaks in the PXRD pattern, and this material cannot be rehydrated and reverted to the original compound after being immersed in water, as confirmed by the PXRD pattern. These results indicate that both the solvent H2O and aqua ligands play important roles in the formation and stability of (I).