Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109030893/sf3111sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270109030893/sf3111Isup2.hkl |
CCDC reference: 749694
For related literature, see: Bauer et al. (2005); Burkholder et al. (2004); Cheetham et al. (1999); Clearfield (1998); Serpaggi & Férey (1999); Stock (2002); Stock et al. (2000a, 2000b); Tang et al. (2006); Yang et al. (2005); Ying et al. (2006, 2008a, 2008b); Zheng et al. (2002).
The phosphonic acid ligand was synthesized by a Mannich-type reaction according to previously reported procedures (Ying, Li et al., 2008). The title compound was synthesized as follows: a mixture of cadmium acetate (0.5 mmol, 0.130 g) and 6-carboxyl dimethylphosphonoaminohexane (0.5 mmol, 0.078 g) in distilled water (15 ml) was sealed in an autoclave equipped with a Teflon liner (20 ml) and then heated at 423 K 150°C for 4 d. Crystals of the title compound (colorless blocks) were obtained. Analysis found: C 25.62, H 4.87, N 3.70%; calculated for C16H36CdN2O16P4 (Mr = 748.75): C 25.64, H 4.81, N 3.74%. IR data (KBr, cm-1): 3436 (m), 3106 (s), 2960 (s), 1712 (m), 1677 (m), 1472 (m), 1437 (m), 1419 (m), 1375 (w), 1325 (s), 1290 (m), 1259 (s), 1235 (s), 1158 (s), 1083 (s), 1049 (s), 970 (m), 931 (s), 792 (m), 771 (m), 734 (m), 582 (s), 570 (s), 533 (m), 469 (s).
All the H atoms were positioned geometrically (C—H = 0.97 Å [please check change], O—H = 0.82 Å and N—H = 0.91 Å) and refined in the riding-model approximation [Uiso(H) = 1.2Ueq(C), 1.5Ueq(O) and 1.2Ueq(N), respectively].
Data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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).
[Cd(C8H18NO8P2)2] | F(000) = 764 |
Mr = 748.75 | Dx = 1.795 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 4271 reflections |
a = 15.4321 (17) Å | θ = 2.6–28.4° |
b = 9.4632 (11) Å | µ = 1.10 mm−1 |
c = 9.9958 (11) Å | T = 273 K |
β = 108.414 (2)° | Block, colourless |
V = 1385.0 (3) Å3 | 0.23 × 0.11 × 0.07 mm |
Z = 2 |
Bruker SMART CCD area-detector diffractometer | 3219 independent reflections |
Radiation source: sealed tube | 2092 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.095 |
ω scans | θmax = 28.0°, θmin = 2.6° |
Absorption correction: multi-scan (North et al., 1968) | h = −19→20 |
Tmin = 0.787, Tmax = 0.927 | k = −12→12 |
10035 measured reflections | l = −13→13 |
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)] = 0.038 | H-atom parameters constrained |
wR(F2) = 0.089 | w = 1/[σ2(Fo2) + (0.0307P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.87 | (Δ/σ)max = 0.025 |
3219 reflections | Δρmax = 1.27 e Å−3 |
179 parameters | Δρmin = −1.20 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0019 (6) |
[Cd(C8H18NO8P2)2] | V = 1385.0 (3) Å3 |
Mr = 748.75 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 15.4321 (17) Å | µ = 1.10 mm−1 |
b = 9.4632 (11) Å | T = 273 K |
c = 9.9958 (11) Å | 0.23 × 0.11 × 0.07 mm |
β = 108.414 (2)° |
Bruker SMART CCD area-detector diffractometer | 3219 independent reflections |
Absorption correction: multi-scan (North et al., 1968) | 2092 reflections with I > 2σ(I) |
Tmin = 0.787, Tmax = 0.927 | Rint = 0.095 |
10035 measured reflections |
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.089 | H-atom parameters constrained |
S = 0.87 | Δρmax = 1.27 e Å−3 |
3219 reflections | Δρmin = −1.20 e Å−3 |
179 parameters |
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 | 0.50000 | 0.50000 | 0.50000 | 0.0196 (1) | |
P1 | 0.54772 (7) | 0.22584 (10) | 0.30183 (9) | 0.0195 (3) | |
P2 | 0.28670 (7) | 0.37672 (10) | 0.28853 (9) | 0.0225 (3) | |
O1 | 0.64054 (17) | 0.1664 (3) | 0.4018 (2) | 0.0304 (9) | |
O2 | 0.54124 (18) | 0.3807 (2) | 0.3314 (2) | 0.0237 (8) | |
O3 | 0.53347 (18) | 0.1894 (2) | 0.1498 (2) | 0.0234 (8) | |
O4 | 0.35878 (17) | 0.4086 (3) | 0.4253 (2) | 0.0254 (8) | |
O5 | 0.25164 (17) | 0.4939 (3) | 0.1826 (3) | 0.0281 (8) | |
O6 | 0.20569 (18) | 0.3046 (3) | 0.3272 (3) | 0.0292 (9) | |
O7 | −0.0707 (2) | −0.2723 (4) | −0.0944 (3) | 0.0566 (11) | |
O8 | −0.0987 (2) | −0.4438 (3) | 0.0386 (3) | 0.0432 (10) | |
N1 | 0.3714 (2) | 0.1136 (3) | 0.2475 (3) | 0.0208 (10) | |
C1 | −0.0510 (3) | −0.3361 (5) | 0.0160 (4) | 0.0345 (14) | |
C2 | 0.0311 (3) | −0.2982 (4) | 0.1398 (4) | 0.0359 (16) | |
C3 | 0.0928 (3) | −0.1931 (5) | 0.1017 (5) | 0.0450 (16) | |
C4 | 0.1750 (3) | −0.1464 (4) | 0.2229 (4) | 0.0338 (14) | |
C5 | 0.2295 (3) | −0.0338 (4) | 0.1772 (4) | 0.0334 (14) | |
C6 | 0.3099 (3) | 0.0162 (4) | 0.2971 (4) | 0.0264 (11) | |
C7 | 0.4626 (2) | 0.1307 (4) | 0.3586 (3) | 0.0228 (11) | |
C8 | 0.3269 (3) | 0.2506 (4) | 0.1845 (3) | 0.0235 (11) | |
H1A | 0.66400 | 0.11530 | 0.35660 | 0.0460* | |
H2A | 0.01060 | −0.25900 | 0.21430 | 0.0430* | |
H2B | 0.06560 | −0.38340 | 0.17590 | 0.0430* | |
H3A | 0.05700 | −0.11010 | 0.06160 | 0.0540* | |
H3B | 0.11430 | −0.23430 | 0.02910 | 0.0540* | |
H4A | 0.21390 | −0.22740 | 0.25900 | 0.0400* | |
H4B | 0.15450 | −0.10970 | 0.29840 | 0.0400* | |
H5A | 0.25100 | −0.07150 | 0.10320 | 0.0400* | |
H5B | 0.19000 | 0.04590 | 0.13860 | 0.0400* | |
H6A | 0.34490 | −0.06490 | 0.34400 | 0.0320* | |
H6B | 0.28800 | 0.06570 | 0.36520 | 0.0320* | |
H6C | 0.16230 | 0.29340 | 0.25530 | 0.0440* | |
H7A | 0.48650 | 0.03770 | 0.39100 | 0.0270* | |
H7B | 0.45390 | 0.18030 | 0.43830 | 0.0270* | |
H8A | 0.27500 | 0.22640 | 0.10340 | 0.0280* | |
H8B | 0.37010 | 0.30000 | 0.14880 | 0.0280* | |
H8C | −0.14410 | −0.45530 | −0.03040 | 0.0650* | |
H10A | 0.38300 | 0.06690 | 0.17540 | 0.0250* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.0282 (2) | 0.0200 (2) | 0.0109 (2) | −0.0013 (2) | 0.0068 (1) | −0.0003 (2) |
P1 | 0.0267 (6) | 0.0200 (5) | 0.0118 (4) | −0.0004 (4) | 0.0062 (4) | −0.0013 (4) |
P2 | 0.0238 (6) | 0.0244 (5) | 0.0186 (5) | −0.0021 (4) | 0.0057 (4) | −0.0006 (4) |
O1 | 0.0291 (17) | 0.0404 (16) | 0.0194 (13) | 0.0078 (13) | 0.0043 (12) | −0.0015 (12) |
O2 | 0.0397 (17) | 0.0198 (13) | 0.0146 (12) | −0.0027 (12) | 0.0127 (11) | −0.0045 (10) |
O3 | 0.0382 (17) | 0.0225 (13) | 0.0110 (11) | −0.0031 (12) | 0.0099 (11) | −0.0029 (10) |
O4 | 0.0253 (15) | 0.0298 (14) | 0.0200 (13) | −0.0043 (12) | 0.0058 (11) | −0.0015 (11) |
O5 | 0.0259 (15) | 0.0256 (13) | 0.0294 (13) | 0.0001 (13) | 0.0040 (11) | 0.0043 (12) |
O6 | 0.0237 (16) | 0.0382 (16) | 0.0250 (14) | −0.0051 (13) | 0.0069 (12) | 0.0003 (12) |
O7 | 0.049 (2) | 0.070 (2) | 0.0376 (18) | −0.0267 (18) | −0.0053 (16) | 0.0209 (17) |
O8 | 0.0386 (19) | 0.0468 (17) | 0.0357 (16) | −0.0179 (15) | −0.0004 (14) | 0.0048 (15) |
N1 | 0.0268 (19) | 0.0213 (16) | 0.0153 (14) | −0.0028 (14) | 0.0080 (13) | −0.0033 (13) |
C1 | 0.028 (3) | 0.039 (2) | 0.037 (2) | −0.008 (2) | 0.011 (2) | −0.006 (2) |
C2 | 0.034 (3) | 0.043 (3) | 0.029 (2) | −0.009 (2) | 0.0077 (19) | −0.005 (2) |
C3 | 0.038 (3) | 0.051 (3) | 0.040 (2) | −0.016 (2) | 0.004 (2) | 0.000 (2) |
C4 | 0.034 (3) | 0.036 (2) | 0.033 (2) | −0.004 (2) | 0.013 (2) | −0.0059 (19) |
C5 | 0.031 (3) | 0.033 (2) | 0.033 (2) | −0.0064 (18) | 0.0057 (19) | −0.0019 (18) |
C6 | 0.028 (2) | 0.028 (2) | 0.0255 (18) | −0.0044 (18) | 0.0117 (16) | −0.0035 (17) |
C7 | 0.032 (2) | 0.0206 (19) | 0.0136 (17) | 0.0003 (17) | 0.0039 (16) | 0.0001 (15) |
C8 | 0.025 (2) | 0.029 (2) | 0.0174 (18) | 0.0005 (17) | 0.0081 (16) | 0.0016 (16) |
Cd1—O2 | 2.280 (2) | N1—C8 | 1.509 (5) |
Cd1—O3i | 2.2875 (19) | N1—H10A | 0.9100 |
Cd1—O4 | 2.242 (3) | C1—C2 | 1.508 (6) |
Cd1—O2ii | 2.280 (2) | C2—C3 | 1.507 (6) |
Cd1—O4ii | 2.242 (3) | C3—C4 | 1.517 (6) |
Cd1—O3iii | 2.2875 (19) | C4—C5 | 1.515 (6) |
P1—O1 | 1.569 (3) | C5—C6 | 1.503 (6) |
P1—O2 | 1.505 (2) | C2—H2A | 0.9700 |
P1—O3 | 1.505 (2) | C2—H2B | 0.9700 |
P1—C7 | 1.825 (4) | C3—H3A | 0.9700 |
P2—O4 | 1.496 (2) | C3—H3B | 0.9700 |
P2—O5 | 1.511 (3) | C4—H4A | 0.9700 |
P2—O6 | 1.576 (3) | C4—H4B | 0.9700 |
P2—C8 | 1.816 (4) | C5—H5A | 0.9700 |
O7—C1 | 1.210 (5) | C5—H5B | 0.9700 |
O8—C1 | 1.318 (6) | C6—H6A | 0.9700 |
O1—H1A | 0.8200 | C6—H6B | 0.9700 |
O6—H6C | 0.8200 | C7—H7A | 0.9700 |
O8—H8C | 0.8200 | C7—H7B | 0.9700 |
N1—C6 | 1.514 (5) | C8—H8A | 0.9700 |
N1—C7 | 1.501 (4) | C8—H8B | 0.9700 |
O2—Cd1—O4 | 91.82 (9) | C3—C4—C5 | 111.6 (3) |
O2—Cd1—O3i | 87.83 (7) | C4—C5—C6 | 112.2 (3) |
O2—Cd1—O4ii | 88.18 (9) | N1—C6—C5 | 112.0 (3) |
O2—Cd1—O3iii | 92.17 (7) | P1—C7—N1 | 115.0 (2) |
O3i—Cd1—O4 | 95.14 (9) | P2—C8—N1 | 121.2 (2) |
O2ii—Cd1—O4 | 88.18 (9) | C1—C2—H2A | 109.00 |
O3iii—Cd1—O4 | 84.86 (9) | C1—C2—H2B | 109.00 |
O2ii—Cd1—O3i | 92.17 (7) | C3—C2—H2A | 109.00 |
O3i—Cd1—O4ii | 84.86 (9) | C3—C2—H2B | 109.00 |
O2ii—Cd1—O4ii | 91.82 (9) | H2A—C2—H2B | 108.00 |
O2ii—Cd1—O3iii | 87.83 (7) | C2—C3—H3A | 108.00 |
O3iii—Cd1—O4ii | 95.14 (9) | C2—C3—H3B | 108.00 |
O1—P1—O2 | 109.15 (15) | C4—C3—H3A | 108.00 |
O1—P1—O3 | 111.94 (14) | C4—C3—H3B | 108.00 |
O1—P1—C7 | 103.13 (15) | H3A—C3—H3B | 108.00 |
O2—P1—O3 | 115.08 (12) | C3—C4—H4A | 109.00 |
O2—P1—C7 | 108.69 (16) | C3—C4—H4B | 109.00 |
O3—P1—C7 | 108.12 (15) | C5—C4—H4A | 109.00 |
O4—P2—O5 | 119.41 (16) | C5—C4—H4B | 109.00 |
O4—P2—O6 | 106.36 (15) | H4A—C4—H4B | 108.00 |
O4—P2—C8 | 111.47 (17) | C4—C5—H5A | 109.00 |
O5—P2—O6 | 110.71 (16) | C4—C5—H5B | 109.00 |
O5—P2—C8 | 101.10 (16) | C6—C5—H5A | 109.00 |
O6—P2—C8 | 107.26 (18) | C6—C5—H5B | 109.00 |
Cd1—O2—P1 | 132.76 (13) | H5A—C5—H5B | 108.00 |
Cd1iv—O3—P1 | 140.46 (12) | N1—C6—H6A | 109.00 |
Cd1—O4—P2 | 138.27 (14) | N1—C6—H6B | 109.00 |
P1—O1—H1A | 109.00 | C5—C6—H6A | 109.00 |
P2—O6—H6C | 109.00 | C5—C6—H6B | 109.00 |
C1—O8—H8C | 109.00 | H6A—C6—H6B | 108.00 |
C7—N1—C8 | 114.4 (3) | P1—C7—H7A | 108.00 |
C6—N1—C8 | 114.2 (3) | P1—C7—H7B | 108.00 |
C6—N1—C7 | 111.2 (3) | N1—C7—H7A | 109.00 |
C8—N1—H10A | 105.00 | N1—C7—H7B | 109.00 |
C7—N1—H10A | 105.00 | H7A—C7—H7B | 108.00 |
C6—N1—H10A | 105.00 | P2—C8—H8A | 107.00 |
O8—C1—C2 | 114.4 (3) | P2—C8—H8B | 107.00 |
O7—C1—C2 | 122.3 (4) | N1—C8—H8A | 107.00 |
O7—C1—O8 | 123.3 (4) | N1—C8—H8B | 107.00 |
C1—C2—C3 | 112.6 (3) | H8A—C8—H8B | 107.00 |
C2—C3—C4 | 115.2 (4) | ||
O1—P1—C7—N1 | −153.6 (2) | C8—N1—C7—P1 | −56.9 (3) |
O2—P1—C7—N1 | 90.7 (3) | C6—N1—C8—P2 | 62.3 (4) |
O3—P1—C7—N1 | −34.9 (3) | C7—N1—C8—P2 | −67.5 (4) |
O4—P2—C8—N1 | 50.4 (4) | O7—C1—C2—C3 | −10.3 (6) |
O5—P2—C8—N1 | 178.4 (3) | O8—C1—C2—C3 | 169.6 (4) |
O6—P2—C8—N1 | −65.7 (4) | C1—C2—C3—C4 | 177.9 (4) |
C7—N1—C6—C5 | −164.5 (3) | C2—C3—C4—C5 | −176.2 (4) |
C8—N1—C6—C5 | 64.2 (4) | C3—C4—C5—C6 | 178.6 (4) |
C6—N1—C7—P1 | 171.9 (2) | C4—C5—C6—N1 | 172.2 (3) |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) −x+1, −y+1, −z+1; (iii) x, −y+1/2, z+1/2; (iv) −x+1, y−1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···O5iv | 0.82 | 1.87 | 2.652 (4) | 159 |
O6—H6C···O7v | 0.82 | 1.79 | 2.605 (4) | 178 |
O8—H8C···O5v | 0.82 | 1.90 | 2.718 (4) | 176 |
N1—H10A···O2iv | 0.91 | 2.13 | 2.823 (4) | 132 |
N1—H10A···O4vi | 0.91 | 2.42 | 3.172 (4) | 140 |
C4—H4B···O8vii | 0.97 | 2.60 | 3.538 (5) | 163 |
C6—H6B···O6 | 0.97 | 2.56 | 3.230 (5) | 126 |
C7—H7A···O2iv | 0.97 | 2.59 | 3.023 (4) | 107 |
C7—H7B···O4 | 0.97 | 2.59 | 3.256 (5) | 126 |
C7—H7B···O3iii | 0.97 | 2.42 | 3.249 (4) | 143 |
Symmetry codes: (iii) x, −y+1/2, z+1/2; (iv) −x+1, y−1/2, −z+1/2; (v) −x, −y, −z; (vi) x, −y+1/2, z−1/2; (vii) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Cd(C8H18NO8P2)2] |
Mr | 748.75 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 273 |
a, b, c (Å) | 15.4321 (17), 9.4632 (11), 9.9958 (11) |
β (°) | 108.414 (2) |
V (Å3) | 1385.0 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.10 |
Crystal size (mm) | 0.23 × 0.11 × 0.07 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (North et al., 1968) |
Tmin, Tmax | 0.787, 0.927 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10035, 3219, 2092 |
Rint | 0.095 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.089, 0.87 |
No. of reflections | 3219 |
No. of parameters | 179 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.27, −1.20 |
Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
Cd1—O2 | 2.280 (2) | Cd1—O4 | 2.242 (3) |
Cd1—O3i | 2.2875 (19) | ||
O2—Cd1—O4 | 91.82 (9) | O2—Cd1—O4ii | 88.18 (9) |
O2—Cd1—O3i | 87.83 (7) |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···O5iii | 0.8200 | 1.8700 | 2.652 (4) | 159 |
O6—H6C···O7iv | 0.8200 | 1.7900 | 2.605 (4) | 178 |
O8—H8C···O5iv | 0.8200 | 1.9000 | 2.718 (4) | 176 |
N1—H10A···O2iii | 0.9100 | 2.1300 | 2.823 (4) | 132 |
N1—H10A···O4v | 0.9100 | 2.4200 | 3.172 (4) | 140 |
Symmetry codes: (iii) −x+1, y−1/2, −z+1/2; (iv) −x, −y, −z; (v) x, −y+1/2, z−1/2. |
Subscribe to Acta Crystallographica Section C: Structural Chemistry
The full text of this article is available to subscribers to the journal.
- Information on subscribing
- Sample issue
- Purchase subscription
- Reduced-price subscriptions
- If you have already subscribed, you may need to register
In recent years, the chemistry of metal phosphonates has been an active research area owing to their potential applications in the area of catalysis, ion exchange, proton conductivity, surface modification, intercalation chemistry, photochemistry and materials chemistry (Clearfield 1998). Metal phosphonates can exhibit structural types such as zero-dimensional (Ying, Chen et al., 2008), one-dimensional chain (Yang et al., 2005), two-dimensional layered (Zheng et al., 2002) or three-dimensional microporous (Burkholder et al., 2004). It has been proved that attaching an additional functional group, such as carboxyl, hydroxy, amine or crown ether groups, to the phosphonic acid is a very useful method for building open-framework structures (Cheetham et al., 1999; Stock, Frey et al., 2000; Serpaggi & Férey, 1999; Ying et al., 2006). Amongst these functional groups, the carboxyl group has been used widely because of its coordination ability. Phosphonic acids such as HOOC–R–PO3H2, HOOC–RN–(CH2PO3H2)2 and HOOC–RNHCH2PO3H2, which contain only one carboxylate group, have been used extensively (Bauer et al., 2005; Tang et al., 2006; Stock, 2002; Stock, Stucky & Cheetham, 2000; Zhang et al., 2005). Amongst these three types of phosphonic acid ligand, several metal phosphonates of the form HOOC–RN–(CH2PO3H2)2 have been reported (Bauer et al., 2005; Tang et al., 2006), but to the best of our knowledge, metal phosphonates of the form HOOC–(CH2)5–N(CH2PO3H2)2 are rare. The only example, namely, Pb2[O2C(CH2)5N(CH2PO3)(CH2PO3H)] has been reported by our group recently (Ying, Li et al., 2008). This compound exhibits a three-dimensional structure and the metal ions are five-coordinate. Transition metal phosphonates formed by this ligand have not been reported before. Hydrothermal reactions of CdII acetate and HOOC–(CH2)5–N(CH2PO3H2)2 resulted in the title compound, (I). We report here its synthesis, characterization and crystal structure.
As shown in Fig. 1, in the title compound, the cadmium(II) ions, which reside on centres of symmetry are coordinated by six O atoms from four phosphonate ligands (O2, O4, O2A, O4A, O3C and O3B). The Cd—O distances range from 2.242 (2) to 2.287 (2) Å (Table 1). The cadmium(II) ions exhibit a distorted octahedral coordination geometry. The phosphonate anion chelates the CdII ion in a bidentate fashion, and also forms a bridge to second CdII ion. The amine group and carboxyl group of the ligand remain non-coordinated. The cross-linkage of CdO6 octahedra by bridging phosphonate ligands results in a cadmium(II) phosphonate layer (Fig. 2). Within the layer, there is a 16-membered ring made up of four (Cd—O2—P1—O3–) sequences. If, for the purposes of classifying the net, we define the chelate ring as a single point of connection to Cd (making each ligand effectively a single linker), so that all Cd atoms can be defined as four-connected nodes, then the layer can be described as a (4,4) grid. Within the layer there is a single hydrogen bond (Table 2). The uncoordinated carboxylate group at the end of the hydrocarbon arm of the molecule penetrates the adjacent layer to form a double hydrogen-bonded CO2H···HO2P motif (Fig. 3 and Table 2).