Buy article online - an online subscription or single-article purchase is required to access this article.
In the title compound, [Cd(C
8H
4O
4)(C
10H
8N
2O
2)(H
2O)]
n, (I), each Cd
II atom is seven-coordinated in a distorted monocapped trigonal prismatic coordination geometry, surrounded by four carboxylate O atoms from two different benzene-1,4-dicarboxylate (1,4-bdc) anions, two O atoms from two distinct 4,4'-bipyridine
N,
N'-dioxide (bpdo) ligands and one water O atom. The Cd
II atom and the water O atom are on a twofold rotation axis. The bpdo and 1,4-bdc ligands are on centers of inversion. Each crystallographically unique Cd
II center is bridged by the 1,4-bdc dianions and bpdo ligands to give a three-dimensional diamond framework containing large adamantanoid cages. Three identical such nets are interlocked with each other, thus directly leading to the formation of a threefold interpenetrated three-dimensional diamond architecture. To the best of our knowledge, (I) is the first example of a threefold interpenetrating diamond net based on both bpdo and carboxylate ligands. There are strong linear O-H
O hydrogen bonds between the water molecules and carboxylate O atoms within different diamond nets. Each diamond net is hydrogen bonded to its two neighbors through these hydrogen bonds, which further consolidates the threefold interpenetrating diamond framework.
Supporting information
CCDC reference: 790626
A mixture of CdCl2.2.5H2O (0.5 mmol), 1,4-H2bdc (0.5 mmol) and bpdo (0.5 mmol) was dissolved in 10 ml N,N-dimethylformamide. The
resulting solution was stirred for about 1 h at room temperature, sealed in a
23 ml Teflon-lined stainless steel autoclave and heated at 393 K for 1 d under
autogenous pressure. Afterwards, the reaction system was slowly cooled to room
temperature. Block crystals of (I) suitable for single-crystal X-ray
diffraction analysis were collected from the final reaction system by
filtration, washed several times with distilled water and dried in air at
ambient temperature. Yield: 38% based on CdII.
Carbon-bound H atoms were positioned geometrically (C—H = 0.93 Å) and
refined as riding, with Uiso(H) fixed at 1.2Ueq(C). The
water H atom was located in a difference Fourier map and refined freely.
Data collection: SMART (Bruker, 1997); cell refinement: SMART (Bruker, 1997); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL-Plus (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
Poly[aqua(µ
2-benzene-1,4-dicarboxylato)(µ
2-4,4'-bipyridine
N,
N'-dioxide)cadmium(II)]
top
Crystal data top
[Cd(C8H4O4)(C10H8N2O2)(H2O)] | F(000) = 960 |
Mr = 482.71 | Dx = 1.905 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 1658 reflections |
a = 14.1052 (15) Å | θ = 2.2–26.0° |
b = 16.8934 (18) Å | µ = 1.35 mm−1 |
c = 8.8967 (10) Å | T = 293 K |
β = 127.451 (1)° | Block, colorless |
V = 1683.0 (3) Å3 | 0.22 × 0.18 × 0.15 mm |
Z = 4 | |
Data collection top
Bruker APEX diffractometer | 1658 independent reflections |
Radiation source: fine-focus sealed tube | 1623 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.064 |
ϕ and ω scans | θmax = 26.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −17→16 |
Tmin = 0.64, Tmax = 0.85 | k = −14→20 |
4629 measured reflections | l = −10→10 |
Refinement top
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 atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0426P)2 + 2.0359P] where P = (Fo2 + 2Fc2)/3 |
1658 reflections | (Δ/σ)max < 0.001 |
132 parameters | Δρmax = 1.07 e Å−3 |
0 restraints | Δρmin = −0.83 e Å−3 |
Crystal data top
[Cd(C8H4O4)(C10H8N2O2)(H2O)] | V = 1683.0 (3) Å3 |
Mr = 482.71 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 14.1052 (15) Å | µ = 1.35 mm−1 |
b = 16.8934 (18) Å | T = 293 K |
c = 8.8967 (10) Å | 0.22 × 0.18 × 0.15 mm |
β = 127.451 (1)° | |
Data collection top
Bruker APEX diffractometer | 1658 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1623 reflections with I > 2σ(I) |
Tmin = 0.64, Tmax = 0.85 | Rint = 0.064 |
4629 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.073 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 1.07 e Å−3 |
1658 reflections | Δρmin = −0.83 e Å−3 |
132 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cd1 | 0.5000 | 0.121775 (12) | 0.2500 | 0.01900 (12) | |
C1 | 0.3978 (2) | 0.18005 (16) | 0.4098 (3) | 0.0234 (5) | |
C2 | 0.3230 (2) | 0.21612 (15) | 0.4602 (3) | 0.0222 (5) | |
C3 | 0.3294 (2) | 0.19039 (16) | 0.6140 (3) | 0.0253 (5) | |
H3 | 0.3827 | 0.1504 | 0.6912 | 0.030* | |
C4 | 0.2426 (2) | 0.27640 (15) | 0.3458 (4) | 0.0263 (5) | |
H4 | 0.2376 | 0.2943 | 0.2423 | 0.032* | |
C5 | 0.1481 (3) | 0.12819 (17) | −0.0186 (4) | 0.0351 (7) | |
H5 | 0.1547 | 0.1827 | −0.0248 | 0.042* | |
C6 | 0.0601 (3) | 0.09790 (19) | −0.0114 (4) | 0.0333 (6) | |
H6 | 0.0084 | 0.1324 | −0.0122 | 0.040* | |
C7 | 0.0473 (2) | 0.01719 (18) | −0.0029 (4) | 0.0337 (6) | |
C8 | 0.1276 (3) | −0.0311 (2) | −0.0051 (6) | 0.0573 (11) | |
H8 | 0.1221 | −0.0858 | −0.0013 | 0.069* | |
C9 | 0.2140 (3) | 0.0007 (2) | −0.0128 (6) | 0.0509 (9) | |
H9 | 0.2657 | −0.0324 | −0.0153 | 0.061* | |
N1 | 0.22446 (19) | 0.07991 (16) | −0.0167 (3) | 0.0333 (6) | |
O1 | 0.30712 (19) | 0.10944 (14) | −0.0268 (3) | 0.0391 (5) | |
O2 | 0.4223 (2) | 0.22237 (12) | 0.3220 (3) | 0.0371 (5) | |
O3 | 0.42876 (19) | 0.10875 (11) | 0.4489 (3) | 0.0266 (4) | |
O1W | 0.5000 | −0.01188 (16) | 0.2500 | 0.0286 (6) | |
H1W | 0.514 (3) | −0.042 (2) | 0.333 (5) | 0.038 (9)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cd1 | 0.01784 (17) | 0.01890 (17) | 0.02478 (17) | 0.000 | 0.01530 (13) | 0.000 |
C1 | 0.0221 (12) | 0.0289 (14) | 0.0234 (11) | 0.0016 (10) | 0.0161 (10) | −0.0009 (10) |
C2 | 0.0227 (12) | 0.0223 (12) | 0.0266 (11) | 0.0010 (9) | 0.0176 (10) | 0.0001 (9) |
C3 | 0.0276 (13) | 0.0241 (12) | 0.0263 (12) | 0.0079 (10) | 0.0175 (11) | 0.0070 (9) |
C4 | 0.0319 (14) | 0.0270 (13) | 0.0266 (11) | 0.0071 (11) | 0.0211 (11) | 0.0068 (10) |
C5 | 0.0331 (17) | 0.0380 (17) | 0.0298 (14) | −0.0069 (12) | 0.0168 (13) | 0.0043 (10) |
C6 | 0.0322 (15) | 0.0350 (15) | 0.0316 (13) | −0.0043 (13) | 0.0188 (12) | 0.0013 (12) |
C7 | 0.0181 (12) | 0.0369 (15) | 0.0314 (13) | −0.0011 (11) | 0.0074 (10) | 0.0115 (11) |
C8 | 0.0265 (15) | 0.0362 (18) | 0.097 (3) | 0.0083 (13) | 0.0313 (18) | 0.0257 (19) |
C9 | 0.0226 (15) | 0.0416 (18) | 0.078 (2) | 0.0071 (13) | 0.0252 (16) | 0.0180 (16) |
N1 | 0.0160 (11) | 0.0467 (15) | 0.0248 (10) | −0.0034 (10) | 0.0059 (9) | 0.0129 (10) |
O1 | 0.0199 (10) | 0.0576 (14) | 0.0315 (10) | −0.0032 (9) | 0.0113 (9) | 0.0189 (9) |
O2 | 0.0497 (12) | 0.0322 (11) | 0.0560 (12) | 0.0098 (9) | 0.0461 (11) | 0.0109 (9) |
O3 | 0.0307 (11) | 0.0267 (9) | 0.0299 (9) | 0.0079 (8) | 0.0223 (9) | 0.0035 (7) |
O1W | 0.0365 (15) | 0.0211 (13) | 0.0236 (12) | 0.000 | 0.0159 (12) | 0.000 |
Geometric parameters (Å, º) top
Cd1—O1W | 2.258 (3) | C4—H4 | 0.9300 |
Cd1—O2 | 2.314 (2) | C5—N1 | 1.342 (4) |
Cd1—O2i | 2.314 (2) | C5—C6 | 1.381 (5) |
Cd1—O1i | 2.316 (2) | C5—H5 | 0.9300 |
Cd1—O1 | 2.316 (2) | C6—C7 | 1.383 (4) |
Cd1—O3i | 2.520 (2) | C6—H6 | 0.9300 |
Cd1—O3 | 2.520 (2) | C7—C8 | 1.406 (5) |
C1—O2 | 1.253 (3) | C7—C7iii | 1.484 (6) |
C1—O3 | 1.256 (3) | C8—C9 | 1.371 (5) |
C1—C2 | 1.503 (3) | C8—H8 | 0.9300 |
C2—C3 | 1.386 (3) | C9—N1 | 1.348 (4) |
C2—C4 | 1.398 (4) | C9—H9 | 0.9300 |
C3—C4ii | 1.385 (4) | N1—O1 | 1.321 (3) |
C3—H3 | 0.9300 | O1W—H1W | 0.81 (3) |
C4—C3ii | 1.385 (4) | | |
| | | |
O1W—Cd1—O2 | 137.26 (5) | C4—C2—C1 | 118.9 (2) |
O1W—Cd1—O2i | 137.26 (5) | C4ii—C3—C2 | 120.7 (2) |
O2—Cd1—O2i | 85.48 (10) | C4ii—C3—H3 | 119.7 |
O1W—Cd1—O1i | 84.84 (6) | C2—C3—H3 | 119.7 |
O2—Cd1—O1i | 102.69 (8) | C3ii—C4—C2 | 120.3 (2) |
O2i—Cd1—O1i | 84.98 (9) | C3ii—C4—H4 | 119.8 |
O1W—Cd1—O1 | 84.84 (6) | C2—C4—H4 | 119.8 |
O2—Cd1—O1 | 84.98 (9) | N1—C5—C6 | 120.8 (3) |
O2i—Cd1—O1 | 102.69 (8) | N1—C5—H5 | 119.6 |
O1i—Cd1—O1 | 169.67 (12) | C6—C5—H5 | 119.6 |
O1W—Cd1—O3i | 84.99 (4) | C5—C6—C7 | 121.2 (3) |
O2—Cd1—O3i | 135.79 (7) | C5—C6—H6 | 119.4 |
O2i—Cd1—O3i | 53.95 (6) | C7—C6—H6 | 119.4 |
O1i—Cd1—O3i | 91.53 (8) | C6—C7—C8 | 116.0 (3) |
O1—Cd1—O3i | 87.57 (8) | C6—C7—C7iii | 122.5 (4) |
O1W—Cd1—O3 | 84.99 (4) | C8—C7—C7iii | 121.5 (4) |
O2—Cd1—O3 | 53.95 (6) | C9—C8—C7 | 121.4 (3) |
O2i—Cd1—O3 | 135.79 (7) | C9—C8—H8 | 119.3 |
O1i—Cd1—O3 | 87.57 (8) | C7—C8—H8 | 119.3 |
O1—Cd1—O3 | 91.53 (8) | N1—C9—C8 | 120.3 (3) |
O3i—Cd1—O3 | 169.98 (9) | N1—C9—H9 | 119.8 |
O2—C1—O3 | 122.5 (2) | C8—C9—H9 | 119.8 |
O2—C1—C2 | 117.7 (2) | O1—N1—C5 | 120.3 (3) |
O3—C1—C2 | 119.7 (2) | O1—N1—C9 | 119.4 (3) |
O2—C1—Cd1 | 56.74 (13) | C5—N1—C9 | 120.2 (3) |
O3—C1—Cd1 | 66.17 (14) | N1—O1—Cd1 | 118.44 (15) |
C2—C1—Cd1 | 169.34 (17) | C1—O2—Cd1 | 96.34 (16) |
C3—C2—C4 | 119.0 (2) | C1—O3—Cd1 | 86.71 (15) |
C3—C2—C1 | 122.1 (2) | Cd1—O1W—H1W | 128 (2) |
| | | |
O1W—Cd1—C1—O2 | −169.19 (15) | C6—C7—C8—C9 | 0.8 (5) |
O2i—Cd1—C1—O2 | 16.1 (2) | C7iii—C7—C8—C9 | 179.2 (4) |
O1i—Cd1—C1—O2 | 103.54 (17) | C7—C8—C9—N1 | 0.6 (6) |
O1—Cd1—C1—O2 | −86.15 (17) | C6—C5—N1—O1 | 178.8 (3) |
O3i—Cd1—C1—O2 | −16.1 (3) | C6—C5—N1—C9 | 1.8 (4) |
O3—Cd1—C1—O2 | 173.2 (3) | C8—C9—N1—O1 | −179.0 (3) |
C1i—Cd1—C1—O2 | 10.81 (15) | C8—C9—N1—C5 | −1.9 (5) |
O1W—Cd1—C1—O3 | 17.57 (16) | C5—N1—O1—Cd1 | 100.1 (2) |
O2—Cd1—C1—O3 | −173.2 (3) | C9—N1—O1—Cd1 | −82.8 (3) |
O2i—Cd1—C1—O3 | −157.19 (15) | O1W—Cd1—O1—N1 | 67.5 (2) |
O1i—Cd1—C1—O3 | −69.70 (16) | O2—Cd1—O1—N1 | −70.9 (2) |
O1—Cd1—C1—O3 | 100.61 (15) | O2i—Cd1—O1—N1 | −155.1 (2) |
O3i—Cd1—C1—O3 | 170.69 (12) | O1i—Cd1—O1—N1 | 67.5 (2) |
C1i—Cd1—C1—O3 | −162.43 (16) | O3i—Cd1—O1—N1 | 152.7 (2) |
O1W—Cd1—C1—C2 | −108.1 (10) | O3—Cd1—O1—N1 | −17.3 (2) |
O2—Cd1—C1—C2 | 61.0 (10) | C1i—Cd1—O1—N1 | 178.1 (2) |
O2i—Cd1—C1—C2 | 77.1 (10) | C1—Cd1—O1—N1 | −43.9 (2) |
O1i—Cd1—C1—C2 | 164.6 (10) | O3—C1—O2—Cd1 | 7.3 (3) |
O1—Cd1—C1—C2 | −25.1 (10) | C2—C1—O2—Cd1 | −169.47 (18) |
O3i—Cd1—C1—C2 | 45.0 (11) | O1W—Cd1—O2—C1 | 15.0 (2) |
O3—Cd1—C1—C2 | −125.7 (10) | O2i—Cd1—O2—C1 | −165.0 (2) |
C1i—Cd1—C1—C2 | 71.9 (10) | O1i—Cd1—O2—C1 | −81.23 (18) |
O2—C1—C2—C3 | −153.5 (3) | O1—Cd1—O2—C1 | 91.77 (17) |
O3—C1—C2—C3 | 29.6 (4) | O3i—Cd1—O2—C1 | 173.06 (14) |
Cd1—C1—C2—C3 | 150.8 (9) | O3—Cd1—O2—C1 | −3.81 (15) |
O2—C1—C2—C4 | 27.9 (4) | C1i—Cd1—O2—C1 | −172.26 (11) |
O3—C1—C2—C4 | −149.0 (3) | O2—C1—O3—Cd1 | −6.7 (3) |
Cd1—C1—C2—C4 | −27.8 (11) | C2—C1—O3—Cd1 | 170.0 (2) |
C4—C2—C3—C4ii | 0.1 (4) | O1W—Cd1—O3—C1 | −163.56 (15) |
C1—C2—C3—C4ii | −178.5 (2) | O2—Cd1—O3—C1 | 3.78 (14) |
C3—C2—C4—C3ii | −0.1 (4) | O2i—Cd1—O3—C1 | 31.16 (19) |
C1—C2—C4—C3ii | 178.6 (2) | O1i—Cd1—O3—C1 | 111.42 (16) |
N1—C5—C6—C7 | −0.3 (4) | O1—Cd1—O3—C1 | −78.88 (16) |
C5—C6—C7—C8 | −0.9 (4) | O3i—Cd1—O3—C1 | −163.56 (15) |
C5—C6—C7—C7iii | −179.4 (3) | C1i—Cd1—O3—C1 | 41.5 (4) |
Symmetry codes: (i) −x+1, y, −z+1/2; (ii) −x+1/2, −y+1/2, −z+1; (iii) −x, −y, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···O3iv | 0.81 (3) | 1.95 (3) | 2.755 (2) | 172 (4) |
Symmetry code: (iv) −x+1, −y, −z+1. |
Experimental details
Crystal data |
Chemical formula | [Cd(C8H4O4)(C10H8N2O2)(H2O)] |
Mr | 482.71 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 14.1052 (15), 16.8934 (18), 8.8967 (10) |
β (°) | 127.451 (1) |
V (Å3) | 1683.0 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.35 |
Crystal size (mm) | 0.22 × 0.18 × 0.15 |
|
Data collection |
Diffractometer | Bruker APEX diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.64, 0.85 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4629, 1658, 1623 |
Rint | 0.064 |
(sin θ/λ)max (Å−1) | 0.617 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.073, 1.07 |
No. of reflections | 1658 |
No. of parameters | 132 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 1.07, −0.83 |
Selected geometric parameters (Å, º) topCd1—O1W | 2.258 (3) | Cd1—O1 | 2.316 (2) |
Cd1—O2 | 2.314 (2) | Cd1—O3 | 2.520 (2) |
| | | |
O1W—Cd1—O2 | 137.26 (5) | O1W—Cd1—O3 | 84.99 (4) |
O2—Cd1—O2i | 85.48 (10) | O2—Cd1—O3 | 53.95 (6) |
O1W—Cd1—O1 | 84.84 (6) | O2i—Cd1—O3 | 135.79 (7) |
O2—Cd1—O1 | 84.98 (9) | O1i—Cd1—O3 | 87.57 (8) |
O2i—Cd1—O1 | 102.69 (8) | O1—Cd1—O3 | 91.53 (8) |
O1i—Cd1—O1 | 169.67 (12) | O3i—Cd1—O3 | 169.98 (9) |
Symmetry code: (i) −x+1, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···O3ii | 0.81 (3) | 1.95 (3) | 2.755 (2) | 172 (4) |
Symmetry code: (ii) −x+1, −y, −z+1. |
Subscribe to Acta Crystallographica Section C: Structural Chemistry
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.
The synthesis of metal–organic frameworks (MOFs) has attracted great attention, not only for their tremendous potential applications in nonlinear optics, catalysis, gas absorption, luminescence, magnetism, ion exchange and zeolite-like materials for molecular selection, but also for their intriguing variety of architectures and topologies (Abrahams et al., 1999; Noro et al., 2000; Spencer et al., 2006). The topologies of the MOFs can often be controlled and modified by selecting the coordination geometry preferred by the metal ion and the chemical structure of the organic ligand chosen. It is well known that careful selection of a suitable organic ligand with certain features is helpful for constructing MOFs with desirable properties (Wang et al., 2006). Recently, it has been demonstrated that 4,4'-bipyridine N,N'-dioxide (bpdo) and its derivatives show some unique features in the construction of MOFs (Hill et al., 2005; Manna et al., 2007) and have been shown to have extremely versatile coordination modes compared with 4,4'-bipyridine and its derivatives (Xu et al., 2005). So far, a number of MOFs based on bpdo ligands have been reported, including one-dimensional chain or ladder, two-dimensional layer, and unusual five-, six-, seven- and eight-connected frameworks (Hill et al., 2005). However, only a few MOFs based on both bpdo and carboxylate ligands have been documented (Manna et al., 2006, 2007; Fabelo et al., 2007). In the new material reported here, bpdo assembles with cadmium 1,4-benzenedicarboxylate (1,4-bdc) to furnish a 1:1 adduct, [Cd(bpdo)(1,4-bdc)(H2O)]n, (I), which exists as an unusual threefold interpenetrating diamond framework.
The asymmetric unit of (I) contains half a CdII atom, half a bpdo ligand, half a 1,4-bdc anion and half a coordination water molecule (Fig. 1). The CdII atom and the water O atom rest on a twofold rotation axis. The bpdo and 1,4-bdc ligands are on centers of inversion that occur at the midpoint of the C7—C7ii [symmetry code: (ii) -x, -y, -z] bond of bpdo and the centroid of the arene ring of 1,4-bdc. Each CdII atom is seven-coordinated in a distorted monocapped, trigonal prism[atic?] coordination geometry, surrounded by four carboxylate O atoms from two different 1,4-bdc anions (O2, O3, O2iii and O3iii) [symmetry code: (iii) 1-x, y, 1/2-z], two O atoms from two distinct bpdo ligands (O1 and O1iii) and one water O atom (OW1). The Cd—Ocarboxylate distances (Table 1) are comparable to those observed for [Cd4(1,4-bix)4(bpea)4].4H2O [1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene; H2bpea = biphenylethene-4,4'-dicarboxylic acid] (Yang et al., 2008). Each crystallographically unique CdII center is bridged by the 1,4-bdc dianions and bpdo ligands to give a three-dimensional framework (Fig. 2). A better insight into the structure of (I) can be achieved by the application of a topological approach, that is, reducing multidimensional structures to simple node-and-linker nets (Batten & Robson, 1998). According to the simplification principle, the CdII center is defined as a four-connected node, while the 1,4-bdc and bpdo ligands serve as linkers. Therefore, on the basis of this concept of chemical topology, the overall structure is a diamond framework containing large adamantanoid cages (Fig. 2). As can be seen, each distorted rectangular ring has six CdII centers, leading to the formation of a hexagon which is the shortest circuit here. In the adamantanoid cage, the Cd···Cd distances bridged by bpdo and 1,4-bdc are 12.624 (5) and 11.245 (4) Å, respectively.
It is well known that diamond networks tend to interpenetrate to fill the voids within a single net. Of particular interest, the most striking feature of (I) is that three identical three-dimensional single nets are interlocked with each other, thus directly leading to the formation of a threefold interpenetrated three-dimensional diamond architecture (Fig. 3). In addition, there are strong linear O—H···O hydrogen bonds between the water molecules and carboxylate O atoms within different diamond nets (Fig. 3). Each diamond net is hydrogen bonded to its two neighbors through these hydrogen bonds, which further consolidates the threefold interpenetrating diamond framework (Table 2). Although many diamond-related nets displaying various interpenetration modes ranging from twofold to 11-fold have been reported, threefold interpenetrating MOFs in the presence of mixed organic ligands with different lengths is relatively rare (Batten, 2001; O'Keeffe et al., 2008; Carlucci et al., 2003). So far, only a few threefold interpenetrating MOFs, including Co(D-cam)(TMDPy).2H2O (D-H2Cam = D-camphoric acid; TMDPy = 4,4'-trimethylenedipyridine) (Zhang et al., 2008), [Cu2(bpy)2(Hbpy)(H2O)](PW12O40) (bpy = 4,4'-bipyridine) (Yang et al., 2009), [Tb(bpdo)(CH3OH)(NO3)3] (Long et al., 2002) and Cu(3,4'-bpdc)(H2O).DMF.2H2O (3,4'-bpdc = 3,4'-biphenyldicarboxylic acid; DMF = dimethylformamide) (Feng et al., 2009), have been reported. The structure of (I) is entirely different from that of the related structure [Cu2(bpy)2(Hbpy)(H2O)](PW12O40), which shows an unprecedented threefold interpenetrating diamond-like network in polyoxometallate chemistry. The structure of (I) is also different from those of the polymers [Tb(bpdo)(CH3OH)(NO3)3] and [Cu(3,4'-bpdc)(H2O)].DMF.2H2O, whose threefold interpenetrating diamond nets only contain single organic ligands. In particular, [Tb(bpdo)(CH3OH)(NO3)3] adopts a zigzag chain structure, which forms threefold interpenetrating diamond frameworks through interchain hydrogen bonding between coordinated methanol and a nitrate group on an adjacent chain. Notably, although the reported compound Co(D-cam)(TMDPy).2H2O is constructed by mixed organic ligands, it exhibits a homochiral threefold interpenetrating diamond topology. Notably, there are only a few previously reported examples of MOFs based on bpdo–carboxylate mixed ligand systems (Manna et al., 2006, 2007; Fabelo et al., 2007). The related compounds [Co(H2O)6](H2bta).bpdo.4H2O and [{Co2(H2O)4(bpdo)}2(bta)].4H2O are discrete molecular complexes (H4bta = 1,2,4,5-benzenetetracarboxylic acid) (Fabelo et al., 2007). The structure of [Co(H2O)2)(bpdo)2(H2bta)]n is constituted by uniform chains of CoII ions bridged by the deprotonated H2bta2- species (Fabelo et al., 2007). The related compounds [Co(H2O)3(bpdo)(bta)1/2]n, {[Co(bpdo)(ox)]}n and [Mn(ox)(bpdo)]n display two-dimensional layer structures (ox = oxalate dianion) (Manna et al., 2006, 2007; Fabelo et al., 2007).