supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

Acta Cryst. (2009). E65, m1116    [ doi:10.1107/S1600536809032760 ]

catena-Poly[[bis(p-toluenesulfonato-[kappa]O)palladium(II)]bis([mu]-1,3-di-4-pyridylpropane-[kappa]2N:N')]

S. Wang, T. Yang, Z. Li and X. Yu

Abstract top

In the title compound, [Pd(C7H7O3S)2(C13H14N2)2]n, the metal ion, located on a twofold rotation axis, exhibits a slightly distorted octahedral coordination environment, with bond angles that deviate by at most 2.2° from an ideal geometry, completed by two O atoms from two deprotonated p-toluenesulfonic acid ligands and four N atoms from four 1,3-di-4-pyridylpropane ligands. One of the sulfonate O atoms is disordered over two positions [ratio 0.70 (5):0.30 (5)].

Comment top

Design and construction of metal-organic frameworks (MOFs) have attracted considerable attention in recent years, not only for their intriguing structural motifs but also for their potential applications in the areas of catalysis, separation, gas absorption, molecular recognition, nonlinear optics, and magnetochemistry (Jia et al. (2007); Li et al. (1996); Seo et al. (2000); Hagrman et al. (1999); Yaghi et al. (1998); Kortz et al. (2003); Liu et al. (2007); Wang et al. (2007)). A successful strategy for the design and synthesis of predictable MOFs is the assembly reaction between metal ions and well designed organic ligands. 1,3-di(4-pyridyl)proane is a very good choice for preparing such MOFs because of its versatile coordination modes with transition metal centers (Xu et al. (2004); Zhu et al. (2002); Mock et al. (2001)). We report here the crystal and molecular structure of the title compound, (I).

In the asymmetric unit of complex (I), exhibit one 1,3-di(4-pyridyl)propane ligand, one depronated p-toluenesulfonic acid, and one Pd(II) ion, figure 1.The metal exhibits an octahedral coordination environment with bond angles that do not exceed 2.2° from the ideal geometry completed by two oxygen atoms from two depronated p-Toluenesulfonic acid and four nitrogen atoms from four 3-(2-pyridyl)pyrazole ligand.The bond distances of Pd—O and Pd—N are in the range of 2.326 (2)–2.339 (2) and 2.338 (2) Å, respectively.The O1 atom is disordered over two positions [0.70 (5)/0.30 (5)].

Related literature top

For the potential applications of metal-organic frameworks, see: Jia et al. (2007); Li et al. (1996); Seo et al. (2000); Hagrman et al. (1999); Yaghi et al. (1998); Kortz et al. (2003); Liu et al. (2007); Wang et al. (2007). 1,3-Di(4-pyridyl)proane has versatile coordination modes with transition metal centers, see: Xu et al. (2004); Zhu et al. (2002); Mock et al. (2001).

Experimental top

A mixture of Pd(II) chloride (1 mmoL), p-Toluenesulfonic acid (1 mmoL), and 1,3-di(4-pyridyl)proane (1 mmoL) in 10 ml distilled water sealed in a 25 ml Teflon-lined stainless steel autoclave was kept at 433 K for three days. Colorless crystals suitable for the X-ray experiment were obtained. Anal. Calc. for C40H42N4O6PdS2: C 56.78, H 4.97, N 6.62%; Found: C 56.35, H 4.78, N 6.52%.

Refinement top

All H atoms were geometrically positioned and refined using a riding model, with C—H = 0.93 A for the aryl, 0.97 A for the methylene, and 0.96 A for the methyl H atoms. Uiso(H) = 1.2Ueq(C) for the aryl, methine and methylene H atoms, and 1.5Ueq(C) for methyl H atoms. The atom O1 is disordered and was modelled using a split model with refined population parameters [O1B/O1A = 0.70 (5)/0.30 (5)].

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); 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).

Figures top
[Figure 1] Fig. 1. A view of (I) with the unique atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Minor component of disordered O1 atom as well as H atoms have been omitted. Unlabeled atoms are related to labeled atoms by the symmetry code (x, 1/2 - y, 1/2 - z)
catena-Poly[[bis(p-toluenesulfonato- κO)palladium(II)]bis(µ-1,3-di-4-pyridylpropane- κ2N:N')] top
Crystal data top
[Pd(C7H7O3S)2(C13H14N2)2]F(000) = 1744
Mr = 845.3Dx = 1.448 Mg m−3
Orthorhombic, PnnaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2a 2bcCell parameters from 7795 reflections
a = 23.818 (2) Åθ = 2.4–28.2°
b = 17.4359 (10) ŵ = 0.64 mm−1
c = 9.3341 (10) ÅT = 273 K
V = 3876.3 (6) Å3Block, colorless
Z = 40.12 × 0.08 × 0.01 mm
Data collection top
Bruker APEXII CCD area-detector
diffractometer		3374 independent reflections
Radiation source: fine-focus sealed tube2761 reflections with I > 2σ(I)
graphiteRint = 0.068
φ and ω scansθmax = 25°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2001)		h = −28→26
Tmin = 0.927, Tmax = 0.994k = −20→20
18799 measured reflectionsl = −11→9
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.091H-atom parameters not refined
S = 1.08 w = 1/[σ2(Fo2) + (0.0492P)2 + 0.7971P]
where P = (Fo2 + 2Fc2)/3
3374 reflections(Δ/σ)max = 0.047
251 parametersΔρmax = 0.61 e Å−3
0 restraintsΔρmin = −0.67 e Å−3
Crystal data top
[Pd(C7H7O3S)2(C13H14N2)2]V = 3876.3 (6) Å3
Mr = 845.3Z = 4
Orthorhombic, PnnaMo Kα radiation
a = 23.818 (2) ŵ = 0.64 mm−1
b = 17.4359 (10) ÅT = 273 K
c = 9.3341 (10) Å0.12 × 0.08 × 0.01 mm
Data collection top
Bruker APEXII CCD area-detector
diffractometer		3374 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)		2761 reflections with I > 2σ(I)
Tmin = 0.927, Tmax = 0.994Rint = 0.068
18799 measured reflectionsθmax = 25°
Refinement top
R[F2 > 2σ(F2)] = 0.033H-atom parameters not refined
wR(F2) = 0.091Δρmax = 0.61 e Å−3
S = 1.08Δρmin = −0.67 e Å−3
3374 reflectionsAbsolute structure: ?
251 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
xyzUiso*/UeqOcc. (<1)
Pd10.405803 (9)0.250.250.02547 (12)
S10.38959 (4)0.12445 (5)0.56888 (8)0.0569 (2)
O1A0.453 (3)0.1210 (9)0.624 (7)0.110 (16)0.30 (5)
O1B0.4230 (9)0.1297 (6)0.6913 (16)0.095 (4)0.70 (5)
O20.40587 (9)0.15978 (13)0.4355 (3)0.0623 (6)
O30.33358 (13)0.15336 (15)0.6086 (3)0.1029 (11)
N10.47636 (8)0.18031 (12)0.1367 (2)0.0352 (5)
N20.33394 (8)0.17892 (12)0.1424 (3)0.0383 (5)
C10.3609 (3)−0.2217 (3)0.4820 (7)0.144 (2)
H1A0.3825−0.24620.55590.216*
H1B0.3744−0.23780.38990.216*
H1C0.3221−0.23570.49180.216*
C20.3669 (2)−0.1344 (2)0.4956 (4)0.0741 (11)
C30.32559 (17)−0.0900 (2)0.5550 (4)0.0739 (11)
H30.2924−0.11320.58470.089*
C40.33176 (13)−0.01173 (19)0.5722 (3)0.0561 (8)
H40.30270.01660.61250.067*
C50.37985 (12)0.02464 (16)0.5309 (3)0.0405 (6)
C60.42192 (14)−0.0190 (2)0.4681 (3)0.0520 (8)
H60.45490.00430.43710.062*
C70.41461 (17)−0.0978 (2)0.4516 (4)0.0663 (10)
H70.4431−0.12640.40930.08*
C80.48162 (10)0.16862 (16)−0.0055 (3)0.0386 (6)
H80.45990.1982−0.0670.046*
C90.51733 (10)0.11541 (16)−0.0644 (3)0.0389 (6)
H90.5190.1092−0.16320.047*
C100.50992 (12)0.13828 (18)0.2226 (3)0.0408 (7)
H100.50790.14610.3210.049*
C110.54674 (10)0.08471 (16)0.1715 (3)0.0410 (7)
H110.56910.05720.23510.049*
C120.55099 (10)0.07100 (14)0.0245 (3)0.0339 (6)
C130.58962 (10)0.01068 (17)−0.0364 (4)0.0442 (7)
H13A0.5701−0.0172−0.11130.053*
H13B0.5993−0.02560.03850.053*
C140.64305 (10)0.04495 (15)−0.0976 (3)0.0398 (6)
H14A0.6620.0064−0.15470.048*
H14B0.63320.0871−0.16050.048*
C150.32321 (11)0.17269 (16)0.0008 (3)0.0402 (6)
H150.34940.1923−0.06340.048*
C160.29563 (12)0.15034 (19)0.2325 (3)0.0423 (7)
H160.30190.15440.33060.051*
C170.24731 (11)0.11523 (15)0.1860 (3)0.0413 (6)
H170.22210.09520.25230.05*
C180.27591 (11)0.13906 (16)−0.0530 (3)0.0419 (7)
H180.27050.136−0.15160.05*
C190.23581 (10)0.10944 (14)0.0402 (3)0.0341 (6)
C200.18311 (10)0.07391 (16)−0.0165 (3)0.0380 (6)
H20A0.19320.0314−0.07830.046*
H20B0.16370.1115−0.07480.046*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd10.01639 (17)0.02857 (17)0.03145 (18)00−0.00186 (10)
S10.0873 (6)0.0455 (4)0.0379 (4)−0.0102 (4)−0.0087 (4)0.0075 (3)
O1A0.17 (3)0.066 (7)0.09 (3)−0.003 (9)−0.09 (2)0.001 (8)
O1B0.157 (9)0.075 (3)0.051 (5)−0.031 (4)−0.053 (6)−0.004 (4)
O20.0648 (14)0.0570 (14)0.0652 (15)−0.0050 (10)0.0055 (11)0.0284 (12)
O30.131 (3)0.0669 (17)0.111 (2)0.0160 (17)0.070 (2)−0.0008 (16)
N10.0283 (11)0.0425 (12)0.0347 (12)0.0029 (9)−0.0016 (9)−0.0028 (10)
N20.0273 (11)0.0437 (13)0.0438 (14)−0.0045 (9)0.0016 (10)−0.0048 (11)
C10.238 (7)0.055 (3)0.139 (5)−0.016 (4)−0.024 (5)−0.015 (3)
C20.112 (3)0.050 (2)0.060 (2)−0.011 (2)−0.016 (2)0.0012 (18)
C30.074 (2)0.067 (2)0.081 (3)−0.027 (2)−0.007 (2)0.012 (2)
C40.0464 (17)0.061 (2)0.061 (2)−0.0019 (15)0.0018 (15)0.0076 (17)
C50.0437 (16)0.0474 (16)0.0304 (14)0.0013 (13)−0.0044 (12)0.0069 (12)
C60.0503 (17)0.070 (2)0.0361 (16)0.0020 (16)−0.0016 (14)0.0063 (15)
C70.092 (3)0.065 (2)0.0421 (19)0.029 (2)−0.0071 (19)−0.0055 (17)
C80.0314 (14)0.0502 (16)0.0342 (14)0.0048 (12)0.0004 (12)0.0043 (12)
C90.0332 (14)0.0546 (16)0.0291 (14)0.0025 (12)0.0021 (11)−0.0025 (12)
C100.0342 (15)0.0593 (18)0.0290 (14)0.0092 (14)−0.0006 (11)−0.0013 (12)
C110.0300 (14)0.0534 (17)0.0397 (17)0.0118 (12)−0.0016 (12)0.0052 (13)
C120.0199 (12)0.0379 (14)0.0438 (16)−0.0053 (10)0.0046 (11)−0.0043 (12)
C130.0272 (14)0.0428 (16)0.063 (2)−0.0035 (11)0.0099 (13)−0.0097 (15)
C140.0245 (13)0.0457 (16)0.0491 (17)−0.0017 (11)0.0087 (12)−0.0088 (13)
C150.0341 (14)0.0463 (16)0.0402 (16)−0.0064 (12)0.0046 (12)−0.0023 (13)
C160.0328 (15)0.0582 (19)0.0359 (16)−0.0070 (14)−0.0038 (12)0.0000 (13)
C170.0299 (14)0.0512 (17)0.0430 (16)−0.0085 (12)−0.0003 (13)0.0016 (14)
C180.0399 (15)0.0504 (17)0.0353 (15)−0.0053 (13)−0.0007 (12)−0.0038 (13)
C190.0298 (13)0.0329 (13)0.0395 (15)0.0017 (10)−0.0011 (11)−0.0022 (11)
C200.0276 (14)0.0416 (15)0.0448 (16)−0.0018 (11)−0.0062 (12)−0.0023 (13)
Geometric parameters (Å, °) top
Pd1—N1i2.328 (2)C7—H70.93
Pd1—N12.328 (2)C8—C91.373 (4)
Pd1—O22.339 (2)C8—H80.93
Pd1—O2i2.339 (2)C9—C121.389 (4)
Pd1—N22.340 (2)C9—H90.93
Pd1—N2i2.340 (2)C10—C111.367 (4)
S1—O1B1.396 (6)C10—H100.93
S1—O21.442 (2)C11—C121.397 (4)
S1—O31.473 (3)C11—H110.93
S1—O1A1.59 (4)C12—C131.508 (4)
S1—C51.791 (3)C13—C141.517 (3)
N1—C81.348 (3)C13—H13A0.97
N1—C101.349 (3)C13—H13B0.97
N2—C161.338 (3)C14—C20ii1.516 (4)
N2—C151.350 (4)C14—H14A0.97
C1—C21.535 (5)C14—H14B0.97
C1—H1A0.96C15—C181.366 (4)
C1—H1B0.96C15—H150.93
C1—H1C0.96C16—C171.374 (4)
C2—C71.367 (5)C16—H160.93
C2—C31.369 (6)C17—C191.392 (4)
C3—C41.382 (5)C17—H170.93
C3—H30.93C18—C191.392 (4)
C4—C51.365 (4)C18—H180.93
C4—H40.93C19—C201.496 (3)
C5—C61.388 (4)C20—C14iii1.516 (4)
C6—C71.394 (5)C20—H20A0.97
C6—H60.93C20—H20B0.97
N1i—Pd1—N187.57 (10)C2—C7—C6122.1 (3)
N1i—Pd1—O290.82 (8)C2—C7—H7119
N1—Pd1—O289.13 (8)C6—C7—H7119
N1i—Pd1—O2i89.13 (8)N1—C8—C9123.6 (3)
N1—Pd1—O2i90.82 (8)N1—C8—H8118.2
O2—Pd1—O2i179.93 (11)C9—C8—H8118.2
N1i—Pd1—N2178.41 (7)C8—C9—C12119.7 (3)
N1—Pd1—N293.24 (8)C8—C9—H9120.2
O2—Pd1—N287.83 (8)C12—C9—H9120.2
O2i—Pd1—N292.23 (8)N1—C10—C11123.0 (2)
N1i—Pd1—N2i93.24 (8)N1—C10—H10118.5
N1—Pd1—N2i178.41 (7)C11—C10—H10118.5
O2—Pd1—N2i92.23 (8)C10—C11—C12120.4 (2)
O2i—Pd1—N2i87.83 (8)C10—C11—H11119.8
N2—Pd1—N2i85.97 (10)C12—C11—H11119.8
O1B—S1—O2121.7 (8)C9—C12—C11116.7 (2)
O1B—S1—O3106.7 (11)C9—C12—C13121.1 (3)
O2—S1—O3108.33 (16)C11—C12—C13122.2 (3)
O2—S1—O1A92 (2)C12—C13—C14112.3 (2)
O3—S1—O1A142 (2)C12—C13—H13A109.2
O1B—S1—C5107.4 (4)C14—C13—H13A109.2
O2—S1—C5106.20 (14)C12—C13—H13B109.2
O3—S1—C5105.37 (15)C14—C13—H13B109.2
O1A—S1—C598.6 (8)H13A—C13—H13B107.9
S1—O2—Pd1157.82 (15)C20ii—C14—C13113.3 (2)
C8—N1—C10116.6 (2)C20ii—C14—H14A108.9
C8—N1—Pd1126.37 (17)C13—C14—H14A108.9
C10—N1—Pd1116.20 (17)C20ii—C14—H14B108.9
C16—N2—C15117.2 (2)C13—C14—H14B108.9
C16—N2—Pd1115.22 (18)H14A—C14—H14B107.7
C15—N2—Pd1126.96 (18)N2—C15—C18123.4 (3)
C2—C1—H1A109.5N2—C15—H15118.3
C2—C1—H1B109.5C18—C15—H15118.3
H1A—C1—H1B109.5N2—C16—C17122.6 (3)
C2—C1—H1C109.5N2—C16—H16118.7
H1A—C1—H1C109.5C17—C16—H16118.7
H1B—C1—H1C109.5C16—C17—C19120.4 (3)
C7—C2—C3117.1 (3)C16—C17—H17119.8
C7—C2—C1121.0 (5)C19—C17—H17119.8
C3—C2—C1121.9 (5)C15—C18—C19119.7 (3)
C2—C3—C4121.9 (3)C15—C18—H18120.2
C2—C3—H3119C19—C18—H18120.2
C4—C3—H3119C17—C19—C18116.7 (2)
C5—C4—C3121.0 (3)C17—C19—C20122.7 (2)
C5—C4—H4119.5C18—C19—C20120.5 (2)
C3—C4—H4119.5C19—C20—C14iii114.7 (2)
C4—C5—C6118.1 (3)C19—C20—H20A108.6
C4—C5—S1120.3 (2)C14iii—C20—H20A108.6
C6—C5—S1121.5 (2)C19—C20—H20B108.6
C5—C6—C7119.8 (3)C14iii—C20—H20B108.6
C5—C6—H6120.1H20A—C20—H20B107.6
C7—C6—H6120.1
O1B—S1—O2—Pd1−103.6 (11)O3—S1—C5—C6169.7 (2)
O3—S1—O2—Pd120.5 (5)O1A—S1—C5—C6−40 (3)
O1A—S1—O2—Pd1−127.1 (14)C4—C5—C6—C7−1.3 (4)
C5—S1—O2—Pd1133.3 (4)S1—C5—C6—C7174.4 (2)
N1i—Pd1—O2—S191.8 (4)C3—C2—C7—C61.1 (5)
N1—Pd1—O2—S1179.3 (4)C1—C2—C7—C6−177.4 (4)
N2—Pd1—O2—S1−87.4 (4)C5—C6—C7—C20.0 (5)
N2i—Pd1—O2—S1−1.5 (4)C10—N1—C8—C92.2 (4)
N1i—Pd1—N1—C8−127.0 (2)Pd1—N1—C8—C9−166.94 (19)
O2—Pd1—N1—C8142.2 (2)N1—C8—C9—C12−0.9 (4)
O2i—Pd1—N1—C8−37.9 (2)C8—N1—C10—C11−1.7 (4)
O2—Pd1—N1—C10−27.1 (2)Pd1—N1—C10—C11168.6 (2)
O2i—Pd1—N1—C10152.9 (2)N1—C10—C11—C12−0.2 (4)
N2—Pd1—N1—C10−114.83 (19)C8—C9—C12—C11−1.0 (4)
N1—Pd1—N2—C16128.3 (2)C8—C9—C12—C13178.5 (2)
O2i—Pd1—N2—C16−140.8 (2)C10—C11—C12—C91.5 (4)
N2i—Pd1—N2—C16−53.09 (18)C10—C11—C12—C13−178.0 (3)
N1—Pd1—N2—C15−61.2 (2)C9—C12—C13—C1478.7 (3)
O2—Pd1—N2—C15−150.2 (2)C11—C12—C13—C14−101.9 (3)
O2i—Pd1—N2—C1529.7 (2)C12—C13—C14—C20ii72.0 (3)
N2i—Pd1—N2—C15117.4 (2)C16—N2—C15—C18−0.1 (4)
C7—C2—C3—C4−0.9 (6)Pd1—N2—C15—C18−170.4 (2)
C1—C2—C3—C4177.5 (4)C15—N2—C16—C170.6 (4)
C2—C3—C4—C5−0.4 (6)Pd1—N2—C16—C17172.0 (2)
C3—C4—C5—C61.5 (5)N2—C16—C17—C19−1.3 (5)
C3—C4—C5—S1−174.3 (3)N2—C15—C18—C190.3 (4)
O1B—S1—C5—C498.9 (12)C16—C17—C19—C181.4 (4)
O2—S1—C5—C4−129.5 (2)C16—C17—C19—C20−178.2 (3)
O3—S1—C5—C4−14.7 (3)C15—C18—C19—C17−0.9 (4)
O1A—S1—C5—C4136 (3)C15—C18—C19—C20178.6 (2)
O1B—S1—C5—C6−76.7 (12)C17—C19—C20—C14iii0.2 (4)
O2—S1—C5—C654.9 (3)C18—C19—C20—C14iii−179.3 (2)
Symmetry codes: (i) x, −y+1/2, −z+1/2; (ii) x+1/2, y, −z; (iii) x−1/2, y, −z.
Acknowledgements top

The authors thank the NSFC (grant No. 20776081) and the Natural Science Foundation of Shandong Province (grant No. Y2006B37).

references
References top

Bruker (2001). SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.

Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.

Hagrman, P. J., Hagrman, D. & Zubieta, J. (1999). Angew. Chem. Int. Ed. 38, 2638–2684.

Jia, H. P., Li, W., Ju, Z. F. & Zhang, J. (2007). Inorg. Chem. Commun. 10, 265–268.

Kortz, U., Hamzeh, S. S. & Nasser, N. A. (2003). Chem. Eur. J. 9, 2945–2952.

Li, H., Eddaoudi, M. O., Keffe, M. & Yaghi, O. M. (1996). Nature (London), 402, 276–279.

Liu, B., Li, X. M., Li, C. B., Gao, G. G. & Che, G. B. (2007). Chin. J. Struct. Chem. 26, 679–682.

Mock, W. L. & Morsch, L. A. (2001). Tetrahedron, 57, 2957–2964.

Seo, J. S., Whang, D., Lee, H., Jun, S. I., Oh, J., Jeon, Y. J. & Kim, K. (2000). Nature (London), 404, 982–986.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Wang, Y. T., Tang, G. M., Wu, Y., Qin, X. Y. & Qin, D. W. (2007). J. Mol. Struct. 831, 61–68.

Xu, C., Mao, H. Y., Zhang, H. Y., Liu, H. L., Wu, Q. A., Hou, H. W. & Zhu, Y. (2004). Chin. J. Struct. Chem. 23, 567–570.

Yaghi, O. M., Li, H., Davis, C., Richardson, D. & Groy, T. L. (1998). Acc. Chem. Res. 31, 474–484.

Zhu, L. G., Cai, G. Q., Susumu, K. & Ho-Chol, C. (2002). Chin. J. Inorg. Chem. 18, 911–914.