Poly[tetra­aqua­(μ8-butane-1,2,3,4-tetra­carboxyl­ato)distrontium]

Cheng, P.-C.; Zhan, J.-X.; Wu, C.-Y.; Lin, C.-H.

doi:10.1107/S1600536811046265

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 12| December 2011| Page m1700

https://doi.org/10.1107/S1600536811046265

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Poly[tetraaqua(μ₈-butane-1,2,3,4-tetracarboxylato)distrontium]

Pei-Chi Cheng,^a Jun-Xiang Zhan,^b Cheng-You Wu ^b and Chia-Her Lin ^b ^*

^aDepartment of Chemistry, R&D Center for Membrane Technology, Center for Nanotechnology, Chung-Yuan Christian University, Chung-Li 320, Taiwan, and ^bDepartment of Chemistry, Chung-Yuan Christian University, Chung-Li 320, Taiwan
^*Correspondence e-mail: chiaher@cycu.edu.tw

(Received 28 October 2011; accepted 2 November 2011; online 5 November 2011)

In the title compound, [Sr₂(C₈H₆O₈)(H₂O)₄)]_n, the Sr^II ion is coordinated by six O atoms of four symmetry-related ligands and two water molecules in a distorted bicapped trigonal–prismatic environment. The butane-1,2,3,4-tetracarboxylate ligands lie on inversion centers and bridge Sr^II ions, forming a three-dimensional network. Within the three-dimensional structure, there are O—H⋯O hydrogen bonds involving the water molecules and carboxylate O atoms.

Related literature

For general background to coordination polymers, see: Jiang & Xu (2011 ); Kam et al. (2007 ); Kitagawa et al. (2004 ); Liu et al. (2009 ). For related structures, see: Ma & Yan (2009 ); Wu (2009 ).

Experimental

Crystal data

[Sr₂(C₈H₆O₈)(H₂O)₄)]
M_r = 477.44
Monoclinic, P 2₁ /n
a = 8.7085 (4) Å
b = 7.9671 (4) Å
c = 10.0697 (4) Å
β = 95.409 (2)°
V = 695.54 (5) Å³
Z = 2
Mo Kα radiation
μ = 7.73 mm⁻¹
T = 296 K
0.25 × 0.15 × 0.13 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2010 ) T_min = 0.248, T_max = 0.433
7782 measured reflections
1746 independent reflections
1443 reflections with I > 2σ(I)
R_int = 0.072

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.061
S = 0.97
1746 reflections
100 parameters
H-atom parameters constrained
Δρ_max = 0.58 e Å⁻³
Δρ_min = −0.46 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WA⋯O3ⁱ	0.85	1.90	2.729 (3)	164.5
O1W—H1WB⋯O4ⁱⁱ	0.85	2.14	2.944 (3)	159.1
O2W—H2WA⋯O4	0.85	2.06	2.841 (3)	153.1
O2W—H2WB⋯O1Wⁱⁱⁱ	0.88	1.99	2.864 (3)	170.1
Symmetry codes: (i) -x, -y, -z+1; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010 ); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536811046265/lh5368sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811046265/lh5368Isup2.hkl

checkCIF report

Comment top

Multicarboxylate ligands, are widely used to construct coordination polymers with interesting properties (Kam, et al., 2007; Liu, et al., 2009, Kitagawa et al., 2004; Jiang & Xu, 2011). The butane-1,2,3,4-tetracarboxylato ligand has already been reported in crystal structures (Ma & Yan, 2009; Wu, 2009). In our continuing investigations on metal coordination polymers we report here the structure of a new Sr coordination polymer based on butane-1,2,3,4-tetracarboxylatic acid.

The asymmetric unit of the title compound consists of one strontium, one half carboxylate ligand and two coordinated water molecules (Fig. 1). The stronium is eight coordinated by six O atoms of four symmetry related ligands and two water molecules. The Sr—O distances range from 2.5491 (18) to 2.688 (2) Å. The ligands bridge the neighboring Sr^II centers forming a three-dimensional framework structure (Fig. 2). The hydrogen bonds involving the water molecules and the carboxylate O atoms further stabilize the three dimensional structure.

Related literature top

For general background to coordination polymers, see: Jiang & Xu (2011); Kam et al. (2007); Kitagawa et al. (2004); Liu et al. (2009). For related structures, see: Ma & Yan (2009); Wu (2009).

Experimental top

Solvothermal reactions were carriedout at 363 K for 2 d in a Teflon-lined acid digestion bomb with an internal volume of 23 ml followed by slow cooling at 6 K/h to room temperature. A single-phase product consisting of colorless crystals of was obtained from a mixture of butane-1,2,3,4-tetracarboxylatic acid (C₈H₁₀O₈, 0.0468 g, 0.2 mmol), Sr(NO₃)₂ (0.0847 g, 0.4 mmol), and ethanol(5.0 ml) and H₂O (1.0 ml).

Structure description top

For general background to coordination polymers, see: Jiang & Xu (2011); Kam et al. (2007); Kitagawa et al. (2004); Liu et al. (2009). For related structures, see: Ma & Yan (2009); Wu (2009).

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. A view of part of the title structure, showing 50% probability displacement ellipsoids. [symmetry codes: (i) 1 - x, -y, 1 - z; (ii) –x + 1/2, y + 1/2, -z + 1/2; (iii) x - 1/2, -y - 1/2, z + 1/2].
	Fig. 2. Part of the crystal structure of the title compound viewed along the a axis.

Poly[tetraaqua(µ₈-butane-1,2,3,4-tetracarboxylato)distrontium] top

Crystal data top

[Sr₂(C₈H₆O₈)(H₂O)₄)]	F(000) = 468
M_r = 477.44	D_x = 2.280 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4783 reflections
a = 8.7085 (4) Å	θ = 3.0–28.5°
b = 7.9671 (4) Å	µ = 7.73 mm⁻¹
c = 10.0697 (4) Å	T = 296 K
β = 95.409 (2)°	Tabular, colourless
V = 695.54 (5) Å³	0.25 × 0.15 × 0.13 mm
Z = 2

Data collection top

Bruker APEXII CCD diffractometer	1746 independent reflections
Radiation source: fine-focus sealed tube	1443 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.072
Detector resolution: 8.3333 pixels mm^-1	θ_max = 28.7°, θ_min = 3.0°
φ and ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Bruker, 2010)	k = −8→10
T_min = 0.248, T_max = 0.433	l = −13→13
7782 measured reflections

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.061	H-atom parameters constrained
S = 0.97	w = 1/[σ²(F_o²) + (0.0282P)²] where P = (F_o² + 2F_c²)/3
1746 reflections	(Δ/σ)_max = 0.001
100 parameters	Δρ_max = 0.58 e Å⁻³
0 restraints	Δρ_min = −0.46 e Å⁻³

Crystal data top

[Sr₂(C₈H₆O₈)(H₂O)₄)]	V = 695.54 (5) Å³
M_r = 477.44	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.7085 (4) Å	µ = 7.73 mm⁻¹
b = 7.9671 (4) Å	T = 296 K
c = 10.0697 (4) Å	0.25 × 0.15 × 0.13 mm
β = 95.409 (2)°

Data collection top

Bruker APEXII CCD diffractometer	1746 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2010)	1443 reflections with I > 2σ(I)
T_min = 0.248, T_max = 0.433	R_int = 0.072
7782 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.061	H-atom parameters constrained
S = 0.97	Δρ_max = 0.58 e Å⁻³
1746 reflections	Δρ_min = −0.46 e Å⁻³
100 parameters

Special details top

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 > 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	U_iso*/U_eq
Sr1	0.22086 (2)	0.04306 (3)	0.60530 (2)	0.01806 (9)
O3	0.2772 (2)	−0.0137 (3)	0.36082 (19)	0.0333 (5)
O1W	0.0092 (2)	0.0561 (3)	0.7699 (2)	0.0285 (5)
H1WA	−0.0857	0.0434	0.7437	0.043*
H1WB	0.0108	0.1483	0.8122	0.043*
O2W	0.4040 (2)	0.2833 (3)	0.5536 (2)	0.0405 (6)
H2WA	0.4624	0.2227	0.5104	0.061*
H2WB	0.4420	0.3623	0.6089	0.061*
O1	0.5067 (2)	−0.3138 (2)	0.03110 (18)	0.0249 (4)
O2	0.69087 (19)	−0.2208 (3)	0.17764 (18)	0.0249 (4)
O4	0.5123 (2)	0.0870 (3)	0.34605 (19)	0.0281 (5)
C1	0.3872 (3)	0.0252 (4)	0.2949 (2)	0.0194 (5)
C2	0.3645 (3)	0.0043 (4)	0.1447 (2)	0.0202 (6)
H2A	0.3107	0.1013	0.1075	0.024*
H2B	0.3001	−0.0920	0.1243	0.024*
C3	0.5739 (3)	−0.1966 (4)	0.0963 (2)	0.0183 (5)
C4	0.5134 (3)	−0.0185 (4)	0.0755 (2)	0.0174 (5)
H4A	0.5914	0.0597	0.1156	0.021*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.01577 (12)	0.01900 (17)	0.01883 (12)	−0.00105 (10)	−0.00146 (8)	−0.00014 (10)
O3	0.0215 (9)	0.0593 (17)	0.0201 (9)	−0.0077 (9)	0.0072 (8)	−0.0053 (9)
O1W	0.0222 (9)	0.0352 (14)	0.0281 (10)	0.0005 (8)	0.0025 (8)	−0.0077 (9)
O2W	0.0443 (12)	0.0363 (15)	0.0418 (12)	−0.0080 (11)	0.0088 (10)	−0.0065 (11)
O1	0.0272 (9)	0.0188 (12)	0.0268 (9)	−0.0009 (8)	−0.0074 (8)	−0.0012 (8)
O2	0.0249 (9)	0.0185 (11)	0.0295 (10)	0.0031 (8)	−0.0080 (8)	−0.0007 (8)
O4	0.0196 (9)	0.0405 (15)	0.0237 (9)	−0.0016 (8)	−0.0004 (7)	−0.0038 (9)
C1	0.0171 (11)	0.0219 (16)	0.0193 (12)	0.0025 (11)	0.0027 (9)	0.0002 (11)
C2	0.0157 (11)	0.0272 (17)	0.0177 (11)	−0.0007 (10)	0.0016 (9)	0.0003 (11)
C3	0.0181 (11)	0.0195 (16)	0.0176 (11)	−0.0007 (10)	0.0029 (9)	0.0026 (10)
C4	0.0182 (11)	0.0195 (16)	0.0144 (11)	−0.0016 (10)	0.0016 (9)	−0.0024 (10)

Geometric parameters (Å, º) top

Sr1—O4ⁱ	2.5491 (18)	O1—Sr1^iv	2.5689 (17)
Sr1—O1ⁱⁱ	2.5690 (17)	O1—Sr1^v	2.6666 (18)
Sr1—O2W	2.576 (2)	O2—C3	1.260 (3)
Sr1—O1W	2.5946 (19)	O2—Sr1ⁱ	2.6565 (18)
Sr1—O3	2.5948 (19)	O2—Sr1^v	2.688 (2)
Sr1—O2ⁱ	2.6565 (18)	O4—C1	1.260 (3)
Sr1—O1ⁱⁱⁱ	2.6666 (18)	O4—Sr1ⁱ	2.5492 (18)
Sr1—O2ⁱⁱⁱ	2.688 (2)	C1—C2	1.516 (3)
Sr1—C3ⁱⁱⁱ	3.040 (3)	C2—C4	1.540 (3)
Sr1—H2WA	2.7869	C2—H2A	0.9615
O3—C1	1.254 (3)	C2—H2B	0.9614
O1W—H1WA	0.8501	C3—C4	1.521 (4)
O1W—H1WB	0.8483	C3—Sr1^v	3.040 (3)
O2W—H2WA	0.8499	C4—C4^vi	1.544 (5)
O2W—H2WB	0.8836	C4—H4A	0.9800
O1—C3	1.254 (3)

O4ⁱ—Sr1—O1ⁱⁱ	157.86 (6)	O4ⁱ—Sr1—H2WA	64.6
O4ⁱ—Sr1—O2W	76.72 (7)	O1ⁱⁱ—Sr1—H2WA	99.1
O1ⁱⁱ—Sr1—O2W	91.33 (6)	O2W—Sr1—H2WA	17.7
O4ⁱ—Sr1—O1W	125.67 (6)	O1W—Sr1—H2WA	143.4
O1ⁱⁱ—Sr1—O1W	76.42 (6)	O3—Sr1—H2WA	63.1
O2W—Sr1—O1W	126.16 (7)	O2ⁱ—Sr1—H2WA	80.7
O4ⁱ—Sr1—O3	82.01 (6)	O1ⁱⁱⁱ—Sr1—H2WA	141.8
O1ⁱⁱ—Sr1—O3	77.02 (6)	O2ⁱⁱⁱ—Sr1—H2WA	132.8
O2W—Sr1—O3	76.20 (7)	C3ⁱⁱⁱ—Sr1—H2WA	141.7
O1W—Sr1—O3	145.32 (6)	Sr1^vii—Sr1—H2WA	125.9
O4ⁱ—Sr1—O2ⁱ	82.57 (6)	C1—O3—Sr1	132.92 (17)
O1ⁱⁱ—Sr1—O2ⁱ	110.61 (6)	Sr1—O1W—H1WA	121.7
O2W—Sr1—O2ⁱ	68.51 (6)	Sr1—O1W—H1WB	112.2
O1W—Sr1—O2ⁱ	67.72 (6)	H1WA—O1W—H1WB	103.2
O3—Sr1—O2ⁱ	143.85 (6)	Sr1—O2W—H2WA	95.3
O4ⁱ—Sr1—O1ⁱⁱⁱ	112.11 (6)	Sr1—O2W—H2WB	127.1
O1ⁱⁱ—Sr1—O1ⁱⁱⁱ	70.75 (7)	H2WA—O2W—H2WB	121.4
O2W—Sr1—O1ⁱⁱⁱ	151.93 (6)	C3—O1—Sr1^iv	155.35 (16)
O1W—Sr1—O1ⁱⁱⁱ	71.71 (6)	C3—O1—Sr1^v	94.78 (14)
O3—Sr1—O1ⁱⁱⁱ	78.74 (6)	Sr1^iv—O1—Sr1^v	109.25 (7)
O2ⁱ—Sr1—O1ⁱⁱⁱ	137.41 (6)	C3—O2—Sr1ⁱ	127.36 (17)
O4ⁱ—Sr1—O2ⁱⁱⁱ	70.72 (6)	C3—O2—Sr1^v	93.61 (16)
O1ⁱⁱ—Sr1—O2ⁱⁱⁱ	118.62 (5)	Sr1ⁱ—O2—Sr1^v	134.76 (7)
O2W—Sr1—O2ⁱⁱⁱ	147.38 (6)	C1—O4—Sr1ⁱ	131.09 (19)
O1W—Sr1—O2ⁱⁱⁱ	76.83 (6)	O3—C1—O4	123.7 (2)
O3—Sr1—O2ⁱⁱⁱ	97.05 (7)	O3—C1—C2	117.8 (2)
O2ⁱ—Sr1—O2ⁱⁱⁱ	108.31 (3)	O4—C1—C2	118.5 (2)
O1ⁱⁱⁱ—Sr1—O2ⁱⁱⁱ	48.59 (5)	C1—C2—C4	115.4 (2)
O4ⁱ—Sr1—C3ⁱⁱⁱ	90.58 (7)	C1—C2—H2A	108.3
O1ⁱⁱ—Sr1—C3ⁱⁱⁱ	94.92 (6)	C4—C2—H2A	108.6
O2W—Sr1—C3ⁱⁱⁱ	159.30 (7)	C1—C2—H2B	108.6
O1W—Sr1—C3ⁱⁱⁱ	74.52 (6)	C4—C2—H2B	108.0
O3—Sr1—C3ⁱⁱⁱ	86.00 (7)	H2A—C2—H2B	107.8
O2ⁱ—Sr1—C3ⁱⁱⁱ	126.65 (6)	O1—C3—O2	122.4 (2)
O1ⁱⁱⁱ—Sr1—C3ⁱⁱⁱ	24.28 (6)	O1—C3—C4	118.9 (2)
O2ⁱⁱⁱ—Sr1—C3ⁱⁱⁱ	24.44 (6)	O2—C3—C4	118.7 (2)
O4ⁱ—Sr1—Sr1^vii	142.42 (5)	O1—C3—Sr1^v	60.94 (13)
O1ⁱⁱ—Sr1—Sr1^vii	36.13 (4)	O2—C3—Sr1^v	61.95 (14)
O2W—Sr1—Sr1^vii	124.41 (5)	C4—C3—Sr1^v	172.02 (16)
O1W—Sr1—Sr1^vii	70.29 (4)	C3—C4—C2	110.1 (2)
O3—Sr1—Sr1^vii	75.10 (4)	C3—C4—C4^vi	109.4 (3)
O2ⁱ—Sr1—Sr1^vii	132.19 (4)	C2—C4—C4^vi	111.5 (2)
O1ⁱⁱⁱ—Sr1—Sr1^vii	34.62 (4)	C3—C4—H4A	108.6
O2ⁱⁱⁱ—Sr1—Sr1^vii	82.83 (3)	C2—C4—H4A	108.6
C3ⁱⁱⁱ—Sr1—Sr1^vii	58.82 (5)	C4^vi—C4—H4A	108.6

Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+1/2, y+1/2, −z+1/2; (iii) x−1/2, −y−1/2, z+1/2; (iv) −x+1/2, y−1/2, −z+1/2; (v) x+1/2, −y−1/2, z−1/2; (vi) −x+1, −y, −z; (vii) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O3^vii	0.85	1.90	2.729 (3)	164.5
O1W—H1WB···O4^viii	0.85	2.14	2.944 (3)	159.1
O2W—H2WA···O4	0.85	2.06	2.841 (3)	153.1
O2W—H2WB···O1W^ix	0.88	1.99	2.864 (3)	170.1

Symmetry codes: (vii) −x, −y, −z+1; (viii) x−1/2, −y+1/2, z+1/2; (ix) −x+1/2, y+1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	[Sr₂(C₈H₆O₈)(H₂O)₄)]
M_r	477.44
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	8.7085 (4), 7.9671 (4), 10.0697 (4)
β (°)	95.409 (2)
V (Å³)	695.54 (5)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	7.73
Crystal size (mm)	0.25 × 0.15 × 0.13

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2010)
T_min, T_max	0.248, 0.433
No. of measured, independent and observed [I > 2σ(I)] reflections	7782, 1746, 1443
R_int	0.072
(sin θ/λ)_max (Å⁻¹)	0.676

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.061, 0.97
No. of reflections	1746
No. of parameters	100
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.58, −0.46

Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2010), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O3ⁱ	0.85	1.90	2.729 (3)	164.5
O1W—H1WB···O4ⁱⁱ	0.85	2.14	2.944 (3)	159.1
O2W—H2WA···O4	0.85	2.06	2.841 (3)	153.1
O2W—H2WB···O1Wⁱⁱⁱ	0.88	1.99	2.864 (3)	170.1

Symmetry codes: (i) −x, −y, −z+1; (ii) x−1/2, −y+1/2, z+1/2; (iii) −x+1/2, y+1/2, −z+3/2.

Acknowledgements

This research was supported by the National Science Council, Taiwan (NSC99–2113-M-033–005-MY2) and by the Center-of-Excellence (COE) Program on Membrane Technology from the Ministry of Education (MOE).

References

Brandenburg, K. (2010). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2010). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Jiang, H.-L. & Xu, Q. (2011). Chem. Commun. 47, 3351–3370. Web of Science CrossRef CAS Google Scholar
Kam, K. C., Young, K. L. M. & Cheetham, A. K. (2007). Cryst. Growth Des. 7, 1522–1532. Web of Science CSD CrossRef CAS Google Scholar
Kitagawa, S., Kitaura, R. & Noro, S. (2004). Angew. Chem. Int. Ed. 43, 2334–2375. Web of Science CrossRef CAS Google Scholar
Liu, H. K., Tsao, T. H., Zhang, Y. T. & Lin, C. H. (2009). CrystEngComm, 11, 1462–1468. Web of Science CSD CrossRef CAS Google Scholar
Ma, C.-H. & Yan, Y.-S. (2009). Acta Cryst. E65, m1555. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wu, L. (2009). Acta Cryst. E65, m1425. Web of Science CrossRef IUCr Journals Google Scholar