Diaqua­bis(2,5-di-4-pyridyl-1,3,4-thia­diazole-κN2)bis­(thio­cyanato-κN)copper(II) dihydrate

Ma, W.-W.; Yang, M.-H.

doi:10.1107/S1600536808008854

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 5| May 2008| Page m630

doi:10.1107/S1600536808008854

Open

access

Diaquabis(2,5-di-4-pyridyl-1,3,4-thiadiazole-κN²)bis(thiocyanato-κN)copper(II) dihydrate

Wei-Wu Ma ^a and Ming-Hua Yang ^a ^*

^aDepartment of Chemistry, Lishui University, 323000 Lishui, ZheJiang, People's Republic of China
^*Correspondence e-mail: zjlsxyhx@126.com

(Received 25 March 2008; accepted 2 April 2008; online 10 April 2008)

In the title compound, [Cu(NCS)₂(C₁₂H₈N₄S)₂(H₂O)₂]·2H₂O, the Cu atom is located on an inversion center and displays an octahedral geometry. Two N atoms of two different 2,5-di-4-pyridyl-1,3,4-thiadiazole ligands and two N atoms from two separate thiocyanate molecules form the equatorial plane, while two coordinated water molecules are in axial positions. The crystal structure is consolidated by extensive hydrogen bonding, forming a two-dimensional network.

Related literature

For related literature, see: Moulton & Zaworotko (2001 ); Su et al. (2003 ); Zhang et al. (2005 ); Zhou et al. (2006 ).

Experimental

Crystal data

[Cu(NCS)₂(C₁₂H₈N₄S)₂(H₂O)₂]·2H₂O
M_r = 732.33
Triclinic, $[P \overline 1]$
a = 7.0555 (11) Å
b = 8.3034 (13) Å
c = 14.849 (2) Å
α = 104.629 (2)°
β = 93.067 (2)°
γ = 112.228 (2)°
V = 768.3 (2) Å³
Z = 1
Mo Kα radiation
μ = 1.03 mm⁻¹
T = 298 (2) K
0.28 × 0.24 × 0.19 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ) T_min = 0.760, T_max = 0.828
3905 measured reflections
2692 independent reflections
1794 reflections with I > 2σ(I)
R_int = 0.028

Refinement

R[F² > 2σ(F²)] = 0.061
wR(F²) = 0.169
S = 1.07
2692 reflections
205 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.69 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2B⋯N5	0.82	2.03	2.835 (6)	169
O2—H2C⋯S2ⁱ	0.82	2.90	3.541 (4)	137
O1—H1B⋯S2ⁱⁱ	0.82	2.50	3.303 (4)	164
O1—H1C⋯O2ⁱⁱⁱ	0.82	1.95	2.761 (6)	171
Symmetry codes: (i) -x, -y+1, -z+1; (ii) x-1, y, z; (iii) x+1, y, z-1.

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ), ORTEP-3 for Windows (Farrugia, 1997 ) and PLATON (Spek, 2003 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808008854/dn2330sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808008854/dn2330Isup2.hkl

checkCIF report

Comment top

In recent years, the rational design and assembly of metal-organic frameworks (MOFs) with well regulated network structures have received remarkable attention in order to develop new functional materials with potential applications (Moulton & Zaworotko, 2001). Nevertheless, it is still a great challenge to predict the exact structures and compositions of polymeric compounds assembled in a motifs, although some structures with various architectures have been reported in MOFs. So far, much of the research has been concentrated on the exploitation of angular ligands with a molecular angle, such as ligands with a T-shape, V-shape etc, in the construction of versatile coordination polymer architectures (Su et al., 2003, Zhou et al., 2006). However, the bent 2,5-di-4-pyridyl-1,3,4-thiadiazole (L), have been less studied as building blocks in the construction of metal-organic frameworks (Zhang et al.; 2005). The angular 2,5-di-4-pyridyl-1,3,4-thiadiazole has flexible coodination modes than general 4,4'-bipyrdine-like ligands due to two more potential N-donors atoms. In this paper, we report the synthesis and crystal structure of the title complex with a multifunctional L ligand,(I).

The Cu atom is located on an inversion center and displays octahedral geometry (Fig. 1). Two nitrogen atoms of two different 2,5-di-4-pyridyl-1,3,4-thiadiazole ligands and two nitrogen atoms from two separated thiocyanate molecules form the basal plane, while two coordinated water molecules hold in axis position. The bond and angle are similar with others complexes with L ligand (Zhang et al., 2005). These monuclear units are held together by means of H bonds involving the coordinated water molecules, sulfur atoms of thiocyanate, lattice water molecules and N atoms of pyridyl rings from L ligands, which further assemble into a 2-D supramolecular sheet (Fig.2, Table 1).

Related literature top

For related literature, see: Moulton & Zaworotko (2001); Su et al. (2003); Zhang et al. (2005); Zhou et al. (2006).

Experimental top

Cu(NCS)₂(0.025 g, 0.13 mmol), L(0.031 g, 0.21 mmol), and NaOH (0.08 g, 0.2 mmol). were added in a solvent of methanol, the mixture was heated for ten hours under reflux. During the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel, Four weeks later some single crystals of the size suitable for X-Ray diffraction analysis.

Computing details top

Data collection: APEX2 (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: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Molecular view of (I), with the atom labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Water molecule and H atoms have been omitted for clarity. [Symmetry code: (i) 1 - x, 2 - y, -z].
	Fig. 2. Partial packing view of (I), showing O—H···O, O—H···S and O—H···N hydrogen bonds leading to the formation of two-dimensional network. Hydrogen bonds are shown as dashed lines.

Diaquabis(2,5-di-4-pyridyl-1,3,4-thiadiazole-κN²)bis(thiocyanato- κN)copper(II) dihydrate top

Crystal data top

[Cu(NCS)₂(C₁₂H₈N₄S)₂(H₂O)₂]·2H₂O	Z = 1
M_r = 732.33	F(000) = 375
Triclinic, P1	D_x = 1.583 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.0555 (11) Å	Cell parameters from 2692 reflections
b = 8.3034 (13) Å	θ = 1.4–25.1°
c = 14.849 (2) Å	µ = 1.03 mm⁻¹
α = 104.629 (2)°	T = 298 K
β = 93.067 (2)°	Block, blue
γ = 112.228 (2)°	0.28 × 0.24 × 0.19 mm
V = 768.3 (2) Å³

Data collection top

Bruker APEXII area-detector diffractometer	2692 independent reflections
Radiation source: fine-focus sealed tube	1794 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.028
ϕ and ω scans	θ_max = 25.1°, θ_min = 1.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −8→5
T_min = 0.761, T_max = 0.828	k = −9→9
3905 measured reflections	l = −17→17

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)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.169	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0774P)² + 0.6059P] where P = (F_o² + 2F_c²)/3
2692 reflections	(Δ/σ)_max < 0.001
205 parameters	Δρ_max = 0.44 e Å⁻³
0 restraints	Δρ_min = −0.69 e Å⁻³

Crystal data top

[Cu(NCS)₂(C₁₂H₈N₄S)₂(H₂O)₂]·2H₂O	γ = 112.228 (2)°
M_r = 732.33	V = 768.3 (2) Å³
Triclinic, P1	Z = 1
a = 7.0555 (11) Å	Mo Kα radiation
b = 8.3034 (13) Å	µ = 1.03 mm⁻¹
c = 14.849 (2) Å	T = 298 K
α = 104.629 (2)°	0.28 × 0.24 × 0.19 mm
β = 93.067 (2)°

Data collection top

Bruker APEXII area-detector diffractometer	2692 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	1794 reflections with I > 2σ(I)
T_min = 0.761, T_max = 0.828	R_int = 0.028
3905 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.061	0 restraints
wR(F²) = 0.169	H-atom parameters constrained
S = 1.07	Δρ_max = 0.44 e Å⁻³
2692 reflections	Δρ_min = −0.69 e Å⁻³
205 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	U_iso*/U_eq
Cu1	0.5000	1.0000	0.0000	0.0423 (3)
S1	−0.0367 (2)	0.7797 (2)	0.40422 (10)	0.0484 (4)
S2	0.7893 (2)	0.5558 (2)	−0.03644 (12)	0.0477 (4)
N1	0.6831 (7)	0.8539 (6)	−0.0062 (3)	0.0417 (11)
N2	0.4011 (6)	0.9385 (6)	0.1283 (3)	0.0349 (10)
N3	0.3261 (7)	0.7924 (7)	0.4413 (3)	0.0486 (13)
N4	0.2304 (8)	0.7563 (7)	0.5165 (3)	0.0489 (13)
N5	−0.3536 (8)	0.6276 (7)	0.7101 (3)	0.0511 (13)
O1	0.2491 (5)	0.7683 (5)	−0.0897 (3)	0.0434 (9)
H1B	0.1349	0.7366	−0.0728	0.065*
H1C	0.2596	0.6773	−0.1223	0.065*
O2	−0.6718 (6)	0.4775 (6)	0.8112 (3)	0.0586 (12)
H2B	−0.5687	0.5204	0.7880	0.088*
H2C	−0.6415	0.4525	0.8582	0.088*
C1	0.7271 (8)	0.7310 (8)	−0.0188 (4)	0.0347 (12)
C2	0.2117 (9)	0.9123 (8)	0.1465 (4)	0.0436 (14)
H2	0.1223	0.9275	0.1043	0.052*
C3	0.1394 (9)	0.8639 (8)	0.2240 (4)	0.0455 (14)
H3	0.0025	0.8407	0.2316	0.055*
C4	0.2713 (8)	0.8505 (7)	0.2895 (4)	0.0379 (13)
C5	0.4715 (9)	0.8795 (8)	0.2725 (4)	0.0475 (15)
H5	0.5660	0.8706	0.3150	0.057*
C6	0.5266 (9)	0.9218 (8)	0.1915 (4)	0.0432 (14)
H6	0.6604	0.9397	0.1802	0.052*
C7	0.2060 (8)	0.8066 (7)	0.3769 (4)	0.0395 (13)
C8	0.0424 (9)	0.7481 (8)	0.5080 (4)	0.0418 (13)
C9	−0.0929 (8)	0.7148 (7)	0.5800 (4)	0.0379 (13)
C10	−0.2927 (9)	0.7063 (8)	0.5682 (4)	0.0442 (14)
H10	−0.3440	0.7292	0.5160	0.053*
C11	−0.4144 (9)	0.6632 (8)	0.6357 (4)	0.0495 (15)
H11	−0.5479	0.6593	0.6276	0.059*
C12	−0.1584 (10)	0.6393 (9)	0.7221 (4)	0.0559 (17)
H12	−0.1112	0.6178	0.7757	0.067*
C13	−0.0248 (9)	0.6813 (8)	0.6596 (4)	0.0497 (15)
H13	0.1090	0.6871	0.6705	0.060*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0421 (6)	0.0432 (6)	0.0477 (6)	0.0197 (5)	0.0129 (4)	0.0186 (5)
S1	0.0490 (9)	0.0680 (11)	0.0412 (9)	0.0289 (8)	0.0147 (7)	0.0281 (8)
S2	0.0484 (9)	0.0420 (9)	0.0663 (11)	0.0258 (7)	0.0192 (8)	0.0252 (8)
N1	0.044 (3)	0.043 (3)	0.052 (3)	0.026 (2)	0.015 (2)	0.020 (2)
N2	0.032 (2)	0.037 (3)	0.038 (3)	0.014 (2)	0.009 (2)	0.015 (2)
N3	0.045 (3)	0.063 (3)	0.043 (3)	0.022 (3)	0.012 (2)	0.023 (3)
N4	0.048 (3)	0.064 (3)	0.041 (3)	0.021 (3)	0.014 (2)	0.027 (3)
N5	0.050 (3)	0.064 (4)	0.044 (3)	0.022 (3)	0.017 (2)	0.022 (3)
O1	0.035 (2)	0.043 (2)	0.051 (2)	0.0140 (17)	0.0117 (17)	0.0118 (18)
O2	0.055 (3)	0.059 (3)	0.051 (3)	0.013 (2)	0.018 (2)	0.011 (2)
C1	0.031 (3)	0.045 (3)	0.031 (3)	0.014 (2)	0.011 (2)	0.016 (3)
C2	0.041 (3)	0.052 (4)	0.043 (3)	0.018 (3)	0.007 (3)	0.023 (3)
C3	0.035 (3)	0.056 (4)	0.046 (3)	0.013 (3)	0.009 (3)	0.022 (3)
C4	0.040 (3)	0.034 (3)	0.036 (3)	0.011 (2)	0.012 (2)	0.009 (2)
C5	0.042 (3)	0.064 (4)	0.045 (4)	0.026 (3)	0.009 (3)	0.025 (3)
C6	0.040 (3)	0.054 (4)	0.043 (3)	0.022 (3)	0.017 (3)	0.020 (3)
C7	0.042 (3)	0.039 (3)	0.036 (3)	0.014 (3)	0.009 (3)	0.012 (3)
C8	0.047 (3)	0.043 (3)	0.037 (3)	0.017 (3)	0.006 (3)	0.014 (3)
C9	0.043 (3)	0.035 (3)	0.036 (3)	0.015 (2)	0.008 (2)	0.012 (3)
C10	0.046 (3)	0.053 (4)	0.047 (3)	0.026 (3)	0.009 (3)	0.026 (3)
C11	0.041 (3)	0.052 (4)	0.058 (4)	0.020 (3)	0.012 (3)	0.017 (3)
C12	0.054 (4)	0.075 (5)	0.042 (4)	0.023 (3)	0.014 (3)	0.026 (3)
C13	0.043 (3)	0.066 (4)	0.043 (4)	0.022 (3)	0.007 (3)	0.023 (3)

Geometric parameters (Å, º) top

Cu1—N1	2.071 (4)	O2—H2C	0.8159
Cu1—N1ⁱ	2.071 (4)	C2—C3	1.372 (8)
Cu1—O1ⁱ	2.118 (4)	C2—H2	0.9300
Cu1—O1	2.118 (4)	C3—C4	1.365 (8)
Cu1—N2	2.178 (4)	C3—H3	0.9300
Cu1—N2ⁱ	2.178 (4)	C4—C5	1.388 (8)
S1—C7	1.725 (6)	C4—C7	1.485 (7)
S1—C8	1.726 (5)	C5—C6	1.372 (7)
S2—C1	1.638 (6)	C5—H5	0.9300
N1—C1	1.150 (7)	C6—H6	0.9300
N2—C6	1.324 (7)	C8—C9	1.479 (7)
N2—C2	1.325 (7)	C9—C13	1.382 (7)
N3—C7	1.301 (7)	C9—C10	1.384 (7)
N3—N4	1.375 (6)	C10—C11	1.382 (8)
N4—C8	1.300 (7)	C10—H10	0.9300
N5—C11	1.305 (7)	C11—H11	0.9300
N5—C12	1.342 (8)	C12—C13	1.372 (8)
O1—H1B	0.8214	C12—H12	0.9300
O1—H1C	0.8200	C13—H13	0.9300
O2—H2B	0.8172

N1—Cu1—N1ⁱ	180.000 (1)	C4—C3—H3	120.5
N1—Cu1—O1ⁱ	89.03 (16)	C2—C3—H3	120.5
N1ⁱ—Cu1—O1ⁱ	90.97 (16)	C3—C4—C5	118.0 (5)
N1—Cu1—O1	90.97 (16)	C3—C4—C7	121.8 (5)
N1ⁱ—Cu1—O1	89.03 (17)	C5—C4—C7	120.2 (5)
O1ⁱ—Cu1—O1	180.0	C6—C5—C4	118.4 (5)
N1—Cu1—N2	91.15 (17)	C6—C5—H5	120.8
N1ⁱ—Cu1—N2	88.85 (17)	C4—C5—H5	120.8
O1ⁱ—Cu1—N2	86.47 (15)	N2—C6—C5	124.1 (5)
O1—Cu1—N2	93.53 (15)	N2—C6—H6	118.0
N1—Cu1—N2ⁱ	88.85 (17)	C5—C6—H6	118.0
N1ⁱ—Cu1—N2ⁱ	91.15 (17)	N3—C7—C4	124.0 (5)
O1ⁱ—Cu1—N2ⁱ	93.53 (15)	N3—C7—S1	113.8 (4)
O1—Cu1—N2ⁱ	86.47 (14)	C4—C7—S1	122.1 (4)
N2—Cu1—N2ⁱ	180.0 (2)	N4—C8—C9	123.7 (5)
C7—S1—C8	87.1 (3)	N4—C8—S1	113.7 (4)
C1—N1—Cu1	159.4 (4)	C9—C8—S1	122.6 (4)
C6—N2—C2	116.5 (5)	C13—C9—C10	118.0 (5)
C6—N2—Cu1	121.5 (4)	C13—C9—C8	119.9 (5)
C2—N2—Cu1	122.0 (3)	C10—C9—C8	122.0 (5)
C7—N3—N4	112.5 (5)	C11—C10—C9	118.6 (5)
C8—N4—N3	112.8 (4)	C11—C10—H10	120.7
C11—N5—C12	117.1 (5)	C9—C10—H10	120.7
Cu1—O1—H1B	118.7	N5—C11—C10	124.0 (6)
Cu1—O1—H1C	124.5	N5—C11—H11	118.0
H1B—O1—H1C	108.3	C10—C11—H11	118.0
H2B—O2—H2C	110.6	N5—C12—C13	123.5 (6)
N1—C1—S2	179.8 (5)	N5—C12—H12	118.2
N2—C2—C3	123.9 (5)	C13—C12—H12	118.2
N2—C2—H2	118.0	C12—C13—C9	118.7 (6)
C3—C2—H2	118.0	C12—C13—H13	120.6
C4—C3—C2	119.0 (5)	C9—C13—H13	120.6

Symmetry code: (i) −x+1, −y+2, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2B···N5	0.82	2.03	2.835 (6)	169
O2—H2C···S2ⁱⁱ	0.82	2.90	3.541 (4)	137
O1—H1B···S2ⁱⁱⁱ	0.82	2.50	3.303 (4)	164
O1—H1C···O2^iv	0.82	1.95	2.761 (6)	171

Symmetry codes: (ii) −x, −y+1, −z+1; (iii) x−1, y, z; (iv) x+1, y, z−1.

Experimental details

Crystal data
Chemical formula	[Cu(NCS)₂(C₁₂H₈N₄S)₂(H₂O)₂]·2H₂O
M_r	732.33
Crystal system, space group	Triclinic, P1
Temperature (K)	298
a, b, c (Å)	7.0555 (11), 8.3034 (13), 14.849 (2)
α, β, γ (°)	104.629 (2), 93.067 (2), 112.228 (2)
V (Å³)	768.3 (2)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	1.03
Crystal size (mm)	0.28 × 0.24 × 0.19

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2004)
T_min, T_max	0.761, 0.828
No. of measured, independent and observed [I > 2σ(I)] reflections	3905, 2692, 1794
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.597

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.061, 0.169, 1.07
No. of reflections	2692
No. of parameters	205
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.44, −0.69

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2B···N5	0.82	2.03	2.835 (6)	168.5
O2—H2C···S2ⁱ	0.82	2.90	3.541 (4)	136.6
O1—H1B···S2ⁱⁱ	0.82	2.50	3.303 (4)	164.3
O1—H1C···O2ⁱⁱⁱ	0.82	1.95	2.761 (6)	171.1

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

Acknowledgements

The authors are grateful to the Natural Science Foundation of Zhejiang Province (No. Y407081).

References

Bruker (2004). APEX2 and SMART. Bruker AXS Inc, Madison, Wisconsin, USA. Google Scholar
Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Moulton, B. & Zaworotko, M. J. (2001). Chem. Rev. 101, 1629–1658. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2004). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar
Su, C. Y., Cai, Y. P., Chen, C. L., Smith, M. D., Kaim, W. & Loye, H. C. (2003). J. Am. Chem. Soc. 125, 8595–8613. Web of Science CSD CrossRef PubMed CAS Google Scholar
Zhang, X. M., Fang, R. Q. & Wu, H. S. (2005). CrystEngComm. 7, 96–101. Web of Science CSD CrossRef CAS Google Scholar
Zhou, C. H., Wang, Y. Y., Li, D. S., Zhou, L. J., Liu, P. & Shi, Q. Z. (2006). Eur. J. Inorg. Chem. pp. 2437–2446. Web of Science CSD CrossRef Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.