Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Previous article
Next article
Previous article
Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Next article

metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 10| October 2012| Page m1234
https://doi.org/10.1107/S1600536812036896

Tetra­kis(di­methyl­ammonium) trans-di­chloridobis[5,5′-(pyrazine-2,3-diyl)bis­(1H-tetra­zol-1-ido-κN1)]copper(II)

Ju-Hsiou Liaoa* and Pei-Shan Shia

aDepartment of Chemistry and Biochemistry, National Chung Cheng University, 168 University Road, Min-Hsiung, Chia-Yi, Taiwan
*Correspondence e-mail: chejhl@ccu.edu.tw

(Received 7 August 2012; accepted 27 August 2012; online 1 September 2012)

The title compound, (C2H8N)4[Cu(C6H2N10)2Cl2], consists of an anionic complex which is composed of a CuII ion surrounded by four N atoms from two pyrazine-2,3-diylbis(1H-tetra­zol-1-ide) ligands, and two Cl− atoms in a trans-Cl2N4 coordination geometry; the CuII atom lies on a site of symmetry 2/m. The Cu—Cl distance of 2.8719 (5) Å is long due to the Jahn–Teller distortion of the d9 electron configuration of CuII ion. The tetra­zole and pyrazine rings make an N—C—C—N torsion angle of 38.25 (17)°. The charge of the anionic complex is balanced by four dimethyl­ammonium cations, which inter­act with the anionic complexes via N—H⋯N and N—H⋯Cl hydrogen bonds.

Related literature

For the coordination compound of 2,3-di-1H-tetra­zol-5-yl­pyrazine, see: Li et al. (2008[Li, J.-R., Tao, Y., Yu, Q., Bu, X.-H., Sakamoto, H. & Kitagawa, S. (2008). Chem. Eur. J. 14, 2771-2776.]). For related structure, see Tao et al. (2010[Tao, Y., Li, J.-R., Chang, Z. & Bu, X.-H. (2010). Cryst. Growth Des. 10, 564-574.]).

[Scheme 1]

Experimental

Crystal data

  • (C2H8N)4[Cu(C6H2N10)2Cl2]

  • Mr = 747.17

  • Orthorhombic, C m c a

  • a = 20.613 (2) Å

  • b = 10.5671 (9) Å

  • c = 15.0687 (12) Å

  • V = 3282.3 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.89 mm−1

  • T = 293 K

  • 0.06 × 0.06 × 0.05 mm
Data collection

  • Bruker SMART APEX diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 1999[Bruker (1999). SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.947, Tmax = 0.959

  • 18389 measured reflections

  • 2079 independent reflections

  • 1888 reflections with I > 2σ(I)

  • Rint = 0.024
Refinement

  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.085

  • S = 1.08

  • 2079 reflections

  • 120 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.74 e Å−3

  • Δρmin = −0.26 e Å−3

Table 1
Selected bond lengths (Å)

Cu1—N1 2.0029 (10)
Cu1—Cl1 2.8719 (5)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N6—H6B⋯Cl1i 0.88 (2) 2.32 (2) 3.1731 (13) 162.7 (18)
N6—H6A⋯N4ii 0.93 (2) 1.91 (2) 2.8381 (17) 175 (2)
Symmetry codes: (i) -x+1, -y, -z+1; (ii) [x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}].

Data collection: SMART (Bruker, 1998[Bruker (1998). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812036896/pk2440sup1.cif

Supporting information file. DOI: https://doi.org/10.1107/S1600536812036896/pk2440Isup2.cdx

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812036896/pk2440Isup3.hkl

checkCIF report


Comment top

Multifunctional tetrazolate ligands have recently been of great interest for the formation of metal-organic frameworks (MOFs). Thus far, the di-topic tetrazolate-based ligand, 2,3-di-1H-tetrazol-5-ylpyrazine (H2dtp) has only been found in a chiral, porous and thermally robust MOF, Zn(dtp) (Li, 2008). In our laboratory, the reaction of H2dtp and CuCl2 in dimethylformamide (DMF) under acidic conditions afforded the title compound (I).

In the title complex anion, the CuII ion is six-coordinated in a distorted octahedral environment, surrounded by two Cl- anions and four N-atoms from two chelating (dtp)2- anionic ligands, forming a trans-Cl2N4 coordination geometry (Fig. 1). The bonding mode is quite different from that observed in Zn(dtp). The asymmetric unit of the [CuCl2(dtp)2]4- anion contains one quarter of the complex, with the CuII ion located at a site of 2/m symmetry, and the two Cl- anions lie in a mirror plane. The Cu—Cl bond length, 2.8719 (5) Å, is unusually long due to Jahn-Teller distortion of the d9 electron configuration of CuII ion, while the Cu—N distance is normal at 2.0029 (10) Å. The tetrazolyl and pyrazinyl rings are not coplanar, with a torsion angle of 38.25 (17)°, in accord with the single-bond character of C1—C2 bond, 1.4678 (17) Å. In the aromatic CN4- tetrazolate ring, the N2—N3 bond, 1.3071 (16) Å, has slightly more double bond character than those of N1—N2 and N3—N4 bonds, 1.3455 (15) Å and 1.3450 (17) Å.

Four equivalents of [(CH3)2NH2]+ cations are present to balance the charge, as shown in the packing diagram (Fig. 2). Slabs parallel to the bc-plane are formed by hydrogen bonding networks, which are constructed by the N—H bonds of [NH2(CH3)2]+ cations interacting with the Cl- atoms and tetrazolate-N atoms of anionic complexes. Such slabs are stacked along the a-axis through van der Waals interactions among the methyl groups of the dimethylammonium cations.

Related literature top

For the coordination compound of 2,3-di-1H-tetrazol-5-ylpyrazine, see: Li et al. (2008). For related structure, see Tao et al. (2010).

Experimental top

4.3-mg (0.025 mmol) CuCl2.2H2O and 10.5-mg (0.05 mmol) H2dtp were dissolved in 1-ml dimethylformamide (DMF) respectively. The solutions were mixed in a reaction vial, adding 50-ml 3M HCl to adjust the pH value to ~1.5. The mixture was ultrasonicated to form a homogeneous yellowish green solution, and was kept at 120°C for three days. The product was washed with a small amount of DMF and acetone, and then dried in air. 18.2 mg of blue plate-like crystals were collected in 97.7% yield, based on Cu.

Refinement top

H atoms, except for H6A and H6B, were positioned geometrically and allowed to ride on their respective parent atoms with C—H = 0.96 Å [methyl, Uiso(H) = 1.5Ueq(C)] and C—H = 0.93 Å [aromatic, Uiso(H) = 1.2Ueq(C)]. H6A and H6B, which are involved in hydrogen bonds, were located in difference Fourier map and are refined freely. The highest peak (0.740 e Å-3) and the deepest hole (-0.257 e Å-3) in the difference Fourier map are located 0.79 Å and 1.19 Å from the atoms C2 and C3, respectively.

Structure description top

Multifunctional tetrazolate ligands have recently been of great interest for the formation of metal-organic frameworks (MOFs). Thus far, the di-topic tetrazolate-based ligand, 2,3-di-1H-tetrazol-5-ylpyrazine (H2dtp) has only been found in a chiral, porous and thermally robust MOF, Zn(dtp) (Li, 2008). In our laboratory, the reaction of H2dtp and CuCl2 in dimethylformamide (DMF) under acidic conditions afforded the title compound (I).

In the title complex anion, the CuII ion is six-coordinated in a distorted octahedral environment, surrounded by two Cl- anions and four N-atoms from two chelating (dtp)2- anionic ligands, forming a trans-Cl2N4 coordination geometry (Fig. 1). The bonding mode is quite different from that observed in Zn(dtp). The asymmetric unit of the [CuCl2(dtp)2]4- anion contains one quarter of the complex, with the CuII ion located at a site of 2/m symmetry, and the two Cl- anions lie in a mirror plane. The Cu—Cl bond length, 2.8719 (5) Å, is unusually long due to Jahn-Teller distortion of the d9 electron configuration of CuII ion, while the Cu—N distance is normal at 2.0029 (10) Å. The tetrazolyl and pyrazinyl rings are not coplanar, with a torsion angle of 38.25 (17)°, in accord with the single-bond character of C1—C2 bond, 1.4678 (17) Å. In the aromatic CN4- tetrazolate ring, the N2—N3 bond, 1.3071 (16) Å, has slightly more double bond character than those of N1—N2 and N3—N4 bonds, 1.3455 (15) Å and 1.3450 (17) Å.

Four equivalents of [(CH3)2NH2]+ cations are present to balance the charge, as shown in the packing diagram (Fig. 2). Slabs parallel to the bc-plane are formed by hydrogen bonding networks, which are constructed by the N—H bonds of [NH2(CH3)2]+ cations interacting with the Cl- atoms and tetrazolate-N atoms of anionic complexes. Such slabs are stacked along the a-axis through van der Waals interactions among the methyl groups of the dimethylammonium cations.

For the coordination compound of 2,3-di-1H-tetrazol-5-ylpyrazine, see: Li et al. (2008). For related structure, see Tao et al. (2010).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1999); 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: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The structure of the title compound, with displacement ellipsoids drawn at the 50% probability level for non-H atoms. Unlabelled atoms are related to the reference atoms by the symmetry operations (1 - x, -y, 1 - z), (x, -y, 1 - z) and (1 - x, y, z).
[Figure 2] Fig. 2. A packing diagram of the title compound. All H-atoms except for those involved in hydrogen bonds are omitted for clarity. Hydrogen-bonding interactions are drawn with dashed lines.
Tetrakis(dimethylammonium) trans-dichloridobis[5,5'-(pyrazine-2,3-diyl)bis(1H-tetrazol- 1-ido-κN1)]copper(II) top
Crystal data top
(C2H8N)4[Cu(C6H2N10)2Cl2]F(000) = 1548
Mr = 747.17Dx = 1.512 Mg m−3
Orthorhombic, CmcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2Cell parameters from 999 reflections
a = 20.613 (2) Åθ = 5–23.5°
b = 10.5671 (9) ŵ = 0.89 mm−1
c = 15.0687 (12) ÅT = 293 K
V = 3282.3 (5) Å3Hexagonal, blue
Z = 40.06 × 0.06 × 0.05 mm
Data collection top
Bruker SMART APEX
diffractometer		2079 independent reflections
Radiation source: fine-focus sealed tube1888 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.024
φ–ω scanθmax = 28.3°, θmin = 2.0°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)		h = −27→26
Tmin = 0.947, Tmax = 0.959k = −14→14
18389 measured reflectionsl = −19→20
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)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.085H atoms treated by a mixture of independent and constrained refinement
S = 1.08 w = 1/[σ2(Fo2) + (0.0517P)2 + 1.6198P]
where P = (Fo2 + 2Fc2)/3
2079 reflections(Δ/σ)max = 0.001
120 parametersΔρmax = 0.74 e Å−3
0 restraintsΔρmin = −0.26 e Å−3
Crystal data top
(C2H8N)4[Cu(C6H2N10)2Cl2]V = 3282.3 (5) Å3
Mr = 747.17Z = 4
Orthorhombic, CmcaMo Kα radiation
a = 20.613 (2) ŵ = 0.89 mm−1
b = 10.5671 (9) ÅT = 293 K
c = 15.0687 (12) Å0.06 × 0.06 × 0.05 mm
Data collection top
Bruker SMART APEX
diffractometer		2079 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)		1888 reflections with I > 2σ(I)
Tmin = 0.947, Tmax = 0.959Rint = 0.024
18389 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0300 restraints
wR(F2) = 0.085H atoms treated by a mixture of independent and constrained refinement
S = 1.08Δρmax = 0.74 e Å−3
2079 reflectionsΔρmin = −0.26 e Å−3
120 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
xyzUiso*/Ueq
Cu10.50000.00000.50000.02900 (12)
Cl10.5000−0.23652 (5)0.59389 (3)0.03605 (14)
C10.42546 (6)0.07284 (12)0.66989 (8)0.0248 (3)
C20.46598 (6)0.00989 (11)0.73673 (8)0.0253 (3)
C30.46657 (8)−0.09929 (14)0.86700 (10)0.0391 (3)
H30.4447−0.13870.91340.047*
C40.32397 (9)0.36802 (17)0.42405 (12)0.0474 (4)
H4A0.31700.33410.48240.071*
H4B0.28360.39850.40060.071*
H4C0.35450.43660.42730.071*
C50.30596 (8)0.15966 (16)0.35528 (11)0.0442 (4)
H5A0.30520.11160.40930.066*
H5B0.32100.10700.30760.066*
H5C0.26300.18940.34210.066*
N10.43237 (5)0.07041 (10)0.58166 (7)0.0266 (2)
N20.38148 (6)0.13511 (11)0.54897 (7)0.0323 (3)
N30.34593 (6)0.17510 (12)0.61510 (8)0.0342 (3)
N40.37226 (6)0.13670 (11)0.69221 (8)0.0312 (3)
N50.43235 (6)−0.04459 (12)0.80258 (8)0.0349 (3)
N60.34981 (6)0.26828 (14)0.36567 (9)0.0364 (3)
H6A0.3595 (11)0.3006 (19)0.3099 (15)0.059 (6)*
H6B0.3887 (12)0.2447 (19)0.3834 (13)0.053 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.01762 (17)0.0475 (2)0.02182 (18)0.0000.000−0.01293 (12)
Cl10.0268 (2)0.0411 (3)0.0402 (3)0.0000.0000.0032 (2)
C10.0213 (6)0.0300 (6)0.0231 (6)−0.0018 (4)0.0021 (4)−0.0041 (5)
C20.0256 (7)0.0273 (6)0.0231 (6)−0.0004 (5)0.0013 (5)−0.0038 (4)
C30.0442 (8)0.0416 (8)0.0316 (7)−0.0034 (7)0.0052 (6)0.0105 (6)
C40.0503 (10)0.0485 (9)0.0433 (9)0.0003 (7)0.0054 (8)0.0000 (7)
C50.0405 (8)0.0494 (9)0.0428 (8)0.0033 (7)−0.0050 (7)−0.0014 (7)
N10.0206 (5)0.0374 (6)0.0219 (5)0.0022 (4)−0.0014 (4)−0.0042 (4)
N20.0238 (5)0.0458 (7)0.0274 (6)0.0061 (5)−0.0025 (4)−0.0016 (5)
N30.0257 (6)0.0451 (7)0.0319 (6)0.0078 (5)0.0006 (4)−0.0013 (5)
N40.0270 (6)0.0386 (6)0.0279 (5)0.0055 (4)0.0045 (4)−0.0020 (5)
N50.0324 (6)0.0413 (6)0.0309 (6)−0.0036 (5)0.0041 (5)0.0050 (5)
N60.0244 (6)0.0565 (8)0.0282 (6)0.0034 (5)0.0017 (5)0.0067 (5)
Geometric parameters (Å, º) top
Cu1—N1i2.0029 (10)C4—H4A0.9600
Cu1—N1ii2.0029 (10)C4—H4B0.9600
Cu1—N12.0029 (10)C4—H4C0.9600
Cu1—N1iii2.0029 (10)C5—N61.469 (2)
Cu1—Cl12.8719 (5)C5—H5A0.9600
C1—N41.3309 (16)C5—H5B0.9600
C1—N11.3374 (15)C5—H5C0.9600
C1—C21.4678 (17)N1—N21.3455 (15)
C2—N51.3405 (17)N1—N21.3455 (15)
C2—C2ii1.402 (3)N2—N31.3071 (16)
C3—N51.3319 (19)N3—N21.3071 (16)
C3—C3ii1.378 (3)N3—N41.3450 (17)
C3—H30.9300N6—H6A0.93 (2)
C4—N61.473 (2)N6—H6B0.88 (2)
N1i—Cu1—N1ii180.0H4B—C4—H4C109.5
N1i—Cu1—N191.77 (6)N6—C5—H5A109.5
N1ii—Cu1—N188.23 (6)N6—C5—H5B109.5
N1i—Cu1—N1iii88.23 (6)H5A—C5—H5B109.5
N1ii—Cu1—N1iii91.77 (6)N6—C5—H5C109.5
N1—Cu1—N1iii180.0H5A—C5—H5C109.5
N1i—Cu1—Cl188.82 (3)H5B—C5—H5C109.5
N1ii—Cu1—Cl191.18 (3)C1—N1—N2105.74 (10)
N1—Cu1—Cl191.18 (3)C1—N1—N2105.74 (10)
N1iii—Cu1—Cl188.82 (3)C1—N1—Cu1133.78 (9)
N4—C1—N1110.40 (11)N2—N1—Cu1120.43 (8)
N4—C1—C2121.69 (11)N2—N1—Cu1120.43 (8)
N1—C1—C2127.80 (11)N3—N2—N1108.79 (10)
N5—C2—C2ii121.15 (8)N2—N3—N4109.56 (11)
N5—C2—C1114.09 (11)N2—N3—N4109.56 (11)
C2ii—C2—C1124.68 (7)C1—N4—N3105.50 (10)
N5—C3—C3ii121.98 (8)C3—N5—C2116.86 (13)
N5—C3—H3119.0C5—N6—C4113.59 (13)
C3ii—C3—H3119.0C5—N6—H6A108.9 (13)
N6—C4—H4A109.5C4—N6—H6A110.8 (13)
N6—C4—H4B109.5C5—N6—H6B111.8 (13)
H4A—C4—H4B109.5C4—N6—H6B110.5 (13)
N6—C4—H4C109.5H6A—N6—H6B100.5 (18)
H4A—C4—H4C109.5
N4—C1—C2—N538.25 (17)
Symmetry codes: (i) x, −y, −z+1; (ii) −x+1, y, z; (iii) −x+1, −y, −z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N6—H6B···Cl1iii0.88 (2)2.32 (2)3.1731 (13)162.7 (18)
N6—H6A···N4iv0.93 (2)1.91 (2)2.8381 (17)175 (2)
Symmetry codes: (iii) −x+1, −y, −z+1; (iv) x, −y+1/2, z−1/2.

Experimental details

Crystal data
Chemical formula(C2H8N)4[Cu(C6H2N10)2Cl2]
Mr747.17
Crystal system, space groupOrthorhombic, Cmca
Temperature (K)293
a, b, c (Å)20.613 (2), 10.5671 (9), 15.0687 (12)
V (Å3)3282.3 (5)
Z4
Radiation typeMo Kα
µ (mm−1)0.89
Crystal size (mm)0.06 × 0.06 × 0.05
Data collection
DiffractometerBruker SMART APEX
Absorption correctionMulti-scan
(SADABS; Bruker, 1999)
Tmin, Tmax0.947, 0.959
No. of measured, independent and
observed [I > 2σ(I)] reflections		18389, 2079, 1888
Rint0.024
(sin θ/λ)max (Å−1)0.667
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.085, 1.08
No. of reflections2079
No. of parameters120
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)0.74, −0.26

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1999), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Selected bond lengths (Å) top
Cu1—N12.0029 (10)Cu1—Cl12.8719 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N6—H6B···Cl1i0.88 (2)2.32 (2)3.1731 (13)162.7 (18)
N6—H6A···N4ii0.93 (2)1.91 (2)2.8381 (17)175 (2)
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x, −y+1/2, z−1/2.
 

Acknowledgements

The authors thank the National Science Council of Taiwan for financial support.

References

First citationBruker (1998). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationBruker (1999). SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
 First citationLi, J.-R., Tao, Y., Yu, Q., Bu, X.-H., Sakamoto, H. & Kitagawa, S. (2008). Chem. Eur. J. 14, 2771–2776.  Web of Science CSD CrossRef PubMed CAS Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationTao, Y., Li, J.-R., Chang, Z. & Bu, X.-H. (2010). Cryst. Growth Des. 10, 564–574.  Web of Science CrossRef CAS 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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 10| October 2012| Page m1234
https://doi.org/10.1107/S1600536812036896
Follow Acta Cryst. E
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS