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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

1,1,2,2-Tetra­kis(1,3-benzoxazol-2-yl)ethene

aDepartment of Chemistry, University of Stellenbosch, Private Bag X1, Matieland, South Africa, bDepartment of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F - bus 2404, B-3001 Heverlee, Belgium, and cInstitut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, D-60348 Frankfurt am Main, Germany
*Correspondence e-mail: lianger@sun.ac.za

(Received 1 July 2011; accepted 5 July 2011; online 13 July 2011)

The title compound, C30H16N4O4, reveals [\overline1] crystallographic and mol­ecular symmetry and accordingly the asymmetric unit comprises one half-mol­ecule. The dihedral angle between the planes of the two geminal benzoxazole rings is 74.39 (5)°. The packing features weak C—H⋯N and ππ inter­actions [centroid–centroid distance = 3.652 (1) Å].

Related literature

For the chloro­form disolvate of 1,1,2,2-tetra­kis­(1,3-benzo­thia­zol-2-yl)ethene, see: Hagos et al. (2010[Hagos, T. K., Nogai, S. D., Dobrzańska, L., Cronje, S. & Raubenheimer, H. G. (2010). Acta Cryst. E66, o2378.]). For bond lengths in the benzoxazole moiety in related compounds, see: Jian et al. (2007[Jian, F.-F., Yi, W., Wang, L.-M. & Wang, J. (2007). Acta Cryst. E63, o3887.]); Lokaj et al. (1997[Lokaj, J., Kettmann, V., Stetinová, J., Kada, R. & Vrábel, V. (1997). Acta Cryst. C53, 1358-1359.]); Muir et al. (1992[Muir, M. M., Cox, O., Bernard, L. & Muir, J. A. (1992). Acta Cryst. C48, 583-585.]). For details of the cut-off applied for C—H⋯N inter­actions, see: Desiraju & Steiner (2006[Desiraju, G. R. & Steiner, T. (2006). In The Weak Hydrogen Bond in Structural Chemistry and Biology. Oxford University Press.]). For the synthesis of AuCl(PPh3), see: Bruce et al. (1989[Bruce, M. I., Nicholson, B. K. & Shawkataly, O. B. (1989). Inorg. Synth. 26, 324-326.]).

[Scheme 1]

Experimental

Crystal data
  • C30H16N4O4

  • Mr = 496.47

  • Monoclinic, P 21 /c

  • a = 9.2697 (9) Å

  • b = 16.1943 (16) Å

  • c = 8.0332 (8) Å

  • β = 104.395 (2)°

  • V = 1168.1 (2) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 273 K

  • 0.30 × 0.25 × 0.15 mm

Data collection
  • Bruker APEX CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1997[Sheldrick, G. M. (1997). SADABS. University of Göttingen, Germany.]) Tmin = 0.972, Tmax = 0.986

  • 6999 measured reflections

  • 2717 independent reflections

  • 2458 reflections with I > 2σ(I)

  • Rint = 0.021

Refinement
  • R[F2 > 2σ(F2)] = 0.049

  • wR(F2) = 0.121

  • S = 1.06

  • 2717 reflections

  • 172 parameters

  • H-atom parameters constrained

  • Δρmax = 0.37 e Å−3

  • Δρmin = −0.30 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C7—H7⋯N12i 0.93 2.71 3.348 (2) 127
C17—H17⋯N3ii 0.93 2.71 3.580 (2) 153
C14—H14⋯N12iii 0.93 2.75 3.387 (2) 127
Symmetry codes: (i) -x, -y+1, -z+2; (ii) [x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (iii) -x+1, -y+1, -z+1.

Data collection: SMART (Bruker, 2001[Bruker (2001). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2002[Bruker (2002). SAINT. 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: Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

The title compound is reminiscent of the crystal structure of 1,1,2,2-tetrakis(1,3-benzothiazol-2-yl)ethene chloroform solvate (Hagos et al., 2010) and was isolated in a similar way. The asymmetric unit consists of half of the molecule with the other part being generated by an inversion centre (Fig. 1). The conformation of the molecule resembles that of the previous compound with a dihedral angle between the planes of the benzoxazole rings attached to the same carbon of 74.39 (5)°, whereas the corresponding value in the benzothiazole derivative was 85.74 (4)°. The bond length of 1.356 (3) Å for C1—C1i (symmetry operation (i): -x,1 - y,1 - z) is almost identical to that in the earlier described structure (1.359 (3) Å). The bond lengths for the benzoxazole rings are comparable with previously reported values (Jian et al., 2007; Lokaj et al., 1997; Muir et al., 1992). The packing is dominated by weak C—H···N (Table 1) and ππ interactions. The hydrogen bonds between C7—H7···N12 and C17—H17···N3 generate corrugated layers which are stabilised by π-π stacking interactions of the oxazole and phenyl rings with a distance of 3.652 (1) Å between the centroids of these rings (symmetry operation: -x,1 - y,2 - z) and ca. 1.41 Å slippage. In addition to this, N12 acts as a bifurcated hydrogen bond acceptor and interlinks the layers through C14—H14···N12 weak interaction to form a three-dimensional assembly (Fig. 2).

Related literature top

For the chloroform disolvate of 1,1,2,2-tetrakis(1,3-benzothiazol-2-yl)ethene, see: Hagos et al. (2010). For bond lengths in the benzoxazole moiety in related compounds, see: Jian et al. (2007); Lokaj et al. (1997); Muir et al. (1992). For details of the cut-off applied for C—H···N interactions, see: Desiraju & Steiner (2006). For the synthesis of AuCl(PPh3), see: Bruce et al. (1989).

Experimental top

A solution of bis(2-benzoxazolyl)methane (0.075 g, 0.30 mmol) in THF (20 mL) at 253 K was treated with n-BuLi in n-hexane (0.25 mL, 1.4 M, 0.35 mmol) and stirred for 1 h. The temperature was then slowly raised to room temperature. A suspension of an excess of S8 (ca 2 mol equivalents) in 20 mL of THF was added to the mixture at 253 K and stirred for 1 h. After treating the resulting mixture with a solution of AuCl(PPh3) (0.15 g, 0.33 mmol) (Bruce et al., 1989) in THF (20 mL), the mixture was allowed to slowly warm to ambient temperature while stirring. The solvent was removed under reduced pressure. Crystallisation of a dichloromethane solution of the residue layered with n-heptane at 253 K afforded light yellow crystals. Single crystal X-ray studies revealed that the unexpected oxidative dimerisation of bis(2-benzoxazolyl)methane had occurred to yield the title compound.

Refinement top

All H atoms were positioned geometrically, with C—H = 0.93 and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Unlabeled atoms are related to the labeled ones by the symmetry operation (i) -x,1 - y,1 - z.
[Figure 2] Fig. 2. Representation of the packing viewed down the c axis. The corrugated layers formed by weak C—H···N and ππ interactions are indicated in blue and red; C14—H14···N12 contacts between these layers are shown as dotted light-blue lines.
1,1,2,2-Tetrakis(1,3-benzoxazol-2-yl)ethene top
Crystal data top
C30H16N4O4F(000) = 512
Mr = 496.47Dx = 1.412 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3523 reflections
a = 9.2697 (9) Åθ = 2.5–28.3°
b = 16.1943 (16) ŵ = 0.10 mm1
c = 8.0332 (8) ÅT = 273 K
β = 104.395 (2)°Block, yellow
V = 1168.1 (2) Å30.30 × 0.25 × 0.15 mm
Z = 2
Data collection top
Bruker APEX CCD area-detector
diffractometer
2717 independent reflections
Radiation source: fine-focus sealed tube2458 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.021
ω scansθmax = 28.3°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)
h = 1212
Tmin = 0.972, Tmax = 0.986k = 1721
6999 measured reflectionsl = 107
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)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.121H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0513P)2 + 0.8168P]
where P = (Fo2 + 2Fc2)/3
2717 reflections(Δ/σ)max < 0.001
172 parametersΔρmax = 0.37 e Å3
0 restraintsΔρmin = 0.30 e Å3
Crystal data top
C30H16N4O4V = 1168.1 (2) Å3
Mr = 496.47Z = 2
Monoclinic, P21/cMo Kα radiation
a = 9.2697 (9) ŵ = 0.10 mm1
b = 16.1943 (16) ÅT = 273 K
c = 8.0332 (8) Å0.30 × 0.25 × 0.15 mm
β = 104.395 (2)°
Data collection top
Bruker APEX CCD area-detector
diffractometer
2717 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)
2458 reflections with I > 2σ(I)
Tmin = 0.972, Tmax = 0.986Rint = 0.021
6999 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0490 restraints
wR(F2) = 0.121H-atom parameters constrained
S = 1.06Δρmax = 0.37 e Å3
2717 reflectionsΔρmin = 0.30 e Å3
172 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
C10.02783 (16)0.46822 (9)0.55330 (19)0.0186 (3)
C20.02821 (16)0.44239 (9)0.69934 (19)0.0199 (3)
N30.01487 (14)0.37588 (8)0.78861 (16)0.0197 (3)
C40.06473 (16)0.37680 (9)0.91493 (19)0.0196 (3)
C50.06558 (18)0.32189 (10)1.0482 (2)0.0240 (3)
H50.00590.27491.06640.029*
C60.15995 (18)0.34088 (10)1.1524 (2)0.0258 (3)
H60.16400.30551.24230.031*
C70.24923 (18)0.41171 (10)1.1263 (2)0.0262 (4)
H70.31140.42181.19880.031*
C80.24768 (18)0.46738 (10)0.9955 (2)0.0246 (3)
H80.30600.51480.97820.029*
C90.15338 (16)0.44734 (9)0.89261 (19)0.0199 (3)
O100.12962 (12)0.48989 (7)0.75253 (14)0.0217 (3)
C110.15956 (17)0.42084 (10)0.53413 (19)0.0217 (3)
N120.29464 (13)0.44984 (7)0.58136 (16)0.0179 (3)
C130.38086 (17)0.38841 (9)0.53122 (19)0.0194 (3)
C140.53275 (17)0.38556 (10)0.5437 (2)0.0251 (3)
H140.59590.42860.59200.030*
C150.58507 (18)0.31551 (11)0.4807 (2)0.0284 (4)
H150.68630.31110.48720.034*
C160.4904 (2)0.25091 (11)0.4074 (2)0.0309 (4)
H160.53070.20480.36660.037*
C170.33806 (19)0.25342 (10)0.3935 (2)0.0284 (4)
H170.27460.21060.34500.034*
C180.28725 (16)0.32445 (9)0.45730 (19)0.0205 (3)
O190.14322 (12)0.34621 (7)0.46062 (15)0.0258 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0167 (7)0.0186 (7)0.0206 (7)0.0016 (5)0.0050 (5)0.0009 (5)
C20.0164 (7)0.0216 (7)0.0211 (7)0.0023 (5)0.0037 (6)0.0013 (6)
N30.0192 (6)0.0191 (6)0.0211 (6)0.0002 (5)0.0057 (5)0.0020 (5)
C40.0190 (7)0.0195 (7)0.0197 (7)0.0035 (5)0.0037 (6)0.0023 (5)
C50.0274 (8)0.0202 (7)0.0233 (8)0.0018 (6)0.0044 (6)0.0016 (6)
C60.0314 (8)0.0260 (8)0.0199 (7)0.0096 (6)0.0062 (6)0.0002 (6)
C70.0272 (8)0.0306 (8)0.0236 (8)0.0072 (6)0.0114 (6)0.0070 (6)
C80.0236 (8)0.0249 (8)0.0266 (8)0.0004 (6)0.0088 (6)0.0039 (6)
C90.0202 (7)0.0197 (7)0.0189 (7)0.0033 (5)0.0035 (5)0.0007 (6)
O100.0217 (5)0.0216 (5)0.0234 (5)0.0014 (4)0.0084 (4)0.0019 (4)
C110.0239 (8)0.0227 (7)0.0197 (7)0.0061 (6)0.0080 (6)0.0067 (6)
N120.0155 (6)0.0149 (6)0.0246 (6)0.0013 (4)0.0075 (5)0.0011 (5)
C130.0210 (7)0.0180 (7)0.0202 (7)0.0026 (5)0.0069 (6)0.0017 (5)
C140.0202 (7)0.0283 (8)0.0270 (8)0.0029 (6)0.0062 (6)0.0031 (6)
C150.0203 (8)0.0376 (9)0.0291 (8)0.0079 (7)0.0097 (6)0.0068 (7)
C160.0343 (9)0.0297 (9)0.0308 (9)0.0113 (7)0.0123 (7)0.0028 (7)
C170.0311 (9)0.0246 (8)0.0291 (8)0.0005 (6)0.0068 (7)0.0056 (6)
C180.0192 (7)0.0223 (7)0.0200 (7)0.0019 (6)0.0047 (6)0.0012 (6)
O190.0220 (6)0.0265 (6)0.0283 (6)0.0015 (4)0.0051 (5)0.0013 (5)
Geometric parameters (Å, º) top
C1—C1i1.356 (3)C9—O101.3830 (18)
C1—C21.458 (2)C11—N121.302 (2)
C1—C111.482 (2)C11—O191.3370 (19)
C2—N31.3006 (19)N12—C131.3966 (18)
C2—O101.3628 (18)C13—C181.386 (2)
N3—C41.3952 (19)C13—C141.387 (2)
C4—C91.393 (2)C14—C151.379 (2)
C4—C51.394 (2)C14—H140.9300
C5—C61.387 (2)C15—C161.398 (3)
C5—H50.9300C15—H150.9300
C6—C71.399 (2)C16—C171.389 (2)
C6—H60.9300C16—H160.9300
C7—C81.387 (2)C17—C181.388 (2)
C7—H70.9300C17—H170.9300
C8—C91.382 (2)C18—O191.3874 (18)
C8—H80.9300
C1i—C1—C2124.77 (17)C2—O10—C9103.63 (11)
C1i—C1—C11121.42 (17)N12—C11—O19116.73 (13)
C2—C1—C11113.75 (12)N12—C11—C1122.70 (14)
N3—C2—O10115.83 (13)O19—C11—C1120.53 (13)
N3—C2—C1124.01 (14)C11—N12—C13103.70 (12)
O10—C2—C1120.14 (13)C18—C13—C14121.47 (14)
C2—N3—C4104.29 (12)C18—C13—N12108.27 (13)
C9—C4—C5120.43 (14)C14—C13—N12130.25 (14)
C9—C4—N3108.48 (13)C15—C14—C13116.37 (15)
C5—C4—N3131.09 (14)C15—C14—H14121.8
C6—C5—C4116.56 (15)C13—C14—H14121.8
C6—C5—H5121.7C14—C15—C16121.96 (15)
C4—C5—H5121.7C14—C15—H15119.0
C5—C6—C7121.96 (15)C16—C15—H15119.0
C5—C6—H6119.0C17—C16—C15122.06 (15)
C7—C6—H6119.0C17—C16—H16119.0
C8—C7—C6121.95 (15)C15—C16—H16119.0
C8—C7—H7119.0C18—C17—C16115.22 (15)
C6—C7—H7119.0C18—C17—H17122.4
C9—C8—C7115.30 (15)C16—C17—H17122.4
C9—C8—H8122.4C13—C18—O19107.75 (13)
C7—C8—H8122.4C13—C18—C17122.92 (14)
C8—C9—O10128.44 (14)O19—C18—C17129.34 (14)
C8—C9—C4123.79 (14)C11—O19—C18103.54 (12)
O10—C9—C4107.77 (13)
C1i—C1—C2—N3171.93 (18)C1i—C1—C11—N1275.2 (2)
C11—C1—C2—N311.0 (2)C2—C1—C11—N12102.04 (16)
C1i—C1—C2—O109.6 (3)C1i—C1—C11—O19102.5 (2)
C11—C1—C2—O10167.47 (13)C2—C1—C11—O1980.33 (17)
O10—C2—N3—C40.47 (17)O19—C11—N12—C131.25 (17)
C1—C2—N3—C4178.99 (13)C1—C11—N12—C13176.47 (13)
C2—N3—C4—C90.45 (15)C11—N12—C13—C180.89 (16)
C2—N3—C4—C5179.84 (16)C11—N12—C13—C14178.08 (16)
C9—C4—C5—C61.1 (2)C18—C13—C14—C150.7 (2)
N3—C4—C5—C6179.58 (15)N12—C13—C14—C15179.59 (15)
C4—C5—C6—C70.4 (2)C13—C14—C15—C160.3 (2)
C5—C6—C7—C80.5 (2)C14—C15—C16—C170.0 (3)
C6—C7—C8—C90.7 (2)C15—C16—C17—C180.1 (3)
C7—C8—C9—O10179.17 (14)C14—C13—C18—O19178.77 (13)
C7—C8—C9—C40.0 (2)N12—C13—C18—O190.32 (16)
C5—C4—C9—C81.0 (2)C14—C13—C18—C170.9 (2)
N3—C4—C9—C8179.59 (14)N12—C13—C18—C17180.00 (14)
C5—C4—C9—O10179.77 (13)C16—C17—C18—C130.6 (2)
N3—C4—C9—O100.30 (16)C16—C17—C18—O19179.05 (15)
N3—C2—O10—C90.29 (16)N12—C11—O19—C181.06 (17)
C1—C2—O10—C9178.87 (13)C1—C11—O19—C18176.71 (13)
C8—C9—O10—C2179.27 (15)C13—C18—O19—C110.38 (15)
C4—C9—O10—C20.03 (15)C17—C18—O19—C11179.28 (16)
Symmetry code: (i) x, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C7—H7···N12ii0.932.713.348 (2)127
C17—H17···N3iii0.932.713.580 (2)153
C14—H14···N12iv0.932.753.387 (2)127
Symmetry codes: (ii) x, y+1, z+2; (iii) x, y+1/2, z1/2; (iv) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC30H16N4O4
Mr496.47
Crystal system, space groupMonoclinic, P21/c
Temperature (K)273
a, b, c (Å)9.2697 (9), 16.1943 (16), 8.0332 (8)
β (°) 104.395 (2)
V3)1168.1 (2)
Z2
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.30 × 0.25 × 0.15
Data collection
DiffractometerBruker APEX CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1997)
Tmin, Tmax0.972, 0.986
No. of measured, independent and
observed [I > 2σ(I)] reflections
6999, 2717, 2458
Rint0.021
(sin θ/λ)max1)0.666
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.121, 1.06
No. of reflections2717
No. of parameters172
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.37, 0.30

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C7—H7···N12i0.932.713.348 (2)127
C17—H17···N3ii0.932.713.580 (2)153
C14—H14···N12iii0.932.753.387 (2)127
Symmetry codes: (i) x, y+1, z+2; (ii) x, y+1/2, z1/2; (iii) x+1, y+1, z+1.
 

Acknowledgements

The authors thank the National Research Foundation of South Africa for financial support. LD also thanks the Research Foundation Flanders (FWO).

References

First citationBruce, M. I., Nicholson, B. K. & Shawkataly, O. B. (1989). Inorg. Synth. 26, 324–326.  CrossRef CAS Web of Science Google Scholar
First citationBruker (2001). SMART. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationBruker (2002). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationDesiraju, G. R. & Steiner, T. (2006). In The Weak Hydrogen Bond in Structural Chemistry and Biology. Oxford University Press.  Google Scholar
First citationHagos, T. K., Nogai, S. D., Dobrzańska, L., Cronje, S. & Raubenheimer, H. G. (2010). Acta Cryst. E66, o2378.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationJian, F.-F., Yi, W., Wang, L.-M. & Wang, J. (2007). Acta Cryst. E63, o3887.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationLokaj, J., Kettmann, V., Stetinová, J., Kada, R. & Vrábel, V. (1997). Acta Cryst. C53, 1358–1359.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationMacrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationMuir, M. M., Cox, O., Bernard, L. & Muir, J. A. (1992). Acta Cryst. C48, 583–585.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationSheldrick, G. M. (1997). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals 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
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds