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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 7| July 2015| Pages o459-o460

Crystal structure of (E)-1,2-bis­­(4-bromo-2,6-di­fluoro­phen­yl)diazene

CROSSMARK_Color_square_no_text.svg

aLudwig-Maximilians-Universität, Department Chemie, Butenandtstrasse 5–13, 81377 München, Germany
*Correspondence e-mail: pemay@cup.uni-muenchen.de

Edited by M. Nieger, University of Helsinki, Finland (Received 12 May 2015; accepted 2 June 2015; online 10 June 2015)

In the crystal, mol­ecules of the centrosymmetric title compound, C12H4Br2F4N2, are linked into strands along [011] by weak C—H⋯F contacts. Furthermore, the mol­ecules are ππ stacked with perpendicular ring distances of 3.4530 (9) Å.

Keywords: crystal structure.

1. Related literature

For background on azo­benzenes, see: Mitscherlich (1834[Mitscherlich, E. (1834). Annalen der Physik und Chemie, XXXII, 224.]); Fehrentz et al. (2011[Fehrentz, T., Schönberger, M. & Trauner, D. (2011). Angew. Chem. Int. Ed. 50, 12156-12182.]); Banghart et al. (2004[Banghart, M., Borges, K., Isacoff, E., Trauner, D. & Kramer, R. H. (2004). Nat. Neurosci. 7, 1381-1386.]); Levitz et al. (2013[Levitz, J., Pantoja, C., Gaub, B., Janovjak, H., Reiner, A., Hoagland, A., Schoppik, D., Kane, B., Stawski, P., Schier, A. F., Trauner, D. & Isacoff, E. Y. (2013). Nat. Neurosci. 16, 507-516.]); Broichhagen et al. (2014[Broichhagen, J., Jurastow, I., Iwan, K., Kummer, W. & Trauner, D. (2014). Angew. Chem. Int. Ed. 53, 7657-7660.]); Velema et al. (2013[Velema, W. A., van der Berg, J. P., Hansen, M. J., Szymanski, W., Driessen, A. J. & Feringa, B. L. (2013). Nat. Chem. 5, 924-928.]); Bléger et al. (2012[Bléger, D., Schwarz, J., Brouwer, A. M. & Hecht, S. (2012). J. Am. Chem. Soc. 134, 20597-20600.]). For the synthesis, see: Bléger et al. (2012[Bléger, D., Schwarz, J., Brouwer, A. M. & Hecht, S. (2012). J. Am. Chem. Soc. 134, 20597-20600.]). For related structures, see: Wragg et al. (2011[Wragg, D. S., Ahmed, M. A. K., Nilsen, O. & Fjellvåg, H. (2011). Acta Cryst. E67, o2326.]); Gabe et al. (1981[Gabe, E. J., Wang, Y. & Le Page, Y. (1981). Acta Cryst. B37, 980-981.]); Crispini et al. (1998[Crispini, A., Ghedini, M. & Pucci, D. (1998). Acta Cryst. C54, 1869-1871.]); Elder & Vargas-Baca (2012[Elder, P. J. W. & Vargas-Baca, I. (2012). Acta Cryst. E68, o3127.]); Komeyama et al. (1973[Komeyama, M., Yamamoto, S., Nishimura, N. & Hasegawa, S. (1973). Bull. Chem. Soc. Jpn, 46, 2606-2607.]); Ferguson et al. (1998[Ferguson, G., Low, J. N., Penner, G. H. & Wardell, J. L. (1998). Acta Cryst. C54, 1974-1977.]); Reichenbächer et al. (2007[Reichenbächer, K., Neels, A., Stoeckli-Evans, H., Balasubramaniyan, P., Müller, K., Matsuo, Y., Nakamura, E., Weber, E. & Hulliger, J. (2007). Cryst. Growth Des. 7, 1399-1405.]).

[Scheme 1]

2. Experimental

2.1. Crystal data

  • C12H4Br2F4N2

  • Mr = 411.98

  • Monoclinic, P 21 /c

  • a = 10.3274 (5) Å

  • b = 4.5667 (2) Å

  • c = 13.1039 (6) Å

  • β = 90.340 (3)°

  • V = 618.00 (5) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 6.60 mm−1

  • T = 173 K

  • 0.14 × 0.07 × 0.02 mm

2.2. Data collection

  • Bruker D8 Quest diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2012[Bruker (2012). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.572, Tmax = 0.746

  • 9803 measured reflections

  • 1523 independent reflections

  • 1218 reflections with I > 2σ(I)

  • Rint = 0.051

2.3. Refinement

  • R[F2 > 2σ(F2)] = 0.027

  • wR(F2) = 0.055

  • S = 1.02

  • 1523 reflections

  • 91 parameters

  • H-atom parameters constrained

  • Δρmax = 0.36 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
C5—H5⋯F2i 0.95 2.53 3.190 (3) 126
Symmetry code: (i) [-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: Bruker Instrument Service (Bruker, 2007[Bruker (2007). APEX2, Bruker Instrument Service and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: APEX2 (Bruker, 2007[Bruker (2007). APEX2, Bruker Instrument Service and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT (Bruker, 2007[Bruker (2007). APEX2, Bruker Instrument Service and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. A71, 3-8.]); molecular graphics: ORTEP-III (Burnett & Johnson, 1996[Burnett, M. N. & Johnson, C. K. (1996). ORTEP-III. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.]); software used to prepare material for publication: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Azobenzenes, first discovered in 1834 [Mitscherlich (1834)], are experiencing a renaissance in the last decade for the photocontrol of biological function [Fehrentz et al. (2011)]. They offer cis-/trans-isomerism upon irradiation with discrete and orthogonal wavelengths of light. When attached to a pharmacophore, this conformational change has an impact on binding affinities to its biological target. Therefore, a wide variety of transmembrane proteins, such as ion-channels [Banghart et al. (2004)] and metabotropic receptors [Levitz et al. (2013)], as well as enzymatic activity [Broichhagen et al. (2014)] and cell survival [Velema et al. (2013)] has been manipulated with azobenzene-based molecular structures. With our ongoing research in photopharmacology, we aimed to synthesize tetrafluoro-azobenzenes, which are characterized by their bistability once isomerized [Bléger et al. (2012)]. During our synthetic studies, we obtained (E)-1,2-bis(4-bromo-2,6-difluorophenyl)diazene (1) in a crystalline form, which we are reporting herein. This symmetric molecule serves as a precursor for further functionalization and implementation in photopharmacological studies, which will be described in a separate publication.

The molecular structure of the title compound is depicted in Figure 1. There are several structures containing (E)-1,2-bis(phenyl)diazene derivatives with at least one halogen substituent in 2-, 4- or 6-position reported in the literature, e.g. Wragg et al. (2011), Gabe et al. (1981), Crispini et al. (1998), Elder & Vargas-Baca (2012) and Komeyama et al. (1973). Furthermore there are two structures reported which contain the 4-bromo-2,6-difluorophenyl moiety [Ferguson et al. (1998), Reichenbächer et al. (2007)]. Due to centrosymmetry the phenyl rings are exactly coplanar, however, the entire molecule deviates significantly from exact planarity. The bond of the azo group forms an angle of 4.04 (16)° with the least-square plane of the phenyl ring while it is much larger with 13.21 (12)° in a related structure [Crispini et al. (1998)]. The C4–Br1 bond encloses an angle of 2.95 (10)° with the least-square plane of the phenyl ring which is quite close to the angle of 0.2 (3)° in a reported 4-bromo-2,6-difluorophenyl derivative [Ferguson et al. (1998)]. The 4-bromo-2,6-difluorophenyl derivative reported of Reichenbächer et al. (2007) is suitable for the comparison of bond lengths with the title compound since both compounds have been investigated at 173 K. In the title compound, the C–Br bond distance is 1.888 (2) Å which is almost in the same range of distances found in the reported structure: 1.889 (5), 1.883 (6) and 1.882 (6) Å. The C–F distances are 1.345 (3) and 1.335 (3) Å in the title compound and in the range of 1.336 (7) to 1.353 (7) Å in the related derivative [Reichenbächer et al. (2007)].

The packing of the title compound is dominated by weak C–H···F contacts, Br-π contacts and π-stacking. Strands along [011] are formed by C–H···F contacts (see Figure 2 and Table 1 for details). The π-stacking is well visible in Figure 3. The molecules are arranged staggered by what the azo group and the Br substituent of adjacent molecules are located above or below a phenyl ring. The centre of gravity of the phenyl ring (coordinates x = 0.28683, y = 0.5321, z = 0.56133) is in a distance of 3.412 and 3.459 Å from the N-atoms of the azo group (N1ii with ii = x,1 + y,z and N1iii with iii = 1 - x,2 - y,-z resp.) and 3.573 (1) Å from an adjacent Br substituent (Br1iv with iv = x,-1 + y,z). The perpendicular distances of phenyl rings interacting by π-contacts are in a narrow range of 3.4528 (9) and 3.4532 (9) Å with a CgCg distance of 4.5665 (14) Å. Besides the π contact the Br substituent forms weak contacts to two adjacent Br substituents in a distance of 3.6817 (4) Å each (Br1v and Br1vi with v = -x,1/2 + y,1/2 - z and vi = -x,-1/2 + y,1/2 - z).

Related literature top

For background on azobenzenes, see: Mitscherlich (1834); Fehrentz et al. (2011); Banghart et al. (2004); Levitz et al. (2013); Broichhagen et al. (2014); Velema et al. (2013); Bléger et al. (2012). For the synthesis, see: Bléger et al. (2012). For related structures, see: Wragg et al. (2011); Gabe et al. (1981); Crispini et al. (1998); Elder & Vargas-Baca (2012); Komeyama et al. (1973); Ferguson et al. (1998); Reichenbächer et al. (2007).

Experimental top

(E)-1,2-bis(4-bromo-2,6-difluorophenyl)diazene (1) was synthesized as reported before and the spectral data matched the previously reported data [Bléger et al. (2012)]. Crystals suitable for X-Ray diffractometry were obtained as deep-red needles by slow evaporization from chloroform.

Refinement top

All H atoms were found in difference maps. C-bonded H atoms were positioned in ideal geometry (C—H = 0.95 Å) and treated as riding on their parent atoms [Uiso(H) = 1.2Ueq(C)].

Computing details top

Data collection: Bruker Instrument Service (Bruker, 2007); cell refinement: APEX2 (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-III (Burnett & Johnson, 1996); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 30% probability level) for non-H atoms. Symmetry code: (i) 1 - x, 2 - y, 1 - z.
[Figure 2] Fig. 2. Weak C—H···F contacts (dotted lines) linking the title compound into strands along [011].
[Figure 3] Fig. 3. The unit cell of the title compound (displacement ellipsoids drawn at 30% probability level).
(E)-1,2-bis(4-bromo-2,6-difluorophenyl)diazene top
Crystal data top
C12H4Br2F4N2F(000) = 392
Mr = 411.98Dx = 2.214 (1) Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 95 reflections
a = 10.3274 (5) Åθ = 5.4–24.6°
b = 4.5667 (2) ŵ = 6.60 mm1
c = 13.1039 (6) ÅT = 173 K
β = 90.340 (3)°Platelet, orange
V = 618.00 (5) Å30.14 × 0.07 × 0.02 mm
Z = 2
Data collection top
Bruker D8 Quest
diffractometer
1523 independent reflections
Radiation source: Microfocus source, Bruker IµS1218 reflections with I > 2σ(I)
Focusing mirrors monochromatorRint = 0.051
Detector resolution: 10.4167 pixels mm-1θmax = 28.4°, θmin = 3.1°
mix of phi and ω scansh = 1313
Absorption correction: multi-scan
(SADABS; Bruker, 2012)
k = 66
Tmin = 0.572, Tmax = 0.746l = 1717
9803 measured reflections
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)] = 0.027Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.055H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.0231P)2 + 0.2317P]
where P = (Fo2 + 2Fc2)/3
1523 reflections(Δ/σ)max < 0.001
91 parametersΔρmax = 0.36 e Å3
0 restraintsΔρmin = 0.30 e Å3
Crystal data top
C12H4Br2F4N2V = 618.00 (5) Å3
Mr = 411.98Z = 2
Monoclinic, P21/cMo Kα radiation
a = 10.3274 (5) ŵ = 6.60 mm1
b = 4.5667 (2) ÅT = 173 K
c = 13.1039 (6) Å0.14 × 0.07 × 0.02 mm
β = 90.340 (3)°
Data collection top
Bruker D8 Quest
diffractometer
1523 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2012)
1218 reflections with I > 2σ(I)
Tmin = 0.572, Tmax = 0.746Rint = 0.051
9803 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0270 restraints
wR(F2) = 0.055H-atom parameters constrained
S = 1.02Δρmax = 0.36 e Å3
1523 reflectionsΔρmin = 0.30 e Å3
91 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 > 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*/Ueq
C10.3771 (2)0.7379 (5)0.52174 (17)0.0188 (5)
C20.2748 (2)0.6243 (6)0.46388 (18)0.0232 (5)
C30.1860 (2)0.4296 (6)0.49948 (18)0.0233 (5)
H30.11790.35940.45700.028*
C40.1983 (2)0.3376 (5)0.59963 (18)0.0197 (5)
C50.2992 (2)0.4325 (5)0.66162 (18)0.0216 (5)
H50.30840.36290.72960.026*
C60.3856 (2)0.6304 (5)0.62162 (18)0.0205 (5)
N10.45691 (19)0.9452 (5)0.47266 (15)0.0234 (4)
F10.26329 (15)0.7158 (4)0.36666 (10)0.0382 (4)
F20.48197 (15)0.7201 (4)0.68235 (11)0.0373 (4)
Br10.07408 (2)0.08357 (6)0.656884 (19)0.02666 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0172 (11)0.0184 (13)0.0208 (12)0.0001 (10)0.0014 (9)0.0017 (10)
C20.0266 (13)0.0257 (14)0.0173 (12)0.0002 (10)0.0020 (9)0.0017 (10)
C30.0206 (12)0.0262 (14)0.0230 (12)0.0035 (11)0.0047 (9)0.0029 (12)
C40.0173 (12)0.0150 (12)0.0270 (13)0.0020 (9)0.0046 (9)0.0014 (10)
C50.0239 (12)0.0215 (13)0.0193 (11)0.0016 (11)0.0011 (9)0.0003 (11)
C60.0203 (12)0.0199 (13)0.0214 (12)0.0000 (10)0.0052 (9)0.0049 (10)
N10.0221 (11)0.0239 (11)0.0243 (11)0.0046 (9)0.0016 (8)0.0014 (10)
F10.0385 (9)0.0555 (11)0.0205 (8)0.0178 (8)0.0093 (6)0.0125 (8)
F20.0372 (9)0.0479 (10)0.0268 (8)0.0201 (8)0.0142 (7)0.0079 (8)
Br10.02328 (14)0.02389 (15)0.03287 (15)0.00452 (11)0.00594 (9)0.00056 (13)
Geometric parameters (Å, º) top
C1—C21.397 (3)C4—C51.387 (3)
C1—C61.400 (3)C4—Br11.888 (2)
C1—N11.412 (3)C5—C61.376 (3)
C2—F11.345 (3)C5—H50.9500
C2—C31.362 (3)C6—F21.335 (3)
C3—C41.383 (3)N1—N1i1.244 (4)
C3—H30.9500
C2—C1—C6114.8 (2)C3—C4—Br1120.30 (18)
C2—C1—N1116.3 (2)C5—C4—Br1117.97 (18)
C6—C1—N1128.9 (2)C6—C5—C4117.9 (2)
F1—C2—C3118.1 (2)C6—C5—H5121.0
F1—C2—C1117.5 (2)C4—C5—H5121.0
C3—C2—C1124.4 (2)F2—C6—C5117.2 (2)
C2—C3—C4117.7 (2)F2—C6—C1119.4 (2)
C2—C3—H3121.2C5—C6—C1123.3 (2)
C4—C3—H3121.2N1i—N1—C1115.1 (2)
C3—C4—C5121.7 (2)
C6—C1—C2—F1178.8 (2)Br1—C4—C5—C6176.42 (17)
N1—C1—C2—F11.6 (3)C4—C5—C6—F2179.8 (2)
C6—C1—C2—C31.7 (4)C4—C5—C6—C10.5 (4)
N1—C1—C2—C3177.9 (2)C2—C1—C6—F2178.4 (2)
F1—C2—C3—C4179.7 (2)N1—C1—C6—F22.1 (4)
C1—C2—C3—C40.2 (4)C2—C1—C6—C51.2 (4)
C2—C3—C4—C51.7 (4)N1—C1—C6—C5178.3 (2)
C2—C3—C4—Br1176.76 (18)C2—C1—N1—N1i176.3 (3)
C3—C4—C5—C62.1 (4)C6—C1—N1—N1i3.2 (4)
Symmetry code: (i) x+1, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···F2ii0.952.533.190 (3)126
Symmetry code: (ii) x+1, y1/2, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···F2i0.952.533.190 (3)126
Symmetry code: (i) x+1, y1/2, z+3/2.
 

Acknowledgements

The authors thank Professor Wolfgang Schnick for generous allocation of diffractometer time.

References

First citationAltomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationBanghart, M., Borges, K., Isacoff, E., Trauner, D. & Kramer, R. H. (2004). Nat. Neurosci. 7, 1381–1386.  Web of Science CrossRef PubMed CAS Google Scholar
First citationBléger, D., Schwarz, J., Brouwer, A. M. & Hecht, S. (2012). J. Am. Chem. Soc. 134, 20597–20600.  Web of Science PubMed Google Scholar
First citationBroichhagen, J., Jurastow, I., Iwan, K., Kummer, W. & Trauner, D. (2014). Angew. Chem. Int. Ed. 53, 7657–7660.  Web of Science CrossRef CAS Google Scholar
First citationBruker (2007). APEX2, Bruker Instrument Service and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationBruker (2012). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationBurnett, M. N. & Johnson, C. K. (1996). ORTEP-III. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.  Google Scholar
First citationCrispini, A., Ghedini, M. & Pucci, D. (1998). Acta Cryst. C54, 1869–1871.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationElder, P. J. W. & Vargas-Baca, I. (2012). Acta Cryst. E68, o3127.  CSD CrossRef IUCr Journals Google Scholar
First citationFehrentz, T., Schönberger, M. & Trauner, D. (2011). Angew. Chem. Int. Ed. 50, 12156–12182.  Web of Science CrossRef CAS Google Scholar
First citationFerguson, G., Low, J. N., Penner, G. H. & Wardell, J. L. (1998). Acta Cryst. C54, 1974–1977.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationGabe, E. J., Wang, Y. & Le Page, Y. (1981). Acta Cryst. B37, 980–981.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationKomeyama, M., Yamamoto, S., Nishimura, N. & Hasegawa, S. (1973). Bull. Chem. Soc. Jpn, 46, 2606–2607.  CrossRef CAS Web of Science Google Scholar
First citationLevitz, J., Pantoja, C., Gaub, B., Janovjak, H., Reiner, A., Hoagland, A., Schoppik, D., Kane, B., Stawski, P., Schier, A. F., Trauner, D. & Isacoff, E. Y. (2013). Nat. Neurosci. 16, 507–516.  Web of Science CrossRef CAS PubMed Google Scholar
First citationMitscherlich, E. (1834). Annalen der Physik und Chemie, XXXII, 224.  Google Scholar
First citationReichenbächer, K., Neels, A., Stoeckli-Evans, H., Balasubramaniyan, P., Müller, K., Matsuo, Y., Nakamura, E., Weber, E. & Hulliger, J. (2007). Cryst. Growth Des. 7, 1399–1405.  Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationVelema, W. A., van der Berg, J. P., Hansen, M. J., Szymanski, W., Driessen, A. J. & Feringa, B. L. (2013). Nat. Chem. 5, 924–928.  Web of Science CrossRef CAS PubMed Google Scholar
First citationWragg, D. S., Ahmed, M. A. K., Nilsen, O. & Fjellvåg, H. (2011). Acta Cryst. E67, o2326.  Web of Science CSD CrossRef 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
Volume 71| Part 7| July 2015| Pages o459-o460
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds