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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 8| August 2013| Pages o1335-o1336
doi:10.1107/S1600536813020102

(E)-1-(2-Phenyl­diazen-2-ium-1-yl)naph­thalen-2-olate

Hassiba Bougueria,a* Souheyla Chetioui,a Issam Boudraa,a Abd el kader Bouchoula and Salah Eddine Bouaouda

aUnité de Recherche de Chimie de l'Environnement et Moléculaire Structurale (CHEMS), Département de Chimie, Université Mentouri de Constantine 1, 25000 Constantine, Algeria
*Correspondence e-mail: bougueriahassiba@gmail.com

(Received 3 July 2013; accepted 20 July 2013; online 27 July 2013)

In the title zwitterionic compound, C16H12N2O, the dihedral angle between the phenyl ring and the naphthalene ring system is 17.85 (8)°; an intra­molecular N—H⋯O hydrogen bond occurs. In the crystal, π–π stacking is observed between naphthalene ring systems of adjacent mol­ecules, the centroid–centroid distance being 3.6486 (11) Å.

Related literature

For general background to azo compounds and their applications in the fields of dyes, pigments and advanced materials, see: Biswas & Umapathy (2000[Biswas, N. & Umapathy, S. (2000). J. Phys. Chem. A, 104, 2734-2745.]); Willner & Rubin (1996[Willner, I. & Rubin, S. (1996). Angew. Chem. Int. Ed. Engl. 35, 367-385.]); Hunger (2003[Hunger, K. (2003). Industrial Dyes, Chemistry, Properties and Applications, edited by K. Hunger, pp. 20-35. Weinheim: Wiley-VCH.]); Catino & Farris (1985[Catino, S. C. & Farris, R. E. (1985). Azo dyes, in Concise Encyclopedia of Chemical Technology, edited by M. Grayson, pp. 142-144. New York: John Wiley and Sons.]); Zollinger (2003[Zollinger, H. (2003). Colour Chemistry: Synthesis, Properties and Applications of Organic Dyes and Pigments, edited by H. Zollinger, 3rd rev. ed. Weinheim: Wiley-VCH.]); Bahatti & Seshadri (2004[Bahatti, H. S. & Seshadri, S. (2004). Color. Technol. 120, 151-155.]); Taniike et al. (1996[Taniike, K., Matsumoto, T., Sato, T., Ozaki, Y., Nakashima, K. & Iriyama, K. (1996). J. Phys. Chem. 100, 15508-15516.]); Fadda et al. (1994[Fadda, A. A., Etmen, H. A., Amer, F. A., Barghout, M. & Mohammed, K. S. J. (1994). J. Chem. Technol. Biotechnol. 61, 343-349.]); Bach et al. (1996[Bach, H., Anderle, K., Fuhrmann, Th. & Wendorff, J. H. (1996). J. Phys. Chem. 100, 4135-4140.]); Clark & Hester (1993[Clark, R. J. H. & Hester, R. E. (1993). Spectroscopy of New Materials: Advances in Spectroscopy, edited by R. J. H. Clark & R. E. Hester. New York: John Wiley and Sons.]). For the synthesis, see: Wang et al. (2003[Wang, M., Funabiki, K. & Matsui, M. (2003). Dyes Pigments, 57, 77-86.]).

[Scheme 1]

Experimental

Crystal data

  • C16H12N2O

  • Mr = 248.28

  • Monoclinic, P 21 /c

  • a = 13.0800 (12) Å

  • b = 13.5170 (13) Å

  • c = 7.0080 (4) Å

  • β = 94.140 (6)°

  • V = 1235.80 (18) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 150 K

  • 0.26 × 0.22 × 0.17 mm
Data collection

  • Nonius KappaCCD diffractometer

  • 4092 measured reflections

  • 2139 independent reflections

  • 1546 reflections with I > 2σ(I)

  • Rint = 0.026
Refinement

  • R[F2 > 2σ(F2)] = 0.054

  • wR(F2) = 0.144

  • S = 1.06

  • 2139 reflections

  • 172 parameters

  • H-atom parameters constrained

  • Δρmax = 0.18 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1⋯O1 0.94 1.73 2.5346 (19) 141

Data collection: KappaCCD Server Software (Nonius, 1999[Nonius (1999). KappaCCD Server Software. Nonius BV, Delft, The Nertherlands.]); cell refinement: KappaCCD Server Software; data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); program(s) used to solve structure: SHELXS86 (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 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]); software used to prepare material for publication: WinGX (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536813020102/xu5718sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813020102/xu5718Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813020102/xu5718Isup3.cml

checkCIF report


Comment top

Azo compounds are very important in the field of dyes, pigments and advanced materials (Hunger, 2003). It has been known for many years that the azo compounds are the most widely used class of dyes, due to their versatile applications in various fields such as the dyeing of textile fibers, the coloring of different materials, colored plastics and polymers, biological-medical studies and advanced applications in organic syntheses (Catino & Farris, 1985; Zollinger, 2003; Bahatti & Seshadri, 2004; Taniike et al., 1996; Fadda et al., 1994). They are also used in the fields of nonlinear optics and optical data storage (Taniike et al., 1996; Bach et al., 1996; Clark & Hester, 1993). Their optical properties depend on not only the spectroscopic properties of the molecules but also their crystallographic arrangements (Biswas & Umapathy, 2000; Willner & Rubin, 1996).

We report here in the crystal structure of the title compound, obtained through the diazotization of aniline followed by a coupling reaction with 2-naphthol.

The molecule of the title compound, with the atom numbering scheme, is shown in Fig. 1, crystallizes in the monoclinic space group P21/c.

The molecular structure of C16 H12 N2 O is illustrated in Fig. 1. The molecule adopts an anti–configuration with the two aryl groups reside on the opposite side of azo–group. The dihedral angle between the benzene ring and naphthalene ring is 17.85 (8)°. An intramolecular N—H···O hydrogen bond is found (Table 1). It is more interesting, that hydrogen atom in the OH-group has transfer to N atom in the azo-group to form the structure of dipolar ion. Moreover, different Fourier map indicate hydrogen site location is closer to nitrogen atom of azo-group. In the crystal molecules are packed by the weak π–π interactions with the closest approach between centroids of aromatic rings is 3.6486 (11) Å.

Related literature top

For general background to azo compounds and their applications in the fields of dyes, pigments and advanced materials, see: Biswas & Umapathy (2000); Willner & Rubin (1996); Hunger (2003); Catino & Farris (1985); Zollinger (2003); Bahatti & Seshadri (2004); Taniike et al. (1996); Fadda et al. (1994); Bach et al. (1996); Clark & Hester (1993). For the synthesis, see: Wang et al. (2003).

Experimental top

The compound was synthesized according to the literature procedure of other aromatic azo-compounds (Wang et al., 2003). Red prism of the compound were obtained by slow evaporation at room temperature from an aqueous solution containing water/THF (1/1, v/v).

Refinement top

N-bound H atom was located in a differece Fourier map and refined with N—H distance constraint of 0.94 Å, other H atoms were placed in calculated positions and refined in riding mode. Uiso(H) = 1.2Ueq(N,C).

Computing details top

Data collection: KappaCCD Server Software (Nonius, 1999); cell refinement: KappaCCD Server Software (Nonius, 1999); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top
[Figure 1] Fig. 1. View of the molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.
(E)-1-(2-Phenyldiazen-2-ium-1-yl)naphthalen-2-olate top
Crystal data top
C16H12N2OF(000) = 520
Mr = 248.28Dx = 1.334 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 2200 reflections
a = 13.0800 (12) Åθ = 1.0–25.4°
b = 13.5170 (13) ŵ = 0.09 mm−1
c = 7.0080 (4) ÅT = 150 K
β = 94.140 (6)°Prism, red
V = 1235.80 (18) Å30.26 × 0.22 × 0.17 mm
Z = 4
Data collection top
Nonius KappaCCD
diffractometer		1546 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.026
Graphite monochromatorθmax = 25.4°, θmin = 2.2°
Detector resolution: 9 pixels mm-1h = −15→15
CCD scansk = −16→16
4092 measured reflectionsl = −7→7
2139 independent 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)] = 0.054Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.144H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0756P)2 + 0.113P]
where P = (Fo2 + 2Fc2)/3
2139 reflections(Δ/σ)max = 0.001
172 parametersΔρmax = 0.18 e Å−3
0 restraintsΔρmin = −0.19 e Å−3
Crystal data top
C16H12N2OV = 1235.80 (18) Å3
Mr = 248.28Z = 4
Monoclinic, P21/cMo Kα radiation
a = 13.0800 (12) ŵ = 0.09 mm−1
b = 13.5170 (13) ÅT = 150 K
c = 7.0080 (4) Å0.26 × 0.22 × 0.17 mm
β = 94.140 (6)°
Data collection top
Nonius KappaCCD
diffractometer		1546 reflections with I > 2σ(I)
4092 measured reflectionsRint = 0.026
2139 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0540 restraints
wR(F2) = 0.144H-atom parameters constrained
S = 1.06Δρmax = 0.18 e Å−3
2139 reflectionsΔρmin = −0.19 e Å−3
172 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 on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > 2sigma(F2) is used only for calculating -R-factor-obs 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
N10.20061 (11)0.46423 (10)0.4042 (2)0.0542 (4)
H10.12870.46660.40470.065*
N20.23990 (12)0.37596 (10)0.4036 (2)0.0524 (4)
O10.02112 (10)0.39323 (10)0.3599 (2)0.0688 (4)
C10.26520 (14)0.54729 (12)0.4226 (2)0.0510 (4)
C20.36888 (15)0.54252 (15)0.3965 (3)0.0630 (5)
H20.39870.48320.36270.076*
C30.42736 (16)0.62723 (15)0.4215 (3)0.0700 (6)
H30.49720.62460.40520.084*
C40.38374 (17)0.71530 (16)0.4701 (3)0.0727 (6)
H40.42400.77180.48680.087*
C50.28076 (17)0.71967 (15)0.4938 (3)0.0718 (6)
H50.25110.77920.52670.086*
C60.22090 (15)0.63589 (13)0.4690 (3)0.0603 (5)
H60.15090.63920.48360.072*
C70.17482 (13)0.29843 (12)0.3881 (2)0.0490 (4)
C80.06510 (15)0.30859 (14)0.3645 (3)0.0563 (5)
C90.00491 (15)0.22000 (16)0.3455 (3)0.0651 (5)
H9−0.06600.22490.32720.078*
C100.04871 (16)0.12996 (15)0.3537 (3)0.0634 (5)
H100.00690.07440.34190.076*
C110.15749 (15)0.11656 (13)0.3798 (2)0.0543 (5)
C120.22131 (14)0.20077 (12)0.3962 (2)0.0509 (4)
C130.32739 (15)0.18637 (15)0.4207 (3)0.0635 (5)
H130.37090.24080.43280.076*
C140.36788 (17)0.09244 (15)0.4270 (3)0.0728 (6)
H140.43850.08400.44370.087*
C150.30467 (18)0.01006 (16)0.4088 (3)0.0723 (6)
H150.3329−0.05310.41190.087*
C160.20132 (17)0.02215 (14)0.3865 (3)0.0647 (5)
H160.1591−0.03320.37550.078*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0545 (9)0.0442 (9)0.0639 (10)0.0000 (7)0.0040 (7)0.0008 (6)
N20.0613 (9)0.0424 (9)0.0534 (9)0.0008 (7)0.0040 (6)−0.0001 (6)
O10.0601 (8)0.0556 (9)0.0902 (10)0.0066 (7)0.0019 (7)−0.0011 (7)
C10.0580 (10)0.0412 (10)0.0534 (10)−0.0017 (8)0.0010 (8)0.0031 (7)
C20.0625 (12)0.0510 (12)0.0760 (13)0.0055 (9)0.0072 (9)−0.0013 (9)
C30.0567 (11)0.0630 (14)0.0899 (15)−0.0042 (10)0.0027 (10)0.0022 (10)
C40.0723 (14)0.0514 (12)0.0939 (16)−0.0106 (11)0.0019 (11)−0.0008 (10)
C50.0777 (14)0.0455 (11)0.0925 (16)0.0029 (10)0.0086 (11)−0.0029 (10)
C60.0580 (11)0.0488 (11)0.0743 (13)0.0035 (9)0.0071 (9)0.0036 (9)
C70.0558 (10)0.0446 (10)0.0466 (10)−0.0025 (8)0.0039 (7)−0.0027 (7)
C80.0641 (12)0.0525 (11)0.0523 (11)−0.0002 (9)0.0044 (8)−0.0025 (8)
C90.0586 (11)0.0626 (13)0.0739 (13)−0.0071 (10)0.0031 (9)−0.0106 (9)
C100.0699 (13)0.0528 (12)0.0679 (12)−0.0153 (10)0.0065 (9)−0.0085 (9)
C110.0702 (12)0.0464 (11)0.0467 (10)−0.0040 (9)0.0061 (8)−0.0048 (7)
C120.0628 (11)0.0451 (10)0.0450 (10)−0.0017 (8)0.0059 (7)−0.0012 (7)
C130.0623 (12)0.0501 (12)0.0780 (13)−0.0001 (9)0.0039 (10)0.0015 (9)
C140.0701 (13)0.0554 (13)0.0928 (16)0.0097 (11)0.0050 (11)0.0043 (11)
C150.0933 (16)0.0450 (12)0.0788 (14)0.0100 (11)0.0081 (11)0.0016 (9)
C160.0843 (14)0.0447 (11)0.0654 (12)−0.0052 (10)0.0079 (10)−0.0032 (8)
Geometric parameters (Å, º) top
N1—N21.2993 (19)C7—C121.453 (2)
N1—C11.405 (2)C8—C91.434 (3)
N1—H10.9418C9—C101.345 (3)
N2—C71.350 (2)C9—H90.9300
O1—C81.280 (2)C10—C111.433 (3)
C1—C61.380 (2)C10—H100.9300
C1—C21.383 (3)C11—C161.398 (3)
C2—C31.381 (3)C11—C121.411 (2)
C2—H20.9300C12—C131.399 (3)
C3—C41.374 (3)C13—C141.375 (3)
C3—H30.9300C13—H130.9300
C4—C51.370 (3)C14—C151.387 (3)
C4—H40.9300C14—H140.9300
C5—C61.381 (3)C15—C161.359 (3)
C5—H50.9300C15—H150.9300
C6—H60.9300C16—H160.9300
C7—C81.439 (3)
N2—N1—C1119.91 (15)O1—C8—C7122.06 (16)
N2—N1—H1115.2C9—C8—C7117.85 (17)
C1—N1—H1124.6C10—C9—C8121.51 (18)
N1—N2—C7117.78 (15)C10—C9—H9119.2
C6—C1—C2120.28 (17)C8—C9—H9119.2
C6—C1—N1117.08 (16)C9—C10—C11122.41 (18)
C2—C1—N1122.64 (16)C9—C10—H10118.8
C3—C2—C1118.96 (18)C11—C10—H10118.8
C3—C2—H2120.5C16—C11—C12119.65 (18)
C1—C2—H2120.5C16—C11—C10121.37 (17)
C4—C3—C2120.9 (2)C12—C11—C10118.98 (16)
C4—C3—H3119.5C13—C12—C11118.24 (16)
C2—C3—H3119.5C13—C12—C7122.67 (16)
C5—C4—C3119.80 (19)C11—C12—C7119.09 (17)
C5—C4—H4120.1C14—C13—C12120.57 (18)
C3—C4—H4120.1C14—C13—H13119.7
C4—C5—C6120.19 (19)C12—C13—H13119.7
C4—C5—H5119.9C13—C14—C15120.8 (2)
C6—C5—H5119.9C13—C14—H14119.6
C1—C6—C5119.85 (18)C15—C14—H14119.6
C1—C6—H6120.1C16—C15—C14119.7 (2)
C5—C6—H6120.1C16—C15—H15120.2
N2—C7—C8123.58 (16)C14—C15—H15120.2
N2—C7—C12116.27 (16)C15—C16—C11121.02 (19)
C8—C7—C12120.16 (16)C15—C16—H16119.5
O1—C8—C9120.09 (18)C11—C16—H16119.5
C1—N1—N2—C7179.15 (14)C8—C9—C10—C11−0.6 (3)
N2—N1—C1—C6−164.58 (16)C9—C10—C11—C16−179.56 (17)
N2—N1—C1—C215.3 (2)C9—C10—C11—C12−0.5 (3)
C6—C1—C2—C31.3 (3)C16—C11—C12—C13−0.6 (2)
N1—C1—C2—C3−178.58 (17)C10—C11—C12—C13−179.67 (16)
C1—C2—C3—C4−0.5 (3)C16—C11—C12—C7179.69 (14)
C2—C3—C4—C5−0.2 (3)C10—C11—C12—C70.6 (2)
C3—C4—C5—C60.0 (3)N2—C7—C12—C130.7 (2)
C2—C1—C6—C5−1.5 (3)C8—C7—C12—C13−179.37 (16)
N1—C1—C6—C5178.41 (17)N2—C7—C12—C11−179.68 (14)
C4—C5—C6—C10.8 (3)C8—C7—C12—C110.3 (2)
N1—N2—C7—C82.6 (2)C11—C12—C13—C140.5 (3)
N1—N2—C7—C12−177.42 (13)C7—C12—C13—C14−179.82 (17)
N2—C7—C8—O1−1.2 (3)C12—C13—C14—C150.1 (3)
C12—C7—C8—O1178.80 (15)C13—C14—C15—C16−0.7 (3)
N2—C7—C8—C9178.63 (15)C14—C15—C16—C110.6 (3)
C12—C7—C8—C9−1.3 (2)C12—C11—C16—C150.1 (3)
O1—C8—C9—C10−178.64 (17)C10—C11—C16—C15179.11 (18)
C7—C8—C9—C101.5 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.941.732.5346 (19)141
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.941.732.5346 (19)141
 

Acknowledgements

The authors would like to thank Professor L. Ouahab, University of Rennes (France), for his valuable collaboration in the recording and inter­pretation of the XRD data and Professor S. E. Bouaoud, University of Constantine (Algeria) for providing laboratory facilities and encouragement.

References

First citationBach, H., Anderle, K., Fuhrmann, Th. & Wendorff, J. H. (1996). J. Phys. Chem. 100, 4135–4140.  CrossRef CAS Web of Science Google Scholar
 First citationBahatti, H. S. & Seshadri, S. (2004). Color. Technol. 120, 151–155.  Google Scholar
 First citationBiswas, N. & Umapathy, S. (2000). J. Phys. Chem. A, 104, 2734–2745.  Web of Science CrossRef CAS Google Scholar
 First citationCatino, S. C. & Farris, R. E. (1985). Azo dyes, in Concise Encyclopedia of Chemical Technology, edited by M. Grayson, pp. 142–144. New York: John Wiley and Sons.  Google Scholar
 First citationClark, R. J. H. & Hester, R. E. (1993). Spectroscopy of New Materials: Advances in Spectroscopy, edited by R. J. H. Clark & R. E. Hester. New York: John Wiley and Sons.  Google Scholar
 First citationFadda, A. A., Etmen, H. A., Amer, F. A., Barghout, M. & Mohammed, K. S. J. (1994). J. Chem. Technol. Biotechnol. 61, 343–349.  CrossRef CAS Web of Science Google Scholar
 First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationHunger, K. (2003). Industrial Dyes, Chemistry, Properties and Applications, edited by K. Hunger, pp. 20–35. Weinheim: Wiley-VCH.  Google Scholar
 First citationNonius (1999). KappaCCD Server Software. Nonius BV, Delft, The Nertherlands.  Google Scholar
 First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationTaniike, K., Matsumoto, T., Sato, T., Ozaki, Y., Nakashima, K. & Iriyama, K. (1996). J. Phys. Chem. 100, 15508–15516.  CrossRef CAS Web of Science Google Scholar
 First citationWang, M., Funabiki, K. & Matsui, M. (2003). Dyes Pigments, 57, 77–86.  Web of Science CrossRef CAS Google Scholar
 First citationWillner, I. & Rubin, S. (1996). Angew. Chem. Int. Ed. Engl. 35, 367–385.  CrossRef CAS Web of Science Google Scholar
 First citationZollinger, H. (2003). Colour Chemistry: Synthesis, Properties and Applications of Organic Dyes and Pigments, edited by H. Zollinger, 3rd rev. ed. Weinheim: Wiley-VCH.  Google Scholar

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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 69| Part 8| August 2013| Pages o1335-o1336
doi:10.1107/S1600536813020102
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