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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 12| December 2012| Pages o3341-o3342

(1S,3R,8R)-2,2-Di­bromo-3,7,7,10-tetra­methyltri­cyclo­[6.4.0.01,3]dodec-9-en-11-one

aLaboratoire de Chimie des Substances Naturelles, "Unité Associé au CNRST (URAC16)", Faculté des Sciences Semlalia, BP 2390 Bd My Abdellah, 40000 Marrakech, Morocco, and bLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Avenue Ibn Battouta, BP 1014 Rabat, Morocco
*Correspondence e-mail: berraho@uca.ma

(Received 29 October 2012; accepted 7 November 2012; online 14 November 2012)

The title compound, C16H22Br2O, was synthesized from β-himachalene (3,5,5,9-tetra­methyl-2,4a,5,6,7,8-hexa­hydro-1H-benzocyclo­heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol­ecule is built up from fused six- and seven-membered rings and an additional three-membered ring from the reaction of himachalene with dibromo­carbene. The six-membered ring has an envelope conformation, with the C atom belonging to the three-membered ring forming the flap, whereas the seven-membered ring displays a screw-boat conformation; the dihedral angle between the rings (all atoms) is 60.92 (16)°.

Related literature

For the isolation of β-himachalene, see: Joseph & Dev (1968[Joseph, T. C. & Dev, S. (1968). Tetrahedron, 24, 3841-3859.]); Plattier & Teiseire (1974[Plattier, M. & Teiseire, P. (1974). Recherche, 19, 131-144.]). For the reactivity of this sesquiterpene, see: Lassaba et al. (1997[Lassaba, E., Chekroun, A., Benharref, A., Chiaroni, A., Riche, C. & Lavergne, J.-P. (1997). Bull. Soc. Chim. Belg. 106, 281-288.]); Chekroun et al. (2000[Chekroun, A., Jarid, A., Benharref, A. & Boutalib, A. (2000). J. Org. Chem. 65, 4431-4434.]); El Jamili et al. (2002[El Jamili, H., Auhmani, A., Dakir, M., Lassaba, E., Benharref, A., Pierrot, M., Chiaroni, A. & Riche, C. (2002). Tetrahedron Lett. 43, 6645-6648.]); Sbai et al. (2002[Sbai, F., Dakir, M., Auhmani, A., El Jamili, H., Akssira, M., Benharref, A., Kenz, A. & Pierrot, M. (2002). Acta Cryst. C58, o518-o520.]); Dakir et al. (2004[Dakir, M., Auhmani, A., Ait Itto, M. Y., Mazoir, N., Akssira, M., Pierrot, M. & Benharref, A. (2004). Synth. Commun. 34, 2001-2008.]). For its biological activity, see: Daoubi et al. (2004[Daoubi, M., Duran-Patron, R., Hmamouchi, M., Hernandez-Galan, R., Benharref, A. & Isidro, G. C. (2004). Pest Manag. Sci. 60, 927-932.]). For conformational analysis, see: Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]).

[Scheme 1]

Experimental

Crystal data
  • C16H22Br2O

  • Mr = 390.16

  • Orthorhombic, P 21 21 21

  • a = 6.7369 (1) Å

  • b = 14.7635 (3) Å

  • c = 16.3543 (3) Å

  • V = 1626.60 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 4.98 mm−1

  • T = 298 K

  • 0.80 × 0.65 × 0.25 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2003[Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.]) Tmin = 0.259, Tmax = 0.746

  • 11891 measured reflections

  • 3330 independent reflections

  • 2939 reflections with I > 2σ(I)

  • Rint = 0.028

Refinement
  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.074

  • S = 1.06

  • 3330 reflections

  • 176 parameters

  • H-atom parameters constrained

  • Δρmax = 0.68 e Å−3

  • Δρmin = −0.37 e Å−3

  • Absolute structure: Flack (1983)[Flack, H. D. (1983). Acta Cryst. A39, 876-881.], 1397 Friedel pairs

  • Flack parameter: 0.021 (12)

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2 and 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: 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


Comment top

The essential oil of the Atlas cedar (Cedrus atlantica) consist mainly (50%) of a bicyclic hydrocarbon called β-himachalene (Plattier & Teiseire(1974); Joseph & Dev (1968)). The reactivity of this sesquiterpene and its derivatives has been studied extensively by our team in order to prepare new products having biological proprieties. (Lassaba et al., 1997; Chekroun et al., 2000; El Jamili et al., 2002; Sbai et al., 2002; Dakir et al., 2004). Indeed, these compounds were tested, using the food poisoning technique, for their potential antifungal activity against the phytopathogen Botrytis cinerea (Daoubi et al., 2004). In a previous work (El Jamili et al., 2002), we have prepared, from β-himachalene, the (1S,3R,8R)-2,2-dibromo- 3,7,7,10- tetramethyltricyclo [6.4.0.01,3] dodec-9-ene, which is treated with N-bromosuccinimide and gave the title compound. The structure of this new product was determined by its single-crystal X-ray structure. The molecule is built up from two fused six-and seven- membered rings and an additional three-membered ring from the reaction with the carbene (Fig.1). The six-membered ring has an envelope conformation, as indicated by the total puckering amplitude QT = 0.433 (3) Å and spherical polar angle θ= 123.1 (4)° with ϕ = 181.6 (5)°, whereas the seven-membered ring display a screw boat conformation with QT = 1.1208 (4) Å, θ = 88.14 (2)°, ϕ2 = -49.94 (2)° and ϕ3 = -93.26 (5)° (Cremer & Pople, 1975). Owing to the presence of Br atoms, the absolute configuration could be fully confirmed, by refining the Flack parameter (Flack & Bernardinelli (2000)) as C1(S), C3(R) and C8(R).

Related literature top

For the isolation of β-himachalene, see: Joseph & Dev (1968); Plattier & Teiseire (1974). For the reactivity of this sesquiterpene, see: Lassaba et al. (1997); Chekroun et al. (2000); El Jamili et al. (2002); Sbai et al. (2002); Dakir et al. (2004). For its biological activity, see: Daoubi et al. (2004). For conformational analysis, see: Cremer & Pople (1975).

Experimental top

In a reactor containing a solution of (1S, 3R, 8R)-2,2-dibromo- 3,7,7,10 tetramethyltricyclo [6.4.0.01,3] dodec-9-ene (1 g, 2,6 mmol) in 50 ml of tetrahydrofuran and water (THF/H2O) (4:1) cooled to 273 K and kept in the dark, was added in small portions 1 g (5,6 mmol) of N-bromosccinimide. The reaction mixture was left stirring for 1 h, after which 20 ml of a saturated solution of NaHCO3 was added. Subsequently, the extraction was performed three times with diethyl ether (3 x 20 ml). The organic extracts were dried over Na2SO4, filtered, concentrated, and chromatographed. The title compound was obtained with a yield of 80% and was recrystallized in n-pentane.

Refinement top

All H atoms were fixed geometrically and treated as riding with C—H = 0.96 Å (methyl),0.97 Å (methylene), 0.98 Å (methine) with Uiso(H) = 1.2Ueq(methylene, methine) or Uiso(H) = 1.5Ueq(methyl).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (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. : Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability. level. H atoms are represented as small spheres of arbitrary radii.
(1S,3R,8R)-2,2-Dibromo-3,7,7,10- tetramethyltricyclo[6.4.0.01,3]dodec-9-en-11-one top
Crystal data top
C16H22Br2OF(000) = 784
Mr = 390.16Dx = 1.593 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 11891 reflections
a = 6.7369 (1) Åθ = 2.8–26.4°
b = 14.7635 (3) ŵ = 4.98 mm1
c = 16.3543 (3) ÅT = 298 K
V = 1626.60 (5) Å3Prism, colourless
Z = 40.80 × 0.65 × 0.25 mm
Data collection top
Bruker APEXII CCD
diffractometer
3330 independent reflections
Radiation source: fine-focus sealed tube2939 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
ω and ϕ scansθmax = 26.4°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
h = 78
Tmin = 0.259, Tmax = 0.746k = 1818
11891 measured reflectionsl = 2020
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.074 w = 1/[σ2(Fo2) + (0.034P)2 + 0.368P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
3330 reflectionsΔρmax = 0.68 e Å3
176 parametersΔρmin = 0.37 e Å3
0 restraintsAbsolute structure: Flack (1983), 1397 Friedel pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.021 (12)
Crystal data top
C16H22Br2OV = 1626.60 (5) Å3
Mr = 390.16Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.7369 (1) ŵ = 4.98 mm1
b = 14.7635 (3) ÅT = 298 K
c = 16.3543 (3) Å0.80 × 0.65 × 0.25 mm
Data collection top
Bruker APEXII CCD
diffractometer
3330 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
2939 reflections with I > 2σ(I)
Tmin = 0.259, Tmax = 0.746Rint = 0.028
11891 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.074Δρmax = 0.68 e Å3
S = 1.06Δρmin = 0.37 e Å3
3330 reflectionsAbsolute structure: Flack (1983), 1397 Friedel pairs
176 parametersAbsolute structure parameter: 0.021 (12)
0 restraints
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
C10.7886 (4)0.8949 (2)0.72986 (18)0.0345 (7)
C20.7652 (4)0.8664 (2)0.8186 (2)0.0381 (7)
C30.8277 (5)0.9620 (2)0.79993 (18)0.0381 (7)
C40.6771 (5)1.0379 (2)0.8104 (2)0.0458 (8)
H4A0.70111.06810.86210.055*
H4B0.54491.01200.81240.055*
C50.6854 (6)1.1078 (2)0.7417 (2)0.0545 (9)
H5A0.55801.13830.73920.065*
H5B0.78421.15290.75600.065*
C60.7335 (7)1.0720 (3)0.6570 (3)0.0635 (11)
H6A0.87041.05160.65780.076*
H6B0.72701.12280.61950.076*
C70.6078 (5)0.9950 (2)0.62020 (19)0.0411 (7)
C80.6031 (4)0.9087 (2)0.67808 (18)0.0353 (7)
H80.49270.91770.71630.042*
C90.5589 (4)0.8232 (2)0.63150 (19)0.0417 (7)
H90.42860.81420.61450.050*
C100.6912 (5)0.7587 (2)0.61230 (18)0.0391 (7)
C110.9012 (4)0.7704 (2)0.63421 (19)0.0399 (7)
C120.9602 (4)0.8536 (2)0.68244 (19)0.0420 (7)
H12A1.01300.89860.64510.050*
H12B1.06490.83740.72040.050*
C131.0396 (5)0.9900 (3)0.8188 (2)0.0537 (9)
H13A1.12850.94180.80420.081*
H13B1.05201.00260.87620.081*
H13C1.07241.04340.78810.081*
C140.3936 (7)1.0248 (3)0.6061 (3)0.0832 (15)
H14A0.39171.07600.56990.125*
H14B0.33451.04130.65740.125*
H14C0.32000.97590.58210.125*
C150.6966 (8)0.9745 (3)0.5362 (3)0.0758 (13)
H15A0.83550.96150.54190.114*
H15B0.67961.02610.50110.114*
H15C0.63040.92310.51280.114*
C160.6372 (7)0.6755 (2)0.5647 (2)0.0584 (10)
H16A0.49810.67680.55200.088*
H16B0.66620.62260.59670.088*
H16C0.71260.67380.51490.088*
Br10.50492 (5)0.83972 (3)0.86363 (2)0.05453 (12)
Br20.94858 (5)0.78265 (3)0.86827 (3)0.06271 (13)
O1.0289 (4)0.71769 (17)0.61207 (15)0.0604 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0291 (15)0.0354 (17)0.0390 (16)0.0008 (13)0.0031 (12)0.0040 (14)
C20.0293 (14)0.0415 (18)0.0434 (17)0.0048 (12)0.0006 (12)0.0004 (15)
C30.0355 (15)0.0398 (17)0.0391 (16)0.0008 (14)0.0006 (13)0.0075 (14)
C40.0517 (19)0.0401 (18)0.0456 (18)0.0045 (16)0.0033 (15)0.0135 (16)
C50.070 (2)0.0361 (19)0.057 (2)0.0011 (18)0.0057 (19)0.0068 (18)
C60.078 (3)0.045 (2)0.067 (3)0.006 (2)0.003 (2)0.002 (2)
C70.0458 (16)0.0382 (16)0.0393 (17)0.0022 (14)0.0020 (14)0.0005 (15)
C80.0297 (14)0.0371 (17)0.0393 (15)0.0010 (13)0.0013 (12)0.0028 (14)
C90.0397 (14)0.0435 (17)0.0419 (16)0.0081 (13)0.0024 (15)0.0010 (16)
C100.0522 (18)0.0337 (16)0.0316 (15)0.0068 (14)0.0025 (13)0.0004 (13)
C110.0483 (16)0.0338 (16)0.0376 (15)0.0066 (14)0.0120 (15)0.0031 (15)
C120.0323 (15)0.0471 (18)0.0465 (17)0.0037 (14)0.0048 (13)0.0093 (15)
C130.0470 (19)0.058 (2)0.0559 (19)0.0065 (18)0.0019 (16)0.0152 (18)
C140.069 (3)0.079 (3)0.102 (4)0.008 (2)0.009 (2)0.042 (3)
C150.095 (3)0.072 (3)0.061 (2)0.010 (3)0.012 (2)0.009 (2)
C160.086 (3)0.037 (2)0.052 (2)0.009 (2)0.0035 (19)0.0003 (17)
Br10.04425 (17)0.0613 (2)0.0581 (2)0.00202 (17)0.01213 (17)0.00965 (18)
Br20.0559 (2)0.0613 (2)0.0710 (2)0.01579 (18)0.00973 (19)0.0117 (2)
O0.0663 (16)0.0493 (14)0.0657 (14)0.0148 (14)0.0091 (13)0.0101 (12)
Geometric parameters (Å, º) top
C1—C21.518 (4)C8—H80.9800
C1—C121.520 (4)C9—C101.341 (5)
C1—C81.524 (4)C9—H90.9300
C1—C31.537 (4)C10—C111.470 (4)
C2—C31.503 (5)C10—C161.499 (5)
C2—Br21.928 (3)C11—O1.216 (4)
C2—Br11.943 (3)C11—C121.512 (5)
C3—C131.518 (4)C12—H12A0.9700
C3—C41.522 (5)C12—H12B0.9700
C4—C51.526 (5)C13—H13A0.9600
C4—H4A0.9700C13—H13B0.9600
C4—H4B0.9700C13—H13C0.9600
C5—C61.517 (5)C14—H14A0.9600
C5—H5A0.9700C14—H14B0.9600
C5—H5B0.9700C14—H14C0.9600
C6—C71.541 (5)C15—H15A0.9600
C6—H6A0.9700C15—H15B0.9600
C6—H6B0.9700C15—H15C0.9600
C7—C141.526 (5)C16—H16A0.9600
C7—C151.529 (5)C16—H16B0.9600
C7—C81.587 (5)C16—H16C0.9600
C8—C91.505 (4)
C2—C1—C12117.1 (3)C1—C8—C7115.0 (2)
C2—C1—C8118.9 (2)C9—C8—H8106.6
C12—C1—C8113.2 (2)C1—C8—H8106.6
C2—C1—C358.9 (2)C7—C8—H8106.6
C12—C1—C3120.6 (3)C10—C9—C8125.7 (3)
C8—C1—C3117.9 (3)C10—C9—H9117.2
C3—C2—C161.1 (2)C8—C9—H9117.2
C3—C2—Br2120.5 (2)C9—C10—C11119.9 (3)
C1—C2—Br2120.9 (2)C9—C10—C16122.8 (3)
C3—C2—Br1121.3 (2)C11—C10—C16117.2 (3)
C1—C2—Br1120.8 (2)O—C11—C10122.2 (3)
Br2—C2—Br1106.75 (16)O—C11—C12119.3 (3)
C2—C3—C13118.5 (3)C10—C11—C12118.4 (3)
C2—C3—C4118.8 (3)C11—C12—C1113.1 (3)
C13—C3—C4113.8 (3)C11—C12—H12A109.0
C2—C3—C159.9 (2)C1—C12—H12A109.0
C13—C3—C1119.3 (3)C11—C12—H12B109.0
C4—C3—C1116.4 (3)C1—C12—H12B109.0
C3—C4—C5113.0 (3)H12A—C12—H12B107.8
C3—C4—H4A109.0C3—C13—H13A109.5
C5—C4—H4A109.0C3—C13—H13B109.5
C3—C4—H4B109.0H13A—C13—H13B109.5
C5—C4—H4B109.0C3—C13—H13C109.5
H4A—C4—H4B107.8H13A—C13—H13C109.5
C6—C5—C4116.4 (3)H13B—C13—H13C109.5
C6—C5—H5A108.2C7—C14—H14A109.5
C4—C5—H5A108.2C7—C14—H14B109.5
C6—C5—H5B108.2H14A—C14—H14B109.5
C4—C5—H5B108.2C7—C14—H14C109.5
H5A—C5—H5B107.4H14A—C14—H14C109.5
C5—C6—C7119.8 (4)H14B—C14—H14C109.5
C5—C6—H6A107.4C7—C15—H15A109.5
C7—C6—H6A107.4C7—C15—H15B109.5
C5—C6—H6B107.4H15A—C15—H15B109.5
C7—C6—H6B107.4C7—C15—H15C109.5
H6A—C6—H6B106.9H15A—C15—H15C109.5
C14—C7—C15106.9 (3)H15B—C15—H15C109.5
C14—C7—C6111.5 (3)C10—C16—H16A109.5
C15—C7—C6106.4 (3)C10—C16—H16B109.5
C14—C7—C8107.6 (3)H16A—C16—H16B109.5
C15—C7—C8112.7 (3)C10—C16—H16C109.5
C6—C7—C8111.7 (3)H16A—C16—H16C109.5
C9—C8—C1109.3 (3)H16B—C16—H16C109.5
C9—C8—C7112.1 (2)

Experimental details

Crystal data
Chemical formulaC16H22Br2O
Mr390.16
Crystal system, space groupOrthorhombic, P212121
Temperature (K)298
a, b, c (Å)6.7369 (1), 14.7635 (3), 16.3543 (3)
V3)1626.60 (5)
Z4
Radiation typeMo Kα
µ (mm1)4.98
Crystal size (mm)0.80 × 0.65 × 0.25
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2003)
Tmin, Tmax0.259, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
11891, 3330, 2939
Rint0.028
(sin θ/λ)max1)0.625
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.074, 1.06
No. of reflections3330
No. of parameters176
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.68, 0.37
Absolute structureFlack (1983), 1397 Friedel pairs
Absolute structure parameter0.021 (12)

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), WinGX (Farrugia, 2012).

 

Acknowledgements

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

References

First citationBruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationChekroun, A., Jarid, A., Benharref, A. & Boutalib, A. (2000). J. Org. Chem. 65, 4431–4434.  Web of Science CrossRef PubMed CAS
First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science
First citationDakir, M., Auhmani, A., Ait Itto, M. Y., Mazoir, N., Akssira, M., Pierrot, M. & Benharref, A. (2004). Synth. Commun. 34, 2001–2008.  Web of Science CrossRef CAS
First citationDaoubi, M., Duran-Patron, R., Hmamouchi, M., Hernandez-Galan, R., Benharref, A. & Isidro, G. C. (2004). Pest Manag. Sci. 60, 927–932.  Web of Science CrossRef PubMed CAS
First citationEl Jamili, H., Auhmani, A., Dakir, M., Lassaba, E., Benharref, A., Pierrot, M., Chiaroni, A. & Riche, C. (2002). Tetrahedron Lett. 43, 6645–6648.  CAS
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals
First citationJoseph, T. C. & Dev, S. (1968). Tetrahedron, 24, 3841–3859.  CrossRef CAS Web of Science
First citationLassaba, E., Chekroun, A., Benharref, A., Chiaroni, A., Riche, C. & Lavergne, J.-P. (1997). Bull. Soc. Chim. Belg. 106, 281–288.  CAS
First citationPlattier, M. & Teiseire, P. (1974). Recherche, 19, 131–144.  CAS
First citationSbai, F., Dakir, M., Auhmani, A., El Jamili, H., Akssira, M., Benharref, A., Kenz, A. & Pierrot, M. (2002). Acta Cryst. C58, o518–o520.  Web of Science CSD CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals

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 12| December 2012| Pages o3341-o3342
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds