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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

2α,8α-Diacet­­oxy-cis-himachalane

aLaboratoire de Chimie Biomoléculaires, Substances Naturelles et Réactivité, URAC16,Faculté des Sciences Semlalia, BP 2390 Bd My Abdellah, 40000 Marrakech, Morocco, and bLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France
*Correspondence e-mail: abenharref@yahoo.fr

(Received 15 September 2010; accepted 17 September 2010; online 25 September 2010)

The title compound, C19H32O4, was synthesized from γ-himachalene, wich was isolated from essential oils of Cedrus atlantica. The mol­ecule is built up from two fused six- and seven-membered rings. The six-membered ring has a screw-boat conformation, whereas the seven-membered ring displays a half-chair conformation; the dihedral angle between the mean planes of the rings is 61.99 (6)°.

Related literature

For background to γ-himachalene derivatives, see: Lassaba et al. (1998[Lassaba, E., Eljamili, H., Chekroun, A., Benharref, A., Chiaroni, A., Riche, C. & Lavergne, J. P. (1998). Synth. Commun. 28, 2641-2651.]); Plattier & Teisseire (1974[Plattier, M. & Teisseire, P. (1974). Recherche, 19, 131-144.]); Plattier et al. (1974[Plattier, M., Rouillier, P. & Teisseire, P. (1974). Recherche, 19, 145-151.]). For a related structure, see: Chiaroni et al. (1996[Chiaroni, A., Riche, C., Lassaba, E. & Benharref, A. (1996). Acta Cryst. C52, 3240-3243.]). For ring puckering analysis, see: Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]).

[Scheme 1]

Experimental

Crystal data
  • C19H32O4

  • Mr = 324.45

  • Monoclinic, P 21

  • a = 5.9316 (2) Å

  • b = 11.7720 (3) Å

  • c = 13.3535 (4) Å

  • β = 99.603 (3)°

  • V = 919.37 (5) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 180 K

  • 0.75 × 0.45 × 0.23 mm

Data collection
  • Oxford Diffraction Xcalibur Eos Gemini Ultra diffractometer

  • Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010[Oxford Diffraction (2010). CrystAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]) Tmin = 0.799, Tmax = 1.000

  • 3681 measured reflections

  • 1976 independent reflections

  • 1894 reflections with I > 2σ(I)

  • Rint = 0.012

Refinement
  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.079

  • S = 1.06

  • 1976 reflections

  • 214 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.17 e Å−3

  • Δρmin = −0.14 e Å−3

Data collection: CrysAlis PRO (Oxford Diffraction, 2010[Oxford Diffraction (2010). CrystAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR2004 (Burla et al., 2005[Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381-388.]); 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, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

This work is a part of our ongoing program concerning the valorization of the most abundant essential oils in Morocco, such as Cedrus atlantica. This oil is made up mainly (75%) of bicyclic sesquiterpene hydrocarbons, among which is found the compound γ- himachalene (Plattier & Teisseire, 1974). This compound is a minority product of the mixture of hydrocarbons of essential oil of the Atlas Cedar (Cedrus atlantica), isolated by Plattier et al. (1974). Literature provides only a few articles on the reactivity of this sesquiterpene, namely its hydrochlorination (Plattier & Teisseire, 1974), its hydroboration (Plattier et al., 1974) and its epoxidation (Chiaroni et al.,1996; Lassaba et al., 1998). Thus the action of two equivalents of diborane followed by oxidation with hydrogen peroxide and soda leads to two diasterioisomers: cis-himachal-2α,8α-diol and cis-himachal-2α,8β-diol. In order to prepare products with high added value, we have treated the mixture of these two isomers with the acetic anhydride in pyridine (see experimental) and obtained a mixture of two isomers (X) and (Y) with a combined yield of 98%. A study of spectral analysis of 1H NMR, 13C NMR and mass spectrometry did not allow us to differentiate between the structures of both isomers. Nevertheless, a X-ray crystallographic study of a single-crystal of (X) has allowed its identification as 2α,8α-diacetoxy-cis-himachalane (Scheme 1) and distinguish it from its isomer (Y), which is 2α,8β-diacetoxy-cis-himachalane. The molecule (Fig.1) is built up from two fused six- and seven-membered rings with the acetoxy groups at positions 2 and 8 in α-configuration. The six-membered ring has a screw boat conformation as indicated by the total puckering amplitude QT = 0.7585 (12) Å and a spherical polar angle of θ= 92.06 (9)° with ϕ= 71.42 (9)°. The seven-membered ring displays a half chair conformation with QT =0.8062 (13) Å, θ = 42.17 (9)°, ϕ2 = -26.97 (14)° and ϕ3 = 169.95 (13)° (Cremer & Pople, 1975).

Related literature top

For background to γ-himachalene derivatives, see: Lassaba et al. (1998); Plattier & Teisseire (1974); Plattier et al. (1974). For a related structure, see: Chiaroni et al. (1996). For ring puckering analysis, see: Cremer & Pople (1975).

Experimental top

To a solution of 1 g of the mixture of two isomers of cis-himachal-2,8-diol (prepared from γ-himachalene) in 30 ml of pyridine was added 20 ml of acetic anhydride. The mixture is stirred overnight at room temperature, then treated with 100 ml of ice water. The reaction mixture was extracted three times with 30 ml of ether. The organic phases obtained are dried over sodium sulfate and then concentrated under vacuum. The residue obtained is chromatographed on silica gel column impregnated with silver nitrate (10%) with a mixture of hexane - ethyl acetate (95–5) used as eluent. The two diastereoisomers 2α,8α-diacetoxy-cis-himachalane (X) and 2α,8β-diacetoxy-cis-himachalane (Y) are obtained by this procedure in a 80/20 ratio and a combined yield of 98%. The title compound (isomer X) is recrystallized from a mixture of hexane and ethyle acetate (40/60).

Refinement top

All H atoms were fixed geometrically and treated as riding with C—H = 0.96 Å (methyl), 0.97 Å (methylene) and 0.98 Å (methine) with Uiso(H) = 1.2 Ueq(CH2, CH) or Uiso(H) = 1.5 Ueq(CH3). In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and thus 1705 Friedel pairs were merged and any references to the Flack parameter were removed.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

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.
2α,8α-Diacetoxy-cis-himachalane top
Crystal data top
C19H32O4F(000) = 356
Mr = 324.45Dx = 1.172 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 8181 reflections
a = 5.9316 (2) Åθ = 3.5–29.2°
b = 11.7720 (3) ŵ = 0.08 mm1
c = 13.3535 (4) ÅT = 180 K
β = 99.603 (3)°Box, colourless
V = 919.37 (5) Å30.75 × 0.45 × 0.23 mm
Z = 2
Data collection top
Oxford Diffraction Xcalibur Eos Gemini Ultra
diffractometer
1976 independent reflections
Radiation source: fine-focus sealed tube1894 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.012
Detector resolution: 16.1978 pixels mm-1θmax = 26.4°, θmin = 3.5°
ω scansh = 77
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2010)
k = 1414
Tmin = 0.799, Tmax = 1.000l = 016
3681 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)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.079H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0489P)2 + 0.0959P]
where P = (Fo2 + 2Fc2)/3
1976 reflections(Δ/σ)max < 0.001
214 parametersΔρmax = 0.17 e Å3
1 restraintΔρmin = 0.14 e Å3
Crystal data top
C19H32O4V = 919.37 (5) Å3
Mr = 324.45Z = 2
Monoclinic, P21Mo Kα radiation
a = 5.9316 (2) ŵ = 0.08 mm1
b = 11.7720 (3) ÅT = 180 K
c = 13.3535 (4) Å0.75 × 0.45 × 0.23 mm
β = 99.603 (3)°
Data collection top
Oxford Diffraction Xcalibur Eos Gemini Ultra
diffractometer
1976 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2010)
1894 reflections with I > 2σ(I)
Tmin = 0.799, Tmax = 1.000Rint = 0.012
3681 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0301 restraint
wR(F2) = 0.079H-atom parameters constrained
S = 1.06Δρmax = 0.17 e Å3
1976 reflectionsΔρmin = 0.14 e Å3
214 parameters
Special details top

Experimental. Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. CrysAlisPro (Oxford Diffraction 2010)

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
C10.0099 (3)0.89742 (14)0.20021 (12)0.0220 (3)
H10.16300.88310.18450.026*
C20.1412 (3)0.92089 (14)0.09491 (12)0.0245 (3)
H20.26220.86340.08270.029*
C30.2509 (3)1.03856 (15)0.08423 (12)0.0270 (4)
H30.13051.09540.08330.032*
C40.3655 (3)1.05982 (16)0.17728 (13)0.0286 (4)
H4A0.47911.00130.18050.034*
H4B0.44411.13230.16940.034*
C50.1940 (3)1.06035 (16)0.27780 (12)0.0271 (4)
H5A0.16991.13780.30200.033*
H5B0.25671.01730.32870.033*
C60.0352 (3)1.00838 (14)0.26315 (12)0.0226 (3)
H60.09431.06280.21830.027*
C70.2205 (3)1.00777 (15)0.35903 (12)0.0254 (3)
H70.34890.96300.34270.030*
C80.1503 (3)0.95438 (17)0.45333 (12)0.0289 (4)
H80.05561.00870.48340.035*
C90.0274 (3)0.84093 (19)0.44034 (13)0.0354 (4)
H9A0.13590.85550.42840.042*
H9B0.06300.79960.50380.042*
C100.0816 (3)0.76424 (16)0.35535 (13)0.0311 (4)
H10A0.05900.68610.37440.037*
H10B0.24240.77310.35120.037*
C110.0575 (3)0.78409 (15)0.24849 (13)0.0253 (3)
C120.4260 (3)1.05045 (19)0.01273 (14)0.0386 (4)
H12A0.35621.03070.07030.058*
H12B0.47941.12750.01950.058*
H12C0.55271.00060.00950.058*
C130.3102 (3)1.12841 (17)0.38390 (15)0.0341 (4)
H130.18791.17550.39890.051*
H13A0.36841.15900.32670.051*
H13B0.43031.12620.44170.051*
C140.3141 (3)0.77332 (17)0.25420 (14)0.0307 (4)
H14A0.40090.77250.18670.046*
H14B0.36090.83670.29110.046*
H14C0.34040.70400.28830.046*
C150.0020 (3)0.68616 (16)0.18139 (14)0.0331 (4)
H15A0.03560.61510.20970.050*
H15B0.16250.68800.17840.050*
H15C0.08380.69420.11420.050*
C160.0647 (3)0.84124 (16)0.06239 (13)0.0300 (4)
C170.1060 (4)0.84018 (18)0.13319 (14)0.0380 (4)
H17A0.25020.81310.09780.057*
H17B0.12420.91580.15760.057*
H17C0.05310.79100.18960.057*
C180.3634 (3)0.95040 (18)0.62200 (13)0.0362 (4)
C190.5969 (4)0.9380 (2)0.68344 (16)0.0516 (6)
H19A0.58920.89020.74100.077*
H19B0.65421.01140.70640.077*
H19C0.69740.90440.64240.077*
O10.0055 (2)0.90900 (10)0.01763 (9)0.0275 (3)
O20.2420 (3)0.78940 (14)0.07569 (10)0.0456 (4)
O30.3679 (2)0.93985 (13)0.52241 (9)0.0338 (3)
O40.1927 (3)0.96866 (19)0.65590 (11)0.0572 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0175 (7)0.0237 (8)0.0255 (7)0.0015 (6)0.0060 (6)0.0003 (7)
C20.0232 (7)0.0266 (9)0.0246 (8)0.0040 (6)0.0071 (6)0.0009 (6)
C30.0260 (8)0.0290 (9)0.0267 (8)0.0013 (7)0.0066 (6)0.0031 (7)
C40.0235 (8)0.0306 (9)0.0330 (9)0.0040 (7)0.0084 (6)0.0037 (8)
C50.0252 (8)0.0301 (9)0.0280 (8)0.0020 (7)0.0100 (6)0.0012 (7)
C60.0217 (7)0.0240 (8)0.0236 (7)0.0017 (6)0.0081 (6)0.0001 (6)
C70.0220 (8)0.0302 (9)0.0250 (8)0.0013 (7)0.0073 (6)0.0035 (7)
C80.0249 (8)0.0396 (10)0.0230 (8)0.0014 (8)0.0060 (6)0.0020 (8)
C90.0334 (9)0.0472 (11)0.0267 (9)0.0070 (9)0.0089 (7)0.0054 (9)
C100.0305 (8)0.0294 (9)0.0333 (9)0.0020 (7)0.0052 (7)0.0067 (8)
C110.0228 (7)0.0239 (8)0.0293 (8)0.0013 (7)0.0050 (6)0.0015 (7)
C120.0380 (10)0.0430 (11)0.0326 (9)0.0067 (9)0.0009 (7)0.0047 (9)
C130.0315 (9)0.0360 (10)0.0360 (10)0.0064 (8)0.0092 (7)0.0082 (8)
C140.0253 (8)0.0303 (9)0.0371 (9)0.0061 (7)0.0066 (7)0.0048 (8)
C150.0358 (9)0.0248 (9)0.0388 (10)0.0002 (7)0.0066 (8)0.0002 (8)
C160.0406 (9)0.0248 (8)0.0236 (8)0.0001 (8)0.0027 (7)0.0002 (7)
C170.0534 (12)0.0319 (10)0.0309 (9)0.0023 (9)0.0133 (8)0.0034 (8)
C180.0507 (11)0.0320 (10)0.0248 (8)0.0009 (9)0.0034 (8)0.0017 (8)
C190.0615 (14)0.0486 (13)0.0372 (11)0.0010 (11)0.0137 (9)0.0020 (10)
O10.0289 (6)0.0309 (7)0.0242 (6)0.0041 (5)0.0086 (5)0.0040 (5)
O20.0528 (8)0.0469 (9)0.0364 (7)0.0179 (7)0.0053 (6)0.0092 (7)
O30.0298 (6)0.0464 (8)0.0246 (6)0.0022 (6)0.0024 (5)0.0034 (6)
O40.0629 (10)0.0831 (13)0.0278 (7)0.0126 (10)0.0140 (7)0.0011 (8)
Geometric parameters (Å, º) top
C1—C61.547 (2)C10—H10A0.9700
C1—C21.561 (2)C10—H10B0.9700
C1—C111.562 (2)C11—C151.537 (3)
C1—H10.9800C11—C141.542 (2)
C2—O11.4632 (19)C12—H12A0.9600
C2—C31.527 (2)C12—H12B0.9600
C2—H20.9800C12—H12C0.9600
C3—C121.525 (2)C13—H130.9600
C3—C41.533 (2)C13—H13A0.9600
C3—H30.9800C13—H13B0.9600
C4—C51.543 (2)C14—H14A0.9600
C4—H4A0.9700C14—H14B0.9600
C4—H4B0.9700C14—H14C0.9600
C5—C61.533 (2)C15—H15A0.9600
C5—H5A0.9700C15—H15B0.9600
C5—H5B0.9700C15—H15C0.9600
C6—C71.542 (2)C16—O21.203 (2)
C6—H60.9800C16—O11.343 (2)
C7—C81.526 (2)C16—C171.496 (3)
C7—C131.533 (3)C17—H17A0.9600
C7—H70.9800C17—H17B0.9600
C8—O31.466 (2)C17—H17C0.9600
C8—C91.518 (3)C18—O41.195 (2)
C8—H80.9800C18—O31.340 (2)
C9—C101.526 (3)C18—C191.495 (3)
C9—H9A0.9700C19—H19A0.9600
C9—H9B0.9700C19—H19B0.9600
C10—C111.542 (2)C19—H19C0.9600
C6—C1—C2109.21 (13)C9—C10—H10A108.1
C6—C1—C11120.34 (13)C11—C10—H10A108.1
C2—C1—C11112.02 (13)C9—C10—H10B108.1
C6—C1—H1104.6C11—C10—H10B108.1
C2—C1—H1104.6H10A—C10—H10B107.3
C11—C1—H1104.6C15—C11—C14106.96 (14)
O1—C2—C3108.37 (13)C15—C11—C10106.64 (14)
O1—C2—C1107.38 (12)C14—C11—C10108.78 (14)
C3—C2—C1114.61 (14)C15—C11—C1107.49 (13)
O1—C2—H2108.8C14—C11—C1114.41 (14)
C3—C2—H2108.8C10—C11—C1112.14 (14)
C1—C2—H2108.8C3—C12—H12A109.5
C12—C3—C2112.44 (15)C3—C12—H12B109.5
C12—C3—C4109.97 (14)H12A—C12—H12B109.5
C2—C3—C4108.18 (14)C3—C12—H12C109.5
C12—C3—H3108.7H12A—C12—H12C109.5
C2—C3—H3108.7H12B—C12—H12C109.5
C4—C3—H3108.7C7—C13—H13109.5
C3—C4—C5112.86 (13)C7—C13—H13A109.5
C3—C4—H4A109.0H13—C13—H13A109.5
C5—C4—H4A109.0C7—C13—H13B109.5
C3—C4—H4B109.0H13—C13—H13B109.5
C5—C4—H4B109.0H13A—C13—H13B109.5
H4A—C4—H4B107.8C11—C14—H14A109.5
C6—C5—C4110.94 (13)C11—C14—H14B109.5
C6—C5—H5A109.5H14A—C14—H14B109.5
C4—C5—H5A109.5C11—C14—H14C109.5
C6—C5—H5B109.5H14A—C14—H14C109.5
C4—C5—H5B109.5H14B—C14—H14C109.5
H5A—C5—H5B108.0C11—C15—H15A109.5
C5—C6—C7114.85 (13)C11—C15—H15B109.5
C5—C6—C1113.48 (13)H15A—C15—H15B109.5
C7—C6—C1116.00 (13)C11—C15—H15C109.5
C5—C6—H6103.4H15A—C15—H15C109.5
C7—C6—H6103.4H15B—C15—H15C109.5
C1—C6—H6103.4O2—C16—O1124.46 (16)
C8—C7—C13109.58 (15)O2—C16—C17124.71 (17)
C8—C7—C6115.63 (13)O1—C16—C17110.82 (15)
C13—C7—C6110.43 (14)C16—C17—H17A109.5
C8—C7—H7106.9C16—C17—H17B109.5
C13—C7—H7106.9H17A—C17—H17B109.5
C6—C7—H7106.9C16—C17—H17C109.5
O3—C8—C9108.97 (15)H17A—C17—H17C109.5
O3—C8—C7103.58 (13)H17B—C17—H17C109.5
C9—C8—C7117.39 (14)O4—C18—O3123.42 (18)
O3—C8—H8108.9O4—C18—C19125.14 (18)
C9—C8—H8108.9O3—C18—C19111.43 (18)
C7—C8—H8108.9C18—C19—H19A109.5
C8—C9—C10116.66 (15)C18—C19—H19B109.5
C8—C9—H9A108.1H19A—C19—H19B109.5
C10—C9—H9A108.1C18—C19—H19C109.5
C8—C9—H9B108.1H19A—C19—H19C109.5
C10—C9—H9B108.1H19B—C19—H19C109.5
H9A—C9—H9B107.3C16—O1—C2118.45 (13)
C9—C10—C11116.86 (15)C18—O3—C8116.89 (14)

Experimental details

Crystal data
Chemical formulaC19H32O4
Mr324.45
Crystal system, space groupMonoclinic, P21
Temperature (K)180
a, b, c (Å)5.9316 (2), 11.7720 (3), 13.3535 (4)
β (°) 99.603 (3)
V3)919.37 (5)
Z2
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.75 × 0.45 × 0.23
Data collection
DiffractometerOxford Diffraction Xcalibur Eos Gemini Ultra
diffractometer
Absorption correctionMulti-scan
(CrysAlis PRO; Oxford Diffraction, 2010)
Tmin, Tmax0.799, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
3681, 1976, 1894
Rint0.012
(sin θ/λ)max1)0.625
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.079, 1.06
No. of reflections1976
No. of parameters214
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.17, 0.14

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

 

Acknowledgements

The authors gratefully acknowledge financial support from the CNRST of Morroco.

References

First citationBurla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381–388.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationChiaroni, A., Riche, C., Lassaba, E. & Benharref, A. (1996). Acta Cryst. C52, 3240–3243.  CSD CrossRef Web of Science IUCr Journals Google Scholar
First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationLassaba, E., Eljamili, H., Chekroun, A., Benharref, A., Chiaroni, A., Riche, C. & Lavergne, J. P. (1998). Synth. Commun. 28, 2641–2651.  Web of Science CrossRef CAS Google Scholar
First citationOxford Diffraction (2010). CrystAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.  Google Scholar
First citationPlattier, M., Rouillier, P. & Teisseire, P. (1974). Recherche, 19, 145–151.  CAS Google Scholar
First citationPlattier, M. & Teisseire, P. (1974). Recherche, 19, 131–144.  CAS 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