(1S,3R,8R)-2,2-Dibromo-10-bromo­methyl-3,7,7-trimethyl­tricyclo­[6.4.0.01,3]dodec-9-ene

Oukhrib, A.; Benharref, A.; Saadi, M.; Daran, J.-C.; Berraho, M.

doi:10.1107/S1600536812046430

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 68| Part 12| December 2012| Pages o3394-o3395

doi:10.1107/S1600536812046430

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(1S,3R,8R)-2,2-Dibromo-10-bromomethyl-3,7,7-trimethyltricyclo[6.4.0.0^1,3]dodec-9-ene

Abdelouahd Oukhrib,^a ^* Ahmed Benharref,^a Mohamed Saadi,^b Jean-Claude Daran ^c and Moha Berraho ^a

^aLaboratoire de Chimie des Substances Naturelles, "Unité Associé au CNRST (URAC16)", Faculté des Sciences Semlalia, BP 2390 Bd My Abdellah, 40000 Marrakech, Morocco, ^bLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Avenue Ibn Battouta, BP 1014 Rabat, Morocco, and ^cLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France
^*Correspondence e-mail: berraho@uca.ma

(Received 6 November 2012; accepted 9 November 2012; online 24 November 2012)

The title compound, C₁₆H₂₃Br₃, 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 (the flap atom being the C atom shared with the three-membered ring, whereas the seven-membered ring displays a screw boat conformation; the dihedral angle between the rings (defined by the near coplanar atoms) is 56.5 (2)°.

Related literature

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 ); Benharref et al. (2010 ). For its biological activity, see: Daoubi et al. (2004 ). For conformational analysis, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₁₆H₂₃Br₃
M_r = 455.07
Orthorhombic, P 2₁ 2₁ 2₁
a = 9.2614 (5) Å
b = 12.8215 (8) Å
c = 14.3966 (11) Å
V = 1709.52 (19) Å³
Z = 4
Mo Kα radiation
μ = 7.07 mm⁻¹
T = 180 K
0.49 × 0.31 × 0.08 mm

Data collection

Agilent Xcalibur (Sapphire1, long nozzle) diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ) T_min = 0.135, T_max = 1.000
9721 measured reflections
3461 independent reflections
3121 reflections with I > 2σ(I)
R_int = 0.049

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.075
S = 1.04
3461 reflections
176 parameters
H-atom parameters constrained
Δρ_max = 0.66 e Å⁻³
Δρ_min = −0.55 e Å⁻³
Absolute structure: Flack (1983 ), 1460 Friedel pairs
Flack parameter: 0.012 (16)

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812046430/im2411sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812046430/im2411Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812046430/im2411Isup3.cml

checkCIF report

Comment top

Our work lies within the framework of the valorization of the most abundant essential oils in Morocco, such as the one from Cedrus atlantica. This oil is made up mainly (75%) of bicyclic sesquiterpenes hydrocarbons, among which is found β-himachalene (Joseph & Dev, 1968; Plattier & Teiseire, 1974). 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; Benharref et al.,2010). 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 (1S,3R,8R)-2,2-dibromo- 3,7,7,10- tetramethyltricyclo [6.4.0.01,3] dodec-9-ene from β-himachalene, which by treatment with N-bromosuccinimide gave the title compound. The structure of this new product was determined by single-crystal X-ray structure analysis. 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 = 0.497 (4) Å and spherical polar angle θ= 129.5 (5)° with ϕ = 149.2 (7)°, whereas the seven-membered ring displays a screw boat conformation with QT = 1.1556 (4) Å, θ = 88.2 (20)°, ϕ2 = -48.26 (20)° and ϕ3 = -117.47 (7)° (Cremer & Pople, 1975). Owing to the presence of Br atoms, the absolute configuration could be fully confirmed as C1(S), C3(R)and C8(R) by refining the Flack (1983) parameter 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); Benharref et al. (2010). 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 (5.2 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 (1S,3R,8R)-2,2,16-tribromo-3,7,7,10-tetramethyltricyclo[6.4.0.0₁,₃]dodec-9-ene was obtained with a yield of 16% (18 mg, 0.4 mmol) and was recrystallized from n-pentane solution at room temperature.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); 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

Fig. 1. Molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability. level. H atoms are represented as small spheres of arbitrary radii.

(1S,3R,8R)-2,2-Dibromo-10-bromomethyl-3,7,7- trimethyltricyclo[6.4.0.0^1,3]dodec-9-ene top

Crystal data top

C₁₆H₂₃Br₃	F(000) = 896
M_r = 455.07	D_x = 1.768 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3461 reflections
a = 9.2614 (5) Å	θ = 3.1–26.4°
b = 12.8215 (8) Å	µ = 7.07 mm⁻¹
c = 14.3966 (11) Å	T = 180 K
V = 1709.52 (19) Å³	Prism, colourless
Z = 4	0.49 × 0.31 × 0.08 mm

Data collection top

Agilent Xcalibur (Sapphire1, long nozzle) diffractometer	3461 independent reflections
Graphite monochromator	3121 reflections with I > 2σ(I)
Detector resolution: 8.2632 pixels mm^-1	R_int = 0.049
ω scans	θ_max = 26.4°, θ_min = 3.1°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	h = −11→11
T_min = 0.135, T_max = 1.000	k = −16→15
9721 measured reflections	l = −15→17

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.034	w = 1/[σ²(F_o²) + (0.0387P)² + 0.0947P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.075	(Δ/σ)_max = 0.001
S = 1.04	Δρ_max = 0.66 e Å⁻³
3461 reflections	Δρ_min = −0.55 e Å⁻³
176 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0034 (4)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1460 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.012 (16)

Crystal data top

C₁₆H₂₃Br₃	V = 1709.52 (19) Å³
M_r = 455.07	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 9.2614 (5) Å	µ = 7.07 mm⁻¹
b = 12.8215 (8) Å	T = 180 K
c = 14.3966 (11) Å	0.49 × 0.31 × 0.08 mm

Data collection top

Agilent Xcalibur (Sapphire1, long nozzle) diffractometer	3461 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	3121 reflections with I > 2σ(I)
T_min = 0.135, T_max = 1.000	R_int = 0.049
9721 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	H-atom parameters constrained
wR(F²) = 0.075	Δρ_max = 0.66 e Å⁻³
S = 1.04	Δρ_min = −0.55 e Å⁻³
3461 reflections	Absolute structure: Flack (1983), 1460 Friedel pairs
176 parameters	Absolute structure parameter: 0.012 (16)
0 restraints

Special details top

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

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

	x	y	z	U_iso*/U_eq
C13	0.9676 (5)	0.5913 (4)	0.4115 (3)	0.0283 (12)
H13A	0.9119	0.6220	0.4606	0.042*
H13B	0.9989	0.5230	0.4299	0.042*
H13C	0.9093	0.5861	0.3565	0.042*
C1	1.1613 (4)	0.6641 (3)	0.2929 (3)	0.0110 (8)
C2	1.0820 (5)	0.7571 (3)	0.3330 (3)	0.0164 (9)
C3	1.0980 (5)	0.6589 (3)	0.3916 (3)	0.0160 (9)
C4	1.2066 (6)	0.6600 (3)	0.4707 (3)	0.0251 (11)
H4A	1.1567	0.6746	0.5285	0.030*
H4B	1.2760	0.7154	0.4602	0.030*
C5	1.2867 (6)	0.5560 (4)	0.4793 (3)	0.0280 (12)
H5A	1.2275	0.5082	0.5151	0.034*
H5B	1.3752	0.5675	0.5139	0.034*
C6	1.3251 (5)	0.5037 (3)	0.3864 (3)	0.0233 (10)
H6A	1.2356	0.4818	0.3573	0.028*
H6B	1.3798	0.4410	0.4001	0.028*
C7	1.4112 (5)	0.5671 (3)	0.3143 (3)	0.0196 (10)
C8	1.3273 (4)	0.6703 (3)	0.2837 (3)	0.0146 (8)
H8	1.3594	0.7261	0.3254	0.018*
C9	1.3668 (4)	0.7037 (3)	0.1861 (3)	0.0186 (10)
H9	1.4614	0.7250	0.1756	0.022*
C10	1.2776 (5)	0.7050 (3)	0.1147 (3)	0.0158 (9)
C11	1.1229 (5)	0.6707 (3)	0.1223 (3)	0.0161 (9)
H11A	1.0988	0.6284	0.0687	0.019*
H11B	1.0611	0.7318	0.1214	0.019*
C12	1.0923 (4)	0.6086 (3)	0.2101 (3)	0.0139 (8)
H12A	1.1318	0.5389	0.2041	0.017*
H12B	0.9889	0.6028	0.2195	0.017*
C14	1.5566 (5)	0.6008 (4)	0.3559 (4)	0.0427 (15)
H14A	1.6119	0.5401	0.3719	0.064*
H14B	1.5400	0.6419	0.4106	0.064*
H14C	1.6088	0.6415	0.3111	0.064*
C15	1.4416 (6)	0.4939 (4)	0.2310 (3)	0.0328 (13)
H15A	1.4933	0.4336	0.2521	0.049*
H15B	1.4985	0.5303	0.1856	0.049*
H15C	1.3518	0.4727	0.2036	0.049*
C16	1.3330 (6)	0.7378 (4)	0.0200 (3)	0.0286 (11)
H16A	1.3172	0.6817	−0.0241	0.034*
H16B	1.4361	0.7506	0.0236	0.034*
Br1	0.89111 (5)	0.79294 (4)	0.28578 (3)	0.02481 (13)
Br2	1.17768 (6)	0.88596 (3)	0.36490 (3)	0.02729 (14)
Br3	1.23443 (7)	0.86490 (4)	−0.02407 (4)	0.04212 (18)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C13	0.030 (3)	0.028 (3)	0.027 (3)	−0.002 (2)	0.016 (2)	0.009 (2)
C1	0.0118 (18)	0.0124 (18)	0.0088 (19)	−0.0009 (16)	0.0025 (16)	0.0028 (17)
C2	0.016 (2)	0.018 (2)	0.015 (2)	−0.0061 (18)	0.0004 (17)	−0.0025 (18)
C3	0.020 (2)	0.015 (2)	0.013 (2)	0.0007 (19)	0.0037 (18)	−0.0005 (17)
C4	0.047 (3)	0.021 (2)	0.007 (2)	0.003 (2)	−0.005 (2)	−0.0004 (18)
C5	0.046 (3)	0.026 (2)	0.013 (2)	0.008 (2)	−0.005 (2)	0.004 (2)
C6	0.032 (3)	0.019 (2)	0.020 (3)	0.007 (2)	−0.001 (2)	0.0051 (18)
C7	0.012 (2)	0.021 (2)	0.026 (3)	0.0040 (19)	−0.0045 (18)	0.0045 (19)
C8	0.0139 (19)	0.015 (2)	0.015 (2)	−0.0022 (17)	−0.0019 (19)	0.0036 (18)
C9	0.010 (2)	0.019 (2)	0.026 (3)	−0.0017 (18)	0.0026 (16)	0.007 (2)
C10	0.021 (2)	0.0145 (19)	0.012 (2)	0.0047 (19)	0.0061 (17)	0.0031 (17)
C11	0.020 (2)	0.018 (2)	0.010 (2)	−0.0006 (18)	−0.0006 (17)	−0.0011 (17)
C12	0.0130 (19)	0.0158 (19)	0.013 (2)	0.0010 (18)	0.0010 (18)	−0.0032 (18)
C14	0.020 (3)	0.042 (3)	0.066 (4)	−0.003 (2)	−0.022 (3)	0.018 (3)
C15	0.029 (3)	0.030 (3)	0.040 (3)	0.015 (2)	0.009 (2)	0.010 (2)
C16	0.033 (3)	0.030 (3)	0.023 (3)	0.010 (2)	0.011 (2)	0.012 (2)
Br1	0.0178 (2)	0.0254 (2)	0.0312 (3)	0.0070 (2)	0.0019 (2)	−0.0009 (2)
Br2	0.0377 (3)	0.0147 (2)	0.0295 (3)	−0.0026 (2)	−0.0072 (2)	−0.0044 (2)
Br3	0.0431 (3)	0.0365 (3)	0.0467 (4)	0.0046 (3)	0.0065 (3)	0.0243 (3)

Geometric parameters (Å, º) top

C13—C3	1.514 (6)	C7—C15	1.549 (6)
C13—H13A	0.9600	C7—C8	1.596 (6)
C13—H13B	0.9600	C8—C9	1.515 (6)
C13—H13C	0.9600	C8—H8	0.9800
C1—C2	1.516 (6)	C9—C10	1.318 (6)
C1—C12	1.528 (5)	C9—H9	0.9300
C1—C3	1.540 (6)	C10—C11	1.503 (6)
C1—C8	1.544 (5)	C10—C16	1.517 (6)
C2—C3	1.523 (6)	C11—C12	1.520 (6)
C2—Br2	1.930 (4)	C11—H11A	0.9700
C2—Br1	1.949 (4)	C11—H11B	0.9700
C3—C4	1.519 (6)	C12—H12A	0.9700
C4—C5	1.532 (6)	C12—H12B	0.9700
C4—H4A	0.9700	C14—H14A	0.9600
C4—H4B	0.9700	C14—H14B	0.9600
C5—C6	1.538 (6)	C14—H14C	0.9600
C5—H5A	0.9700	C15—H15A	0.9600
C5—H5B	0.9700	C15—H15B	0.9600
C6—C7	1.541 (6)	C15—H15C	0.9600
C6—H6A	0.9700	C16—Br3	1.973 (4)
C6—H6B	0.9700	C16—H16A	0.9700
C7—C14	1.535 (6)	C16—H16B	0.9700

C3—C13—H13A	109.5	C14—C7—C8	107.5 (4)
C3—C13—H13B	109.5	C6—C7—C8	111.8 (3)
H13A—C13—H13B	109.5	C15—C7—C8	112.1 (4)
C3—C13—H13C	109.5	C9—C8—C1	109.5 (3)
H13A—C13—H13C	109.5	C9—C8—C7	111.9 (3)
H13B—C13—H13C	109.5	C1—C8—C7	114.7 (3)
C2—C1—C12	117.5 (3)	C9—C8—H8	106.7
C2—C1—C3	59.8 (3)	C1—C8—H8	106.7
C12—C1—C3	122.7 (3)	C7—C8—H8	106.7
C2—C1—C8	118.3 (4)	C10—C9—C8	125.1 (4)
C12—C1—C8	112.0 (3)	C10—C9—H9	117.4
C3—C1—C8	117.4 (4)	C8—C9—H9	117.4
C1—C2—C3	60.9 (3)	C9—C10—C11	122.5 (4)
C1—C2—Br2	122.8 (3)	C9—C10—C16	119.5 (4)
C3—C2—Br2	122.1 (3)	C11—C10—C16	118.0 (4)
C1—C2—Br1	119.5 (3)	C10—C11—C12	113.0 (3)
C3—C2—Br1	118.5 (3)	C10—C11—H11A	109.0
Br2—C2—Br1	107.3 (2)	C12—C11—H11A	109.0
C13—C3—C4	113.1 (4)	C10—C11—H11B	109.0
C13—C3—C2	120.0 (4)	C12—C11—H11B	109.0
C4—C3—C2	118.1 (4)	H11A—C11—H11B	107.8
C13—C3—C1	120.2 (4)	C11—C12—C1	109.1 (3)
C4—C3—C1	116.1 (4)	C11—C12—H12A	109.9
C2—C3—C1	59.3 (3)	C1—C12—H12A	109.9
C3—C4—C5	111.9 (4)	C11—C12—H12B	109.9
C3—C4—H4A	109.2	C1—C12—H12B	109.9
C5—C4—H4A	109.2	H12A—C12—H12B	108.3
C3—C4—H4B	109.2	C7—C14—H14A	109.5
C5—C4—H4B	109.2	C7—C14—H14B	109.5
H4A—C4—H4B	107.9	H14A—C14—H14B	109.5
C4—C5—C6	114.9 (4)	C7—C14—H14C	109.5
C4—C5—H5A	108.5	H14A—C14—H14C	109.5
C6—C5—H5A	108.5	H14B—C14—H14C	109.5
C4—C5—H5B	108.5	C7—C15—H15A	109.5
C6—C5—H5B	108.5	C7—C15—H15B	109.5
H5A—C5—H5B	107.5	H15A—C15—H15B	109.5
C5—C6—C7	118.4 (4)	C7—C15—H15C	109.5
C5—C6—H6A	107.7	H15A—C15—H15C	109.5
C7—C6—H6A	107.7	H15B—C15—H15C	109.5
C5—C6—H6B	107.7	C10—C16—Br3	111.2 (3)
C7—C6—H6B	107.7	C10—C16—H16A	109.4
H6A—C6—H6B	107.1	Br3—C16—H16A	109.4
C14—C7—C6	109.9 (4)	C10—C16—H16B	109.4
C14—C7—C15	108.2 (4)	Br3—C16—H16B	109.4
C6—C7—C15	107.2 (4)	H16A—C16—H16B	108.0

Experimental details

Crystal data
Chemical formula	C₁₆H₂₃Br₃
M_r	455.07
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	180
a, b, c (Å)	9.2614 (5), 12.8215 (8), 14.3966 (11)
V (Å³)	1709.52 (19)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	7.07
Crystal size (mm)	0.49 × 0.31 × 0.08

Data collection
Diffractometer	Agilent Xcalibur (Sapphire1, long nozzle) diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2010)
T_min, T_max	0.135, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	9721, 3461, 3121
R_int	0.049
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.075, 1.04
No. of reflections	3461
No. of parameters	176
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.66, −0.55
Absolute structure	Flack (1983), 1460 Friedel pairs
Absolute structure parameter	0.012 (16)

Computer programs: CrysAlis PRO (Agilent, 2010), 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 and CNRST) for the X-ray measurements.

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