Ethyl 2-(2,3,4,5,6-Penta­bromo­phen­yl)acetate

Sauer, A.M.; Mack, A.G.; Elnagar, H.Y.; Fronczek, F.R.

doi:10.1107/S1600536810025626

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 66| Part 8| August 2010| Page o1994

https://doi.org/10.1107/S1600536810025626

Open

access

Ethyl 2-(2,3,4,5,6-Pentabromophenyl)acetate

Anne M. Sauer,^a Art G. Mack,^a Hassan Y. Elnagar ^a and Frank R. Fronczek ^b ^*

^aAlbemarle Process Development Center, Albemarle Corporation, PO Box 341, Baton Rouge, LA 70821, USA, and ^bDepartment of Chemistry, Louisiana State University, Baton Rouge, LA 70803-1804, USA
^*Correspondence e-mail: ffroncz@lsu.edu

(Received 3 June 2010; accepted 29 June 2010; online 14 July 2010)

The title compound PBPEA, C₁₀H₇Br₅O₂, has its ethyl acetate portion nearly orthogonal to the benzene ring, with a C—C—C—C torsion angle of 88.3 (5)°. The packing involves an intermolecular contact with a Br⋯Br distance of 3.491 (1) Å, having C—Br⋯Br angles of 173.4 (2) and 106.0 (2)°. The crystal studied was an inversion twin.

Related literature

For synthetic procedures, see: Holmes & Lightner (1995 ); Adams & Thal (1941 ). For a description of the Cambridge Structural Database, see: Allen (2002 ). For related structures, see: Eriksson & Hu (2002a ,b ); Eriksson et al. (1999 ); Köppen et al. (2007 ); Krigbaum & Wildman (1971 ); Mrse et al. (2000 ); Pedireddi et al. (1994 ); Williams et al. (1985 ).

Experimental

Crystal data

C₁₀H₇Br₅O₂
M_r = 558.71
Monoclinic, C c
a = 4.6136 (10) Å
b = 22.548 (5) Å
c = 13.195 (2) Å
β = 90.993 (11)°
V = 1372.4 (5) Å³
Z = 4
Mo Kα radiation
μ = 14.63 mm⁻¹
T = 90 K
0.25 × 0.12 × 0.12 mm

Data collection

Nonius KappaCCD diffractometer with Oxford Cryostream
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997 ) T_min = 0.121, T_max = 0.273
10525 measured reflections
3863 independent reflections
3676 reflections with I > 2σ(I)
R_int = 0.013

Refinement

R[F² > 2σ(F²)] = 0.025
wR(F²) = 0.053
S = 1.17
3863 reflections
157 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.65 e Å⁻³
Δρ_min = −0.66 e Å⁻³
Absolute structure: Flack (1983 ), 1846 Friedel pairs
Flack parameter: 0.467 (13)

Data collection: COLLECT (Nonius, 2000 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810025626/jj2038sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810025626/jj2038Isup2.hkl

checkCIF report

Comment top

In an effort to prepare a series of proposed pentabromophenyl-substituted compounds necessary as analytical standards, the title ethyl ester derivative rendered itself to be an important intermediate and was synthesized via PBBN as an intermediate. This PBBN nitrile precursor was prepared by known procedures (Holmes & Lightner, 1995) from hexabromotoluene, henceforth referred to as pentabromobenzyl bromide, PBBB. Subsequent conversion of the resulting pentabromobenzyl nitrile intermediate to PBPEA was completed with ethanol in sulfuric acid. (Adams & Thal, 1941). The nature of such sterically hindered and electronically deprived pentabromo-compounds has provided a unique opportunity to examine the reactivity and resulting isolation / purification tendencies associated with these systems.

The ethyl acetate portion of the molecule (Fig. 1) is extended, with torsion angles C1—C7—C8—O1 174.8 (3)°, C7—C8—O1—C9 179.3 (3)°, C8—O1—C9—C10 - 165.1 (3)°, and it is nearly orthogonal to the phenyl ring, with C2—C1—C7—C8 torsion angle 88.3 (5)°. The C—Br distances are in the range 1.876 (4)–1.896 (4) Å, with mean value 1.887 Å. This value compares favorably with the mean value of 1.880 Å in decabromodiphenylethane (Köppen et al., 2007), the only ordered entry in the CSD (version 5.31, Nov. 2009; Allen 2002) with Br₅Ph on an sp³ C atom. The structure of pentabromotoluene has also been reported (Krigbaum & Wildman, 1971), but it has the methyl group statistically disordered, sharing all six sites with Br. Structures of several pentabromophenyl ethers have also been reported (Eriksson & Hu, 2002a,b; Eriksson et al., 1999; Mrse et al., 2000; Williams et al., 1985), and the geometries of their Br₅Ph groups are similar.

Packing of compounds containing Br₅Ph groups usually involves intermolecular Br···Br contacts, and one such interaction exists in the structure of the title compound, as illustrated in Fig. 2. The contact is between glide-related molecules, and has Br3···Br5 distance 3.491 (1) Å. The angular disposition of the contact is termed type II by Pedireddi et al. (1994), having one C–Br···Br angle near linear and the other nearly orthogonal. In this case, the angle about Br5 is 173.4 (2)°, and the angle about Br3 is 106.0 (2)°. Also, both O atoms make intermolecular contacts with Br, O1···Br4(1 + x, 1 - y, 1/2 + z) 3.184 (3) Å; O2···Br2 (x - 1/2, 3/2 - y, 1/2 + z) 3.123 (3) Å.

Related literature top

For synthetic procedures, see: Holmes & Lightner (1995); Adams & Thal (1941). For a description of the Cambridge Structural Database, see: Allen (2002). For related structures, see: Eriksson & Hu (2002a,b); Eriksson et al. (1999); Köppen et al. (2007); Krigbaum & Wildman (1971); Mrse et al. (2000); Pedireddi et al. (1994); Williams et al. (1985).

Experimental top

Preparation of PBBN (9263–183):(Fig. 3) To a 3-neck, 100-ml RBF, fitted with a nitrogen inlet, thermocouple and septum, was charged the starting PBBB (5 g, 8.84 mmol) in DMSO (50 ml). To this slurry was added the sodium cyanide (0.44 g, 8.98 mmol) in one portion at room temperature and the reaction mixture immediately became mint in color. This color quickly dissipated and became brown. The reaction was allowed to heat for one hour, with vigorous stirring, at 80 °C under an inert atmosphere. Upon conclusion, the contents were filtered hot to remove an insoluble material (1.01 g) and the resulting brown filtrate was treated with water to precipitate the PBBN product. The light brown solids (fluffy) were collected via suction filtration. Drying overnight afforded a dark brown solid. Solids were rinsed with IPA and filtered to provide 2.58 g PBBN material (light brown in color and free flowing) upon drying (~57% yield), mp = 178.6 & 179.5 °C. Purity of the crude PBBN was found to be ~70% (trimethylbenzene as internal standard) and was used without further purification. The trace unreacted sodium cyanide was destroyed by bleach solution in the aqueous DMSO solution.

Preparation of PBPEA (9263–189): (Fig. 3) To a 3-neck, 100-ml RBF, fitted with a reflux condenser, thermocouple, and nitrogen inlet was charged absolute ethanol (30 g). Concentrated sulfuric acid (30 g) as added slowly as to minimize exotherm. When heating subsided, the starting nitrile, PBBN (1.0 g), was added in one portion. The temperature was set to ~96 °C, and the contents were allowed to reflux for 7 h. After heating for ~15 minutes, the reaction turned dark brown in color with no visible evidence of insoluble PBBN. After 2 h. heating, reflux had stabilized. Gradually, the temperature dropped to ~88 °C. The reactor was cooled, and the contents were poured into ice water. Immediately, a grey-brown solid precipitate was formed and subsequently collected via suction filtration. Air-drying overnight provided 1.65 grams crude material. The solids were slurried in acetone and filtered to collect 0.46 grams (42.2% yield) brown solid on drying. Crude NMR revealed desired ethyl ester as the major component. ¹H NMR: (400 MHz, DMSO-d6): δ = 4.32 (singlet, benzylic –CH₂–, 2H), 4.17–4.12 (quartet, ester methylene, 2H), 1.22–1.19 (triplet, ester methyl, 3H). (Impurities consist of the acetic acid derivative, along with the amide intermediate.) Recrystallization from acetone / IPA afforded the title ester compound obtained in pure form as spear-like needles, mp (DSC-melt) = 142.9–145.8 °C.

Structure description top

For synthetic procedures, see: Holmes & Lightner (1995); Adams & Thal (1941). For a description of the Cambridge Structural Database, see: Allen (2002). For related structures, see: Eriksson & Hu (2002a,b); Eriksson et al. (1999); Köppen et al. (2007); Krigbaum & Wildman (1971); Mrse et al. (2000); Pedireddi et al. (1994); Williams et al. (1985).

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Ellipsoids at the 50% probability level, with H atoms having arbitrary radius.
	Fig. 2. The intermolecular Br···Br contact. H atoms are omitted.
	Fig. 3. Preparation of the title compound.

Ethyl 2-(2,3,4,5,6-Pentabromophenyl)acetate top

Crystal data top

C₁₀H₇Br₅O₂	F(000) = 1032
M_r = 558.71	D_x = 2.704 Mg m⁻³
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2yc	Cell parameters from 2027 reflections
a = 4.6136 (10) Å	θ = 2.5–30.0°
b = 22.548 (5) Å	µ = 14.63 mm⁻¹
c = 13.195 (2) Å	T = 90 K
β = 90.993 (11)°	Needle fragment, light brown
V = 1372.4 (5) Å³	0.25 × 0.12 × 0.12 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer with Oxford Cryostream	3863 independent reflections
Radiation source: fine-focus sealed tube	3676 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.013
ω and φ scans	θ_max = 30.0°, θ_min = 3.0°
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	h = −6→6
T_min = 0.121, T_max = 0.273	k = −31→31
10525 measured reflections	l = −18→18

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.025	w = 1/[σ²(F_o²) + (0.0154P)² + 2.9894P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.053	(Δ/σ)_max = 0.002
S = 1.17	Δρ_max = 0.65 e Å⁻³
3863 reflections	Δρ_min = −0.66 e Å⁻³
157 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.00100 (7)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1842 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.467 (13)

Crystal data top

C₁₀H₇Br₅O₂	V = 1372.4 (5) Å³
M_r = 558.71	Z = 4
Monoclinic, Cc	Mo Kα radiation
a = 4.6136 (10) Å	µ = 14.63 mm⁻¹
b = 22.548 (5) Å	T = 90 K
c = 13.195 (2) Å	0.25 × 0.12 × 0.12 mm
β = 90.993 (11)°

Data collection top

Nonius KappaCCD diffractometer with Oxford Cryostream	3863 independent reflections
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	3676 reflections with I > 2σ(I)
T_min = 0.121, T_max = 0.273	R_int = 0.013
10525 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.025	H-atom parameters constrained
wR(F²) = 0.053	Δρ_max = 0.65 e Å⁻³
S = 1.17	Δρ_min = −0.66 e Å⁻³
3863 reflections	Absolute structure: Flack (1983), 1842 Friedel pairs
157 parameters	Absolute structure parameter: 0.467 (13)
2 restraints

Special details top

Experimental. PBBN: ¹H NMR: (400MHz, DMSO-d6): δ = 4.46 (singlet, benzylic –CH₂–, 2H); ¹³C NMR: (125MHz, DMSO-d6): δ = 134.06, 130.18, 129.66, 127.90, 116.37, 31.29.

PBPEA: ¹H NMR: (400 MHz, CDCl₃): δ = 4.36 (singlet, benzylic –CH₂–, 2H), 4.26–4.20 (quartet, ester methylene, 2H), 1.32–1.28 (triplet, ester methyl 2H), 4.26–4.20 (quartet, ester methylene, 2H), 1.32–1.28 (triplet, ester methyl, 3H). ¹³C NMR: (100 MHz, CDCl₃): δ = 168.79, 137.56, 129.37, 129.1, 128.55, 61.98, 47.94, 14.60.

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

	x	y	z	U_iso*/U_eq
Br1	0.88580 (8)	0.721320 (18)	0.44969 (3)	0.01668 (9)
Br2	0.57652 (8)	0.735821 (17)	0.22457 (3)	0.01500 (9)
Br3	0.16294 (9)	0.628526 (18)	0.13378 (3)	0.01501 (9)
Br4	0.06205 (8)	0.507432 (18)	0.26957 (3)	0.01482 (9)
Br5	0.36995 (8)	0.495585 (18)	0.49436 (3)	0.01383 (9)
O1	0.7331 (6)	0.61466 (13)	0.7294 (2)	0.0136 (6)
O2	0.3795 (6)	0.65392 (14)	0.6300 (2)	0.0162 (6)
C1	0.6196 (9)	0.60801 (18)	0.4523 (3)	0.0113 (7)
C2	0.6548 (8)	0.65956 (18)	0.3941 (3)	0.0115 (8)
C3	0.5193 (9)	0.66594 (17)	0.3000 (3)	0.0096 (7)
C4	0.3429 (8)	0.62048 (18)	0.2616 (3)	0.0103 (7)
C5	0.2983 (8)	0.56956 (18)	0.3187 (3)	0.0110 (8)
C6	0.4373 (8)	0.56364 (18)	0.4137 (3)	0.0118 (8)
C7	0.7750 (9)	0.60088 (18)	0.5534 (3)	0.0122 (8)
H7A	0.9647	0.6213	0.5510	0.015*
H7B	0.8118	0.5582	0.5660	0.015*
C8	0.6017 (8)	0.62599 (17)	0.6398 (3)	0.0101 (7)
C9	0.5844 (9)	0.6377 (2)	0.8175 (3)	0.0148 (8)
H9A	0.4116	0.6132	0.8316	0.018*
H9B	0.5200	0.6790	0.8046	0.018*
C10	0.7928 (10)	0.6360 (2)	0.9071 (3)	0.0170 (9)
H10A	0.8614	0.5953	0.9176	0.026*
H10B	0.6938	0.6497	0.9679	0.026*
H10C	0.9583	0.6620	0.8939	0.026*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0201 (2)	0.01398 (19)	0.0157 (2)	−0.00486 (17)	−0.00499 (16)	0.00049 (16)
Br2	0.0221 (2)	0.01098 (19)	0.01185 (18)	−0.00063 (16)	−0.00041 (15)	0.00243 (15)
Br3	0.0200 (2)	0.01540 (18)	0.00946 (16)	0.00203 (16)	−0.00374 (14)	−0.00085 (16)
Br4	0.01717 (19)	0.0141 (2)	0.0131 (2)	−0.00421 (16)	−0.00080 (16)	−0.00249 (16)
Br5	0.01896 (19)	0.01114 (19)	0.0114 (2)	−0.00113 (16)	0.00103 (16)	0.00194 (15)
O1	0.0148 (13)	0.0184 (15)	0.0076 (12)	0.0050 (11)	−0.0008 (11)	−0.0002 (11)
O2	0.0156 (14)	0.0184 (15)	0.0144 (13)	0.0054 (12)	−0.0028 (11)	−0.0036 (12)
C1	0.0129 (17)	0.0116 (19)	0.0095 (17)	0.0013 (14)	0.0024 (15)	0.0005 (14)
C2	0.0104 (18)	0.0118 (19)	0.0125 (18)	−0.0011 (14)	0.0040 (15)	−0.0021 (14)
C3	0.0133 (17)	0.0070 (18)	0.0086 (16)	0.0010 (14)	0.0003 (14)	0.0017 (13)
C4	0.0103 (17)	0.0134 (19)	0.0072 (16)	0.0023 (14)	−0.0022 (14)	−0.0004 (14)
C5	0.0112 (18)	0.0114 (19)	0.0105 (18)	−0.0019 (14)	−0.0001 (14)	−0.0039 (14)
C6	0.0149 (19)	0.0101 (19)	0.0106 (18)	0.0026 (15)	0.0040 (15)	0.0014 (14)
C7	0.0127 (18)	0.0109 (18)	0.0129 (19)	−0.0013 (14)	−0.0018 (15)	0.0000 (15)
C8	0.0121 (18)	0.0098 (17)	0.0081 (16)	−0.0021 (14)	−0.0031 (14)	−0.0023 (14)
C9	0.015 (2)	0.019 (2)	0.0101 (18)	0.0031 (16)	−0.0008 (15)	−0.0034 (16)
C10	0.016 (2)	0.022 (2)	0.0139 (19)	0.0032 (17)	−0.0003 (16)	−0.0005 (16)

Geometric parameters (Å, º) top

Br1—C2	1.894 (4)	C3—C4	1.398 (6)
Br2—C3	1.885 (4)	C4—C5	1.391 (6)
Br3—C4	1.876 (4)	C5—C6	1.404 (5)
Br4—C5	1.883 (4)	C7—C8	1.514 (5)
Br5—C6	1.896 (4)	C7—H7A	0.9900
O1—C8	1.344 (5)	C7—H7B	0.9900
O1—C9	1.456 (5)	C9—C10	1.511 (6)
O2—C8	1.208 (5)	C9—H9A	0.9900
C1—C6	1.397 (6)	C9—H9B	0.9900
C1—C2	1.404 (5)	C10—H10A	0.9800
C1—C7	1.512 (5)	C10—H10B	0.9800
C2—C3	1.388 (6)	C10—H10C	0.9800

C8—O1—C9	115.0 (3)	C1—C7—H7A	109.2
C6—C1—C2	117.9 (4)	C8—C7—H7A	109.2
C6—C1—C7	121.2 (4)	C1—C7—H7B	109.2
C2—C1—C7	120.9 (4)	C8—C7—H7B	109.2
C3—C2—C1	121.4 (4)	H7A—C7—H7B	107.9
C3—C2—Br1	120.8 (3)	O2—C8—O1	124.2 (4)
C1—C2—Br1	117.8 (3)	O2—C8—C7	124.9 (4)
C2—C3—C4	119.9 (4)	O1—C8—C7	110.8 (3)
C2—C3—Br2	119.6 (3)	O1—C9—C10	108.3 (3)
C4—C3—Br2	120.5 (3)	O1—C9—H9A	110.0
C5—C4—C3	120.0 (3)	C10—C9—H9A	110.0
C5—C4—Br3	120.0 (3)	O1—C9—H9B	110.0
C3—C4—Br3	120.0 (3)	C10—C9—H9B	110.0
C4—C5—C6	119.5 (4)	H9A—C9—H9B	108.4
C4—C5—Br4	121.2 (3)	C9—C10—H10A	109.5
C6—C5—Br4	119.3 (3)	C9—C10—H10B	109.5
C1—C6—C5	121.3 (4)	H10A—C10—H10B	109.5
C1—C6—Br5	118.6 (3)	C9—C10—H10C	109.5
C5—C6—Br5	120.1 (3)	H10A—C10—H10C	109.5
C1—C7—C8	112.1 (3)	H10B—C10—H10C	109.5

C6—C1—C2—C3	−1.6 (6)	C2—C1—C6—C5	1.5 (6)
C7—C1—C2—C3	178.3 (4)	C7—C1—C6—C5	−178.5 (4)
C6—C1—C2—Br1	176.8 (3)	C2—C1—C6—Br5	−176.6 (3)
C7—C1—C2—Br1	−3.3 (5)	C7—C1—C6—Br5	3.5 (5)
C1—C2—C3—C4	0.2 (6)	C4—C5—C6—C1	0.1 (6)
Br1—C2—C3—C4	−178.1 (3)	Br4—C5—C6—C1	178.6 (3)
C1—C2—C3—Br2	−179.5 (3)	C4—C5—C6—Br5	178.1 (3)
Br1—C2—C3—Br2	2.2 (5)	Br4—C5—C6—Br5	−3.4 (4)
C2—C3—C4—C5	1.5 (6)	C6—C1—C7—C8	−91.8 (5)
Br2—C3—C4—C5	−178.9 (3)	C2—C1—C7—C8	88.3 (5)
C2—C3—C4—Br3	−179.3 (3)	C9—O1—C8—O2	1.2 (6)
Br2—C3—C4—Br3	0.4 (5)	C9—O1—C8—C7	179.3 (3)
C3—C4—C5—C6	−1.6 (6)	C1—C7—C8—O2	−7.1 (6)
Br3—C4—C5—C6	179.1 (3)	C1—C7—C8—O1	174.8 (3)
C3—C4—C5—Br4	180.0 (3)	C8—O1—C9—C10	−165.1 (3)
Br3—C4—C5—Br4	0.7 (5)

Experimental details

Crystal data
Chemical formula	C₁₀H₇Br₅O₂
M_r	558.71
Crystal system, space group	Monoclinic, Cc
Temperature (K)	90
a, b, c (Å)	4.6136 (10), 22.548 (5), 13.195 (2)
β (°)	90.993 (11)
V (Å³)	1372.4 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	14.63
Crystal size (mm)	0.25 × 0.12 × 0.12

Data collection
Diffractometer	Nonius KappaCCD diffractometer with Oxford Cryostream
Absorption correction	Multi-scan (SCALEPACK; Otwinowski & Minor, 1997)
T_min, T_max	0.121, 0.273
No. of measured, independent and observed [I > 2σ(I)] reflections	10525, 3863, 3676
R_int	0.013
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.025, 0.053, 1.17
No. of reflections	3863
No. of parameters	157
No. of restraints	2
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.65, −0.66
Absolute structure	Flack (1983), 1842 Friedel pairs
Absolute structure parameter	0.467 (13)

Computer programs: COLLECT (Nonius, 2000), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997).

Acknowledgements

The purchase of the diffractometer was made possible by grant No. LEQSF(1999–2000)-ENH-TR-13, administered by the Louisiana Board of Regents.

References

Adams, R. & Thal, A. F. (1941). Org. Synth. 1, 270–. Google Scholar
Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
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. Web of Science CrossRef CAS IUCr Journals Google Scholar
Eriksson, J., Eriksson, L. & Jakobsson, E. (1999). Acta Cryst. C55, 2169–2171. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Eriksson, L. & Hu, J. (2002a). Acta Cryst. E58, o794–o796. Web of Science CSD CrossRef IUCr Journals Google Scholar
Eriksson, L. & Hu, J. (2002b). Acta Cryst. E58, o1147–o1149. Web of Science CSD CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Holmes, D. L. & Lightner, D. A. (1995). Tetrahedron, 51, 1607–1622. CrossRef CAS Web of Science Google Scholar
Köppen, R., Emmerling, F. & Becker, R. (2007). Acta Cryst. E63, o585–o586. Web of Science CSD CrossRef IUCr Journals Google Scholar
Krigbaum, W. R. & Wildman, G. C. (1971). Acta Cryst. B27, 2353–2358. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Mrse, A. A., Watkins, S. F. & Fronczek, F. R. (2000). Acta Cryst. C56, e576–e577. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
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. Google Scholar
Pedireddi, V. R., Reddy, D. S., Goud, B. S., Craig, D. C., Rae, A. D. & Desiraju, G. R. (1994). J. Chem. Soc. Perkin Trans. 2, pp. 2353–2360. CSD CrossRef Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Williams, D. R., Gaston, R. D. & Horton, I. B. (1985). Tetrahedron Lett. 26, 1391–1394. CrossRef CAS Web of Science Google Scholar