Methyl 3,5-dibromo-2-diacetyl­amino­benzoate

Jasinski, J.P.; Golen, J.A.; Praveen, A.S.; Yathirajan, H.S.; Narayana, B.

doi:10.1107/S1600536811034568

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 9| September 2011| Page o2503

doi:10.1107/S1600536811034568

Open

access

Methyl 3,5-dibromo-2-diacetylaminobenzoate

Jerry P. Jasinski,^a ^* James A. Golen,^a A. S. Praveen,^b H. S. Yathirajan ^b and B. Narayana ^c

^aDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA, ^bDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India, and ^cDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri, 574 199, India
^*Correspondence e-mail: jjasinski@keene.edu

(Received 15 August 2011; accepted 22 August 2011; online 27 August 2011)

The title methyl benzoate compound, C₁₂H₁₁Br₂NO₄, consists of an ortho-substituted diacetylamino group and meta-substituted Br atoms. The crystal packing is stabilized by weak intermolecular C—H⋯O interactions.

Related literature

For the use of halogenated benzoates to stimulate the microbial dechlorination of polychlorinated biphenyls, see: Deweerd & Bedard (1999 ). For related structures, see: Gowda et al. (2008 ); Saeed et al. (2010 ); Yathirajan et al. (2007 ). For bond lengths, see Allen et al. (1987 ).

Experimental

Crystal data

C₁₂H₁₁Br₂NO₄
M_r = 393.04
Triclinic, $[P \overline 1]$
a = 7.6386 (8) Å
b = 8.8870 (6) Å
c = 10.8691 (8) Å
α = 78.186 (6)°
β = 76.155 (7)°
γ = 82.750 (7)°
V = 698.91 (10) Å³
Z = 2
Mo Kα radiation
μ = 5.81 mm⁻¹
T = 173 K
0.24 × 0.20 × 0.18 mm

Data collection

Oxford Diffraction Xcalibur Eos Gemini diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ) T_min = 0.336, T_max = 0.421
5598 measured reflections
2864 independent reflections
2186 reflections with I > 2σ(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.070
S = 1.00
2864 reflections
175 parameters
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.55 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1A⋯O4ⁱ	0.98	2.44	3.404 (4)	168
C6—H6A⋯O4ⁱⁱ	0.95	2.46	3.237 (4)	140
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) -x+1, -y+1, -z.

Data collection: CrysAlis PRO (Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ); cell refinement: CrysAlis PRO; data reduction: CrysAlis RED (Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811034568/dn2715sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811034568/dn2715Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811034568/dn2715Isup3.cml

checkCIF report

Comment top

The title compound, (I), was obtained as an unexpected product in the present synthetic reaction (Fig. 1). Benzoates have wide importance in the plastics, food and pharmaceutical industries. The use of halogenated benzoates to stimulate the microbial dechlorination of poly chlorinated biphenyls is discussed (Deweerd & Bedard, 1999). The crystal structures of 4-bromophenyl benzoate (Gowda et al., 2008), methyl 4-(bromomethyl)benzoate (Yathirajan et al., 2007) and methyl 3,5-dibromo-4-methylbenzoate (Saeed et al., 2010) have been reported. In view of the importance of benzoates, the crystal structure of title compound, (I), C₁₂H₁₁Br₂NO₄, is reported.

The title methyl benzoate compound, (I), consists of an ortho substituted N, N diacetyl group and meta substituted dibromine atoms (Fig. 2). Crystal packing is stabilized by weak C—H···O intermolecular interactions (Table 1).

Related literature top

For the use of halogenated benzoates to stimulate the microbial dechlorination of polychlorinated biphenyls, see: Deweerd & Bedard, (1999). For related structures, see: Gowda et al. (2008); Saeed et al. (2010); Yathirajan et al. (2007). For bond lengths, see Allen et al. (1987).

Experimental top

Preparation of 2-amino-3, 5-dibromobenzoic acid: A mixture of 2-aminobenzoic acid (25 g, 0.1822 mol) in acetic acid (50 mL) was cooled at 273 –278 K. A mixture of bromine (32.79 g, 10.5 mL, 0.1822 mol) in acetic acid (1:1 by Vol.) was added drop wise over 30 min. After addition, the mixture was stirred at 273-278 K for one hour and at room temperature for 3-4 hours. To the mixture, water (100ml) was added at 288-293 K. The solid was filtered, washed with water (50 mL x 2), and dried at 353 K for 5 hrs (Yield - 93 %).

Preparation of methyl 2-(N-acetylacetamido)-3,5-dibromobenzoate: In a 500 mL round bottomed flask, acetic anhydride (150 mL) warmed at 353 K, 2-amino-3,5-dibromobenzoic acid ( 50 g, 0.1695 mol) was added over 30 minutes. The mixture was refluxed at 411-413 K and maintained for 4 hrs, cooled to room temperature and filtered.

The crystallization was done using methanol. The title compound was obtained as an unexpected product as shown in Scheme 1. X-ray quality crystals were obtained by a slow evaporation from methanol solution (m.p.: 380-383 K).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis RED (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Reaction scheme of the title compound.
	Fig. 2. Molecular structure of the title compound showing the atom labeling scheme and 50% probability displacement ellipsoids.

Methyl 3,5-dibromo-2-diacetylaminobenzoate top

Crystal data top

C₁₂H₁₁Br₂NO₄	Z = 2
M_r = 393.04	F(000) = 384
Triclinic, P1	D_x = 1.868 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.6386 (8) Å	Cell parameters from 2420 reflections
b = 8.8870 (6) Å	θ = 3.0–32.2°
c = 10.8691 (8) Å	µ = 5.81 mm⁻¹
α = 78.186 (6)°	T = 173 K
β = 76.155 (7)°	Block, colorless
γ = 82.750 (7)°	0.24 × 0.20 × 0.18 mm
V = 698.91 (10) Å³

Data collection top

Oxford Diffraction Xcalibur Eos Gemini diffractometer	2864 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2186 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
Detector resolution: 16.1500 pixels mm^-1	θ_max = 26.4°, θ_min = 3.0°
ω scans	h = −9→9
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2010)	k = −11→11
T_min = 0.336, T_max = 0.421	l = −11→13
5598 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.070	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0286P)² + 0.0926P] where P = (F_o² + 2F_c²)/3
2864 reflections	(Δ/σ)_max < 0.001
175 parameters	Δρ_max = 0.43 e Å⁻³
0 restraints	Δρ_min = −0.55 e Å⁻³

Crystal data top

C₁₂H₁₁Br₂NO₄	γ = 82.750 (7)°
M_r = 393.04	V = 698.91 (10) Å³
Triclinic, P1	Z = 2
a = 7.6386 (8) Å	Mo Kα radiation
b = 8.8870 (6) Å	µ = 5.81 mm⁻¹
c = 10.8691 (8) Å	T = 173 K
α = 78.186 (6)°	0.24 × 0.20 × 0.18 mm
β = 76.155 (7)°

Data collection top

Oxford Diffraction Xcalibur Eos Gemini diffractometer	2864 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2010)	2186 reflections with I > 2σ(I)
T_min = 0.336, T_max = 0.421	R_int = 0.024
5598 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	0 restraints
wR(F²) = 0.070	H-atom parameters constrained
S = 1.00	Δρ_max = 0.43 e Å⁻³
2864 reflections	Δρ_min = −0.55 e Å⁻³
175 parameters

Special details top

Experimental. The compound was further characterized by 1H nmr and mass spectrum. ¹H NMR (CDCl₃; 400MHz): - δ 8.165 - 8.17 (d, 1H, J = 2,ArH), 8.038 8.044 (s, 1H, J = 2, ArH,), 3.87 (s, 3H, OCH₃), 2.27 (s, 6H , (COCH₃)₂); ¹³C NMR ( CDCl₃; 100 MHz): - 171.7, 163.39, 139.72, 137.9, 134.0, 131.7, 126.9, 123.3, 53.1, 26.2. Mass data: m/e: - 391 (Molecular ion peak; M+), 393(Isotope peak; M+2), 395 (Isotope peak - M+4).

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 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	0.13746 (6)	0.87278 (3)	0.09518 (4)	0.05337 (14)
Br2	0.30614 (5)	0.27415 (4)	−0.01150 (3)	0.04699 (13)
O1	0.2257 (4)	0.2652 (3)	0.5162 (2)	0.0654 (8)
O2	0.2736 (3)	0.5047 (2)	0.5174 (2)	0.0455 (6)
O3	0.2313 (3)	−0.0469 (2)	0.3783 (2)	0.0538 (7)
O4	0.6102 (3)	0.2554 (2)	0.2194 (2)	0.0447 (6)
N1	0.3244 (3)	0.1887 (2)	0.2730 (2)	0.0273 (6)
C1	0.2881 (5)	0.4583 (4)	0.6502 (3)	0.0501 (9)
H1A	0.3009	0.5492	0.6844	0.075*
H1B	0.3942	0.3848	0.6553	0.075*
H1C	0.1789	0.4095	0.7009	0.075*
C2	0.2475 (4)	0.3942 (3)	0.4608 (3)	0.0327 (7)
C3	0.2407 (4)	0.4522 (3)	0.3230 (3)	0.0280 (7)
C4	0.2016 (4)	0.6093 (3)	0.2801 (3)	0.0307 (7)
H4A	0.1821	0.6801	0.3377	0.037*
C5	0.1916 (4)	0.6603 (3)	0.1535 (3)	0.0331 (7)
C6	0.2210 (4)	0.5630 (3)	0.0665 (3)	0.0347 (8)
H6A	0.2134	0.6009	−0.0206	0.042*
C7	0.2621 (4)	0.4075 (3)	0.1094 (3)	0.0296 (7)
C8	0.2720 (4)	0.3498 (3)	0.2359 (3)	0.0276 (7)
C9	0.1899 (4)	0.0844 (3)	0.3316 (3)	0.0355 (8)
C10	−0.0001 (5)	0.1457 (4)	0.3313 (4)	0.0465 (9)
H10A	−0.0798	0.0614	0.3641	0.070*
H10B	−0.0102	0.1924	0.2431	0.070*
H10C	−0.0359	0.2239	0.3865	0.070*
C11	0.5116 (5)	0.1516 (3)	0.2524 (3)	0.0344 (8)
C12	0.5843 (5)	−0.0138 (4)	0.2654 (4)	0.0577 (11)
H12A	0.7103	−0.0208	0.2173	0.086*
H12B	0.5118	−0.0714	0.2308	0.086*
H12C	0.5785	−0.0575	0.3565	0.086*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0831 (3)	0.02434 (17)	0.0510 (2)	0.00970 (17)	−0.0241 (2)	−0.00047 (15)
Br2	0.0767 (3)	0.03558 (18)	0.0315 (2)	−0.00369 (17)	−0.01384 (17)	−0.01074 (14)
O1	0.128 (3)	0.0388 (13)	0.0342 (14)	−0.0195 (15)	−0.0302 (15)	0.0034 (11)
O2	0.0726 (17)	0.0369 (12)	0.0323 (13)	−0.0037 (12)	−0.0202 (12)	−0.0084 (10)
O3	0.0661 (18)	0.0289 (12)	0.0581 (17)	−0.0092 (12)	−0.0070 (13)	0.0061 (11)
O4	0.0358 (14)	0.0382 (12)	0.0600 (17)	−0.0055 (11)	−0.0124 (11)	−0.0050 (11)
N1	0.0329 (15)	0.0171 (11)	0.0305 (14)	−0.0010 (10)	−0.0078 (11)	−0.0009 (10)
C1	0.067 (3)	0.057 (2)	0.034 (2)	−0.0039 (19)	−0.0207 (18)	−0.0143 (17)
C2	0.041 (2)	0.0287 (15)	0.0307 (17)	0.0017 (14)	−0.0128 (14)	−0.0078 (14)
C3	0.0289 (17)	0.0247 (14)	0.0307 (17)	0.0013 (13)	−0.0103 (13)	−0.0035 (12)
C4	0.0350 (18)	0.0253 (14)	0.0332 (17)	0.0015 (13)	−0.0101 (14)	−0.0076 (13)
C5	0.0384 (19)	0.0211 (13)	0.0383 (19)	0.0014 (13)	−0.0115 (14)	−0.0008 (13)
C6	0.041 (2)	0.0314 (15)	0.0301 (18)	−0.0020 (14)	−0.0107 (15)	0.0013 (13)
C7	0.0352 (18)	0.0265 (14)	0.0277 (16)	−0.0022 (13)	−0.0080 (13)	−0.0055 (12)
C8	0.0296 (17)	0.0225 (13)	0.0307 (17)	−0.0007 (12)	−0.0098 (13)	−0.0020 (12)
C9	0.047 (2)	0.0299 (16)	0.0297 (17)	−0.0079 (15)	−0.0066 (15)	−0.0038 (13)
C10	0.040 (2)	0.0471 (19)	0.050 (2)	−0.0118 (17)	−0.0065 (17)	−0.0031 (17)
C11	0.041 (2)	0.0291 (15)	0.0328 (18)	0.0052 (15)	−0.0118 (15)	−0.0065 (13)
C12	0.048 (2)	0.0378 (18)	0.081 (3)	0.0135 (17)	−0.015 (2)	−0.0056 (19)

Geometric parameters (Å, º) top

Br1—C5	1.891 (3)	C3—C8	1.403 (4)
Br2—C7	1.889 (3)	C4—C5	1.376 (4)
O1—C2	1.193 (3)	C4—H4A	0.9500
O2—C2	1.318 (4)	C5—C6	1.370 (4)
O2—C1	1.444 (4)	C6—C7	1.387 (4)
O3—C9	1.209 (3)	C6—H6A	0.9500
O4—C11	1.207 (4)	C7—C8	1.383 (4)
N1—C11	1.400 (4)	C9—C10	1.485 (5)
N1—C9	1.416 (4)	C10—H10A	0.9800
N1—C8	1.439 (3)	C10—H10B	0.9800
C1—H1A	0.9800	C10—H10C	0.9800
C1—H1B	0.9800	C11—C12	1.495 (4)
C1—H1C	0.9800	C12—H12A	0.9800
C2—C3	1.492 (4)	C12—H12B	0.9800
C3—C4	1.397 (4)	C12—H12C	0.9800

C2—O2—C1	115.9 (3)	C8—C7—C6	121.9 (3)
C11—N1—C9	125.7 (2)	C8—C7—Br2	120.3 (2)
C11—N1—C8	114.4 (2)	C6—C7—Br2	117.8 (2)
C9—N1—C8	119.8 (2)	C7—C8—C3	118.9 (2)
O2—C1—H1A	109.5	C7—C8—N1	119.2 (3)
O2—C1—H1B	109.5	C3—C8—N1	121.8 (3)
H1A—C1—H1B	109.5	O3—C9—N1	120.5 (3)
O2—C1—H1C	109.5	O3—C9—C10	123.1 (3)
H1A—C1—H1C	109.5	N1—C9—C10	116.3 (2)
H1B—C1—H1C	109.5	C9—C10—H10A	109.5
O1—C2—O2	123.0 (3)	C9—C10—H10B	109.5
O1—C2—C3	124.9 (3)	H10A—C10—H10B	109.5
O2—C2—C3	112.0 (3)	C9—C10—H10C	109.5
C4—C3—C8	119.5 (3)	H10A—C10—H10C	109.5
C4—C3—C2	119.9 (3)	H10B—C10—H10C	109.5
C8—C3—C2	120.5 (2)	O4—C11—N1	118.5 (3)
C5—C4—C3	119.2 (3)	O4—C11—C12	121.8 (3)
C5—C4—H4A	120.4	N1—C11—C12	119.6 (3)
C3—C4—H4A	120.4	C11—C12—H12A	109.5
C6—C5—C4	122.5 (3)	C11—C12—H12B	109.5
C6—C5—Br1	118.1 (2)	H12A—C12—H12B	109.5
C4—C5—Br1	119.3 (2)	C11—C12—H12C	109.5
C5—C6—C7	117.9 (3)	H12A—C12—H12C	109.5
C5—C6—H6A	121.0	H12B—C12—H12C	109.5
C7—C6—H6A	121.0

C1—O2—C2—O1	4.5 (5)	Br2—C7—C8—N1	2.8 (4)
C1—O2—C2—C3	−178.0 (3)	C4—C3—C8—C7	−0.4 (4)
O1—C2—C3—C4	156.5 (3)	C2—C3—C8—C7	179.1 (3)
O2—C2—C3—C4	−21.0 (4)	C4—C3—C8—N1	175.9 (3)
O1—C2—C3—C8	−23.1 (5)	C2—C3—C8—N1	−4.6 (4)
O2—C2—C3—C8	159.5 (3)	C11—N1—C8—C7	85.5 (4)
C8—C3—C4—C5	1.1 (4)	C9—N1—C8—C7	−97.8 (3)
C2—C3—C4—C5	−178.5 (3)	C11—N1—C8—C3	−90.8 (3)
C3—C4—C5—C6	−0.9 (5)	C9—N1—C8—C3	85.9 (4)
C3—C4—C5—Br1	179.7 (2)	C11—N1—C9—O3	5.9 (5)
C4—C5—C6—C7	0.0 (5)	C8—N1—C9—O3	−170.3 (3)
Br1—C5—C6—C7	179.5 (2)	C11—N1—C9—C10	−173.9 (3)
C5—C6—C7—C8	0.6 (5)	C8—N1—C9—C10	9.9 (4)
C5—C6—C7—Br2	−179.0 (2)	C9—N1—C11—O4	−168.9 (3)
C6—C7—C8—C3	−0.4 (5)	C8—N1—C11—O4	7.5 (4)
Br2—C7—C8—C3	179.2 (2)	C9—N1—C11—C12	14.0 (5)
C6—C7—C8—N1	−176.8 (3)	C8—N1—C11—C12	−169.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···O4ⁱ	0.98	2.44	3.404 (4)	168
C6—H6A···O4ⁱⁱ	0.95	2.46	3.237 (4)	140

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y+1, −z.

Experimental details

Crystal data
Chemical formula	C₁₂H₁₁Br₂NO₄
M_r	393.04
Crystal system, space group	Triclinic, P1
Temperature (K)	173
a, b, c (Å)	7.6386 (8), 8.8870 (6), 10.8691 (8)
α, β, γ (°)	78.186 (6), 76.155 (7), 82.750 (7)
V (Å³)	698.91 (10)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	5.81
Crystal size (mm)	0.24 × 0.20 × 0.18

Data collection
Diffractometer	Oxford Diffraction Xcalibur Eos Gemini diffractometer
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2010)
T_min, T_max	0.336, 0.421
No. of measured, independent and observed [I > 2σ(I)] reflections	5598, 2864, 2186
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.070, 1.00
No. of reflections	2864
No. of parameters	175
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.55

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), CrysAlis RED (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···O4ⁱ	0.98	2.44	3.404 (4)	168.0
C6—H6A···O4ⁱⁱ	0.95	2.46	3.237 (4)	139.5

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y+1, −z.

Acknowledgements

ASP thanks University of Mysore and R. L. Fine Chem, Bangalore for access to their research facilities. JPJ acknowledges the NSF–MRI program (grant No. CHE1039027) for funds to purchase the X-ray diffractometer.

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19. CrossRef Web of Science Google Scholar
Deweerd, K. & Bedard, D. (1999). Environ. Sci. Technol. 33, 2057–2063. CAS Google Scholar
Gowda, B. T., Foro, S., Babitha, K. S. & Fuess, H. (2008). Acta Cryst. E64, o771. Web of Science CSD CrossRef IUCr Journals Google Scholar
Oxford Diffraction (2010). CrysAlis PRO and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England. Google Scholar
Saeed, A., Rafique, H., Simpson, J. & Ashraf, Z. (2010). Acta Cryst. E66, o982–o983. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yathirajan, H. S., Bindya, S., Sarojini, B. K., Narayana, B. & Bolte, M. (2007). Acta Cryst. E63, o1334–o1335. Web of Science CSD CrossRef IUCr Journals Google Scholar