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ISSN: 2056-9890

N-(2,6-Di­chloro­phen­yl)-5-methyl-1,2-oxazole-4-carboxamide monohydrate

aState Key Laboratory of Materials-Oriented Chemical Engineering, School of Pharmaceutical Sciences, Nanjing University of Technology, Xinmofan Road No. 5 Nanjing, Nanjing 210009, People's Republic of China
*Correspondence e-mail: dc_wang@hotmail.com

(Received 6 October 2011; accepted 26 October 2011; online 5 November 2011)

In the title compound, C11H8Cl2N2O2·H2O, the dihedral angle between the benzene and isoxazole rings is 59.10 (7)°. In the crystal, the components are linked by N—H⋯O and O—H⋯O hydrogen bonds into a three-dimensional network. The crystal structure is further stabilized by ππ stacking inter­actions [centroid–centroid distance = 3.804 (2) Å].

Related literature

The title compound was synthesised as a new and potent immunomodulating leflunomide {systematic name: 5-methyl-N-[4-(trifluoro­meth­yl)phen­yl]-isoxazole-4-carboxamide} ana­log (Huang et al., 2003[Huang, W. H., Yang, C. L., LEE, A. R. & Chiu, H. F. (2003). Chem. Pharm. Bull. 51, 313-314.]). For the application of leflunomide in the treatment of rheumatoid arthritis, see: Shaw et al. (2011[Shaw, J. J., Chen, B., Wooley, P., Palfey, B., Lee, A. R., Huang, W. H. & Zeng, D. (2011). Am. J. Biomed. Sci. 3, 218-227.]); Schattenkirchner et al. (2000[Schattenkirchner, M. (2000). Immunopharmacology, 47, 291-298.]).

[Scheme 1]

Experimental

Crystal data
  • C11H8Cl2N2O2·H2O

  • Mr = 289.11

  • Orthorhombic, P n a 21

  • a = 12.047 (2) Å

  • b = 8.2290 (16) Å

  • c = 13.086 (3) Å

  • V = 1297.3 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.50 mm−1

  • T = 293 K

  • 0.30 × 0.20 × 0.10 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: ψ scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.864, Tmax = 0.952

  • 2333 measured reflections

  • 2333 independent reflections

  • 1906 reflections with I > 2σ(I)

  • 3 standard reflections every 200 reflections intensity decay: 1%

Refinement
  • R[F2 > 2σ(F2)] = 0.045

  • wR(F2) = 0.118

  • S = 1.00

  • 2333 reflections

  • 164 parameters

  • 1 restraint

  • H-atom parameters constrained

  • Δρmax = 0.19 e Å−3

  • Δρmin = −0.18 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 1107 Friedel pairs

  • Flack parameter: 0.04 (9)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1A⋯OWi 0.86 2.07 2.897 (4) 161
OW—HWB⋯O1ii 0.85 2.00 2.839 (3) 168
Symmetry codes: (i) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z]; (ii) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z+{\script{1\over 2}}].

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994[Enraf-Nonius (1994). CAD-4 EXPRESS. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo,1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); 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: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Leflunomide is one of the most effective isoxazole-containing heterocyclic disease modifying anti-rheumatic drugs for treating rheumatoid arthritis(Shaw et al., 2011; Schattenkirchner et al., 2000). The title compound 5-methyl-N-(2,6-dichlorophenyl)isoxazole -4-carboxamide monohydrate,(I), was synthesized as a novel and potent immunomodulating leflunomide analog (Huang, et al., 2003). We report herein the crystal structure of the title compound.

As illustrated in Fig. 1, the molecular structure of the title compound is not planar and consists of one 5-methyl-N-(2,6-dichlorophenyl)isoxazole-4-carboxamide molecule and one solvate water molecule. The dihedral angle between the C1—C6 benzene and the C8—C10/N2/O2 isoxazole ring is 59.10 (7) °. The central nitrogen atom (N1) and carbon atom (C7) are nearly coplanar with the benzene ring and the benzoyl rings[N1—C6—C5—C4 torsion angles = -178.5 (3) ° and C7—C8—C9—O2 torsion angles = -179.2 (3) °], respectively. The length of the C10=N2 double bond is 1.299 (5) Å, slightly longer than standard 1.28 Å value of a C=N double bond. The crystal structure is stabilized by N—H···O and O—H···O hydrogen bonds (Table 1), which is further stabilized by /p-/p stacking interactions.

Related literature top

The title compound was synthesised as a new and potent immunomodulating leflunomide {systematic name: 5-methyl-N-[4-(trifluoromethyl)phenyl]-isoxazole-4-carboxamide} analog (Huang et al., 2003). For the application of leflunomide in the treatment of rheumatoid arthritis, see: Shaw et al. (2011); Schattenkirchner et al. (2000).

Experimental top

A solution of 0.005 mole of 5-methylisoxazole-4-carboxylic acid chloride (0.73 g) in 2 ml of acetonitrile is added dropwise, while stirring,to 0.01 mole of 2,6-dichloroaniline(1.62 g),dissolved in 15 ml of acetonitrile at room temperature.After stirring for 20 minutes,the precipitated 2,6-dichloroaniline hydrochloride is filtered off and washed with 10 ml portions of acetonitrile,and the combined filtrates are concentrated under reduced pressure.10.6 g(78.5% of theory) of white crytalline 5-methyl-N-(2,6-dichlorophenyl)isoxazole-4-carboxamide are thus obtained. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of an methylbenzene solution.

Refinement top

H atoms of the water molecule were located in a difference Fourier map and refined as riding with O—H = 0.85 Å, with Uiso(H) = 1.5 Ueq. Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.96 (methyl), 0.97 (methylene) and N—H = 0.86 Å, Uiso(H) = 1.2 or 1.5 Ueq(C, N).

Structure description top

Leflunomide is one of the most effective isoxazole-containing heterocyclic disease modifying anti-rheumatic drugs for treating rheumatoid arthritis(Shaw et al., 2011; Schattenkirchner et al., 2000). The title compound 5-methyl-N-(2,6-dichlorophenyl)isoxazole -4-carboxamide monohydrate,(I), was synthesized as a novel and potent immunomodulating leflunomide analog (Huang, et al., 2003). We report herein the crystal structure of the title compound.

As illustrated in Fig. 1, the molecular structure of the title compound is not planar and consists of one 5-methyl-N-(2,6-dichlorophenyl)isoxazole-4-carboxamide molecule and one solvate water molecule. The dihedral angle between the C1—C6 benzene and the C8—C10/N2/O2 isoxazole ring is 59.10 (7) °. The central nitrogen atom (N1) and carbon atom (C7) are nearly coplanar with the benzene ring and the benzoyl rings[N1—C6—C5—C4 torsion angles = -178.5 (3) ° and C7—C8—C9—O2 torsion angles = -179.2 (3) °], respectively. The length of the C10=N2 double bond is 1.299 (5) Å, slightly longer than standard 1.28 Å value of a C=N double bond. The crystal structure is stabilized by N—H···O and O—H···O hydrogen bonds (Table 1), which is further stabilized by /p-/p stacking interactions.

The title compound was synthesised as a new and potent immunomodulating leflunomide {systematic name: 5-methyl-N-[4-(trifluoromethyl)phenyl]-isoxazole-4-carboxamide} analog (Huang et al., 2003). For the application of leflunomide in the treatment of rheumatoid arthritis, see: Shaw et al. (2011); Schattenkirchner et al. (2000).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo,1995); 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
[Figure 1] Fig. 1. The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids.
N-(2,6-Dichlorophenyl)-5-methyl-1,2-oxazole-4-carboxamide monohydrate top
Crystal data top
C11H8Cl2N2O2·H2ODx = 1.480 Mg m3
Mr = 289.11Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pna21Cell parameters from 25 reflections
a = 12.047 (2) Åθ = 9–13°
b = 8.2290 (16) ŵ = 0.50 mm1
c = 13.086 (3) ÅT = 293 K
V = 1297.3 (4) Å3Block, white
Z = 40.30 × 0.20 × 0.10 mm
F(000) = 592
Data collection top
Enraf–Nonius CAD-4
diffractometer
1906 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 25.4°, θmin = 3.0°
ω/2θ scansh = 014
Absorption correction: ψ scan
(SADABS; Sheldrick, 1996)
k = 90
Tmin = 0.864, Tmax = 0.952l = 1515
2333 measured reflections3 standard reflections every 200 reflections
2333 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.045 w = 1/[σ2(Fo2) + (0.073P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.118(Δ/σ)max < 0.001
S = 1.00Δρmax = 0.19 e Å3
2333 reflectionsΔρmin = 0.18 e Å3
164 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.038 (3)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1107 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.04 (9)
Crystal data top
C11H8Cl2N2O2·H2OV = 1297.3 (4) Å3
Mr = 289.11Z = 4
Orthorhombic, Pna21Mo Kα radiation
a = 12.047 (2) ŵ = 0.50 mm1
b = 8.2290 (16) ÅT = 293 K
c = 13.086 (3) Å0.30 × 0.20 × 0.10 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
1906 reflections with I > 2σ(I)
Absorption correction: ψ scan
(SADABS; Sheldrick, 1996)
Rint = 0.000
Tmin = 0.864, Tmax = 0.9523 standard reflections every 200 reflections
2333 measured reflections intensity decay: 1%
2333 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.045H-atom parameters constrained
wR(F2) = 0.118Δρmax = 0.19 e Å3
S = 1.00Δρmin = 0.18 e Å3
2333 reflectionsAbsolute structure: Flack (1983), 1107 Friedel pairs
164 parametersAbsolute structure parameter: 0.04 (9)
1 restraint
Special details top

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
Cl10.34861 (10)0.10973 (15)0.99733 (8)0.0766 (4)
N10.4813 (2)0.0638 (3)0.8429 (2)0.0426 (6)
H1A0.50090.12940.89070.051*
O10.5393 (2)0.1120 (4)0.7213 (2)0.0572 (7)
C10.2951 (3)0.0268 (5)0.8868 (3)0.0482 (9)
Cl20.40753 (8)0.20917 (15)0.64182 (8)0.0679 (3)
N20.8178 (3)0.0689 (5)0.9349 (3)0.0695 (10)
C20.1817 (3)0.0353 (5)0.8670 (4)0.0654 (12)
H2B0.13400.08290.91420.078*
O20.85611 (19)0.0172 (4)0.8485 (2)0.0633 (8)
C30.1411 (3)0.0275 (6)0.7769 (4)0.0689 (12)
H3A0.06540.02130.76310.083*
C40.2092 (3)0.0973 (5)0.7089 (4)0.0605 (10)
H4A0.18070.13690.64780.073*
C50.3222 (3)0.1113 (4)0.7288 (3)0.0479 (8)
C60.3673 (3)0.0494 (4)0.8180 (3)0.0405 (7)
C70.5598 (3)0.0226 (4)0.7937 (2)0.0400 (7)
C80.6743 (3)0.0017 (4)0.8333 (3)0.0447 (8)
C90.7686 (3)0.0582 (4)0.7899 (3)0.0474 (8)
C100.7108 (3)0.0774 (5)0.9239 (3)0.0579 (10)
H10A0.66360.12910.96980.069*
C110.7943 (3)0.1487 (6)0.6956 (3)0.0623 (11)
H11A0.87280.16790.69190.094*
H11B0.77120.08630.63740.094*
H11C0.75580.25080.69620.094*
OW0.9991 (2)0.2436 (4)1.02747 (19)0.0577 (7)
HWA0.98560.14411.03980.069*
HWB0.98820.30051.08070.069*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0827 (8)0.0957 (8)0.0513 (6)0.0078 (6)0.0037 (5)0.0203 (6)
N10.0319 (13)0.0569 (17)0.0391 (14)0.0007 (12)0.0025 (12)0.0103 (13)
O10.0431 (13)0.0740 (18)0.0546 (16)0.0039 (13)0.0028 (12)0.0211 (14)
C10.045 (2)0.055 (2)0.0453 (19)0.0018 (16)0.0044 (16)0.0008 (17)
Cl20.0573 (6)0.0872 (7)0.0594 (6)0.0051 (5)0.0004 (5)0.0229 (5)
N20.0433 (19)0.087 (3)0.078 (3)0.0051 (17)0.0078 (16)0.007 (2)
C20.041 (2)0.069 (3)0.086 (3)0.0103 (18)0.016 (2)0.004 (2)
O20.0347 (14)0.080 (2)0.0756 (19)0.0004 (12)0.0016 (14)0.0016 (16)
C30.035 (2)0.077 (3)0.094 (4)0.001 (2)0.008 (2)0.001 (3)
C40.039 (2)0.070 (3)0.073 (3)0.0044 (19)0.0099 (19)0.005 (2)
C50.0416 (18)0.051 (2)0.051 (2)0.0009 (16)0.0008 (15)0.0015 (17)
C60.0289 (15)0.0504 (18)0.0423 (17)0.0050 (13)0.0009 (13)0.0030 (14)
C70.0285 (16)0.0519 (19)0.0397 (18)0.0010 (14)0.0024 (13)0.0005 (16)
C80.0377 (17)0.0455 (19)0.051 (2)0.0009 (14)0.0019 (16)0.0037 (17)
C90.0363 (19)0.050 (2)0.055 (2)0.0010 (16)0.0024 (16)0.0094 (17)
C100.038 (2)0.077 (3)0.059 (2)0.0035 (18)0.0050 (18)0.007 (2)
C110.053 (2)0.071 (3)0.063 (2)0.0140 (19)0.010 (2)0.001 (2)
OW0.0544 (14)0.0756 (18)0.0430 (12)0.0051 (13)0.0021 (12)0.0017 (12)
Geometric parameters (Å, º) top
Cl1—C11.724 (4)C3—H3A0.9300
N1—C71.347 (4)C4—C51.391 (5)
N1—C61.416 (4)C4—H4A0.9300
N1—H1A0.8600C5—C61.384 (5)
O1—C71.224 (4)C7—C81.483 (4)
C1—C21.392 (5)C8—C91.352 (5)
C1—C61.400 (5)C8—C101.423 (5)
Cl2—C51.733 (4)C9—C111.474 (5)
N2—C101.299 (5)C10—H10A0.9300
N2—O21.412 (5)C11—H11A0.9600
C2—C31.378 (6)C11—H11B0.9600
C2—H2B0.9300C11—H11C0.9600
O2—C91.347 (4)OW—HWA0.8500
C3—C41.340 (6)OW—HWB0.8499
C7—N1—C6121.8 (3)C5—C6—N1123.0 (3)
C7—N1—H1A119.1C1—C6—N1119.4 (3)
C6—N1—H1A119.1O1—C7—N1123.0 (3)
C2—C1—C6120.8 (4)O1—C7—C8121.9 (3)
C2—C1—Cl1120.2 (3)N1—C7—C8115.2 (3)
C6—C1—Cl1119.0 (3)C9—C8—C10104.4 (3)
C10—N2—O2105.2 (3)C9—C8—C7126.5 (3)
C3—C2—C1119.3 (4)C10—C8—C7129.2 (3)
C3—C2—H2B120.4O2—C9—C8109.4 (3)
C1—C2—H2B120.4O2—C9—C11116.0 (3)
C9—O2—N2109.0 (3)C8—C9—C11134.6 (4)
C4—C3—C2120.7 (4)N2—C10—C8112.0 (4)
C4—C3—H3A119.6N2—C10—H10A124.0
C2—C3—H3A119.6C8—C10—H10A124.0
C3—C4—C5120.7 (4)C9—C11—H11A109.5
C3—C4—H4A119.6C9—C11—H11B109.5
C5—C4—H4A119.6H11A—C11—H11B109.5
C6—C5—C4120.8 (4)C9—C11—H11C109.5
C6—C5—Cl2119.5 (3)H11A—C11—H11C109.5
C4—C5—Cl2119.7 (3)H11B—C11—H11C109.5
C5—C6—C1117.6 (3)HWA—OW—HWB110.3
C6—C1—C2—C32.1 (6)C7—N1—C6—C1109.6 (4)
Cl1—C1—C2—C3178.1 (4)C6—N1—C7—O14.0 (5)
C10—N2—O2—C90.8 (4)C6—N1—C7—C8176.2 (3)
C1—C2—C3—C40.5 (7)O1—C7—C8—C98.6 (6)
C2—C3—C4—C51.5 (7)N1—C7—C8—C9171.2 (3)
C3—C4—C5—C61.8 (6)O1—C7—C8—C10170.2 (4)
C3—C4—C5—Cl2177.5 (4)N1—C7—C8—C109.9 (6)
C4—C5—C6—C10.2 (5)N2—O2—C9—C80.6 (4)
Cl2—C5—C6—C1179.1 (3)N2—O2—C9—C11179.7 (3)
C4—C5—C6—N1178.5 (3)C10—C8—C9—O20.2 (4)
Cl2—C5—C6—N10.8 (5)C7—C8—C9—O2179.2 (3)
C2—C1—C6—C51.8 (5)C10—C8—C9—C11179.0 (4)
Cl1—C1—C6—C5178.5 (3)C7—C8—C9—C111.9 (7)
C2—C1—C6—N1176.6 (3)O2—N2—C10—C80.7 (5)
Cl1—C1—C6—N13.1 (5)C9—C8—C10—N20.3 (5)
C7—N1—C6—C572.1 (4)C7—C8—C10—N2178.7 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···OWi0.862.072.897 (4)161
OW—HWB···O1ii0.852.002.839 (3)168
Symmetry codes: (i) x1/2, y+1/2, z; (ii) x+3/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC11H8Cl2N2O2·H2O
Mr289.11
Crystal system, space groupOrthorhombic, Pna21
Temperature (K)293
a, b, c (Å)12.047 (2), 8.2290 (16), 13.086 (3)
V3)1297.3 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.50
Crystal size (mm)0.30 × 0.20 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionψ scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.864, 0.952
No. of measured, independent and
observed [I > 2σ(I)] reflections
2333, 2333, 1906
Rint0.000
(sin θ/λ)max1)0.603
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.045, 0.118, 1.00
No. of reflections2333
No. of parameters164
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.19, 0.18
Absolute structureFlack (1983), 1107 Friedel pairs
Absolute structure parameter0.04 (9)

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo,1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···OWi0.862.072.897 (4)160.5
OW—HWB···O1ii0.852.002.839 (3)167.6
Symmetry codes: (i) x1/2, y+1/2, z; (ii) x+3/2, y+1/2, z+1/2.
 

Acknowledgements

The work was supported by the Center of Testing and Analysis, Nanjing University.

References

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First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
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First citationSchattenkirchner, M. (2000). Immunopharmacology, 47, 291–298.  Web of Science CrossRef PubMed CAS Google Scholar
First citationShaw, J. J., Chen, B., Wooley, P., Palfey, B., Lee, A. R., Huang, W. H. & Zeng, D. (2011). Am. J. Biomed. Sci. 3, 218–227.  CrossRef CAS Google Scholar
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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