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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 5| May 2008| Page o788
doi:10.1107/S1600536808007721

1-(4-Hydr­­oxy-2-methyl-1,1-dioxo-2H-1,2-benzo­thia­zin-3-yl)ethanone

Matloob Ahmad,a* Hamid Latif Siddiqui,a Muhammad Zia-ur-Rehman,b Muhammad Irfan Ashiqc and Graham John Tizzardc

aInstitute of Chemistry, University of the Punjab, Lahore-54590, Pakistan, bApplied Chemistry Research Centre, PCSIR Laboratories Complex, Lahore-54600, Pakistan, and cSchool of Chemistry, University of Southampton, England
*Correspondence e-mail: matloob_123@yahoo.com

(Received 3 March 2008; accepted 20 March 2008; online 2 April 2008)

In the title compound, C11H11NO4S, the thia­zine ring adopts a distorted half-chair conformation. The enolic H atom is involved in an intra­molecular O—H⋯O hydrogen bond, forming a six-membered ring. Mol­ecules are linked through weak inter­molecular C—H⋯O hydrogen bonds, resulting in chains lying along the b axis.

Related literature

For related literature, see: Bihovsky et al. (2004[Bihovsky, R., Tao, M., Mallamo, J. P. & Wells, G. J. (2004). Bioorg. Med. Chem. Lett. 14, 1035-1038.]); Fabiola et al. (1998[Fabiola, G. F., Pattabhi, V., Manjunatha, S. G., Rao, G. V. & Nagarajan, K. (1998). Acta Cryst. C54, 2001-2003.]); Golič & Leban (1987[Golič, L. & Leban, I. (1987). Acta Cryst. C43, 280-282.]); Zia-ur-Rehman et al. (2005[Zia-ur-Rehman, M. Z., Choudary, J. A. & Ahmad, S. (2005). Bull. Korean Chem. Soc. 26, 1771-1175.], 2006[Zia-ur-Rehman, M. Z., Choudary, J. A., Ahmad, S. & Siddiqui, H. L. (2006). Chem. Pharm. Bull. 54, 1175-1178.], 2007[Zia-ur-Rehman, M., Choudary, J. A., Elsegood, M. R. J., Siddiqui, H. L. & Weaver, G. W. (2007). Acta Cryst. E63, o4215-o4216.]); Turck et al. (1996[Turck, D., Busch, U., Heinzel, G., Narjes, H. & Nehmiz, G. (1996). Clin. Pharm. 36, 79-84.]).

[Scheme 1]

Experimental

Crystal data

  • C11H11NO4S

  • Mr = 253.27

  • Triclinic, [P \overline 1]

  • a = 6.8523 (1) Å

  • b = 8.3222 (2) Å

  • c = 10.4880 (2) Å

  • α = 72.1321 (11)°

  • β = 77.9619 (12)°

  • γ = 80.0360 (12)°

  • V = 552.89 (2) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.29 mm−1

  • T = 120 (2) K

  • 0.40 × 0.20 × 0.14 mm
Data collection

  • Bruker–Nonius KappaCCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2007[Sheldrick, G. M. (2007). SADABS. University of Göttingen, Germany.]) Tmin = 0.891, Tmax = 0.960

  • 12691 measured reflections

  • 2529 independent reflections

  • 2248 reflections with I > 2σ(I)

  • Rint = 0.033
Refinement

  • R[F2 > 2σ(F2)] = 0.034

  • wR(F2) = 0.092

  • S = 1.11

  • 2529 reflections

  • 157 parameters

  • H-atom parameters constrained

  • Δρmax = 0.31 e Å−3

  • Δρmin = −0.53 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
O3—H3A⋯O4 0.84 1.78 2.525 (2) 146
C4—H4⋯O2i 0.95 2.36 3.193 (2) 146
Symmetry code: (i) x, y+1, z.

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft,The Netherlands.]); cell refinement: DENZO (Otwinowski & Minor, 1997[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.]); data reduction: DENZO and COLLECT; 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: CAMERON (Pearce & Watkin, 1993[Pearce, L. J. & Watkin, D. J. (1993). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808007721/pv2072sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808007721/pv2072Isup2.hkl

checkCIF report


Comment top

In order to discover new useful therapeutic agents, many new compounds are continuously being synthesized. Benzothiazine dioxides and their derivatives are reported to possess numerous types of biological activities. Owing to their applications as non-steroidal anti-inflammatory compounds (Turck et al., 1996), considerable attention has been given to 1,2-benzothiazine 1,1-dioxides and their precursor intermediates (Golič & Leban, 1987). Various 1,2-benzothiazines derivatives are also known as potent calpain I inhibitors (Bihovsky et al., 2004), while benzothiaine-3-yl-quinazolin-4-ones showed marked activity against Bacillus subtilis (Zia-ur-Rehman et al., 2006). As part of a research program synthesizing various bioactive benzothiazines (Zia-ur-Rehman et al., 2005, 2006), we herein report the crystal structure of the title compound, (I).

In the molecule of the title compound (Fig. 1), the thiazine ring exhibits a distorted half-chair conformation with S1/C1/C6/C7 atoms lying in a plane and N1 showing significant departure from the plane due to its pyramidal geometry projecting the methyl group approximately perpendicular to the ring; the deviations of N1 and C8 from the least square plane being -0.895 (2) and -0.413 (3) Å, respectively. Like other 1,2-benzothiazine 1,1-dioxide derivatives (Fabiola et al., 1998; Zia-ur-Rehman et al., 2007), the enolic hydrogen on O3 is involved in intramolecular hydrogen bonding (Table 1). Also, C7—C8 bond length [1.378 Å] (very close to normal C?C bond; 1.36 Å) indicates a partial double-bond character indicating the dominance of enolic form in the molecule. The C1—S1 bond distance [1.7580 (14) Å] is as expected for typical C(sp2)—S bond (1.751 Å).

Each molecule is linked to its adjacent one through a hydrogen bond [C4—H4···O2] resulting in a chain of molecules lying along the b axis (Table 1 and Fig. 2). Each molecule in the chain is linked with its neighbour through weak slipped π-π interactions at inversion centres; the closest C–C contacts are between C3–C3i separated by 3.316 Å.

Related literature top

For related literature, see: Bihovsky et al. (2004); Fabiola et al. (1998); Golič & Leban (1987); Zia-ur-Rehman et al. (2005, 2006, 2007); Turck et al. (1996).

Experimental top

A mixture of 1-(4-hydroxy-1,1-dioxido-2H-1,2-benzothiazin-3-yl) ethanone (239 mg, 1.0 mmol) dissolved in acetone (10 ml), aqueous NaOH (3 ml, 5%) and dimethyl sulfate (0.5 ml) was stirred for half an hour followed by careful addition of dilute HCl (5%) to maintain the pH to Congo Red. Precipitates of (I) thus obtained were filtered, washed with water and dried. Colourless crystals were grown by slow evaporation of a solution of (I) in methanol at room temperature.

Refinement top

The hydrogen atoms were included in the refinements in a riding mode with the following constraints: aryl, methyl and hydroxyl C/O—H distances 0.95, 0.98 and 0.84 Å, respectively, and Uiso(H) = 1.2 Ueq(aryl C) and 1.5 Ueq(methyl C and O).

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CAMERON (Pearce & Watkin, 1993); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing displacement ellipsoids at the 50% probability level for non-H atoms; dashed lines denote hydrogen bonds.
[Figure 2] Fig. 2. Unit cell packing of (I), showing intermolecular H-bonds resulting in the chains of molecules lying along the b axis; H atoms not involved in H-bonding have been omitted.
1-(4-Hydroxy-2-methyl-1,1-dioxo-2H-1,2-benzothiazin-3-yl)ethanone top
Crystal data top
C11H11NO4SZ = 2
Mr = 253.27F(000) = 264
Triclinic, P1Dx = 1.521 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.8523 (1) ÅCell parameters from 15360 reflections
b = 8.3222 (2) Åθ = 2.9–27.5°
c = 10.4880 (2) ŵ = 0.30 mm−1
α = 72.1321 (11)°T = 120 K
β = 77.9619 (12)°Shard, colourless
γ = 80.0360 (12)°0.40 × 0.20 × 0.14 mm
V = 552.89 (2) Å3
Data collection top
Bruker–Nonius CCD camera on κ-goniostat
diffractometer		2529 independent reflections
Radiation source: Bruker Nonius FR591 Rotating Anode2248 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.033
Detector resolution: 9.091 pixels mm-1θmax = 27.5°, θmin = 3.1°
ϕ & ω scans to fill the asymmetric unith = −8→8
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)		k = −10→10
Tmin = 0.891, Tmax = 0.960l = −13→13
12691 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)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.092H-atom parameters constrained
S = 1.11 w = 1/[σ2(Fo2) + (0.041P)2 + 0.3066P]
where P = (Fo2 + 2Fc2)/3
2529 reflections(Δ/σ)max = 0.030
157 parametersΔρmax = 0.31 e Å−3
0 restraintsΔρmin = −0.53 e Å−3
Crystal data top
C11H11NO4Sγ = 80.0360 (12)°
Mr = 253.27V = 552.89 (2) Å3
Triclinic, P1Z = 2
a = 6.8523 (1) ÅMo Kα radiation
b = 8.3222 (2) ŵ = 0.30 mm−1
c = 10.4880 (2) ÅT = 120 K
α = 72.1321 (11)°0.40 × 0.20 × 0.14 mm
β = 77.9619 (12)°
Data collection top
Bruker–Nonius CCD camera on κ-goniostat
diffractometer		2529 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)		2248 reflections with I > 2σ(I)
Tmin = 0.891, Tmax = 0.960Rint = 0.033
12691 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0340 restraints
wR(F2) = 0.092H-atom parameters constrained
S = 1.11Δρmax = 0.31 e Å−3
2529 reflectionsΔρmin = −0.53 e Å−3
157 parameters
Special details top

Experimental. SADABS was used to perform the Absorption correction Estimated minimum and maximum transmission: 0.6696 0.7456 The given Tmin and Tmax were generated using the SHELX SIZE command

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
C10.3007 (2)0.32223 (18)0.37041 (14)0.0135 (3)
C20.2992 (2)0.31686 (19)0.50412 (15)0.0164 (3)
H20.32460.21170.57020.020*
C30.2595 (2)0.4692 (2)0.53933 (16)0.0191 (3)
H30.25750.46840.63040.023*
C40.2228 (2)0.6220 (2)0.44168 (16)0.0199 (3)
H40.19730.72520.46650.024*
C50.2229 (2)0.62640 (19)0.30802 (15)0.0184 (3)
H50.19830.73200.24220.022*
C60.2593 (2)0.47505 (18)0.27093 (14)0.0148 (3)
C70.2558 (2)0.47385 (19)0.13150 (14)0.0153 (3)
C80.2396 (2)0.32881 (19)0.09905 (14)0.0157 (3)
C90.2507 (2)0.3316 (2)−0.04098 (16)0.0204 (3)
C100.2518 (3)0.1701 (2)−0.07671 (18)0.0332 (4)
H10A0.11360.1532−0.07640.050*
H10B0.31130.0740−0.00980.050*
H10C0.33100.1775−0.16720.050*
C110.0024 (2)0.1379 (2)0.25625 (16)0.0210 (3)
H11A−0.07100.23010.29330.031*
H11B−0.00220.02980.32790.031*
H11C−0.05980.13210.18190.031*
N10.21494 (18)0.17080 (16)0.20411 (12)0.0152 (3)
O10.56456 (16)0.12980 (14)0.24794 (11)0.0202 (2)
O20.30103 (17)−0.00587 (13)0.42939 (11)0.0212 (3)
O30.27313 (18)0.62312 (14)0.03808 (11)0.0220 (3)
H3A0.27850.6110−0.03920.033*
O40.26152 (18)0.46897 (16)−0.13289 (11)0.0264 (3)
S10.36145 (5)0.13574 (4)0.31790 (3)0.01424 (12)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0111 (6)0.0140 (7)0.0157 (7)−0.0025 (5)−0.0013 (5)−0.0046 (5)
C20.0141 (7)0.0192 (7)0.0154 (7)−0.0029 (6)−0.0034 (5)−0.0033 (6)
C30.0167 (7)0.0257 (8)0.0181 (7)−0.0037 (6)−0.0031 (6)−0.0101 (6)
C40.0189 (7)0.0187 (8)0.0251 (8)−0.0044 (6)−0.0014 (6)−0.0107 (6)
C50.0181 (7)0.0145 (7)0.0205 (7)−0.0024 (5)−0.0011 (6)−0.0032 (6)
C60.0128 (7)0.0160 (7)0.0148 (7)−0.0026 (5)−0.0010 (5)−0.0034 (5)
C70.0120 (7)0.0171 (7)0.0132 (7)0.0003 (5)−0.0008 (5)−0.0009 (5)
C80.0135 (7)0.0193 (7)0.0129 (7)0.0005 (5)−0.0023 (5)−0.0037 (5)
C90.0164 (7)0.0277 (8)0.0176 (7)0.0039 (6)−0.0049 (6)−0.0092 (6)
C100.0463 (11)0.0342 (10)0.0245 (9)0.0043 (8)−0.0133 (8)−0.0164 (7)
C110.0152 (7)0.0230 (8)0.0249 (8)−0.0049 (6)−0.0035 (6)−0.0056 (6)
N10.0144 (6)0.0165 (6)0.0157 (6)−0.0018 (5)−0.0045 (5)−0.0050 (5)
O10.0138 (5)0.0234 (6)0.0246 (6)0.0025 (4)−0.0036 (4)−0.0108 (5)
O20.0292 (6)0.0133 (5)0.0202 (5)−0.0044 (4)−0.0086 (5)0.0005 (4)
O30.0287 (6)0.0182 (6)0.0143 (5)−0.0019 (5)−0.0022 (5)0.0009 (4)
O40.0300 (6)0.0322 (7)0.0140 (5)0.0020 (5)−0.0058 (5)−0.0038 (5)
S10.01453 (19)0.01270 (19)0.01608 (19)0.00015 (13)−0.00467 (13)−0.00442 (13)
Geometric parameters (Å, º) top
C1—C21.387 (2)C8—C91.448 (2)
C1—C61.404 (2)C9—O41.251 (2)
C1—S11.7580 (14)C9—C101.501 (2)
C2—C31.394 (2)C10—H10A0.9800
C2—H20.9500C10—H10B0.9800
C3—C41.388 (2)C10—H10C0.9800
C3—H30.9500C11—N11.4864 (19)
C4—C51.391 (2)C11—H11A0.9800
C4—H40.9500C11—H11B0.9800
C5—C61.397 (2)C11—H11C0.9800
C5—H50.9500N1—S11.6438 (12)
C6—C71.471 (2)O1—S11.4319 (11)
C7—O31.3316 (17)O2—S11.4314 (11)
C7—C81.378 (2)O3—H3A0.8400
C8—N11.4430 (18)
C2—C1—C6122.15 (13)O4—C9—C10119.76 (14)
C2—C1—S1120.70 (11)C8—C9—C10120.31 (15)
C6—C1—S1117.13 (11)C9—C10—H10A109.5
C1—C2—C3118.54 (14)C9—C10—H10B109.5
C1—C2—H2120.7H10A—C10—H10B109.5
C3—C2—H2120.7C9—C10—H10C109.5
C4—C3—C2120.14 (14)H10A—C10—H10C109.5
C4—C3—H3119.9H10B—C10—H10C109.5
C2—C3—H3119.9N1—C11—H11A109.5
C3—C4—C5121.04 (14)N1—C11—H11B109.5
C3—C4—H4119.5H11A—C11—H11B109.5
C5—C4—H4119.5N1—C11—H11C109.5
C4—C5—C6119.79 (14)H11A—C11—H11C109.5
C4—C5—H5120.1H11B—C11—H11C109.5
C6—C5—H5120.1C8—N1—C11114.26 (11)
C5—C6—C1118.30 (13)C8—N1—S1112.75 (10)
C5—C6—C7121.47 (13)C11—N1—S1116.79 (10)
C1—C6—C7120.23 (13)C7—O3—H3A109.5
O3—C7—C8122.30 (13)O2—S1—O1119.39 (7)
O3—C7—C6114.96 (13)O2—S1—N1108.47 (7)
C8—C7—C6122.73 (13)O1—S1—N1107.24 (6)
C7—C8—N1120.44 (12)O2—S1—C1109.27 (7)
C7—C8—C9120.64 (14)O1—S1—C1108.93 (7)
N1—C8—C9118.91 (13)N1—S1—C1102.15 (6)
O4—C9—C8119.92 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3A···O40.841.782.525 (2)146
C4—H4···O2i0.952.363.193 (2)146
Symmetry code: (i) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC11H11NO4S
Mr253.27
Crystal system, space groupTriclinic, P1
Temperature (K)120
a, b, c (Å)6.8523 (1), 8.3222 (2), 10.4880 (2)
α, β, γ (°)72.1321 (11), 77.9619 (12), 80.0360 (12)
V (Å3)552.89 (2)
Z2
Radiation typeMo Kα
µ (mm−1)0.30
Crystal size (mm)0.40 × 0.20 × 0.14
Data collection
DiffractometerBruker–Nonius CCD camera on κ-goniostat
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2007)
Tmin, Tmax0.891, 0.960
No. of measured, independent and
observed [I > 2σ(I)] reflections		12691, 2529, 2248
Rint0.033
(sin θ/λ)max (Å−1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.092, 1.11
No. of reflections2529
No. of parameters157
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.31, −0.53

Computer programs: , DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), CAMERON (Pearce & Watkin, 1993), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3A···O40.841.782.525 (2)146
C4—H4···O2i0.952.363.193 (2)146
Symmetry code: (i) x, y+1, z.
 

Acknowledgements

We gratefully acknowledge the Higher Education Commission of Pakistan and the University of the Punjab, Lahore, for financial support.

References

First citationBihovsky, R., Tao, M., Mallamo, J. P. & Wells, G. J. (2004). Bioorg. Med. Chem. Lett. 14, 1035–1038.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationFabiola, G. F., Pattabhi, V., Manjunatha, S. G., Rao, G. V. & Nagarajan, K. (1998). Acta Cryst. C54, 2001–2003.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
 First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
 First citationGolič, L. & Leban, I. (1987). Acta Cryst. C43, 280–282.  CSD CrossRef Web of Science IUCr Journals Google Scholar
 First citationNonius (1998). COLLECT. Nonius BV, Delft,The Netherlands.  Google Scholar
 First citationOtwinowski, 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
 First citationPearce, L. J. & Watkin, D. J. (1993). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.  Google Scholar
 First citationSheldrick, G. M. (2007). 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
 First citationTurck, D., Busch, U., Heinzel, G., Narjes, H. & Nehmiz, G. (1996). Clin. Pharm. 36, 79–84.  Google Scholar
 First citationZia-ur-Rehman, M. Z., Choudary, J. A. & Ahmad, S. (2005). Bull. Korean Chem. Soc. 26, 1771–1175.  CAS Google Scholar
 First citationZia-ur-Rehman, M. Z., Choudary, J. A., Ahmad, S. & Siddiqui, H. L. (2006). Chem. Pharm. Bull. 54, 1175–1178.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationZia-ur-Rehman, M., Choudary, J. A., Elsegood, M. R. J., Siddiqui, H. L. & Weaver, G. W. (2007). Acta Cryst. E63, o4215–o4216.  Web of Science CSD CrossRef 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
Volume 64| Part 5| May 2008| Page o788
doi:10.1107/S1600536808007721
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