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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 65| Part 8| August 2009| Pages o1852-o1853

(Z)-1-(2,5-Di­chloro-3-thien­yl)ethanone semicarbazone

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, bSeQuent Scientific Limited, No. 120 A&B, Industrial Area, Baikampady, New Mangalore, Karnataka 575 011, India, cDepartment of Chemistry, NITTE Institute of Technology, Yelahanka, Bangalore 560 064, India, and dDepartment of Chemistry, National Institute of Technology-Karnataka, Surathkal, Mangalore 575 025, India
*Correspondence e-mail: hkfun@usm.my

(Received 7 July 2009; accepted 8 July 2009; online 15 July 2009)

The title mol­ecule, C7H7Cl2N3OS, is approximately planar [maximum deviation = 0.062 (1) Å]. Short inter­molecular distances between the centroids of the five-membered rings [3.5340 (8) Å] indicate the existence of ππ inter­actions. An inter­esting feature of the crystal structure is the presence of short intra­molecular Cl⋯N inter­actions [3.0015 (11) Å]. Mol­ecules are linked via pairs of inter­molecular N—H⋯O hydrogen bonds, generating R22(8) ring motifs. Furthermore, N—H⋯O hydrogen bonds form R21(7) ring motifs with C—H⋯O contacts, further consolidating the crystal structure. In the crystal, mol­ecules are linked by these inter­molecular inter­actions, forming chains along [001].

Related literature

For the synthetic utility and applications of semicarbazone derivatives, see: Warren et al. (1977[Warren, J. D., Woodward, D. L. & Hargreaves, R. T. (1977). J. Med. Chem. 20, 1520-1521.]); Chandra & Gupta (2005[Chandra, S. & Gupta, L. K. (2005). Spectrochim. Acta Part A, 62, 1089-1094.]); Jain et al. (2002[Jain, V. K., Handa, A., Pandya, R., Shrivastav, P. & Agrawal, Y. K. (2002). React. Funct. Polym. 51, 101-110.]); Pilgram (1978[Pilgram, K. H. G. (1978). US Patent No. 4 108 399.]); Yogeeswari et al. (2004[Yogeeswari, P., Sriram, D., Pandeya, S. N. & Stables, J. P. (2004). Farmaco, 59, 609-613.]). For related structures, see: Fun et al. (2009a[Fun, H.-K., Quah, C. K., Padaki, M., Malladi, S. & Isloor, A. M. (2009a). Acta Cryst. E65, o1634-o1635.],b[Fun, H.-K., Yeap, C. S., Padaki, M., Malladi, S. & Isloor, A. M. (2009b). Acta Cryst. E65, o1619-o1620.]). For the preparation, see: Furniss et al. (1978[Furniss, B. S., Hannaford, A. J., Rogers, V., Smith, P. W. G. & Tatchell, A. R. (1978). Vogel's Textbook of Practical Organic Chemistry, 4th ed. p. 1112. London: ELBS.]). For hydrogen-bond motifs, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986[Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105-107.]).

[Scheme 1]

Experimental

Crystal data
  • C7H7Cl2N3OS

  • Mr = 252.12

  • Monoclinic, C 2/c

  • a = 13.0796 (2) Å

  • b = 10.4316 (2) Å

  • c = 14.4352 (2) Å

  • β = 94.599 (1)°

  • V = 1963.21 (6) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.84 mm−1

  • T = 100 K

  • 0.49 × 0.22 × 0.08 mm

Data collection
  • Bruker SMART APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.683, Tmax = 0.934

  • 16375 measured reflections

  • 3742 independent reflections

  • 3060 reflections with I > 2σ(I)

  • Rint = 0.029

Refinement
  • R[F2 > 2σ(F2)] = 0.034

  • wR(F2) = 0.100

  • S = 1.13

  • 3742 reflections

  • 140 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.46 e Å−3

  • Δρmin = −0.35 e Å−3

Table 1
Selected interatomic distance (Å)

Cg1⋯Cg1i 3.7188 (6)
Symmetry code: (i) [x+{\script{5\over 2}}, y+{\script{1\over 2}}, z+1]. Cg1 is the centroid of the S1/C3–C6 five-membered ring.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1N1⋯O1ii 0.86 (2) 2.02 (2) 2.8766 (15) 177.3 (19)
N2—H1N2⋯O1iii 0.863 (19) 2.035 (19) 2.8949 (14) 174.2 (17)
C7—H7A⋯O1iii 0.96 2.38 3.3370 (17) 176
Symmetry codes: (ii) [-x+1, y, -z+{\script{1\over 2}}]; (iii) -x+1, -y, -z+1.

Data collection: APEX2 (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Semicarbazones find immense applications in the field of synthetic chemistry, such as medicinal chemistry (Warren et al., 1977), organometallics (Chandra & Gupta, 2005), polymers (Jain et al., 2002) and herbicides (Pilgram, 1978). Futher, 4-sulphamoylphenyl semicarbazones were found to possess anti-convulsant activity (Yogeeswari et al., 2004). Herein, we report the crystal structure of the title semicarbazone (I).

The bond lengths and angles in (I), Fig. 1, are comparable to those observed in two closely related structures (Fun et al., 2009a, b). The molecule is approximately planar, with an r.m.s. deviation of 0.062 (1) Å for atom O1. The short intramolecular distances between the centroids of five-membered rings [3.5340 (8) Å] prove existence of ππ interactions (Table 1). The interesting feature of the crystal structure is the short intermolecular Cl···N interactions [3.0015 (11) Å]".

The molecules are linked via pairs of intermolecular N1—H1N1···O1 and N2—H1N2···O1 (Table 2) hydrogen bonds to generate R22(8) ring motifs (Bernstein et al., 1995) (Fig. 2). Furthermore, N2—H1N2···O1 hydrogen bonds form R21(7) ring motifs with C7—H7A···O1 contacts to further consolidate the crystal structure. The molecules are linked by these intermolecular interactions to form 1-D chains along the [0 0 1] direction.

Related literature top

For the synthetic utility and applications of semicarbazone derivatives, see: Warren et al. (1977); Chandra & Gupta (2005); Jain et al. (2002); Pilgram (1978); Yogeeswari et al. (2004). For related structures, see: Fun et al. (2009a,b). For the preparation, see: Furniss et al. (1978). For hydrogen-bond motifs, see: Bernstein et al. (1995). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986). Cg1 is the centroid of the S1/C3–C6 five-membered ring.

Experimental top

Semicarbazide hydrochloride (1.84 g, 16.5 mmol) and freshly recrystallized sodium acetate (1.64 g, 20.0 mmol) was dissolved in water (15 ml) according to a literature procedure (Furniss et al., 1978). The reaction mixture was stirred at room temperature for 10 minutes. To this, 2,5-dichloro-3-acetylthiophene (3.0 g, 15.4 mmol) in ethanol (15 ml) was added and stirred well for 6 h. The separated semicarbazone was filtered, washed with chilled water and recrystallized from an ethanol/dimethylformamide mixture. Yield: 3.19 g, 82.22%. M.p. 491–493 K.

Refinement top

N-bound H atoms were located in a difference Fourier map and were allowed to refine freely, see Table 2 for distances. All the other H atoms were placed in calculated positions, with C–H = 0.93 or 0.96 Å, and refined using a riding model with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating-group model was applied for the methyl group.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme.
[Figure 2] Fig. 2. The crystal packing in (I), viewed along the b axis. The dashed lines indicate hydrogen bonds and C-H···O contacts.
(Z)-1-(2,5-Dichloro-3-thienyl)ethanone semicarbazone top
Crystal data top
C7H7Cl2N3OSF(000) = 1024
Mr = 252.12Dx = 1.706 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 6313 reflections
a = 13.0796 (2) Åθ = 2.5–33.2°
b = 10.4316 (2) ŵ = 0.84 mm1
c = 14.4352 (2) ÅT = 100 K
β = 94.599 (1)°Plate, colourless
V = 1963.21 (6) Å30.49 × 0.22 × 0.08 mm
Z = 8
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
3742 independent reflections
Radiation source: fine-focus sealed tube3060 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
ϕ and ω scansθmax = 33.2°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 2019
Tmin = 0.683, Tmax = 0.934k = 1615
16375 measured reflectionsl = 2222
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) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.13 w = 1/[σ2(Fo2) + (0.0516P)2 + 0.6332P]
where P = (Fo2 + 2Fc2)/3
3742 reflections(Δ/σ)max = 0.002
140 parametersΔρmax = 0.46 e Å3
0 restraintsΔρmin = 0.35 e Å3
Crystal data top
C7H7Cl2N3OSV = 1963.21 (6) Å3
Mr = 252.12Z = 8
Monoclinic, C2/cMo Kα radiation
a = 13.0796 (2) ŵ = 0.84 mm1
b = 10.4316 (2) ÅT = 100 K
c = 14.4352 (2) Å0.49 × 0.22 × 0.08 mm
β = 94.599 (1)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
3742 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
3060 reflections with I > 2σ(I)
Tmin = 0.683, Tmax = 0.934Rint = 0.029
16375 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0340 restraints
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.13Δρmax = 0.46 e Å3
3742 reflectionsΔρmin = 0.35 e Å3
140 parameters
Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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
Cl11.17736 (3)0.23231 (4)0.62567 (3)0.02794 (10)
Cl20.88955 (3)0.12728 (4)0.31571 (2)0.02421 (10)
S11.06944 (2)0.19596 (3)0.43833 (3)0.01940 (9)
O10.48318 (7)0.00827 (9)0.37962 (6)0.01622 (18)
N10.62401 (10)0.02718 (15)0.30045 (8)0.0247 (3)
N20.63508 (8)0.03704 (11)0.46052 (7)0.0150 (2)
N30.73470 (8)0.07286 (10)0.45321 (7)0.0146 (2)
C10.57608 (9)0.01731 (12)0.37865 (8)0.0147 (2)
C20.79348 (9)0.09889 (12)0.52643 (9)0.0141 (2)
C30.89959 (10)0.13686 (12)0.51073 (9)0.0150 (2)
C40.97547 (10)0.16495 (13)0.58619 (9)0.0183 (2)
H4A0.96210.16170.64850.022*
C51.06803 (10)0.19643 (13)0.55714 (10)0.0194 (3)
C60.94260 (10)0.15031 (13)0.42725 (9)0.0167 (2)
C70.76299 (11)0.09363 (16)0.62397 (9)0.0232 (3)
H7A0.69130.07340.62340.035*
H7B0.77570.17530.65330.035*
H7C0.80240.02880.65790.035*
H1N10.5931 (16)0.0142 (19)0.2466 (16)0.036 (5)*
H2N10.6797 (17)0.0442 (19)0.3063 (14)0.030 (5)*
H1N20.6027 (14)0.0324 (17)0.5102 (13)0.022 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.01347 (16)0.0327 (2)0.0365 (2)0.00378 (13)0.00478 (14)0.00720 (15)
Cl20.01543 (15)0.0411 (2)0.01659 (15)0.00354 (13)0.00432 (11)0.00003 (12)
S10.01115 (15)0.02034 (16)0.02707 (17)0.00210 (11)0.00391 (12)0.00104 (12)
O10.0101 (4)0.0251 (5)0.0135 (4)0.0015 (4)0.0005 (3)0.0007 (3)
N10.0116 (5)0.0502 (8)0.0124 (5)0.0061 (5)0.0008 (4)0.0013 (5)
N20.0102 (4)0.0224 (5)0.0122 (4)0.0034 (4)0.0008 (4)0.0002 (4)
N30.0095 (4)0.0199 (5)0.0148 (4)0.0027 (4)0.0018 (4)0.0003 (4)
C10.0121 (5)0.0185 (6)0.0136 (5)0.0006 (4)0.0020 (4)0.0001 (4)
C20.0113 (5)0.0156 (5)0.0152 (5)0.0010 (4)0.0010 (4)0.0004 (4)
C30.0113 (5)0.0154 (5)0.0182 (5)0.0006 (4)0.0006 (4)0.0008 (4)
C40.0137 (6)0.0199 (6)0.0208 (6)0.0011 (5)0.0010 (5)0.0029 (5)
C50.0121 (5)0.0195 (6)0.0261 (6)0.0011 (5)0.0020 (5)0.0041 (5)
C60.0117 (5)0.0192 (6)0.0192 (6)0.0010 (5)0.0016 (4)0.0000 (4)
C70.0164 (6)0.0390 (8)0.0140 (5)0.0029 (6)0.0005 (5)0.0002 (5)
Geometric parameters (Å, º) top
Cl1—C51.7137 (14)N3—C21.2851 (16)
Cl2—C61.7182 (13)C2—C31.4782 (18)
S1—C51.7167 (15)C2—C71.4949 (18)
S1—C61.7211 (13)C3—C61.3773 (19)
O1—C11.2452 (15)C3—C41.4436 (18)
N1—C11.3384 (17)C4—C51.3530 (19)
N1—H1N10.86 (2)C4—H4A0.9300
N1—H2N10.75 (2)C7—H7A0.9600
N2—N31.3677 (15)C7—H7B0.9600
N2—C11.3741 (16)C7—H7C0.9600
N2—H1N20.863 (19)
Cg1···Cg1i3.7188 (6)Cl2···N33.0015 (11)
C5—S1—C690.35 (6)C4—C3—C2122.41 (12)
C1—N1—H1N1122.3 (14)C5—C4—C3113.17 (13)
C1—N1—H2N1116.2 (16)C5—C4—H4A123.4
H1N1—N1—H2N1122 (2)C3—C4—H4A123.4
N3—N2—C1116.57 (10)C4—C5—Cl1126.87 (12)
N3—N2—H1N2127.8 (12)C4—C5—S1112.98 (10)
C1—N2—H1N2115.3 (12)Cl1—C5—S1120.14 (8)
C2—N3—N2120.34 (11)C3—C6—Cl2130.02 (10)
O1—C1—N1123.33 (12)C3—C6—S1113.90 (10)
O1—C1—N2120.24 (11)Cl2—C6—S1116.08 (8)
N1—C1—N2116.44 (11)C2—C7—H7A109.5
N3—C2—C3115.96 (11)C2—C7—H7B109.5
N3—C2—C7125.43 (11)H7A—C7—H7B109.5
C3—C2—C7118.61 (11)C2—C7—H7C109.5
C6—C3—C4109.59 (11)H7A—C7—H7C109.5
C6—C3—C2128.00 (12)H7B—C7—H7C109.5
C1—N2—N3—C2176.77 (12)C3—C4—C5—Cl1178.46 (10)
N3—N2—C1—O1175.87 (11)C3—C4—C5—S10.65 (16)
N3—N2—C1—N14.15 (18)C6—S1—C5—C40.70 (11)
N2—N3—C2—C3179.86 (11)C6—S1—C5—Cl1178.47 (9)
N2—N3—C2—C70.1 (2)C4—C3—C6—Cl2179.02 (11)
N3—C2—C3—C61.5 (2)C2—C3—C6—Cl20.5 (2)
C7—C2—C3—C6178.55 (13)C4—C3—C6—S10.35 (15)
N3—C2—C3—C4177.95 (12)C2—C3—C6—S1179.82 (10)
C7—C2—C3—C42.03 (19)C5—S1—C6—C30.60 (11)
C6—C3—C4—C50.19 (17)C5—S1—C6—Cl2178.86 (9)
C2—C3—C4—C5179.32 (12)
Symmetry code: (i) x+5/2, y+1/2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O1ii0.86 (2)2.02 (2)2.8766 (15)177.3 (19)
N2—H1N2···O1iii0.863 (19)2.035 (19)2.8949 (14)174.2 (17)
C7—H7A···O1iii0.962.383.3370 (17)176
Symmetry codes: (ii) x+1, y, z+1/2; (iii) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC7H7Cl2N3OS
Mr252.12
Crystal system, space groupMonoclinic, C2/c
Temperature (K)100
a, b, c (Å)13.0796 (2), 10.4316 (2), 14.4352 (2)
β (°) 94.599 (1)
V3)1963.21 (6)
Z8
Radiation typeMo Kα
µ (mm1)0.84
Crystal size (mm)0.49 × 0.22 × 0.08
Data collection
DiffractometerBruker SMART APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.683, 0.934
No. of measured, independent and
observed [I > 2σ(I)] reflections
16375, 3742, 3060
Rint0.029
(sin θ/λ)max1)0.770
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.100, 1.13
No. of reflections3742
No. of parameters140
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.46, 0.35

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Selected interatomic distances (Å) top
Cg1···Cg1i3.7188 (6)Cl2···N33.0015 (11)
Symmetry code: (i) x+5/2, y+1/2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O1ii0.86 (2)2.02 (2)2.8766 (15)177.3 (19)
N2—H1N2···O1iii0.863 (19)2.035 (19)2.8949 (14)174.2 (17)
C7—H7A···O1iii0.962.383.3370 (17)176.1
Symmetry codes: (ii) x+1, y, z+1/2; (iii) x+1, y, z+1.
 

Footnotes

Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: A-5525-2009.

Current address: Department of Chemistry, National Institute of Technology-Karnataka, Surathkal, Mangalore 575 025, India.

Acknowledgements

HKF and CKQ thank Universiti Sains Malaysia (USM) for the Research University Golden Goose Grant (No. 1001/PFIZIK/811012). CKQ thanks USM for a Research Fellowship. AMI is grateful to the Head of the Department of Chemistry and the Director, NITK, Surathkal, India, for providing research facilities.

References

First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science Google Scholar
First citationBruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChandra, S. & Gupta, L. K. (2005). Spectrochim. Acta Part A, 62, 1089–1094.  CrossRef Google Scholar
First citationCosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationFun, H.-K., Quah, C. K., Padaki, M., Malladi, S. & Isloor, A. M. (2009a). Acta Cryst. E65, o1634–o1635.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationFun, H.-K., Yeap, C. S., Padaki, M., Malladi, S. & Isloor, A. M. (2009b). Acta Cryst. E65, o1619–o1620.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationFurniss, B. S., Hannaford, A. J., Rogers, V., Smith, P. W. G. & Tatchell, A. R. (1978). Vogel's Textbook of Practical Organic Chemistry, 4th ed. p. 1112. London: ELBS.  Google Scholar
First citationJain, V. K., Handa, A., Pandya, R., Shrivastav, P. & Agrawal, Y. K. (2002). React. Funct. Polym. 51, 101–110.  Web of Science CrossRef CAS Google Scholar
First citationPilgram, K. H. G. (1978). US Patent No. 4 108 399.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWarren, J. D., Woodward, D. L. & Hargreaves, R. T. (1977). J. Med. Chem. 20, 1520–1521.  CrossRef CAS PubMed Web of Science Google Scholar
First citationYogeeswari, P., Sriram, D., Pandeya, S. N. & Stables, J. P. (2004). Farmaco, 59, 609–613.  CrossRef PubMed CAS Google Scholar

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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 65| Part 8| August 2009| Pages o1852-o1853
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