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

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ISSN: 2056-9890

(1E,4E)-1,5-Bis(thio­phen-3-yl)penta-1,4-dien-3-one

aChemistry Research Centre, SSMRV College, 4th T Block, Jayanagar, Bangalore 560 041, India, bDepartment of Physics, Bhavan's Sheth R. A. College of Science, Ahmedabad, Gujarat 380 001, India, cDepartment of Chemistry, Sri Sathya Sai Institute of Higher Learning, Andhra Pradesh, Ananthapur 515 134, India, and dDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
*Correspondence e-mail: edward.tiekink@gmail.com

(Received 9 August 2011; accepted 10 August 2011; online 17 August 2011)

The title compound, C13H10OS2, exhibits twists between the central C3O and ethene residues [O—C—C—C torsion angles = −8.4 (3) and 11.8 (3)°], and between the ethene and adjacent thio­phenyl residues [C—C—C—C torsion angles = −4.2 (3) and 10.5 (3)°]. As a result, the mol­ecule is non-planar, the dihedral angle formed between the terminal thio­phenyl groups being 15.45 (10)°. The presence of C—H⋯O inter­actions involving the bifurcated carbonyl O atom leads to supra­molecular arrays in the ac plane. These are linked into a three-dimensional architecture by C—H⋯π inter­actions involving both thio­phenyl residues.

Related literature

For the use of chalcones in organic synthesis, see: Nehad et al. (2007[Nehad, A., El-Latif, A., El-Galil, A., Amr, E. & Ibrahiem, A. A. (2007). Monatsh. Chem. 138, 559-567.]); Xu et al. (2001[Xu, J., Wang, C. & Zhang, Q. (2001). Heteroat. Chem. 6, 557-559.]). For the biological activity of chalcones, see: Lambert et al. (2009[Lambert, D. M., Aichaoui, H., Guenadil, F., Kapanda, C. N., Poupaert, J. H. & McCurdy, C. R. (2009). Med. Chem. Res. 18, 467-476.]); Boumendjel et al. (2008[Boumendjel, A., Boccard, J., Carrupt, P. N., Nicolle, E., Blanc, M., Geze, A., Choisnard, L., Wouessidjewe, D., Matera, E.-L. & Dumontet, C. (2008). J. Med. Chem. 51, 2307-2310.]). Semi-empirical quantum chemical calculations were performed using MOPAC2009, see: Stewart (2009[Stewart, J. P. (2009). MOPAC2009. Stewart Computational Chemistry. http://OpenMOPAC.net.]).

[Scheme 1]

Experimental

Crystal data
  • C13H10OS2

  • Mr = 246.33

  • Orthorhombic, P b c a

  • a = 11.8908 (3) Å

  • b = 7.1807 (1) Å

  • c = 28.3004 (6) Å

  • V = 2416.41 (9) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.42 mm−1

  • T = 293 K

  • 0.40 × 0.20 × 0.10 mm

Data collection
  • Bruker SMART APEX CCD diffractometer

  • 39245 measured reflections

  • 2760 independent reflections

  • 2187 reflections with I > 2σ(I)

  • Rint = 0.033

Refinement
  • R[F2 > 2σ(F2)] = 0.040

  • wR(F2) = 0.121

  • S = 1.09

  • 2760 reflections

  • 145 parameters

  • H-atom parameters constrained

  • Δρmax = 0.33 e Å−3

  • Δρmin = −0.32 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 and Cg2 are the centroids of the S1,C1–C4 and S2,C10–C13 rings, respectively.

D—H⋯A D—H H⋯A DA D—H⋯A
C1—H1⋯O1i 0.93 2.49 3.256 (2) 140
C12—H12⋯O1ii 0.93 2.44 3.355 (2) 169
C2—H2⋯Cg1iii 0.93 2.86 3.671 (2) 147
C4—H4⋯Cg1iv 0.93 2.97 3.809 (2) 151
C11—H11⋯Cg2iv 0.93 2.83 3.702 (2) 156
Symmetry codes: (i) [x+{\script{1\over 2}}, y, -z+{\script{3\over 2}}]; (ii) [x+{\script{1\over 2}}, -y-{\script{1\over 2}}, -z+1]; (iii) [-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) [-x-{\script{1\over 2}}, y-{\script{1\over 2}}, z].

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: APEX2 and SAINT (Bruker, 2004[Bruker (2004). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT and XPREP (Bruker, 2004[Bruker (2004). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]); 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: ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and DIAMOND (Brandenburg, 2006[Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

Chalcones attract interest as important chemical intermediates in the synthesis of various organic compounds containing five- (Nehad et al., 2007) and seven-membered (Xu et al., 2001) heterocycles. They also have a wide spectrum of biological activity, e.g. as anti-oxidants, neuroprotective, anti-miotics, anti-malarials, etc. (Lambert et al., 2009; Boumendjel et al., 2008). In this contribution the synthesis, crystal structure determination and theoretical structure of the title compound, 1,5-bis(3-thiophenyl)-1,4-pentadiene-3-one (I), are reported.

The configuration about each of the ethene [C5C6 = 1.327 (2) Å and C8C9 = 1.324 (2) Å] bonds in (I) is E, Fig. 1. Small but significant twists in the molecule are observed so that there are notable deviations from planarity. In particular, the carbonyl and ethene groups deviate from co-planarity as seen in the values of the C5—C6—C7—O1 and C9—C8—C7—O1 torsion angles of -8.4 (3) and 11.8 (3) °, respectively. While the S1-thiophenyl ring is effectively co-planar with the adjacent ethene bond [C2—C3—C5—C6 is -4.2 (3) °], the S2-thiophenyl ring is twisted with the C13—C10—C9—C8 torsion angle being 10.5 (3) °. Overall, with reference to the central C3O atoms, the thiophenyl groups lie to the same side of the molecule, and form a dihedral angle of 15.45 (10) ° with each other. The conformation of the crystallographic determined molecule structure was subjected to energy minimization calculations using the MOPAC2009 programme with the Parametrization Model 6 (PM6) approximation together with the restricted Hartree Fock closed-shell wavefunction (Stewart, 2009). The minimizations were terminated at a r.m.s. gradient less than 0.01 kJ mol-1 Å-1. The optimized structure showed that the molecule adopts a non-planar conformation in the gas phase with the dihedral angle between the thiophenyl groups being 9.9 °. A planar arrangement in (I) is precluded owing to the unfavourable H···H interactions that would ensure.

In the crystal packing, the carbonyl-O1 atom plays a prominent role in that it is bifurcated, forming two C—H···O interactions, Table 1. These lead to supramolecular layers in the ac plane, Fig. 2. Connections between layers are of the type C—H···π and involve both thiophenyl rings, Table 1. These interactions result in a three-dimensional architecture, Fig. 3.

Related literature top

For the use of chalcones in organic synthesis, see: Nehad et al. (2007); Xu et al. (2001). For the biological activity of chalcones, see: Lambert et al. (2009); Boumendjel et al. (2008). Semi-empirical quantum chemical calculations were performed using MOPAC2009, see: Stewart (2009).

Experimental top

NaOH (5 g) was dissolved in distilled water (50 ml) and cooled to room temperature. The alkali solution and ethanol (50 ml) were transferred to a 250 ml round bottomed flask. The temperature of the solution was maintained at 298 K and stirred vigorously using a magnetic stirrer. One-half of previously prepared mixture of 0.05 moles of thiophene-3-carboxaldehyde and 0.025 moles of acetone was added to the NaOH-EtOH solution which was then stirred manually. A flocculent precipitate formed within 2–3 minutes of addition. After 15 minutes, the remaining half of the aldehyde-acetone mixture was added to the round bottomed flask, and the mixture was stirred for a further 45 minutes. The solids were filtered under vacuum and washed repeatedly with ice-cold water to eliminate alkali. The solid was pressed between filter paper and dried at room temperature in a desiccator overnight. The compound was recrystallized from EtOH. Yield 82%. M. pt. 407–408 K. Colourless needles were obtained by its re-crystallization from hot ethanol solution.

Refinement top

The C-bound H atoms were geometrically placed (C–H = 0.93 Å) and refined as riding with Uiso(H) = 1.2Ueq(parent atom).

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 35% probability level.
[Figure 2] Fig. 2. View of the supramolecular array in the ac plane in (I) mediated by C–H···O interactions, shown as orange dashed lines.
[Figure 3] Fig. 3. A view in projection down the a axis of the unit-cell contents for (I). The C—H···O and C—H···π interactions are shown as orange and purple dashed lines, respectively.
(1E,4E)-1,5-Bis(thiophen-3-yl)penta-1,4-dien-3-one top
Crystal data top
C13H10OS2F(000) = 1024
Mr = 246.33Dx = 1.354 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 50 reflections
a = 11.8908 (3) Åθ = 5.0–30.0°
b = 7.1807 (1) ŵ = 0.42 mm1
c = 28.3004 (6) ÅT = 293 K
V = 2416.41 (9) Å3Needle, colorless
Z = 80.40 × 0.20 × 0.10 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
2187 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.033
Graphite monochromatorθmax = 27.5°, θmin = 1.4°
ω and ϕ scansh = 1515
39245 measured reflectionsk = 89
2760 independent reflectionsl = 3636
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)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.121H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0528P)2 + 0.9807P]
where P = (Fo2 + 2Fc2)/3
2760 reflections(Δ/σ)max = 0.002
145 parametersΔρmax = 0.33 e Å3
0 restraintsΔρmin = 0.32 e Å3
Crystal data top
C13H10OS2V = 2416.41 (9) Å3
Mr = 246.33Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 11.8908 (3) ŵ = 0.42 mm1
b = 7.1807 (1) ÅT = 293 K
c = 28.3004 (6) Å0.40 × 0.20 × 0.10 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
2187 reflections with I > 2σ(I)
39245 measured reflectionsRint = 0.033
2760 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0400 restraints
wR(F2) = 0.121H-atom parameters constrained
S = 1.09Δρmax = 0.33 e Å3
2760 reflectionsΔρmin = 0.32 e Å3
145 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
S10.38360 (5)0.12409 (9)0.833684 (17)0.0655 (2)
S20.38292 (5)0.15855 (9)0.398067 (18)0.0658 (2)
O10.17784 (11)0.0181 (2)0.61498 (4)0.0581 (4)
C30.35238 (14)0.0577 (2)0.74599 (6)0.0422 (4)
C50.29957 (15)0.0511 (2)0.69974 (6)0.0441 (4)
H50.22940.10720.69710.053*
C80.33643 (16)0.0925 (3)0.57374 (6)0.0476 (4)
H80.40610.15000.57700.057*
C20.45551 (15)0.0286 (3)0.75867 (6)0.0516 (4)
H20.50020.09440.73750.062*
C100.34646 (15)0.1238 (2)0.48658 (6)0.0462 (4)
C60.34072 (15)0.0264 (3)0.66085 (6)0.0467 (4)
H60.41210.07940.66170.056*
C110.30593 (18)0.0723 (3)0.44352 (7)0.0569 (5)
H110.24270.00240.43950.068*
C90.29452 (16)0.0692 (3)0.53080 (6)0.0472 (4)
H90.22460.01180.52880.057*
C40.30471 (17)0.1448 (3)0.78394 (6)0.0518 (4)
H40.23660.20840.78270.062*
C70.27673 (15)0.0308 (2)0.61635 (6)0.0447 (4)
C10.48190 (17)0.0050 (3)0.80489 (7)0.0616 (5)
H10.54600.05360.81910.074*
C130.44370 (16)0.2385 (3)0.48152 (7)0.0550 (5)
H130.48360.28730.50690.066*
C120.47191 (17)0.2690 (3)0.43574 (8)0.0616 (5)
H120.53260.34150.42610.074*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0834 (4)0.0759 (4)0.0373 (3)0.0050 (3)0.0023 (2)0.0014 (2)
S20.0802 (4)0.0740 (4)0.0433 (3)0.0006 (3)0.0076 (2)0.0057 (2)
O10.0456 (7)0.0847 (10)0.0442 (7)0.0005 (7)0.0025 (5)0.0016 (7)
C30.0453 (9)0.0400 (8)0.0411 (8)0.0032 (7)0.0018 (7)0.0029 (7)
C50.0441 (9)0.0442 (9)0.0440 (9)0.0013 (7)0.0045 (7)0.0027 (7)
C80.0482 (10)0.0500 (9)0.0447 (9)0.0014 (8)0.0005 (8)0.0020 (8)
C20.0456 (10)0.0615 (11)0.0476 (10)0.0033 (8)0.0019 (8)0.0032 (8)
C100.0496 (10)0.0457 (9)0.0432 (9)0.0017 (8)0.0014 (7)0.0031 (7)
C60.0463 (9)0.0509 (10)0.0428 (9)0.0003 (8)0.0030 (7)0.0022 (7)
C110.0659 (12)0.0604 (11)0.0445 (10)0.0106 (10)0.0001 (9)0.0047 (8)
C90.0485 (9)0.0485 (9)0.0447 (9)0.0013 (8)0.0004 (7)0.0025 (7)
C40.0583 (11)0.0530 (10)0.0441 (9)0.0040 (9)0.0001 (8)0.0026 (8)
C70.0455 (10)0.0478 (9)0.0408 (9)0.0068 (8)0.0012 (7)0.0023 (7)
C10.0542 (11)0.0799 (14)0.0507 (11)0.0015 (10)0.0095 (9)0.0139 (10)
C130.0482 (10)0.0634 (12)0.0535 (11)0.0015 (9)0.0024 (8)0.0028 (9)
C120.0508 (11)0.0693 (13)0.0648 (12)0.0012 (10)0.0094 (9)0.0111 (10)
Geometric parameters (Å, º) top
S1—C41.6982 (19)C2—H20.9300
S1—C11.700 (2)C10—C111.362 (3)
S2—C111.6960 (19)C10—C131.427 (3)
S2—C121.699 (2)C10—C91.450 (2)
O1—C71.228 (2)C6—C71.472 (2)
C3—C41.366 (2)C6—H60.9300
C3—C21.420 (2)C11—H110.9300
C3—C51.452 (2)C9—H90.9300
C5—C61.327 (2)C4—H40.9300
C5—H50.9300C1—H10.9300
C8—C91.324 (2)C13—C121.356 (3)
C8—C71.468 (2)C13—H130.9300
C8—H80.9300C12—H120.9300
C2—C11.356 (3)
C4—S1—C191.73 (9)C10—C11—H11123.6
C11—S2—C1291.76 (10)S2—C11—H11123.6
C4—C3—C2111.06 (16)C8—C9—C10126.70 (17)
C4—C3—C5122.97 (16)C8—C9—H9116.7
C2—C3—C5125.93 (16)C10—C9—H9116.7
C6—C5—C3127.01 (17)C3—C4—S1112.49 (15)
C6—C5—H5116.5C3—C4—H4123.8
C3—C5—H5116.5S1—C4—H4123.8
C9—C8—C7122.26 (17)O1—C7—C8121.58 (16)
C9—C8—H8118.9O1—C7—C6121.05 (16)
C7—C8—H8118.9C8—C7—C6117.36 (16)
C1—C2—C3112.91 (18)C2—C1—S1111.80 (15)
C1—C2—H2123.5C2—C1—H1124.1
C3—C2—H2123.5S1—C1—H1124.1
C11—C10—C13110.73 (17)C12—C13—C10112.92 (18)
C11—C10—C9123.24 (17)C12—C13—H13123.5
C13—C10—C9126.03 (17)C10—C13—H13123.5
C5—C6—C7121.90 (17)C13—C12—S2111.74 (16)
C5—C6—H6119.1C13—C12—H12124.1
C7—C6—H6119.1S2—C12—H12124.1
C10—C11—S2112.85 (15)
C4—C3—C5—C6178.38 (18)C5—C3—C4—S1178.21 (13)
C2—C3—C5—C64.2 (3)C1—S1—C4—C30.77 (16)
C4—C3—C2—C10.2 (2)C9—C8—C7—O111.8 (3)
C5—C3—C2—C1177.47 (18)C9—C8—C7—C6167.02 (17)
C3—C5—C6—C7177.39 (16)C5—C6—C7—O18.4 (3)
C13—C10—C11—S20.2 (2)C5—C6—C7—C8170.49 (17)
C9—C10—C11—S2179.36 (15)C3—C2—C1—S10.7 (2)
C12—S2—C11—C100.47 (17)C4—S1—C1—C20.87 (17)
C7—C8—C9—C10179.69 (17)C11—C10—C13—C120.2 (3)
C11—C10—C9—C8170.5 (2)C9—C10—C13—C12178.87 (18)
C13—C10—C9—C810.5 (3)C10—C13—C12—S20.6 (2)
C2—C3—C4—S10.5 (2)C11—S2—C12—C130.61 (18)
Hydrogen-bond geometry (Å, º) top
Cg1 and Cg2 are the centroids of the S1,C1–C4 and S2,C10–C13 rings, respectively.
D—H···AD—HH···AD···AD—H···A
C1—H1···O1i0.932.493.256 (2)140
C12—H12···O1ii0.932.443.355 (2)169
C2—H2···Cg1iii0.932.863.671 (2)147
C4—H4···Cg1iv0.932.973.809 (2)151
C11—H11···Cg2iv0.932.833.702 (2)156
Symmetry codes: (i) x+1/2, y, z+3/2; (ii) x+1/2, y1/2, z+1; (iii) x+1, y1/2, z+3/2; (iv) x1/2, y1/2, z.

Experimental details

Crystal data
Chemical formulaC13H10OS2
Mr246.33
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)293
a, b, c (Å)11.8908 (3), 7.1807 (1), 28.3004 (6)
V3)2416.41 (9)
Z8
Radiation typeMo Kα
µ (mm1)0.42
Crystal size (mm)0.40 × 0.20 × 0.10
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
39245, 2760, 2187
Rint0.033
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.121, 1.09
No. of reflections2760
No. of parameters145
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.33, 0.32

Computer programs: APEX2 (Bruker, 2004), APEX2 and SAINT (Bruker, 2004), SAINT and XPREP (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
Cg1 and Cg2 are the centroids of the S1,C1–C4 and S2,C10–C13 rings, respectively.
D—H···AD—HH···AD···AD—H···A
C1—H1···O1i0.932.493.256 (2)140
C12—H12···O1ii0.932.443.355 (2)169
C2—H2···Cg1iii0.932.863.671 (2)147
C4—H4···Cg1iv0.932.973.809 (2)151
C11—H11···Cg2iv0.932.833.702 (2)156
Symmetry codes: (i) x+1/2, y, z+3/2; (ii) x+1/2, y1/2, z+1; (iii) x+1, y1/2, z+3/2; (iv) x1/2, y1/2, z.
 

Footnotes

Additional correspondence author, e-mail: mmjotani@rediffmail.com.

Acknowledgements

The authors are thankful to the Department of Science and Technology (DST) and the Indian Institute of Science, Bangalore, India, for the X-ray data collection.

References

First citationBoumendjel, A., Boccard, J., Carrupt, P. N., Nicolle, E., Blanc, M., Geze, A., Choisnard, L., Wouessidjewe, D., Matera, E.-L. & Dumontet, C. (2008). J. Med. Chem. 51, 2307–2310.  Web of Science CrossRef PubMed CAS Google Scholar
First citationBrandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2004). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationLambert, D. M., Aichaoui, H., Guenadil, F., Kapanda, C. N., Poupaert, J. H. & McCurdy, C. R. (2009). Med. Chem. Res. 18, 467–476.  Google Scholar
First citationNehad, A., El-Latif, A., El-Galil, A., Amr, E. & Ibrahiem, A. A. (2007). Monatsh. Chem. 138, 559–567.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationStewart, J. P. (2009). MOPAC2009. Stewart Computational Chemistry. http://OpenMOPAC.net.  Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationXu, J., Wang, C. & Zhang, Q. (2001). Heteroat. Chem. 6, 557–559.  Web of Science CrossRef Google Scholar

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