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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

2,5-Di­hexyl­thio­phene 1,1-dioxide

aDepartment of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
*Correspondence e-mail: nagagold@gmail.com

(Received 29 October 2012; accepted 14 November 2012; online 24 November 2012)

In the title mol­ecule, C16H28O2S, the two n-hexyl groups are in all-trans conformations. Their C atoms are situated close to the plane of the thio­phene ring with a maximum deviation of 0.718 (6) Å for one of the terminal methyl groups. In the crystal, a short C—H⋯O contact is observed between thio­phene 1,1-dioxide groups.

Related literature

For the preparation of the title compound, see: Barbarella et al. (1998[Barbarella, G., Favaretto, L., Sotgiu, G., Zambianchi, M., Antolini, L., Pudova, O. & Bongini, A. (1998). J. Org. Chem. 63, 5497-5506.]). For a review on thio­phene-1,1-dioxide derivatives and their applications, see: Nakayama et al. (1999[Nakayama, J. & Sugihara, Y. (1999). Top. Curr. Chem. 205, 131-195.]). For the biological activity of sulfone compounds, see: Naesens et al. (2006[Naesens, L., Stephens, C. E., Andrei, G., Loregian, A., De Bolle, L., Snoeck, R., Sowell, J. W. & De Clercq, E. (2006). Antivir. Res. 72, 60-67.]); Kim et al. (2008[Kim, S. H., Tran, M. T., Ruebsam, F., Xiang, A. X., Ayida, B., McGuire, H., Ellis, D., Blazel, J., Tran, C. V., Murphy, D. E., Webber, S. E., Zhou, Y., Shah, A. M., Tsan, M., Showalter, R. E., Patel, R., Gobbi, A., LeBrun, L. A., Bartkowski, D. M., Nolan, T. G., Norris, D. A., Sergeeva, M. V., Kirkovsky, L., Zhao, Q., Han, Q. & Kissinger, C. R. (2008). Bioorg. Med. Chem. Lett. 18, 4181-4185.]); Sagardoy et al. (2010[Sagardoy, A. A., Gil, M. J., Villar, R., Viñas, M., Arrazola, A., Encío, I. & Martinez-Merino, V. (2010). Bioorg. Med. Chem. 18, 5701-5707.]).

[Scheme 1]

Experimental

Crystal data
  • C16H28O2S

  • Mr = 284.44

  • Monoclinic, P 21 /n

  • a = 5.8249 (11) Å

  • b = 11.248 (2) Å

  • c = 27.207 (6) Å

  • β = 91.770 (8)°

  • V = 1781.7 (6) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.18 mm−1

  • T = 293 K

  • 1.00 × 0.30 × 0.10 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA.]) Tmin = 0.841, Tmax = 0.982

  • 18944 measured reflections

  • 3149 independent reflections

  • 2207 reflections with I > 2σ(I)

  • Rint = 0.072

Refinement
  • R[F2 > 2σ(F2)] = 0.062

  • wR(F2) = 0.167

  • S = 1.07

  • 3149 reflections

  • 174 parameters

  • H-atom parameters constrained

  • Δρmax = 0.26 e Å−3

  • Δρmin = −0.20 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C3—H3⋯O2i 0.93 2.54 3.186 (3) 126
Symmetry code: (i) [-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 2008[Bruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA.]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and WinGX (Farrugia 2012)[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]; program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg & Putz, 2005[Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Tetrahydrothiophene 1,1-dioxide otherwise known as sulfolane, is an important industrial solvent used in the purification of natural gas, particularly for the extraction of aromatic hydrocarbon from the other hydrocarbon mixtures. Thiophene 1,1-dioxide is an important intermediate in the synthesis of various class of organic compounds. This class of compound is also known for their bioapplications (Nakayama et al., 1999; Naesens et al., 2006; Kim et al., 2008; Sagardoy et al., 2010). For example, some of them have been found to be effective inhibitors of hepatitis C virus polymerase (Kim et al., 2008).

The title compound, 2,5-dihexyl-thiophene-1,1-dioxide, was synthesized by the procedure of Barbarella et al. (1998).

Related literature top

For the preparation of the title compound, see: Barbarella et al. (1998). For a review on thiophene-1,1-dioxide derivatives and their applications, see: Nakayama et al. (1999). For the biological activity of sulfone compounds, see: Naesens et al. (2006); Kim et al. (2008); Sagardoy et al. (2010).

Experimental top

A mixture of 2,5-dihexylthiophene (0.500 g; 2.0 mmol) and NaHCO3 (0.667 g; 7.9 mmol; 4.0 eq) was taken in dichloromethane(30 ml) at 0 °C and allowed to stir vigorously for a few minutes. To which a freshly recrystallized (from dichloromethane) solid of m-chloroperbenzoic acid (1.411 g; 8.2 mmol; 4.1 eq.) was added in portion over 60 min. After 16hrs of stirring, the precipitate was removed by filtration and successively washed with dichloromethane (2 x 5 ml). The collective filtrate was then evaporated to dryness. Crystals of title compound were obtained as white needles from n-pentane. Yield: 0.304 g; 53.9%. 1H NMR (600 MHz, CDCl3) δ 6.28 – 6.24 (2H, m, H-3,4), 2.46 (4H, t, J = 7.7 Hz, H-1'), 1.68 – 1.61 (4H, m, H-2'), 1.41 – 1.34 (4H, m, H-3'), 1.33 – 1.26 (8H, m, H-4',5'), 0.91 – 0.86 (6H, m, H-6'). 13 C NMR (151 MHz, CDCl3) δ 144.08 (C-2,5), 121.80 (C-3,4), 31.51 (C-4',5'), 28.91 (C-3'), 26.67 (C-2'), 24.41 (C-1'), 22.63 (C-4',5'), 14.16 (C-6'). EI—MS m/z: 284.10 (35.47%; M+), 165.10 (78.57), 95.10 (100.00), 81.05 (83.06).

Refinement top

All H atoms were positioned geometrically with C—H distances in the range 0.93 - 0.97 Å. and allowed to ride on their parent atoms, with Uiso(H) =1.2Ueq(C) except methyl group where Uiso(H) = 1.5Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus (Bruker, 2008); program(s) used to solve structure: SHELXTL (Sheldrick, 2008) and WinGX (Farrugia 2012); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound with displacement ellipsoids shown at the 50% probability level.
2,5-Dihexylthiophene 1,1-dioxide top
Crystal data top
C16H28O2SF(000) = 624
Mr = 284.44Dx = 1.060 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 4797 reflections
a = 5.8249 (11) Åθ = 2.4–23.1°
b = 11.248 (2) ŵ = 0.18 mm1
c = 27.207 (6) ÅT = 293 K
β = 91.770 (8)°Needle, colourless
V = 1781.7 (6) Å31.00 × 0.30 × 0.10 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer
3149 independent reflections
Radiation source: sealed tube2207 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.072
ϕ and ω scansθmax = 25.1°, θmin = 2.4°
Absorption correction: multi-scan
(SADABS; Bruker 2008)
h = 65
Tmin = 0.841, Tmax = 0.982k = 1313
18944 measured reflectionsl = 3232
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)] = 0.062Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.167H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0703P)2 + 0.6152P]
where P = (Fo2 + 2Fc2)/3
3149 reflections(Δ/σ)max < 0.001
174 parametersΔρmax = 0.26 e Å3
0 restraintsΔρmin = 0.20 e Å3
Crystal data top
C16H28O2SV = 1781.7 (6) Å3
Mr = 284.44Z = 4
Monoclinic, P21/nMo Kα radiation
a = 5.8249 (11) ŵ = 0.18 mm1
b = 11.248 (2) ÅT = 293 K
c = 27.207 (6) Å1.00 × 0.30 × 0.10 mm
β = 91.770 (8)°
Data collection top
Bruker APEXII CCD
diffractometer
3149 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker 2008)
2207 reflections with I > 2σ(I)
Tmin = 0.841, Tmax = 0.982Rint = 0.072
18944 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0620 restraints
wR(F2) = 0.167H-atom parameters constrained
S = 1.07Δρmax = 0.26 e Å3
3149 reflectionsΔρmin = 0.20 e Å3
174 parameters
Special details top

Experimental. Crystal was mounted and automatically centered on a Bruker SMART X2S bench top crystallographic system. Data were collected at 20°C with 60 s/frame exposure time (total of 1260, width 0.5°) covering up to θ = 25.11° and 99.9% completeness accomplished.

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
S10.46906 (11)1.12674 (5)0.21332 (3)0.0601 (3)
O10.3088 (3)1.17815 (16)0.17855 (8)0.0747 (6)
O20.6195 (3)1.20741 (15)0.23951 (8)0.0810 (7)
C10.3264 (5)1.0326 (2)0.25486 (11)0.0626 (7)
C20.4059 (5)0.9226 (2)0.24780 (11)0.0694 (8)
H20.35640.85780.26590.083*
C30.5755 (5)0.9109 (2)0.20979 (12)0.0723 (9)
H30.64180.83820.20220.087*
C40.6296 (5)1.0103 (2)0.18666 (11)0.0607 (7)
C50.7877 (5)1.0372 (2)0.14685 (13)0.0754 (9)
H5A0.89101.10020.15770.090*
H5B0.69901.06640.11860.090*
C60.9293 (6)0.9312 (3)0.13111 (14)0.0841 (9)
H6A1.02450.90510.15890.101*
H6B0.82600.86660.12220.101*
C71.0796 (6)0.9554 (3)0.08902 (15)0.0989 (11)
H7A1.18241.02040.09770.119*
H7B0.98460.98060.06100.119*
C81.2227 (7)0.8481 (4)0.07397 (17)0.1131 (13)
H8A1.32080.82460.10170.136*
H8B1.11960.78240.06650.136*
C91.3646 (10)0.8683 (5)0.0321 (2)0.157 (2)
H9A1.46680.93440.03960.189*
H9B1.26600.89180.00440.189*
C101.5056 (10)0.7652 (6)0.0169 (2)0.174 (2)
H10A1.62330.75000.04160.261*
H10B1.57510.78270.01380.261*
H10C1.40930.69630.01310.261*
C110.1562 (5)1.0832 (2)0.28819 (12)0.0699 (8)
H11A0.04571.12960.26890.084*
H11B0.23451.13680.31100.084*
C120.0284 (6)0.9910 (3)0.31714 (13)0.0772 (9)
H12A0.05500.93950.29420.093*
H12B0.13950.94230.33520.093*
C130.1368 (6)1.0412 (3)0.35249 (13)0.0923 (10)
H13A0.24371.09310.33480.111*
H13B0.05281.08890.37670.111*
C140.2728 (7)0.9448 (4)0.37919 (16)0.1160 (14)
H14A0.35490.89710.35470.139*
H14B0.16440.89290.39640.139*
C150.4357 (10)0.9875 (5)0.4140 (2)0.155 (2)
H15A0.54331.04100.39740.186*
H15B0.35471.03210.43960.186*
C160.5686 (10)0.8855 (7)0.4373 (2)0.192 (3)
H16A0.65040.84170.41210.288*
H16B0.67580.91740.46000.288*
H16C0.46300.83360.45450.288*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0592 (4)0.0319 (3)0.0888 (5)0.0010 (3)0.0051 (4)0.0004 (3)
O10.0735 (12)0.0499 (10)0.0999 (15)0.0105 (9)0.0096 (11)0.0143 (10)
O20.0808 (13)0.0438 (10)0.1173 (17)0.0150 (9)0.0117 (12)0.0124 (10)
C10.0659 (17)0.0403 (13)0.0810 (19)0.0032 (12)0.0056 (15)0.0016 (12)
C20.081 (2)0.0363 (13)0.091 (2)0.0026 (13)0.0022 (17)0.0073 (13)
C30.0754 (19)0.0374 (13)0.103 (2)0.0078 (13)0.0057 (18)0.0004 (14)
C40.0541 (15)0.0411 (13)0.0864 (19)0.0029 (12)0.0040 (15)0.0038 (13)
C50.0680 (19)0.0589 (16)0.099 (2)0.0019 (15)0.0018 (18)0.0043 (16)
C60.073 (2)0.075 (2)0.104 (2)0.0089 (17)0.0018 (19)0.0114 (19)
C70.088 (2)0.100 (3)0.109 (3)0.008 (2)0.014 (2)0.013 (2)
C80.103 (3)0.119 (3)0.118 (3)0.013 (3)0.022 (3)0.011 (3)
C90.147 (4)0.176 (6)0.150 (5)0.038 (4)0.033 (4)0.011 (4)
C100.158 (5)0.202 (6)0.164 (5)0.069 (4)0.033 (4)0.040 (5)
C110.0752 (19)0.0464 (14)0.088 (2)0.0014 (14)0.0038 (16)0.0020 (14)
C120.081 (2)0.0609 (17)0.090 (2)0.0078 (15)0.0033 (18)0.0062 (16)
C130.099 (3)0.086 (2)0.093 (2)0.007 (2)0.013 (2)0.009 (2)
C140.108 (3)0.135 (4)0.106 (3)0.004 (3)0.019 (3)0.021 (3)
C150.147 (4)0.189 (6)0.130 (4)0.039 (4)0.022 (4)0.009 (4)
C160.152 (5)0.277 (8)0.149 (5)0.087 (5)0.016 (4)0.075 (5)
Geometric parameters (Å, º) top
S1—O11.4306 (19)C9—H9A0.9700
S1—O21.4353 (19)C9—H9B0.9700
S1—C11.774 (3)C10—H10A0.9600
S1—C41.777 (3)C10—H10B0.9600
C1—C21.337 (4)C10—H10C0.9600
C1—C111.478 (4)C11—C121.512 (4)
C2—C31.458 (4)C11—H11A0.9700
C2—H20.9300C11—H11B0.9700
C3—C41.325 (4)C12—C131.492 (5)
C3—H30.9300C12—H12A0.9700
C4—C51.475 (4)C12—H12B0.9700
C5—C61.519 (4)C13—C141.539 (5)
C5—H5A0.9700C13—H13A0.9700
C5—H5B0.9700C13—H13B0.9700
C6—C71.488 (5)C14—C151.443 (6)
C6—H6A0.9700C14—H14A0.9700
C6—H6B0.9700C14—H14B0.9700
C7—C81.529 (5)C15—C161.533 (7)
C7—H7A0.9700C15—H15A0.9700
C7—H7B0.9700C15—H15B0.9700
C8—C91.446 (7)C16—H16A0.9600
C8—H8A0.9700C16—H16B0.9600
C8—H8B0.9700C16—H16C0.9600
C9—C101.487 (7)
O1—S1—O2116.66 (12)C8—C9—H9B108.4
O1—S1—C1110.71 (13)C10—C9—H9B108.4
O2—S1—C1110.61 (13)H9A—C9—H9B107.5
O1—S1—C4111.64 (13)C9—C10—H10A109.5
O2—S1—C4110.35 (13)C9—C10—H10B109.5
C1—S1—C494.74 (13)H10A—C10—H10B109.5
C2—C1—C11133.4 (3)C9—C10—H10C109.5
C2—C1—S1106.8 (2)H10A—C10—H10C109.5
C11—C1—S1119.78 (19)H10B—C10—H10C109.5
C1—C2—C3115.5 (2)C1—C11—C12113.9 (2)
C1—C2—H2122.3C1—C11—H11A108.8
C3—C2—H2122.3C12—C11—H11A108.8
C4—C3—C2115.9 (2)C1—C11—H11B108.8
C4—C3—H3122.0C12—C11—H11B108.8
C2—C3—H3122.0H11A—C11—H11B107.7
C3—C4—C5133.2 (3)C13—C12—C11114.4 (3)
C3—C4—S1107.0 (2)C13—C12—H12A108.6
C5—C4—S1119.80 (19)C11—C12—H12A108.6
C4—C5—C6113.8 (3)C13—C12—H12B108.6
C4—C5—H5A108.8C11—C12—H12B108.6
C6—C5—H5A108.8H12A—C12—H12B107.6
C4—C5—H5B108.8C12—C13—C14112.9 (3)
C6—C5—H5B108.8C12—C13—H13A109.0
H5A—C5—H5B107.7C14—C13—H13A109.0
C7—C6—C5114.3 (3)C12—C13—H13B109.0
C7—C6—H6A108.7C14—C13—H13B109.0
C5—C6—H6A108.7H13A—C13—H13B107.8
C7—C6—H6B108.7C15—C14—C13115.7 (4)
C5—C6—H6B108.7C15—C14—H14A108.4
H6A—C6—H6B107.6C13—C14—H14A108.4
C6—C7—C8113.6 (3)C15—C14—H14B108.4
C6—C7—H7A108.8C13—C14—H14B108.4
C8—C7—H7A108.8H14A—C14—H14B107.4
C6—C7—H7B108.8C14—C15—C16111.9 (5)
C8—C7—H7B108.8C14—C15—H15A109.2
H7A—C7—H7B107.7C16—C15—H15A109.2
C9—C8—C7114.6 (4)C14—C15—H15B109.2
C9—C8—H8A108.6C16—C15—H15B109.2
C7—C8—H8A108.6H15A—C15—H15B107.9
C9—C8—H8B108.6C15—C16—H16A109.5
C7—C8—H8B108.6C15—C16—H16B109.5
H8A—C8—H8B107.6H16A—C16—H16B109.5
C8—C9—C10115.5 (5)C15—C16—H16C109.5
C8—C9—H9A108.4H16A—C16—H16C109.5
C10—C9—H9A108.4H16B—C16—H16C109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3···O2i0.932.543.186 (3)126
Symmetry code: (i) x+3/2, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC16H28O2S
Mr284.44
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)5.8249 (11), 11.248 (2), 27.207 (6)
β (°) 91.770 (8)
V3)1781.7 (6)
Z4
Radiation typeMo Kα
µ (mm1)0.18
Crystal size (mm)1.00 × 0.30 × 0.10
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker 2008)
Tmin, Tmax0.841, 0.982
No. of measured, independent and
observed [I > 2σ(I)] reflections
18944, 3149, 2207
Rint0.072
(sin θ/λ)max1)0.597
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.062, 0.167, 1.07
No. of reflections3149
No. of parameters174
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.26, 0.20

Computer programs: APEX2 (Bruker, 2008), SAINT-Plus (Bruker, 2008), SHELXTL (Sheldrick, 2008) and WinGX (Farrugia 2012), SHELXTL (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3···O2i0.932.543.186 (3)126
Symmetry code: (i) x+3/2, y1/2, z+1/2.
 

Acknowledgements

The University of the Free State and Sasol Ltd are gratefully acknowledged for the financial support. Special thanks to Professor Andreas Roodt.

References

First citationBarbarella, G., Favaretto, L., Sotgiu, G., Zambianchi, M., Antolini, L., Pudova, O. & Bongini, A. (1998). J. Org. Chem. 63, 5497–5506.  Web of Science CSD CrossRef CAS Google Scholar
First citationBrandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2008). APEX2, SAINT-Plus and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationKim, S. H., Tran, M. T., Ruebsam, F., Xiang, A. X., Ayida, B., McGuire, H., Ellis, D., Blazel, J., Tran, C. V., Murphy, D. E., Webber, S. E., Zhou, Y., Shah, A. M., Tsan, M., Showalter, R. E., Patel, R., Gobbi, A., LeBrun, L. A., Bartkowski, D. M., Nolan, T. G., Norris, D. A., Sergeeva, M. V., Kirkovsky, L., Zhao, Q., Han, Q. & Kissinger, C. R. (2008). Bioorg. Med. Chem. Lett. 18, 4181–4185.  Web of Science CrossRef PubMed CAS Google Scholar
First citationNaesens, L., Stephens, C. E., Andrei, G., Loregian, A., De Bolle, L., Snoeck, R., Sowell, J. W. & De Clercq, E. (2006). Antivir. Res. 72, 60–67.  Web of Science CrossRef PubMed CAS Google Scholar
First citationNakayama, J. & Sugihara, Y. (1999). Top. Curr. Chem. 205, 131–195.  CrossRef CAS Google Scholar
First citationSagardoy, A. A., Gil, M. J., Villar, R., Viñas, M., Arrazola, A., Encío, I. & Martinez-Merino, V. (2010). Bioorg. Med. Chem. 18, 5701–5707.  Web of Science CrossRef CAS PubMed Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS 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
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds