supplementary materials


yk2095 scheme

Acta Cryst. (2013). E69, o1243    [ doi:10.1107/S1600536813018229 ]

2-(4-Chlorophenyl)-1-pentyl-4,5-diphenyl-1H-imidazole

S. K. Mohamed, M. Akkurt, K. Singh, A. A. Marzouk and A. A. Abdelhamid

Abstract top

In the title compound, C26H25ClN2, the phenyl rings and the 2-(4-chlorophenyl) group make dihedral angles of 30.03 (11), 67.49 (12) and 41.56 (11)°, respectively, with the imidazole ring. In the crystal, the molecules interact with each other via very weak C-H...[pi] contacts, forming layers parallel to (110).

Comment top

Various substituted imidazole derivatives have been found to possess a significant biological exhibition such as anti-helminthic, analgesic, antibacterial, antifungal, antiviral, tuberculostatic, cytostatic, and anti-inflammation activities (Shalini et al., 2011). Tetra-substituted imidazoles in particular represent the core structure in many biological systems such as Losartan, Trifenagrel, Eprosartan and Olmesartan (Ramesh et al., 2012; Wolkenberg et al., 2004). Based on literature and further to our ongoing study in synthesis of bio-active molecules the title compound has been synthesized and herein we report its crystal structure.

As shown in Fig. 1, the title molecule adopts a non-planar conformation. The two phenyl (C17–C22 and C23–C28) and 2-(4-chlorophenyl) (C11–C16) groups make the dihedral angles of 30.03 (11), 67.49 (12) and 41.56 (11) °, respectively, with the imidazole ring (N1/C2/N3/C4/C5). The N1–C6–C7–C8 and C7–C8–C9–C10 torsion angles are -168.61 (16) and -176.82 (19)°, respectively. The values of the geometric parameters of (I) are in the normal range and comparable to those reported for the similar compounds (Simpson et al., 2013; Akkurt et al., 2013).

The crystal structure of (I) is stabilized by intra and intermolecular Cl···H(C) contacts [Cl1···H13 = 2.80 Å, Cl1···H15 = 2.80 Å, Cl1···H6Ai = 3.10 Å, Cl1···H8Bi = 3.05 Å, Cl1···H24ii = 3.14 Å, Cl1···H10Biii = 3.02 Å (symmetry codes: (i) 1 - x, 1 - y, 2 - z; (ii) 2 - x, 1 - y, 2 - z; (iii) -1/2 + x, 3/2 - y, 1/2 + z)]. Fig. 2 shows the molecular packing of (I) along the b axis.

Related literature top

For biological applications of imidazole derivatives, see: Shalini et al. (2011); Ramesh et al. (2012); Wolkenberg et al. (2004). For related structures, see: Simpson et al. (2013); Akkurt et al. (2013).

Experimental top

The title compound was synthesized following the previously reported procedure (Simpson et al., 2013). Colourless grains of product (M.p. 399 K) were collected with 89% yield. The crystals of sufficient quality for X-ray diffraction study were obtained by slow evaporation of the ethanol solution of the title compound.

Refinement top

All H atoms were placed in geometrically idealized positions [C—H = 0.95 Å (aromatic), C—H = 0.99 Å (methylene), and C—H = 0.98 Å (methyl)] and refined as riding on their parent atoms with Uiso(H) = 1.2 Ueq (C). treated as riding on their parent atoms, with Uiso(H) = 1.2–1.5Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The structure of the title molecule with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.
[Figure 2] Fig. 2. View of the packing diagram of the title compound along the b axis direction. All H atoms omitted for clarity.
2-(4-Chlorophenyl)-1-pentyl-4,5-diphenyl-1H-imidazole top
Crystal data top
C26H25ClN2F(000) = 848
Mr = 400.93Dx = 1.200 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 811 reflections
a = 10.471 (2) Åθ = 2.8–23.3°
b = 9.7798 (19) ŵ = 0.19 mm1
c = 21.682 (4) ÅT = 150 K
β = 91.080 (4)°Block, colourless
V = 2219.9 (7) Å30.36 × 0.14 × 0.11 mm
Z = 4
Data collection top
Bruker APEX 2000 CCD area-detector
diffractometer
4346 independent reflections
Radiation source: fine-focus sealed tube2593 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.088
φ and ω scansθmax = 26.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
h = 1212
Tmin = 0.969, Tmax = 0.980k = 1211
16940 measured reflectionsl = 2626
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.053H-atom parameters constrained
wR(F2) = 0.110 W = 1/[Σ2(FO2) + (0.0377P)2] WHERE P = (FO2 + 2FC2)/3
S = 0.89(Δ/σ)max = 0.001
4346 reflectionsΔρmax = 0.26 e Å3
263 parametersΔρmin = 0.31 e Å3
Crystal data top
C26H25ClN2V = 2219.9 (7) Å3
Mr = 400.93Z = 4
Monoclinic, P21/nMo Kα radiation
a = 10.471 (2) ŵ = 0.19 mm1
b = 9.7798 (19) ÅT = 150 K
c = 21.682 (4) Å0.36 × 0.14 × 0.11 mm
β = 91.080 (4)°
Data collection top
Bruker APEX 2000 CCD area-detector
diffractometer
4346 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
2593 reflections with I > 2σ(I)
Tmin = 0.969, Tmax = 0.980Rint = 0.088
16940 measured reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.053H-atom parameters constrained
wR(F2) = 0.110Δρmax = 0.26 e Å3
S = 0.89Δρmin = 0.31 e Å3
4346 reflectionsAbsolute structure: ?
263 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All s.u.'s are estimated from the variances of the (full) variance-covariance matrix. The cell s.u.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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
Cl10.48467 (6)0.57406 (7)1.11900 (3)0.0565 (3)
N10.95325 (15)0.25818 (17)0.95080 (7)0.0286 (6)
N31.02899 (16)0.24351 (18)1.04691 (7)0.0308 (6)
C20.9371 (2)0.2951 (2)1.01115 (9)0.0286 (7)
C41.10784 (19)0.1722 (2)1.00835 (9)0.0295 (7)
C51.06275 (19)0.1789 (2)0.94862 (9)0.0288 (7)
C60.87851 (19)0.3032 (2)0.89685 (9)0.0304 (7)
C70.94069 (19)0.4250 (2)0.86571 (9)0.0338 (8)
C80.8550 (2)0.4923 (2)0.81788 (10)0.0373 (8)
C90.9151 (2)0.6130 (3)0.78703 (11)0.0500 (9)
C100.8260 (2)0.6845 (3)0.74173 (11)0.0629 (11)
C110.82661 (19)0.3684 (2)1.03559 (9)0.0293 (7)
C120.7711 (2)0.4823 (2)1.00771 (10)0.0358 (8)
C130.6648 (2)0.5448 (2)1.03269 (10)0.0393 (8)
C140.6155 (2)0.4937 (3)1.08642 (10)0.0384 (8)
C150.6700 (2)0.3823 (2)1.11571 (10)0.0381 (8)
C160.7750 (2)0.3207 (2)1.09032 (9)0.0336 (8)
C171.22136 (19)0.1012 (2)1.03386 (9)0.0304 (7)
C181.2830 (2)0.1515 (3)1.08647 (10)0.0429 (9)
C191.3879 (2)0.0841 (3)1.11173 (11)0.0534 (10)
C201.4320 (2)0.0343 (3)1.08535 (12)0.0519 (10)
C211.3724 (2)0.0846 (3)1.03348 (11)0.0462 (9)
C221.2677 (2)0.0180 (2)1.00781 (10)0.0366 (8)
C231.1111 (2)0.1239 (2)0.88975 (9)0.0304 (8)
C241.2243 (2)0.1728 (3)0.86639 (10)0.0445 (9)
C251.2713 (2)0.1218 (3)0.81166 (11)0.0564 (10)
C261.2062 (3)0.0227 (3)0.77984 (11)0.0522 (10)
C271.0928 (3)0.0263 (3)0.80242 (10)0.0509 (10)
C281.0457 (2)0.0242 (2)0.85709 (10)0.0401 (8)
H6A0.791500.328700.909700.0360*
H6B0.870700.226900.867000.0360*
H7A0.964800.493400.897500.0410*
H7B1.020000.394200.845800.0410*
H8A0.831200.423800.786000.0450*
H8B0.775500.522500.837900.0450*
H9A0.991800.581900.765000.0600*
H9B0.943300.679200.819000.0600*
H10A0.796600.619300.710200.0950*
H10B0.871300.759900.722000.0950*
H10C0.752200.720500.763600.0950*
H120.806500.518000.971000.0430*
H130.626600.621701.013000.0470*
H150.635500.348501.152900.0460*
H160.812900.244201.110500.0400*
H181.252800.232801.105300.0510*
H191.429700.119901.147500.0640*
H201.503400.080801.103100.0620*
H211.403100.165901.015000.0550*
H221.227000.054300.971900.0440*
H241.270400.242000.888100.0530*
H251.349400.156000.796200.0680*
H261.238700.012300.742400.0630*
H271.046900.095000.780400.0610*
H280.967500.010100.872300.0480*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0404 (4)0.0733 (5)0.0562 (4)0.0153 (3)0.0123 (3)0.0120 (4)
N10.0299 (10)0.0311 (11)0.0249 (10)0.0013 (9)0.0005 (8)0.0005 (8)
N30.0310 (10)0.0337 (12)0.0279 (10)0.0011 (9)0.0048 (8)0.0006 (9)
C20.0315 (13)0.0272 (13)0.0273 (12)0.0010 (10)0.0035 (10)0.0005 (10)
C40.0312 (12)0.0274 (13)0.0301 (12)0.0002 (10)0.0042 (10)0.0013 (10)
C50.0292 (12)0.0275 (13)0.0298 (12)0.0013 (10)0.0029 (10)0.0007 (10)
C60.0263 (12)0.0357 (14)0.0290 (12)0.0025 (10)0.0025 (10)0.0003 (10)
C70.0326 (13)0.0381 (15)0.0309 (12)0.0019 (11)0.0025 (10)0.0019 (11)
C80.0393 (14)0.0359 (15)0.0366 (13)0.0003 (11)0.0021 (11)0.0027 (11)
C90.0488 (15)0.0581 (19)0.0432 (15)0.0014 (14)0.0070 (12)0.0190 (14)
C100.071 (2)0.063 (2)0.0550 (18)0.0116 (16)0.0071 (15)0.0256 (15)
C110.0298 (12)0.0291 (14)0.0291 (12)0.0025 (10)0.0013 (10)0.0034 (10)
C120.0378 (14)0.0355 (15)0.0344 (13)0.0015 (11)0.0081 (11)0.0004 (11)
C130.0353 (14)0.0414 (16)0.0412 (14)0.0057 (11)0.0010 (11)0.0024 (12)
C140.0317 (13)0.0453 (16)0.0383 (14)0.0041 (12)0.0053 (11)0.0108 (12)
C150.0401 (14)0.0449 (16)0.0295 (13)0.0035 (12)0.0099 (11)0.0039 (12)
C160.0365 (13)0.0327 (14)0.0317 (13)0.0019 (11)0.0028 (11)0.0014 (11)
C170.0300 (12)0.0316 (14)0.0299 (12)0.0008 (11)0.0056 (10)0.0064 (11)
C180.0434 (15)0.0466 (17)0.0385 (14)0.0065 (12)0.0032 (12)0.0010 (12)
C190.0455 (16)0.070 (2)0.0441 (15)0.0057 (15)0.0117 (13)0.0017 (15)
C200.0370 (15)0.065 (2)0.0537 (17)0.0133 (14)0.0014 (13)0.0149 (15)
C210.0429 (15)0.0426 (17)0.0533 (16)0.0119 (13)0.0082 (13)0.0090 (14)
C220.0373 (14)0.0348 (15)0.0378 (13)0.0022 (11)0.0018 (11)0.0057 (11)
C230.0344 (13)0.0294 (14)0.0275 (12)0.0072 (11)0.0003 (10)0.0017 (10)
C240.0357 (14)0.0588 (18)0.0391 (14)0.0044 (12)0.0073 (11)0.0100 (13)
C250.0418 (15)0.082 (2)0.0458 (16)0.0031 (15)0.0155 (13)0.0067 (16)
C260.0646 (19)0.062 (2)0.0304 (14)0.0183 (15)0.0098 (13)0.0049 (14)
C270.078 (2)0.0425 (17)0.0323 (14)0.0033 (15)0.0013 (13)0.0064 (12)
C280.0503 (15)0.0360 (15)0.0341 (13)0.0045 (12)0.0049 (12)0.0016 (11)
Geometric parameters (Å, º) top
Cl1—C141.741 (2)C25—C261.365 (4)
N1—C21.371 (2)C26—C271.379 (4)
N1—C51.386 (3)C27—C281.384 (3)
N1—C61.463 (3)C6—H6A0.9900
N3—C21.324 (3)C6—H6B0.9900
N3—C41.376 (3)C7—H7A0.9900
C2—C111.468 (3)C7—H7B0.9900
C4—C51.372 (3)C8—H8A0.9900
C4—C171.475 (3)C8—H8B0.9900
C5—C231.483 (3)C9—H9A0.9900
C6—C71.522 (3)C9—H9B0.9900
C7—C81.510 (3)C10—H10A0.9800
C8—C91.501 (3)C10—H10B0.9800
C9—C101.513 (3)C10—H10C0.9800
C11—C121.390 (3)C12—H120.9500
C11—C161.394 (3)C13—H130.9500
C12—C131.389 (3)C15—H150.9500
C13—C141.377 (3)C16—H160.9500
C14—C151.379 (3)C18—H180.9500
C15—C161.378 (3)C19—H190.9500
C17—C181.390 (3)C20—H200.9500
C17—C221.387 (3)C21—H210.9500
C18—C191.385 (3)C22—H220.9500
C19—C201.375 (4)C24—H240.9500
C20—C211.367 (4)C25—H250.9500
C21—C221.383 (3)C26—H260.9500
C23—C241.383 (3)C27—H270.9500
C23—C281.379 (3)C28—H280.9500
C24—C251.386 (3)
C2—N1—C5107.28 (16)C6—C7—H7B109.00
C2—N1—C6127.60 (16)C8—C7—H7A109.00
C5—N1—C6124.87 (16)C8—C7—H7B109.00
C2—N3—C4105.97 (16)H7A—C7—H7B108.00
N1—C2—N3110.93 (17)C7—C8—H8A109.00
N1—C2—C11125.82 (18)C7—C8—H8B109.00
N3—C2—C11122.92 (17)C9—C8—H8A109.00
N3—C4—C5110.47 (17)C9—C8—H8B109.00
N3—C4—C17119.95 (17)H8A—C8—H8B108.00
C5—C4—C17129.58 (18)C8—C9—H9A109.00
N1—C5—C4105.36 (17)C8—C9—H9B109.00
N1—C5—C23121.90 (17)C10—C9—H9A109.00
C4—C5—C23132.71 (19)C10—C9—H9B109.00
N1—C6—C7111.31 (16)H9A—C9—H9B108.00
C6—C7—C8113.10 (16)C9—C10—H10A109.00
C7—C8—C9113.60 (17)C9—C10—H10B109.00
C8—C9—C10113.21 (19)C9—C10—H10C110.00
C2—C11—C12124.08 (18)H10A—C10—H10B109.00
C2—C11—C16117.69 (18)H10A—C10—H10C109.00
C12—C11—C16118.23 (18)H10B—C10—H10C109.00
C11—C12—C13120.99 (19)C11—C12—H12119.00
C12—C13—C14119.1 (2)C13—C12—H12120.00
Cl1—C14—C13119.34 (19)C12—C13—H13120.00
Cl1—C14—C15119.46 (17)C14—C13—H13120.00
C13—C14—C15121.2 (2)C14—C15—H15120.00
C14—C15—C16119.20 (19)C16—C15—H15120.00
C11—C16—C15121.28 (19)C11—C16—H16119.00
C4—C17—C18119.97 (19)C15—C16—H16119.00
C4—C17—C22121.91 (18)C17—C18—H18120.00
C18—C17—C22118.1 (2)C19—C18—H18120.00
C17—C18—C19120.6 (2)C18—C19—H19120.00
C18—C19—C20120.4 (2)C20—C19—H19120.00
C19—C20—C21119.6 (2)C19—C20—H20120.00
C20—C21—C22120.5 (2)C21—C20—H20120.00
C17—C22—C21120.8 (2)C20—C21—H21120.00
C5—C23—C24119.91 (19)C22—C21—H21120.00
C5—C23—C28121.60 (19)C17—C22—H22120.00
C24—C23—C28118.5 (2)C21—C22—H22120.00
C23—C24—C25120.6 (2)C23—C24—H24120.00
C24—C25—C26120.4 (2)C25—C24—H24120.00
C25—C26—C27119.5 (2)C24—C25—H25120.00
C26—C27—C28120.2 (2)C26—C25—H25120.00
C23—C28—C27120.7 (2)C25—C26—H26120.00
N1—C6—H6A109.00C27—C26—H26120.00
N1—C6—H6B109.00C26—C27—H27120.00
C7—C6—H6A109.00C28—C27—H27120.00
C7—C6—H6B109.00C23—C28—H28120.00
H6A—C6—H6B108.00C27—C28—H28120.00
C6—C7—H7A109.00
C5—N1—C2—N30.3 (2)N1—C6—C7—C8168.61 (16)
C5—N1—C2—C11173.78 (19)C6—C7—C8—C9179.75 (18)
C6—N1—C2—N3174.66 (18)C7—C8—C9—C10176.82 (19)
C6—N1—C2—C1111.9 (3)C2—C11—C12—C13178.54 (19)
C2—N1—C5—C40.2 (2)C16—C11—C12—C131.8 (3)
C2—N1—C5—C23178.41 (18)C2—C11—C16—C15178.87 (19)
C6—N1—C5—C4174.38 (17)C12—C11—C16—C151.4 (3)
C6—N1—C5—C233.9 (3)C11—C12—C13—C141.0 (3)
C2—N1—C6—C794.4 (2)C12—C13—C14—Cl1178.44 (17)
C5—N1—C6—C779.0 (2)C12—C13—C14—C150.2 (3)
C4—N3—C2—N10.7 (2)Cl1—C14—C15—C16178.79 (17)
C4—N3—C2—C11174.34 (18)C13—C14—C15—C160.5 (3)
C2—N3—C4—C50.8 (2)C14—C15—C16—C110.3 (3)
C2—N3—C4—C17179.98 (19)C4—C17—C18—C19178.5 (2)
N1—C2—C11—C1245.1 (3)C22—C17—C18—C190.2 (3)
N1—C2—C11—C16135.2 (2)C4—C17—C22—C21178.4 (2)
N3—C2—C11—C12142.2 (2)C18—C17—C22—C210.1 (3)
N3—C2—C11—C1637.5 (3)C17—C18—C19—C200.5 (4)
N3—C4—C5—N10.6 (2)C18—C19—C20—C210.7 (4)
N3—C4—C5—C23178.6 (2)C19—C20—C21—C220.6 (4)
C17—C4—C5—N1179.72 (19)C20—C21—C22—C170.3 (4)
C17—C4—C5—C232.3 (4)C5—C23—C24—C25179.5 (2)
N3—C4—C17—C1829.6 (3)C28—C23—C24—C250.5 (3)
N3—C4—C17—C22148.7 (2)C5—C23—C28—C27179.6 (2)
C5—C4—C17—C18151.4 (2)C24—C23—C28—C270.4 (3)
C5—C4—C17—C2230.4 (3)C23—C24—C25—C260.2 (4)
N1—C5—C23—C24111.6 (2)C24—C25—C26—C270.2 (4)
N1—C5—C23—C2868.3 (3)C25—C26—C27—C280.3 (4)
C4—C5—C23—C2466.1 (3)C26—C27—C28—C230.0 (4)
C4—C5—C23—C28114.0 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C20—H20···C25i0.953.003.887 (3)157
C24—H24···C13ii0.952.783.697 (3)163
C28—H28···N3iii0.952.883.444 (3)119
C28—H28···C17iii0.953.003.894 (3)158
Symmetry codes: (i) x+3, y, z+2; (ii) x+2, y+1, z+2; (iii) x+2, y, z+2.

Experimental details

Crystal data
Chemical formulaC26H25ClN2
Mr400.93
Crystal system, space groupMonoclinic, P21/n
Temperature (K)150
a, b, c (Å)10.471 (2), 9.7798 (19), 21.682 (4)
β (°) 91.080 (4)
V3)2219.9 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.19
Crystal size (mm)0.36 × 0.14 × 0.11
Data collection
DiffractometerBruker APEX 2000 CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.969, 0.980
No. of measured, independent and
observed [I > 2σ(I)] reflections
16940, 4346, 2593
Rint0.088
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.110, 0.89
No. of reflections4346
No. of parameters263
No. of restraints0
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.26, 0.31

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), WinGX (Farrugia, 2012) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C20—H20···C25i0.953.003.887 (3)157
C24—H24···C13ii0.952.783.697 (3)163
C28—H28···N3iii0.952.883.444 (3)119
C28—H28···C17iii0.953.003.894 (3)158
Symmetry codes: (i) x+3, y, z+2; (ii) x+2, y+1, z+2; (iii) x+2, y, z+2.
Acknowledgements top

Manchester Metropolitan University, Erciyes University and the University of Leicester are gratefully acknowledged for supporting this study.

references
References top

Akkurt, M., Mohamed, S. K., Singh, K., Marzouk, A. A. & Abdelhamid, A. A. (2013). Acta Cryst. E69, o846–o847.

Bruker (2001). SAINT, SMART and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.

Ramesh, K., Murthy, S. N., Karnakar, K., Nageswar, Y. V. D., Vijayalakhshmi, K., Devi, B. L. A. P. & Prasad, R. P. N. (2012). Tetrahedron Lett. 53, 1126–1129.

Shalini, K., Kumar, N. & Sharma, P. K. (2011). Biointerface Res. Appl. Chem. 1, 184–190.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Simpson, J., Mohamed, S. K., Marzouk, A. A., Talybov, A. H. & Abdelhamid, A. A. (2013). Acta Cryst. E69, o5–o6.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Wolkenberg, S. E., Wisnoski, D. D., Leister, W. H., Wang, Y., Zhao, Z. & Lindsley, C. W. (2004). Org. Lett. 6, 1453–1456.