supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

dn2369 scheme

Acta Cryst. (2008). E64, o1588-o1589    [ doi:10.1107/S1600536808022629 ]

1-[2-(3,4-Dichlorobenzyloxy)-2-phenylethyl]-1H-benzimidazole

Ö. Özel Güven, T. Erdogan, S. J. Coles and T. Hökelek

Abstract top

In the molecule of the title compound, C22H18Cl2N2O, the planar benzimidazole ring system is oriented with respect to the phenyl and dichlorobenzene rings at dihedral angles of 12.73 (3) and 36.57 (4)°, respectively. The dihedral angle between the dichlorobenzene and phenyl rings is 29.95 (6)°. There are C-H...[pi] contacts between the benzimidazole and dichlorobenzene rings, between the benzimidazole and phenyl rings, and between a methylene group and the dichlorobenzene ring.

Comment top

In recent years, there has been increasing interest in synthesis of heterocyclic compounds having biological and commercial importances. Clotrimazole (Song & Shin, 1998), econazole (Freer et al., 1986), ketoconazole (Peeters et al., 1979a) and miconazole (Peeters et al., 1979b) are well known imidazole ring containing, while itraconazole (Peeters et al., 1996) and fluconazole (Caira et al., 2004) are 1H-1,2,4-triazole ring containing, azole derivatives. They have been developed for clinical uses as antifungal agents (Brammer & Feczko, 1988). Lately, similar structures to miconazole and econazole have been reported to show antibacterial activity more than antifungal activity (Özel Güven et al., 2007a,b). In these structures, benzimidazole ring has been found in place of the imidazole ring of miconazole and econazole. Recently, we reported the crystal structures of furyl and fluorobenzene substituted compounds (Özel Güven et al., 2008a,b), and we report herein the crystal structure of title benzimidazole derivative.

In the molecule of the title compound (Fig. 1) the bond lengths and angles are generally within normal ranges. The planar benzimidazole ring system is oriented with respect to the phenyl and dichlorobenzene rings at dihedral angles of 12.73 (3)° and 36.57 (4)°, respectively. Atoms C8, C9 and C16 are -0.125 (2), 0.062 (2) and 0.076 (2) Å away from the ring planes of the corresponding benzimidazole, phenyl and dichlorobenzene, respectively. So, they are nearly coplanar with the adjacent rings. The dichlorobenzene ring is oriented with respect to the phenyl ring at a dihedral angle of 29.95 (6)°.

In the crystal structure, the molecules are elongated along [101], and stacked along the b axis. The C—H···π contacts (Table 1) between the benzimidazole and the dichlorobenzene rings, the benzimidazole and the phenyl rings and the dichlorobenzene ring and the methylene group may stabilize the structure.

Related literature top

For general background, see: Brammer & Feczko (1988); Özel Güven et al. (2007a,b). For related literature, see: Song & Shin (1998); Freer et al. (1986); Peeters et al. (1996); Peeters et al. (1979a,b); Caira et al. (2004); Özel Güven et al. (2008a,b).

Experimental top

The title compound was synthesized by the reaction of 2-(1H-benzimidazol-1-yl) -1-phenylethanol (Özel Güven et al., 2007a) with NaH and appropriate benzyl halide. To the solution of alcohol (300 mg, 1.259 mmol) in DMF (2.4 ml) was added NaH (63 mg, 1.574 mmol) in small fractions. The appropriate benzyl halide (238 mg, 1.259 mmol) in DMF (1.2 ml) was added dropwise. The mixture was stirred at room temperature for 2 h, and excess hydride was decomposed with a small amount of methyl alcohol. After evaporation to dryness under reduced pressure, the crude residue was suspended with water and extracted with methylene chloride. The organic layer was dried over anhydrous sodium sulfate and then evaporated to dryness. The crude residue was purified by chromatography on a silica-gel column using chloroform-methanol as eluent. Crystals suitable for X-ray analysis were obtained by the recrystallization of the ether from a mixture of hexane/ethyl acetate (1:2) (yield; 229 mg, 46%).

Refinement top

H atoms were positioned geometrically, with C—H = 0.93, 0.98 and 0.97 Å for aromatic, methine and methylene H, respectively, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); 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, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
1-[2-(3,4-Dichlorobenzyloxy)-2-phenylethyl]-1H-benzimidazole top
Crystal data top
C22H18Cl2N2OF000 = 824
Mr = 397.28Dx = 1.388 Mg m−3
Monoclinic, P21/nMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 4593 reflections
a = 14.4664 (3) Åθ = 2.9–27.5º
b = 7.3995 (2) ŵ = 0.36 mm−1
c = 19.1030 (3) ÅT = 120 (2) K
β = 111.6530 (10)ºBlock, colorless
V = 1900.57 (7) Å30.40 × 0.40 × 0.30 mm
Z = 4
Data collection top
Bruker–Nonius Kappa CCD
diffractometer		4358 independent reflections
Radiation source: fine-focus sealed tube3480 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.044
Detector resolution: 9.091 pixels mm-1θmax = 27.5º
T = 120(2) Kθmin = 3.0º
φ and ω scansh = −18→18
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)		k = −9→9
Tmin = 0.871, Tmax = 0.901l = −24→24
23210 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.049  w = 1/[σ2(Fo2) + (0.0784P)2 + 0.7143P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.137(Δ/σ)max < 0.001
S = 1.09Δρmax = 1.00 e Å−3
4358 reflectionsΔρmin = −0.45 e Å−3
245 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.029 (2)
Secondary atom site location: difference Fourier map
Crystal data top
C22H18Cl2N2OV = 1900.57 (7) Å3
Mr = 397.28Z = 4
Monoclinic, P21/nMo Kα
a = 14.4664 (3) ŵ = 0.36 mm−1
b = 7.3995 (2) ÅT = 120 (2) K
c = 19.1030 (3) Å0.40 × 0.40 × 0.30 mm
β = 111.6530 (10)º
Data collection top
Bruker–Nonius Kappa CCD
diffractometer		4358 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2007)		3480 reflections with I > 2σ(I)
Tmin = 0.871, Tmax = 0.901Rint = 0.044
23210 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.049245 parameters
wR(F2) = 0.137H-atom parameters constrained
S = 1.09Δρmax = 1.00 e Å−3
4358 reflectionsΔρmin = −0.45 e Å−3
Special details top

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
Cl10.08238 (4)1.15550 (8)0.12348 (3)0.03377 (18)
Cl20.27151 (4)1.15173 (8)0.27688 (3)0.03349 (17)
O−0.00599 (9)0.69157 (18)0.39047 (7)0.0198 (3)
N1−0.11880 (11)0.5111 (2)0.25401 (8)0.0181 (3)
N2−0.25862 (12)0.6632 (2)0.18736 (9)0.0248 (4)
C1−0.20915 (13)0.5751 (3)0.24963 (11)0.0226 (4)
H1−0.23380.55770.28770.027*
C2−0.19558 (13)0.6596 (2)0.14714 (10)0.0201 (4)
C3−0.20642 (15)0.7361 (3)0.07797 (10)0.0256 (4)
H3−0.26360.79990.05020.031*
C4−0.13019 (16)0.7146 (3)0.05170 (10)0.0292 (5)
H4−0.13670.76430.00540.035*
C5−0.04303 (16)0.6198 (3)0.09293 (11)0.0268 (4)
H50.00690.60790.07350.032*
C6−0.03008 (14)0.5433 (3)0.16255 (10)0.0207 (4)
H60.02760.48070.19040.025*
C7−0.10738 (13)0.5649 (2)0.18831 (9)0.0177 (4)
C8−0.04415 (13)0.4222 (3)0.31792 (9)0.0189 (4)
H8A−0.01600.32120.30020.023*
H8B−0.07530.37510.35120.023*
C90.03905 (13)0.5531 (2)0.36165 (9)0.0167 (4)
H90.06620.60790.32660.020*
C100.12201 (13)0.4534 (2)0.42245 (9)0.0165 (4)
C110.21552 (13)0.4418 (3)0.41786 (10)0.0194 (4)
H110.22750.49950.37880.023*
C120.29134 (14)0.3446 (3)0.47127 (11)0.0231 (4)
H120.35370.33780.46780.028*
C130.27398 (14)0.2579 (3)0.52970 (10)0.0237 (4)
H130.32460.19240.56530.028*
C140.18091 (15)0.2691 (3)0.53482 (10)0.0246 (4)
H140.16920.21190.57410.029*
C150.10499 (14)0.3660 (3)0.48123 (10)0.0207 (4)
H150.04260.37240.48460.025*
C160.04829 (15)0.8583 (3)0.40680 (10)0.0225 (4)
H16A0.11440.83640.44380.027*
H16B0.01500.94260.42860.027*
C170.05701 (13)0.9422 (2)0.33712 (10)0.0193 (4)
C18−0.02613 (14)0.9540 (2)0.27082 (10)0.0202 (4)
H18−0.08770.91630.27020.024*
C19−0.01811 (14)1.0213 (3)0.20569 (10)0.0221 (4)
H19−0.07391.02700.16140.027*
C200.07358 (15)1.0803 (3)0.20677 (10)0.0237 (4)
C210.15655 (14)1.0755 (3)0.27335 (11)0.0229 (4)
C220.14856 (14)1.0041 (3)0.33816 (10)0.0216 (4)
H220.20440.99770.38240.026*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0443 (3)0.0369 (3)0.0292 (3)0.0115 (2)0.0242 (2)0.0078 (2)
Cl20.0271 (3)0.0344 (3)0.0450 (3)−0.0047 (2)0.0204 (2)−0.0018 (2)
O0.0211 (6)0.0179 (7)0.0222 (6)−0.0002 (5)0.0103 (5)0.0002 (5)
N10.0156 (7)0.0187 (8)0.0181 (7)−0.0008 (6)0.0042 (6)0.0008 (6)
N20.0180 (8)0.0252 (9)0.0280 (8)0.0022 (6)0.0050 (7)−0.0017 (7)
C10.0163 (9)0.0259 (10)0.0250 (9)−0.0021 (7)0.0067 (7)−0.0020 (8)
C20.0170 (9)0.0175 (9)0.0208 (9)0.0003 (7)0.0012 (7)−0.0028 (7)
C30.0264 (10)0.0206 (10)0.0209 (9)0.0028 (8)−0.0017 (7)0.0006 (7)
C40.0390 (12)0.0280 (11)0.0175 (9)−0.0024 (9)0.0069 (8)0.0020 (8)
C50.0321 (11)0.0271 (11)0.0241 (10)−0.0015 (8)0.0138 (8)−0.0030 (8)
C60.0188 (9)0.0189 (9)0.0220 (9)0.0016 (7)0.0048 (7)−0.0032 (7)
C70.0170 (8)0.0163 (9)0.0161 (8)−0.0018 (7)0.0018 (6)−0.0018 (6)
C80.0191 (9)0.0180 (9)0.0165 (8)−0.0013 (7)0.0030 (7)0.0022 (7)
C90.0188 (8)0.0160 (9)0.0151 (8)0.0017 (7)0.0062 (6)0.0007 (6)
C100.0174 (8)0.0161 (9)0.0138 (8)−0.0010 (7)0.0031 (6)−0.0017 (6)
C110.0194 (9)0.0211 (10)0.0160 (8)−0.0012 (7)0.0045 (7)0.0005 (7)
C120.0182 (9)0.0247 (10)0.0241 (9)0.0010 (7)0.0050 (7)−0.0018 (7)
C130.0240 (9)0.0201 (10)0.0207 (9)0.0026 (8)0.0009 (7)0.0004 (7)
C140.0305 (10)0.0237 (10)0.0190 (9)0.0008 (8)0.0084 (7)0.0045 (7)
C150.0201 (9)0.0221 (10)0.0208 (9)0.0007 (7)0.0086 (7)0.0017 (7)
C160.0277 (10)0.0180 (10)0.0204 (9)−0.0024 (7)0.0071 (7)−0.0016 (7)
C170.0223 (9)0.0121 (9)0.0212 (9)−0.0007 (7)0.0055 (7)−0.0018 (7)
C180.0200 (9)0.0151 (9)0.0246 (9)−0.0006 (7)0.0073 (7)−0.0025 (7)
C190.0234 (9)0.0183 (9)0.0221 (9)0.0041 (7)0.0055 (7)−0.0012 (7)
C200.0337 (11)0.0185 (10)0.0245 (9)0.0062 (8)0.0172 (8)0.0002 (7)
C210.0221 (9)0.0183 (10)0.0310 (10)0.0010 (7)0.0128 (8)−0.0031 (8)
C220.0219 (9)0.0167 (9)0.0232 (9)0.0005 (7)0.0046 (7)−0.0023 (7)
Geometric parameters (Å, °) top
Cl1—C201.7340 (19)C9—H90.9800
Cl2—C211.7339 (19)C11—C101.390 (2)
O—C91.429 (2)C11—C121.391 (3)
O—C161.434 (2)C11—H110.9300
N1—C11.363 (2)C12—C131.388 (3)
N1—C71.383 (2)C12—H120.9300
N1—C81.455 (2)C13—H130.9300
N2—C11.313 (3)C14—C131.388 (3)
N2—C21.393 (2)C14—H140.9300
C1—H10.9300C15—C101.394 (2)
C2—C31.392 (3)C15—C141.392 (3)
C2—C71.413 (2)C15—H150.9300
C3—C41.379 (3)C16—H16A0.9700
C3—H30.9300C16—H16B0.9700
C4—H40.9300C17—C161.516 (2)
C5—C41.403 (3)C18—C171.391 (2)
C5—H50.9300C18—H180.9300
C6—C51.393 (3)C19—C181.384 (3)
C6—H60.9300C19—C201.389 (3)
C7—C61.387 (3)C19—H190.9300
C8—H8A0.9700C21—C201.390 (3)
C8—H8B0.9700C22—C171.395 (3)
C9—C81.531 (2)C22—C211.389 (3)
C9—C101.518 (2)C22—H220.9300
C9—O—C16114.20 (14)C15—C10—C9121.13 (15)
C1—N1—C7106.09 (15)C10—C11—C12120.52 (17)
C1—N1—C8127.33 (15)C10—C11—H11119.7
C7—N1—C8126.25 (15)C12—C11—H11119.7
C1—N2—C2103.97 (15)C13—C12—C11120.07 (18)
N2—C1—N1114.69 (17)C13—C12—H12120.0
N2—C1—H1122.7C11—C12—H12120.0
N1—C1—H1122.7C14—C13—C12119.79 (17)
C3—C2—N2130.43 (17)C14—C13—H13120.1
C3—C2—C7119.48 (18)C12—C13—H13120.1
N2—C2—C7110.06 (16)C13—C14—C15120.10 (17)
C4—C3—C2118.26 (18)C13—C14—H14119.9
C4—C3—H3120.9C15—C14—H14119.9
C2—C3—H3120.9C14—C15—C10120.35 (17)
C3—C4—C5121.79 (18)C14—C15—H15119.8
C3—C4—H4119.1C10—C15—H15119.8
C5—C4—H4119.1O—C16—C17112.19 (14)
C6—C5—C4121.03 (19)O—C16—H16A109.2
C6—C5—H5119.5C17—C16—H16A109.2
C4—C5—H5119.5O—C16—H16B109.2
C7—C6—C5116.73 (17)C17—C16—H16B109.2
C7—C6—H6121.6H16A—C16—H16B107.9
C5—C6—H6121.6C18—C17—C22119.34 (17)
N1—C7—C6132.09 (16)C18—C17—C16120.09 (16)
N1—C7—C2105.19 (15)C22—C17—C16120.56 (16)
C6—C7—C2122.71 (17)C19—C18—C17120.66 (17)
N1—C8—C9111.26 (15)C19—C18—H18119.7
N1—C8—H8A109.4C17—C18—H18119.7
C9—C8—H8A109.4C18—C19—C20119.73 (17)
N1—C8—H8B109.4C18—C19—H19120.1
C9—C8—H8B109.4C20—C19—H19120.1
H8A—C8—H8B108.0C19—C20—C21120.17 (17)
O—C9—C10113.44 (13)C19—C20—Cl1118.70 (15)
O—C9—C8106.58 (14)C21—C20—Cl1121.12 (15)
C10—C9—C8110.51 (15)C22—C21—C20119.83 (17)
O—C9—H9108.7C22—C21—Cl2118.88 (14)
C10—C9—H9108.7C20—C21—Cl2121.27 (15)
C8—C9—H9108.7C21—C22—C17120.19 (17)
C11—C10—C15119.17 (16)C21—C22—H22119.9
C11—C10—C9119.64 (15)C17—C22—H22119.9
C16—O—C9—C1081.33 (18)O—C9—C10—C11−125.62 (17)
C16—O—C9—C8−156.82 (14)C8—C9—C10—C11114.75 (18)
C9—O—C16—C1761.95 (19)O—C9—C10—C1557.3 (2)
C2—N2—C1—N1−0.7 (2)C8—C9—C10—C15−62.3 (2)
C1—N2—C2—C3−177.7 (2)C10—C11—C12—C130.1 (3)
C1—N2—C2—C70.3 (2)C12—C11—C10—C15−0.1 (3)
C7—N1—C1—N20.9 (2)C12—C11—C10—C9−177.28 (17)
C8—N1—C1—N2174.54 (17)C11—C12—C13—C14−0.3 (3)
C1—N1—C7—C6178.1 (2)C15—C14—C13—C120.5 (3)
C8—N1—C7—C64.3 (3)C14—C15—C10—C110.3 (3)
C1—N1—C7—C2−0.58 (19)C14—C15—C10—C9177.43 (17)
C8—N1—C7—C2−174.36 (16)C10—C15—C14—C13−0.5 (3)
C1—N1—C8—C9−100.7 (2)C18—C17—C16—O46.3 (2)
C7—N1—C8—C971.8 (2)C22—C17—C16—O−132.13 (18)
N2—C2—C3—C4178.49 (19)C19—C18—C17—C222.0 (3)
C7—C2—C3—C40.6 (3)C19—C18—C17—C16−176.48 (17)
C3—C2—C7—N1178.44 (16)C20—C19—C18—C17−1.0 (3)
N2—C2—C7—N10.2 (2)C18—C19—C20—C21−1.4 (3)
C3—C2—C7—C6−0.4 (3)C18—C19—C20—Cl1177.45 (14)
N2—C2—C7—C6−178.63 (17)C22—C21—C20—C192.8 (3)
C2—C3—C4—C5−0.5 (3)Cl2—C21—C20—C19−178.87 (15)
C6—C5—C4—C30.0 (3)C22—C21—C20—Cl1−176.03 (15)
C7—C6—C5—C40.3 (3)Cl2—C21—C20—Cl12.3 (2)
N1—C7—C6—C5−178.58 (19)C21—C22—C17—C18−0.5 (3)
C2—C7—C6—C5−0.1 (3)C21—C22—C17—C16177.89 (17)
O—C9—C8—N162.89 (17)C17—C22—C21—C20−1.8 (3)
C10—C9—C8—N1−173.43 (14)C17—C22—C21—Cl2179.81 (14)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C3—H3···Cg3i0.932.873.583 (2)135
C8—H8A···Cg4ii0.972.713.670 (2)171
C13—H13···Cg2iii0.932.683.474 (2)144
C18—H18···Cg10.932.783.380 (2)124
Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) x, y−1, z; (iii) x+1/2, −y+1/2, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C3—H3···Cg3i0.932.873.583 (2)135
C8—H8A···Cg4ii0.972.713.670 (2)171
C13—H13···Cg2iii0.932.683.474 (2)144
C18—H18···Cg10.932.783.380 (2)124
Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) x, y−1, z; (iii) x+1/2, −y+1/2, z+1/2.
Acknowledgements top

The authors acknowledge the Zonguldak Karaelmas University Research Fund (grant No. 2004-13-02-16).

references
References top

Brammer, K. W. & Feczko, J. M. (1988). Antifungal Drugs, edited by V. St Georgiev, pp. 561–563. New York: NY Academy of Science.

Caira, M. R., Alkhamis, K. A. & Obaidat, R. M. (2004). J. Pharm. Sci. 93, 601–611.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.

Freer, A. A., Pearson, A. & Salole, E. G. (1986). Acta Cryst. C42, 1350–1352.

Hooft, R. W. W. (1998). COLLECT. Nonius BV, Delft, The Netherlands.

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.

Özel Güven, Ö., Erdoğan, T., Coles, S. J. & Hökelek, T. (2008a). Acta Cryst. E64, o1437.

Özel Güven, Ö., Erdoğan, T., Coles, S. J. & Hökelek, T. (2008b). Acta Cryst. E64, o1496–o1497.

Özel Güven, Ö., Erdoğan, T., Göker, H. & Yıldız, S. (2007a). Bioorg. Med. Chem. Lett. 17, 2233–2236.

Özel Güven, Ö., Erdoğan, T., Göker, H. & Yıldız, S. (2007b). J. Het. Chem. 44, 731–734.

Peeters, O. M., Blaton, N. M. & De Ranter, C. J. (1979a). Acta Cryst. B35, 2461–2464.

Peeters, O. M., Blaton, N. M. & De Ranter, C. J. (1979b). Bull. Soc. Chim. Belg. 88, 265–272.

Peeters, O. M., Blaton, N. M. & De Ranter, C. J. (1996). Acta Cryst. C52, 2225–2229.

Sheldrick, G. M. (2007). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

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

Song, H. & Shin, H.-S. (1998). Acta Cryst. C54, 1675–1677.

Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13.