Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807035544/cv2279sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807035544/cv2279Isup2.hkl |
CCDC reference: 657842
A mixture of 4-chloro-8-(trifluoromethyl)quinoline (2.31 g, 0.01 mol), 1-(4-aminophenyl)ethanone, (1.35 g, 0.01 mol) and anhydrous potassium carbonate (2.76 g 0.02 mol) in 30 ml of dimethyl formamide (DMF) was heated over water bath for 6 h. The resulting mixture was filtered and the solution was concentrated on water bath to get the title compound. The crystals were obtained from acetone by slow evapoaration (M.p. 509 K). Elemental analysis found: C: 65.36; H: 3.94; N: 8.41%. C18H13F3N2O requires C, 65.45, H, 3.97, N, 8.48%
Atom H2B was located on a difference map, but placed in idealized position, N—H = 0.87 Å. C-bound H atoms were geometrically positioned, C—H = 0.94–0.97 Å. All H-atoms were refined as riding, with Uiso(H) = 1.2–1.5 Ueq of the parent atom. In the absence of any significant anomalous scatters in the molecule, 1777 Friedel pairs were merged before the final refinement.
In recent years fluorinated compounds find much importance in the pharmaceutical field. Fluorinated compounds in general, fluorinated heterocycles in particular, are those focused on much in modern-day medicinal chemistry. Incorporation of a fluorine atom instead of hydrogen one can alter the course of the reaction as well as its biological activities. Further introduction of a fluorine atom as the CF3 group provides a more lipophilically and pharmacologically interesting compound compared to their non fluorinated analogues. The trifluoromethyl substituted compounds have been reported to possess biological activities as herbicides, fungicides and inhibitors for platelet aggregation. Quinolines are known to researchers for many years because a large number of natural products contain these heterocycles. They are found in numerous commericial products, including pharmaceuticals, fragrances and dyes. Quinoline alkaloids such as quinine, chloroquin, mefloquine and amodiaquine are used as efficient drugs for the treatment of malaria. Several quinoline derivatives have been evaluated in vitro against several parasites and HTLV-1 transformed cells. Prompted by the varied biological activities, the crystal structure of the title compound, C18H13F3N2O, (I), is here reported.
In (I) (Fig. 1), the mean planes of the quinolin-4-yl and phenyl-ethanone groups are twisted with a dihedral angle of 57.4 (1)°. In the crystal, intermolecular hydrogen bond interactions occur between N2–H2B and C5–H5A both to the same O1 (Table 1), which link the molecules into zigzag chains running in direction [011] (Fig. 2).
For related structures, see: Lynch & McClenaghan (2001); Yathirajan et al. (2007). For related literature, see: Kucukguzel et al. (2000); Jung et al. (2002); Franck et al. (2004).
Data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
C18H13F3N2O | Dx = 1.460 Mg m−3 |
Mr = 330.30 | Cu Kα radiation, λ = 1.54178 Å |
Orthorhombic, Pna21 | Cell parameters from 5931 reflections |
a = 24.4690 (6) Å | θ = 4.7–32.5° |
b = 4.5342 (2) Å | µ = 1.00 mm−1 |
c = 13.5408 (3) Å | T = 203 K |
V = 1502.32 (8) Å3 | Chunk, pale yellow |
Z = 4 | 0.46 × 0.37 × 0.25 mm |
F(000) = 680 |
Oxford Diffraction Gemini R diffractometer | 1777 independent reflections |
Radiation source: fine-focus sealed tube | 1657 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.017 |
Detector resolution: 10.5081 pixels mm-1 | θmax = 87.8°, θmin = 10.3° |
φ and ω scans | h = −31→23 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | k = −5→5 |
Tmin = 0.909, Tmax = 1.000 | l = −17→17 |
8038 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.076 | H-atom parameters constrained |
S = 1.18 | w = 1/[σ2(Fo2) + (0.0428P)2 + 0.1154P] where P = (Fo2 + 2Fc2)/3 |
1777 reflections | (Δ/σ)max = 0.010 |
218 parameters | Δρmax = 0.16 e Å−3 |
0 restraints | Δρmin = −0.14 e Å−3 |
C18H13F3N2O | V = 1502.32 (8) Å3 |
Mr = 330.30 | Z = 4 |
Orthorhombic, Pna21 | Cu Kα radiation |
a = 24.4690 (6) Å | µ = 1.00 mm−1 |
b = 4.5342 (2) Å | T = 203 K |
c = 13.5408 (3) Å | 0.46 × 0.37 × 0.25 mm |
Oxford Diffraction Gemini R diffractometer | 1777 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007) | 1657 reflections with I > 2σ(I) |
Tmin = 0.909, Tmax = 1.000 | Rint = 0.017 |
8038 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.076 | H-atom parameters constrained |
S = 1.18 | Δρmax = 0.16 e Å−3 |
1777 reflections | Δρmin = −0.14 e Å−3 |
218 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
F1 | 0.12637 (5) | 0.0249 (3) | 0.31930 (11) | 0.0505 (3) | |
F2 | 0.13325 (5) | −0.3655 (3) | 0.23050 (13) | 0.0542 (4) | |
F3 | 0.14003 (5) | 0.0597 (3) | 0.16310 (11) | 0.0522 (4) | |
O1 | −0.30621 (6) | −0.7599 (4) | 0.62756 (11) | 0.0519 (4) | |
N1 | 0.03926 (6) | −0.4026 (4) | 0.35402 (12) | 0.0316 (3) | |
N2 | −0.13031 (6) | −0.4360 (4) | 0.29863 (11) | 0.0368 (4) | |
H2B | −0.1408 | −0.3692 | 0.2414 | 0.044* | |
C1 | 0.00518 (8) | −0.5549 (5) | 0.40932 (15) | 0.0331 (4) | |
H1A | 0.0203 | −0.6616 | 0.4622 | 0.040* | |
C2 | −0.05134 (8) | −0.5721 (4) | 0.39652 (14) | 0.0321 (4) | |
H2A | −0.0727 | −0.6860 | 0.4398 | 0.038* | |
C3 | −0.07551 (7) | −0.4197 (4) | 0.31947 (13) | 0.0284 (4) | |
C4 | −0.04056 (7) | −0.2480 (4) | 0.25738 (12) | 0.0259 (3) | |
C5 | −0.06027 (8) | −0.0777 (4) | 0.17722 (14) | 0.0323 (4) | |
H5A | −0.0980 | −0.0719 | 0.1643 | 0.039* | |
C6 | −0.02561 (9) | 0.0770 (5) | 0.11878 (15) | 0.0375 (5) | |
H6A | −0.0395 | 0.1882 | 0.0658 | 0.045* | |
C7 | 0.03120 (8) | 0.0723 (5) | 0.13691 (15) | 0.0356 (4) | |
H7A | 0.0549 | 0.1796 | 0.0958 | 0.043* | |
C8 | 0.05185 (8) | −0.0878 (4) | 0.21401 (14) | 0.0306 (4) | |
C9 | 0.01659 (7) | −0.2505 (4) | 0.27749 (13) | 0.0266 (3) | |
C10 | 0.11244 (8) | −0.0927 (4) | 0.23199 (18) | 0.0373 (4) | |
C11 | −0.17126 (7) | −0.5504 (5) | 0.36096 (13) | 0.0316 (4) | |
C12 | −0.21175 (7) | −0.7282 (5) | 0.32065 (14) | 0.0357 (4) | |
H12A | −0.2103 | −0.7796 | 0.2535 | 0.043* | |
C13 | −0.25430 (8) | −0.8302 (5) | 0.37915 (14) | 0.0348 (4) | |
H13A | −0.2815 | −0.9505 | 0.3514 | 0.042* | |
C14 | −0.25686 (7) | −0.7552 (5) | 0.47883 (15) | 0.0314 (4) | |
C15 | −0.21584 (7) | −0.5776 (5) | 0.51915 (13) | 0.0363 (4) | |
H15A | −0.2171 | −0.5275 | 0.5865 | 0.044* | |
C16 | −0.17363 (8) | −0.4753 (5) | 0.46115 (14) | 0.0371 (5) | |
H16A | −0.1464 | −0.3549 | 0.4889 | 0.045* | |
C17 | −0.30242 (7) | −0.8529 (5) | 0.54293 (15) | 0.0367 (4) | |
C18 | −0.34396 (9) | −1.0632 (6) | 0.50333 (19) | 0.0498 (6) | |
H18A | −0.3709 | −1.1050 | 0.5540 | 0.075* | |
H18B | −0.3261 | −1.2450 | 0.4838 | 0.075* | |
H18C | −0.3619 | −0.9762 | 0.4465 | 0.075* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.0364 (6) | 0.0521 (8) | 0.0630 (8) | −0.0090 (6) | −0.0096 (6) | −0.0003 (7) |
F2 | 0.0363 (6) | 0.0363 (6) | 0.0902 (10) | 0.0073 (5) | 0.0131 (7) | 0.0046 (8) |
F3 | 0.0365 (6) | 0.0493 (7) | 0.0707 (9) | −0.0057 (6) | 0.0151 (6) | 0.0126 (7) |
O1 | 0.0369 (7) | 0.0842 (13) | 0.0346 (7) | −0.0088 (8) | 0.0094 (6) | 0.0041 (8) |
N1 | 0.0266 (7) | 0.0337 (8) | 0.0346 (8) | −0.0006 (7) | −0.0037 (6) | 0.0004 (7) |
N2 | 0.0250 (7) | 0.0607 (12) | 0.0246 (8) | −0.0036 (7) | −0.0007 (6) | 0.0070 (8) |
C1 | 0.0324 (8) | 0.0370 (11) | 0.0301 (8) | 0.0016 (8) | −0.0053 (8) | 0.0037 (8) |
C2 | 0.0318 (8) | 0.0368 (10) | 0.0276 (8) | −0.0053 (8) | 0.0001 (7) | 0.0035 (8) |
C3 | 0.0258 (8) | 0.0363 (10) | 0.0232 (7) | −0.0007 (7) | −0.0005 (7) | −0.0040 (8) |
C4 | 0.0274 (7) | 0.0279 (8) | 0.0223 (7) | 0.0012 (7) | 0.0000 (6) | −0.0042 (7) |
C5 | 0.0296 (8) | 0.0367 (10) | 0.0305 (9) | 0.0037 (8) | −0.0017 (7) | 0.0007 (8) |
C6 | 0.0414 (10) | 0.0376 (11) | 0.0334 (9) | 0.0051 (9) | 0.0007 (8) | 0.0077 (9) |
C7 | 0.0377 (9) | 0.0329 (10) | 0.0363 (10) | −0.0010 (8) | 0.0079 (8) | 0.0048 (8) |
C8 | 0.0302 (8) | 0.0265 (9) | 0.0353 (9) | −0.0006 (7) | 0.0043 (7) | −0.0042 (8) |
C9 | 0.0280 (7) | 0.0249 (8) | 0.0269 (8) | 0.0007 (7) | 0.0014 (7) | −0.0044 (7) |
C10 | 0.0299 (9) | 0.0296 (9) | 0.0524 (12) | −0.0012 (8) | 0.0052 (9) | 0.0014 (10) |
C11 | 0.0226 (8) | 0.0461 (11) | 0.0259 (8) | −0.0003 (8) | 0.0007 (7) | 0.0017 (8) |
C12 | 0.0301 (8) | 0.0528 (12) | 0.0243 (8) | −0.0030 (9) | 0.0002 (7) | −0.0027 (8) |
C13 | 0.0286 (8) | 0.0432 (11) | 0.0326 (9) | −0.0044 (8) | −0.0027 (7) | −0.0018 (8) |
C14 | 0.0235 (7) | 0.0407 (10) | 0.0299 (8) | 0.0020 (8) | 0.0010 (7) | 0.0044 (8) |
C15 | 0.0292 (9) | 0.0555 (13) | 0.0241 (8) | −0.0024 (9) | 0.0008 (7) | −0.0027 (8) |
C16 | 0.0284 (9) | 0.0527 (13) | 0.0303 (10) | −0.0077 (9) | −0.0006 (7) | −0.0050 (9) |
C17 | 0.0272 (8) | 0.0476 (11) | 0.0352 (10) | 0.0037 (8) | 0.0010 (8) | 0.0107 (9) |
C18 | 0.0384 (10) | 0.0592 (15) | 0.0518 (13) | −0.0143 (11) | 0.0038 (10) | 0.0103 (11) |
F1—C10 | 1.341 (3) | C7—C8 | 1.368 (3) |
F2—C10 | 1.338 (2) | C7—H7A | 0.9400 |
F3—C10 | 1.343 (2) | C8—C9 | 1.424 (3) |
O1—C17 | 1.225 (3) | C8—C10 | 1.502 (3) |
N1—C1 | 1.316 (3) | C11—C12 | 1.389 (3) |
N1—C9 | 1.363 (2) | C11—C16 | 1.400 (3) |
N2—C3 | 1.372 (2) | C12—C13 | 1.388 (3) |
N2—C11 | 1.409 (2) | C12—H12A | 0.9400 |
N2—H2B | 0.8700 | C13—C14 | 1.393 (3) |
C1—C2 | 1.396 (3) | C13—H13A | 0.9400 |
C1—H1A | 0.9400 | C14—C15 | 1.398 (3) |
C2—C3 | 1.384 (3) | C14—C17 | 1.480 (3) |
C2—H2A | 0.9400 | C15—C16 | 1.378 (3) |
C3—C4 | 1.430 (2) | C15—H15A | 0.9400 |
C4—C5 | 1.417 (3) | C16—H16A | 0.9400 |
C4—C9 | 1.425 (2) | C17—C18 | 1.493 (3) |
C5—C6 | 1.356 (3) | C18—H18A | 0.9700 |
C5—H5A | 0.9400 | C18—H18B | 0.9700 |
C6—C7 | 1.412 (3) | C18—H18C | 0.9700 |
C6—H6A | 0.9400 | ||
C1—N1—C9 | 116.11 (15) | F2—C10—F3 | 105.89 (16) |
C3—N2—C11 | 126.27 (15) | F1—C10—F3 | 106.28 (15) |
C3—N2—H2B | 116.9 | F2—C10—C8 | 112.74 (16) |
C11—N2—H2B | 116.9 | F1—C10—C8 | 112.83 (17) |
N1—C1—C2 | 125.90 (18) | F3—C10—C8 | 112.08 (18) |
N1—C1—H1A | 117.0 | C12—C11—C16 | 119.50 (18) |
C2—C1—H1A | 117.0 | C12—C11—N2 | 119.05 (16) |
C3—C2—C1 | 119.27 (17) | C16—C11—N2 | 121.36 (18) |
C3—C2—H2A | 120.4 | C13—C12—C11 | 120.28 (17) |
C1—C2—H2A | 120.4 | C13—C12—H12A | 119.9 |
N2—C3—C2 | 123.06 (17) | C11—C12—H12A | 119.9 |
N2—C3—C4 | 119.53 (16) | C12—C13—C14 | 120.37 (19) |
C2—C3—C4 | 117.36 (16) | C12—C13—H13A | 119.8 |
C5—C4—C9 | 119.01 (15) | C14—C13—H13A | 119.8 |
C5—C4—C3 | 122.93 (15) | C13—C14—C15 | 119.11 (18) |
C9—C4—C3 | 118.06 (15) | C13—C14—C17 | 121.93 (18) |
C6—C5—C4 | 121.08 (17) | C15—C14—C17 | 118.95 (18) |
C6—C5—H5A | 119.5 | C16—C15—C14 | 120.64 (17) |
C4—C5—H5A | 119.5 | C16—C15—H15A | 119.7 |
C5—C6—C7 | 120.45 (19) | C14—C15—H15A | 119.7 |
C5—C6—H6A | 119.8 | C15—C16—C11 | 120.10 (18) |
C7—C6—H6A | 119.8 | C15—C16—H16A | 120.0 |
C8—C7—C6 | 120.29 (18) | C11—C16—H16A | 120.0 |
C8—C7—H7A | 119.9 | O1—C17—C14 | 120.18 (19) |
C6—C7—H7A | 119.9 | O1—C17—C18 | 120.28 (19) |
C7—C8—C9 | 120.77 (17) | C14—C17—C18 | 119.54 (19) |
C7—C8—C10 | 119.72 (17) | C17—C18—H18A | 109.5 |
C9—C8—C10 | 119.51 (18) | C17—C18—H18B | 109.5 |
N1—C9—C4 | 123.29 (16) | H18A—C18—H18B | 109.5 |
N1—C9—C8 | 118.32 (16) | C17—C18—H18C | 109.5 |
C4—C9—C8 | 118.38 (16) | H18A—C18—H18C | 109.5 |
F2—C10—F1 | 106.50 (18) | H18B—C18—H18C | 109.5 |
C9—N1—C1—C2 | −0.3 (3) | C7—C8—C9—C4 | 1.5 (3) |
N1—C1—C2—C3 | 0.2 (3) | C10—C8—C9—C4 | −178.49 (16) |
C11—N2—C3—C2 | 14.5 (3) | C7—C8—C10—F2 | −122.3 (2) |
C11—N2—C3—C4 | −168.10 (19) | C9—C8—C10—F2 | 57.6 (3) |
C1—C2—C3—N2 | 176.70 (19) | C7—C8—C10—F1 | 117.0 (2) |
C1—C2—C3—C4 | −0.8 (3) | C9—C8—C10—F1 | −63.1 (2) |
N2—C3—C4—C5 | 3.6 (3) | C7—C8—C10—F3 | −2.9 (3) |
C2—C3—C4—C5 | −178.81 (18) | C9—C8—C10—F3 | 177.01 (16) |
N2—C3—C4—C9 | −176.21 (17) | C3—N2—C11—C12 | −137.8 (2) |
C2—C3—C4—C9 | 1.4 (2) | C3—N2—C11—C16 | 45.8 (3) |
C9—C4—C5—C6 | 1.3 (3) | C16—C11—C12—C13 | 0.1 (3) |
C3—C4—C5—C6 | −178.56 (19) | N2—C11—C12—C13 | −176.3 (2) |
C4—C5—C6—C7 | −0.2 (3) | C11—C12—C13—C14 | 0.0 (3) |
C5—C6—C7—C8 | −0.3 (3) | C12—C13—C14—C15 | −0.4 (3) |
C6—C7—C8—C9 | −0.4 (3) | C12—C13—C14—C17 | 178.27 (19) |
C6—C7—C8—C10 | 179.56 (19) | C13—C14—C15—C16 | 0.6 (3) |
C1—N1—C9—C4 | 0.9 (3) | C17—C14—C15—C16 | −178.1 (2) |
C1—N1—C9—C8 | −178.53 (18) | C14—C15—C16—C11 | −0.4 (3) |
C5—C4—C9—N1 | 178.66 (18) | C12—C11—C16—C15 | 0.1 (3) |
C3—C4—C9—N1 | −1.5 (2) | N2—C11—C16—C15 | 176.5 (2) |
C5—C4—C9—C8 | −1.9 (2) | C13—C14—C17—O1 | −172.9 (2) |
C3—C4—C9—C8 | 177.96 (17) | C15—C14—C17—O1 | 5.8 (3) |
C7—C8—C9—N1 | −179.05 (18) | C13—C14—C17—C18 | 6.5 (3) |
C10—C8—C9—N1 | 1.0 (3) | C15—C14—C17—C18 | −174.8 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2B···O1i | 0.87 | 2.08 | 2.901 (2) | 158 |
C5—H5A···O1i | 0.94 | 2.54 | 3.436 (2) | 159 |
Symmetry code: (i) −x−1/2, y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C18H13F3N2O |
Mr | 330.30 |
Crystal system, space group | Orthorhombic, Pna21 |
Temperature (K) | 203 |
a, b, c (Å) | 24.4690 (6), 4.5342 (2), 13.5408 (3) |
V (Å3) | 1502.32 (8) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 1.00 |
Crystal size (mm) | 0.46 × 0.37 × 0.25 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini R |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2007) |
Tmin, Tmax | 0.909, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8038, 1777, 1657 |
Rint | 0.017 |
(sin θ/λ)max (Å−1) | 0.648 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.076, 1.18 |
No. of reflections | 1777 |
No. of parameters | 218 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.16, −0.14 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2007), CrysAlis PRO, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2B···O1i | 0.87 | 2.08 | 2.901 (2) | 158.2 |
C5—H5A···O1i | 0.94 | 2.54 | 3.436 (2) | 158.8 |
Symmetry code: (i) −x−1/2, y+1/2, z−1/2. |
In recent years fluorinated compounds find much importance in the pharmaceutical field. Fluorinated compounds in general, fluorinated heterocycles in particular, are those focused on much in modern-day medicinal chemistry. Incorporation of a fluorine atom instead of hydrogen one can alter the course of the reaction as well as its biological activities. Further introduction of a fluorine atom as the CF3 group provides a more lipophilically and pharmacologically interesting compound compared to their non fluorinated analogues. The trifluoromethyl substituted compounds have been reported to possess biological activities as herbicides, fungicides and inhibitors for platelet aggregation. Quinolines are known to researchers for many years because a large number of natural products contain these heterocycles. They are found in numerous commericial products, including pharmaceuticals, fragrances and dyes. Quinoline alkaloids such as quinine, chloroquin, mefloquine and amodiaquine are used as efficient drugs for the treatment of malaria. Several quinoline derivatives have been evaluated in vitro against several parasites and HTLV-1 transformed cells. Prompted by the varied biological activities, the crystal structure of the title compound, C18H13F3N2O, (I), is here reported.
In (I) (Fig. 1), the mean planes of the quinolin-4-yl and phenyl-ethanone groups are twisted with a dihedral angle of 57.4 (1)°. In the crystal, intermolecular hydrogen bond interactions occur between N2–H2B and C5–H5A both to the same O1 (Table 1), which link the molecules into zigzag chains running in direction [011] (Fig. 2).