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Acta Crystallogr Sect E Struct Rep Online. 2008 February 1; 64(Pt 2): o538.
Published online 2008 January 30. doi:  10.1107/S1600536808002602
PMCID: PMC2960364

Racemic 1,2,3,4,7,8,9,10-octa­fluoro-6H,12H-5,11-methano­dibenzo[b,f][1,5]diazo­cine: an octa­fluorinated analogue of Tröger’s base

Abstract

The title compound, C15H6F8N2, possesses a non-crystal­lographic twofold axis. The dihedral angle between the two benzene rings is 98.4 (2)°. The crystal structure involves intermolecular C—H(...)F hydrogen bonds.

Related literature

For recent reviews on the chemistry of Tröger’s base (Tröger, 1887 [triangle]; Spielman, 1935 [triangle]), see: Valík et al. (2005 [triangle]) and Dolensky et al. (2007 [triangle]). For related literature on the chirality of Tröger’s base, see: Prelog & Wieland (1944 [triangle]); for mol­ecular clefts, see: Wilcox et al. (1987 [triangle]) and Artacho et al. (2006 [triangle]) and references cited therein; for (poly)halo-substituted Tröger’s base analogues, see: Jensen & Wärnmark (2001 [triangle]), Sergeyev & Diederich (2004 [triangle]), Hansson et al. (2003 [triangle]), Li et al. (2005 [triangle]) and Faroughi et al. (2006 [triangle]). For related literature, see: Zabrodsky et al. (1993 [triangle]).

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Object name is e-64-0o538-scheme1.jpg

Experimental

Crystal data

  • C15H6F8N2
  • M r = 366.22
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o538-efi1.jpg
  • a = 8.075 (3) Å
  • b = 10.469 (2) Å
  • c = 17.628 (6) Å
  • β = 117.15 (2)°
  • V = 1326.0 (8) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.19 mm−1
  • T = 290 (1) K
  • 0.3 × 0.2 × 0.2 mm

Data collection

  • Enraf–Nonius MACH3 diffractometer
  • Absorption correction: none
  • 5028 measured reflections
  • 2412 independent reflections
  • 1353 reflections with I > 2σ(I)
  • R int = 0.078
  • 3 standard reflections every 73 reflections intensity decay: 4%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.044
  • wR(F 2) = 0.128
  • S = 1.03
  • 2412 reflections
  • 251 parameters
  • All H-atom parameters refined
  • Δρmax = 0.20 e Å−3
  • Δρmin = −0.25 e Å−3

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 [triangle]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]) and PLATON (Spek, 2003 [triangle]).

Table 1
C—H (...) F contacts (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808002602/pk2080sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808002602/pk2080Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

S. Sergeyev is grateful to Professor Y. Geerts (Université Libre de Bruxelles) for the opportunity to conduct an independent research programme in his laboratory and for generous financial support.

supplementary crystallographic information

Comment

1,2,3,4,7,8,9,10-Octafluoro-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine is a fluorinated derivative of Tröger's base (Tröger, 1887; Spielman, 1935), a polycyclic diamine which is chiral due to severely hindered inversion at the bridgehead N-atoms (Prelog & Wieland, 1944). For recent reviews on its chemistry, see Valík et al. (2005) and Dolensky et al. (2007). Recently, a considerable interest has developed in relatively unfunctionalized receptors with concave aromatic surfaces (termed molecular clefts or tweezers). Wilcox et al. (1987) pioneered the incorporation of the Tröger's base framework in chiral molecular clefts by fusing the methanodiazocine core of Tröger's base with two bicyclic aromatic building blocks. Later, molecular clefts comprising two or three fused methanodiazocine cores have been reported (Artacho et al., 2006, and references cited therein). Our interest in the title compound was raised due to the prospect of using highly fluorinated aromatic systems in the design of molecular clefts, thus providing a possibility to explore different supramolecular interactions.

Synthesis of halo-derivatives of Tröger's base was pioneered by Wärnmark (Jensen & Wärnmark, 2001). Later, a number of fluoro-, chloro-, bromo-, and iodo-derivatives of Tröger's base, with the halogen atoms in different positions on the aromatic rings were reported (Sergeyev & Diederich, 2004 and Hansson et al., 2003). However, they typically contain only one halogen atom on each aromatic ring of the methanodiazocine skeleton. Exceptions are the recently reported 2,4,8,10-tetrafluoro- (Li et al., 2005) and tetrabromo-analogs (Faroughi et al., 2006) of Tröger's base. However, polyhalo-analogs of Tröger's base such as the octafluoro analog presented here are unprecedented. To the best of our knowledge, no X-ray crystal structure of a Tröger's base analog with fluorine in the aromatic ring has been reported.

The racemic octafluoro analog of Tröger's base crystallizes in the centrosymmetric space group P21/c with one molecule in the asymmetric unit. The molecule has a non-crystallographic twofold symmetry axis through the bridging carbon C13. The CSM (Continuous Symmetry Measure) is 0.0183 (Zabrodsky et al., 1993). Bond lengths and angles are within expectations. TLS analysis returns quasi-isotropic values for the librational amplitudes, and the values for the resulting corrections of the bond lengths are all below the 2σ level. The dihedral angle between the two benzene rings is 98.4 (2)°, which lies within the normal range for analogs of Tröger's base (Dolensky et al., 2007). Cohesion in the structure appears to be mainly provided by aromatic π-π interactions between the fluorinated benzene rings, leading to pairwise ordering of enantiomers around the centers of inversion, with an interplanar distance of under 4 Å. The most clear examples of this in the structure are Cg(2)···Cg(2)i (i=-x,1 - y,1 - z), 3.713 (2) Å, 3.476 (3)Å perp., with a slippage of 1.305 (3) Å, and Cg(1) ··· Cg(1)ii (ii=1 - x,-y,1 - z), 4.805 (2) Å, 3.538 (3)Å perp., with a slippage of 3.251 (3) Å. Cg(x) indicates the centroid of benzene ring x, perp. indicates the perpendicular distance between the ring planes. Due to the lack of suitable hydrogen bond donors, the N-atoms display no close contacts whatsoever. There are a number of F-π contacts in the structure, e.g. F(3)···Cg(2)ii 3.672 (3) Å, C3—F3···Cg(2)ii 161.7 (2)°. Also, H—F contacts occur that are substantially shorter than the van der Waals radii, but these are not usually understood as hydrogen bonds. They are given in Table 1.

Experimental

2,3,4,5-Tetrafluoroaniline (330 mg, 2 mmol) and paraformaldehyde (120 mg, 4 mmol) were added under vigorous stirring to CF3COOH (4 ml) at -15°C. The resulting mixture was allowed to reach room temperature and stirred for 14 days, then slowly added to a stirred mixture of ice and 30% aqueous NH3 (7 ml). Extraction with CH2Cl2 (2 x 20 ml), drying of the organic layer over MgSO4, and removal of the solvent in vacuo gave a crude product which was purified by flash chromatography (SiO2/CH2Cl2). Yield of the title compound: 135 mg (37%). Crystals suitable for X-ray diffraction were grown by slow evaporation from CHCl3 solution.

1H NMR (300 MHz, CDCl3, 25°C): d = 4.20–4.30 (m, 4H, H61, H62, H121, H122), 4.50 (d, J = 17.5 Hz, 2H, H131, H132); 13C NMR (75 MHz, CDCl3, 25°C): d = 50.1, 66.5, 111.9 (ddt, J =17.7, 3.4, 1.7 Hz), 130.8 (dddd, J = 10.6, 5.2, 3.7, 1.9 Hz), 137.3 (dddd, J = 252.0, 16.5, 13.0, 3.1 Hz), 140.2 (dddd, J = 251.3, 14.9, 13.0, 5.0 Hz), 141.7 (dddd, J = 248.2, 11.2, 4.1, 1.3 Hz), 144.0 (ddt, J = 245.2, 10.9, 3.7 Hz). HR—EI—MS: m/z: calcd. for C15H6F8N2 ([M]+): 366.0403; found: 366.0405.

Refinement

Hydrogen atoms were located in the Fourier difference map and refined freely. (C—H 0.93 (3)–1.03 (3) Å)

Figures

Fig. 1.
View of the structure with 50% probability displacement ellipsoids. H atoms are numbered according to their attached C-atoms.
Fig. 2.
View of the unit cell down the b axis.

Crystal data

C15H6F8N2Dx = 1.834 Mg m3
Mr = 366.22Melting point: 192(1) K
Monoclinic, P21/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 8.075 (3) Åθ = 5–12º
b = 10.469 (2) ŵ = 0.19 mm1
c = 17.628 (6) ÅT = 290 (1) K
β = 117.15 (2)ºCell measurement pressure: 101(1) kPa
V = 1326.0 (8) Å3Rhomb, colourless
Z = 40.3 × 0.2 × 0.2 mm
F000 = 728

Data collection

Enraf–Nonius MACH3 diffractometerRint = 0.078
Radiation source: sealed tubeθmax = 25.3º
Monochromator: pyrolytic graphiteθmin = 2.3º
T = 290(1) Kh = 0→9
P = 101(1) kPak = −12→12
profiled ω/2θ scansl = −21→18
Absorption correction: none3 standard reflections
5028 measured reflections every 73 reflections
2412 independent reflections intensity decay: 4%
1353 reflections with I > 2σ(I)

Refinement

Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullAll H-atom parameters refined
R[F2 > 2σ(F2)] = 0.044  w = 1/[σ2(Fo2) + (0.06P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.128(Δ/σ)max < 0.001
S = 1.03Δρmax = 0.20 e Å3
2412 reflectionsΔρmin = −0.25 e Å3
251 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.008 (2)
Secondary atom site location: difference Fourier map

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
H131−0.193 (4)0.216 (3)0.8025 (17)0.051 (8)*
H1210.305 (4)0.121 (3)0.810 (2)0.069 (9)*
H1220.136 (5)0.176 (3)0.726 (2)0.077 (10)*
H62−0.105 (5)0.310 (3)0.9326 (17)0.057 (9)*
H132−0.111 (4)0.269 (3)0.741 (2)0.060 (9)*
H610.092 (4)0.374 (3)0.9788 (19)0.053 (9)*
F70.1474 (3)0.21118 (18)1.10195 (11)0.0715 (6)
F100.2539 (3)−0.08189 (16)0.87533 (11)0.0699 (6)
F10.5029 (3)0.29145 (19)0.78363 (12)0.0679 (6)
F90.3839 (3)−0.15905 (16)1.03755 (11)0.0729 (6)
N110.0509 (3)0.1395 (2)0.81513 (13)0.0506 (6)
F80.3308 (3)−0.01382 (19)1.15148 (10)0.0730 (6)
C12A0.2581 (4)0.3151 (3)0.81963 (16)0.0467 (7)
F40.1600 (3)0.58222 (17)0.92368 (14)0.0845 (7)
F30.4753 (3)0.66558 (18)0.92211 (15)0.0919 (7)
C10A0.1288 (4)0.1067 (3)0.90262 (15)0.0417 (6)
C90.2933 (4)−0.0464 (3)1.01318 (17)0.0489 (7)
F20.6451 (3)0.5220 (2)0.85025 (14)0.0852 (6)
C70.1727 (4)0.1397 (3)1.04471 (16)0.0471 (7)
N5−0.0035 (3)0.3514 (2)0.85287 (15)0.0570 (7)
C4A0.1674 (4)0.3903 (3)0.85490 (17)0.0488 (7)
C10.4148 (4)0.3626 (3)0.81791 (18)0.0510 (8)
C80.2668 (4)0.0260 (3)1.07054 (16)0.0491 (7)
C100.2252 (4)−0.0074 (3)0.93048 (16)0.0450 (7)
C6A0.1055 (4)0.1831 (3)0.96176 (17)0.0460 (7)
C13−0.0834 (5)0.2423 (4)0.7960 (2)0.0611 (9)
C20.4898 (4)0.4799 (3)0.8519 (2)0.0583 (8)
C40.2450 (5)0.5081 (3)0.88958 (18)0.0584 (8)
C30.4040 (5)0.5512 (3)0.8886 (2)0.0616 (9)
C60.0168 (5)0.3137 (3)0.9374 (2)0.0577 (9)
C120.1908 (5)0.1805 (3)0.78815 (19)0.0530 (8)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
F70.1095 (15)0.0648 (11)0.0538 (10)0.0031 (11)0.0490 (11)−0.0071 (9)
F100.1081 (15)0.0474 (10)0.0537 (10)0.0049 (10)0.0364 (10)−0.0103 (8)
F10.0709 (12)0.0683 (12)0.0764 (12)0.0122 (10)0.0440 (10)0.0101 (10)
F90.0981 (15)0.0433 (10)0.0660 (12)0.0137 (10)0.0276 (10)0.0114 (9)
N110.0534 (14)0.0571 (16)0.0335 (12)0.0002 (13)0.0130 (10)0.0035 (11)
F80.1033 (15)0.0666 (12)0.0379 (9)0.0000 (11)0.0224 (9)0.0098 (9)
C12A0.0484 (17)0.0506 (16)0.0352 (14)0.0092 (14)0.0139 (12)0.0113 (13)
F40.1074 (17)0.0539 (11)0.1061 (16)0.0224 (11)0.0607 (14)−0.0004 (11)
F30.1082 (17)0.0477 (11)0.1105 (17)−0.0089 (12)0.0419 (14)−0.0055 (12)
C10A0.0435 (15)0.0430 (14)0.0348 (14)−0.0044 (13)0.0144 (12)0.0002 (12)
C90.0557 (17)0.0351 (15)0.0481 (16)0.0008 (14)0.0170 (14)0.0039 (13)
F20.0694 (13)0.0731 (13)0.1142 (16)−0.0077 (11)0.0429 (12)0.0129 (12)
C70.0589 (18)0.0477 (17)0.0397 (15)−0.0058 (15)0.0268 (13)−0.0068 (13)
N50.0536 (15)0.0572 (15)0.0577 (15)0.0156 (14)0.0233 (12)0.0161 (13)
C4A0.0512 (17)0.0468 (17)0.0455 (16)0.0137 (15)0.0195 (14)0.0172 (14)
C10.0523 (17)0.0547 (19)0.0478 (16)0.0145 (16)0.0244 (14)0.0120 (14)
C80.0609 (18)0.0467 (16)0.0316 (14)−0.0078 (15)0.0140 (13)0.0058 (13)
C100.0570 (17)0.0389 (15)0.0376 (14)−0.0047 (14)0.0201 (13)−0.0074 (13)
C6A0.0489 (17)0.0457 (16)0.0443 (15)0.0000 (13)0.0220 (13)0.0014 (13)
C130.0468 (19)0.078 (2)0.0480 (19)0.0021 (17)0.0123 (15)0.0164 (18)
C20.0519 (19)0.0541 (18)0.067 (2)0.0070 (16)0.0250 (16)0.0183 (16)
C40.072 (2)0.0476 (18)0.0587 (19)0.0222 (17)0.0330 (17)0.0108 (16)
C30.067 (2)0.0402 (17)0.067 (2)0.0048 (16)0.0217 (17)0.0091 (15)
C60.058 (2)0.058 (2)0.064 (2)0.0141 (17)0.0335 (18)0.0116 (17)
C120.063 (2)0.0587 (19)0.0358 (15)0.0005 (16)0.0215 (15)0.0011 (14)

Geometric parameters (Å, °)

F7—C71.345 (3)F2—C21.342 (3)
F10—C101.347 (3)C7—C81.373 (4)
F1—C11.348 (3)C7—C6A1.384 (4)
F9—C91.350 (3)N5—C4A1.423 (4)
N11—C10A1.417 (3)N5—C131.461 (4)
N11—C131.454 (4)N5—C61.476 (4)
N11—C121.476 (4)C4A—C41.393 (5)
F8—C81.343 (3)C1—C21.380 (5)
C12A—C11.372 (4)C6A—C61.513 (4)
C12A—C4A1.400 (4)C13—H1310.98 (3)
C12A—C121.520 (4)C13—H1320.93 (3)
F4—C41.346 (3)C2—C31.365 (5)
F3—C31.343 (4)C4—C31.368 (5)
C10A—C101.387 (4)C6—H620.95 (3)
C10A—C6A1.393 (4)C6—H610.95 (3)
C9—C81.357 (4)C12—H1211.03 (3)
C9—C101.365 (4)C12—H1220.98 (3)
C10A—N11—C13110.2 (2)C7—C6A—C10A118.7 (3)
C10A—N11—C12113.3 (2)C7—C6A—C6120.2 (3)
C13—N11—C12108.1 (3)C10A—C6A—C6121.0 (3)
C1—C12A—C4A118.7 (3)N11—C13—N5111.7 (2)
C1—C12A—C12120.5 (3)N11—C13—H131112.5 (18)
C4A—C12A—C12120.7 (3)N5—C13—H131106.2 (17)
C10—C10A—C6A118.3 (2)N11—C13—H132105.1 (19)
C10—C10A—N11119.5 (2)N5—C13—H132107 (2)
C6A—C10A—N11122.1 (3)H131—C13—H132114 (3)
F9—C9—C8119.9 (3)F2—C2—C3120.8 (3)
F9—C9—C10119.8 (3)F2—C2—C1120.8 (3)
C8—C9—C10120.3 (3)C3—C2—C1118.4 (3)
F7—C7—C8119.0 (2)F4—C4—C3119.3 (3)
F7—C7—C6A119.3 (3)F4—C4—C4A119.2 (3)
C8—C7—C6A121.7 (3)C3—C4—C4A121.6 (3)
C4A—N5—C13111.1 (3)F3—C3—C2119.2 (3)
C4A—N5—C6113.0 (2)F3—C3—C4120.3 (3)
C13—N5—C6107.1 (3)C2—C3—C4120.5 (3)
C4—C4A—C12A118.1 (3)N5—C6—C6A110.4 (3)
C4—C4A—N5120.1 (3)N5—C6—H62106.7 (17)
C12A—C4A—N5121.8 (3)C6A—C6—H62109 (2)
F1—C1—C12A119.3 (3)N5—C6—H61109.5 (17)
F1—C1—C2118.0 (3)C6A—C6—H61109.4 (18)
C12A—C1—C2122.7 (3)H62—C6—H61112 (2)
F8—C8—C9120.2 (3)N11—C12—C12A110.5 (3)
F8—C8—C7120.5 (3)N11—C12—H121113.2 (18)
C9—C8—C7119.3 (2)C12A—C12—H121107.9 (19)
F10—C10—C9118.6 (3)N11—C12—H122109 (2)
F10—C10—C10A119.8 (2)C12A—C12—H122111 (2)
C9—C10—C10A121.6 (3)H121—C12—H122105 (3)
C13—N11—C10A—C10164.7 (3)F7—C7—C6A—C64.4 (4)
C12—N11—C10A—C10−74.1 (3)C8—C7—C6A—C6−174.9 (3)
C13—N11—C10A—C6A−12.6 (4)C10—C10A—C6A—C7−2.5 (4)
C12—N11—C10A—C6A108.7 (3)N11—C10A—C6A—C7174.8 (2)
C1—C12A—C4A—C4−2.4 (4)C10—C10A—C6A—C6174.6 (3)
C12—C12A—C4A—C4174.4 (3)N11—C10A—C6A—C6−8.1 (4)
C1—C12A—C4A—N5175.1 (2)C10A—N11—C13—N553.2 (3)
C12—C12A—C4A—N5−8.2 (4)C12—N11—C13—N5−71.2 (3)
C13—N5—C4A—C4165.8 (3)C4A—N5—C13—N1151.4 (3)
C6—N5—C4A—C4−73.8 (3)C6—N5—C13—N11−72.5 (3)
C13—N5—C4A—C12A−11.6 (3)F1—C1—C2—F20.4 (4)
C6—N5—C4A—C12A108.8 (3)C12A—C1—C2—F2178.8 (3)
C4A—C12A—C1—F1−179.6 (2)F1—C1—C2—C3−178.4 (3)
C12—C12A—C1—F13.7 (4)C12A—C1—C2—C30.0 (4)
C4A—C12A—C1—C22.0 (4)C12A—C4A—C4—F4179.9 (2)
C12—C12A—C1—C2−174.7 (3)N5—C4A—C4—F42.4 (4)
F9—C9—C8—F80.1 (4)C12A—C4A—C4—C30.9 (4)
C10—C9—C8—F8178.7 (3)N5—C4A—C4—C3−176.6 (3)
F9—C9—C8—C7−179.3 (3)F2—C2—C3—F31.1 (5)
C10—C9—C8—C7−0.8 (4)C1—C2—C3—F3179.9 (3)
F7—C7—C8—F80.7 (4)F2—C2—C3—C4179.6 (3)
C6A—C7—C8—F8179.9 (3)C1—C2—C3—C4−1.6 (5)
F7—C7—C8—C9−179.8 (3)F4—C4—C3—F30.7 (4)
C6A—C7—C8—C9−0.6 (4)C4A—C4—C3—F3179.7 (3)
F9—C9—C10—F10−1.3 (4)F4—C4—C3—C2−177.8 (3)
C8—C9—C10—F10−179.9 (3)C4A—C4—C3—C21.2 (5)
F9—C9—C10—C10A179.0 (3)C4A—N5—C6—C6A−75.7 (4)
C8—C9—C10—C10A0.5 (4)C13—N5—C6—C6A47.0 (3)
C6A—C10A—C10—F10−178.4 (2)C7—C6A—C6—N5166.7 (3)
N11—C10A—C10—F104.2 (4)C10A—C6A—C6—N5−10.4 (4)
C6A—C10A—C10—C91.2 (4)C10A—N11—C12—C12A−75.3 (3)
N11—C10A—C10—C9−176.2 (3)C13—N11—C12—C12A47.2 (3)
F7—C7—C6A—C10A−178.5 (3)C1—C12A—C12—N11166.2 (2)
C8—C7—C6A—C10A2.3 (4)C4A—C12A—C12—N11−10.5 (4)

Table 1 C—H ··· F contacts (Å, °) (i) -x, -1/2+y, 1/2-z (ii) x-1, y, z (iii) x, 1/2-y, -1/2+z

C—H···FC—HH···FC···FC—H···F
C13—H132···F10i0.93 (3)2.41 (3)3.257 (4)151 (3)
C13—H131···F1ii0.98 (4)2.46 (3)3.287 (5)143 (2)
C12—H122···F7iii0.98 (3)2.52 (3)3.336 (4)141 (3)

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PK2080).

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