structure of the complex reveals a face-to-face stacked orienta-
tion between one phenyl ring and one perfluorophenyl ring of
the two molecules, while the other two aryl rings are separated
electrostatic interactions have significant effects on the ob-
served orientations.
In conclusion, we demonstrate that perfluorophenyl–per-
fluorophenyl rings can adopt the offset-stacked geometry,
which might be preferred in energy. Compound 1, and complex
1:2 will be utilized for the on-going molecular design of
topochemical polymerization15 of cisoid 1,3-butadienes.
J. Liu acknowledges financial support from Kentucky NSF
EPSCoR and Howard Hughes Medical Institution.
(
Fig. 2a). The packing diagram of complex 1:2 shows the
neighboring complexes are joined together via similar phenyl–
perfluorophenyl face-to-face-stacked orientations to form a zig-
zag supramolecular architecture (Fig. 2b). All H…F distances
with geometrically placed hydrogens are greater than 2.46 Å.
Therefore, noncovalent p stacking interactions are mainly
responsible for the higher melting point of the 1 : 1 complex
¯
1:2). Moreover, the observed triclinic form (space group: P1)
(
of complex 1:2 is in good agreement with the space group of
Notes and references
most phenyl–perfluorophenyl complexes reported in recent
‡
Crystal data. Compound 1, C21
H
10
F
10, M = 452.29, triclinic, space
literature1
0,11
and could be a notable feature of the co-crystals of
¯
group: P1; a = 9.1151(11), b = 9.1761(16), c = 11.3748(14) Å, a =
the conjugated systems containing two perfluorophenyl rings
coupled with the corresponding aromatic hydrocarbons. The
cisoid conformation of the conjugated systems in 1:2 has little
influence on this feature.
3
6
=
9.683(2), b = 78.016(2), g = 84.341(2)°, V = 872.40(18) Å , Z = 2, Dcalc
23
21
1.722 Mg m , µ = 0.175 mm , R1 = 0.0362 for 3253 data [I > 2s(I)]
and = 0.0449 for all 3926 data. Compound 2, C21 , M = 272.39,
H
20
1
monoclinic, space group: P2 /n; a = 6.0081(8), b = 11.5316(15), c =
3
Despite their frequent occurrence, there is no unifying picture
22.082(3) Å, b = 91.343(2)°, V = 1529.5(3) Å , Z = 4, Dcalc = 1.183 Mg
23
21
m
, µ = 0.066 mm , R1 = 0.0457 for 3130 data [I > 2s(I)] and = 0.0520
for all 3507 data. Complex 1:2, C21 10, M = 724.68, triclinic,
space group: P1; a = 10.550(3), b = 12.981(3), c = 13.366(3) Å, a =
as to the nature of the p–p interactions. Electrostatic inter-
actions12 (quadrapole–quadrapole and quadrapole–dipole, and
H
10
20·C21H F
¯
13
14
dipole–dipole), hydrophobic effects and van der Waals have
been proposed as important factors. Because perfluorobenzene
has a positive quadrupole moment, the offset-stacked geometry
3
1
D
03.043(5), b = 90.336(5), g = 113.064(5)°, V = 1631.6(7) Å , Z = 2,
23
21
calc = 1.475 Mg m , µ = 0.125 mm , R1 = 0.0431 for 3884 data
[
=
I > 2s(I)] and = 0.0717 for all 5744 data. For all data collection, l(MoKa)
(Fig. 1) minimizes p-electron repulsion and maximizes the
0.71073 Å, T = 173(2) K. Bruker SMART area diffractometer, data
attraction between the positive central core and the negative
periphery. On the other hand, benzene has a negative quadru-
pole moment. Thus, the quadrapole–quadrapole attraction
between phenyl–perfluorophenyl rings explains the preferred
face-to-face-stacked arrangement of complex 1:2 (Fig. 2b). The
observed offset and face-to-face geometries suggest that the
integration was carried out with SAINT V6.1 (Bruker Analytical X-Ray
Systems, Madison, WI), corrections for absorption and decay were applied
using SADABS (R. Blessing, Acta Crystallogr. Sect. A, 1995, 51, 33–38).
The structure was solved, by direct methods, and refined using the
SHELXTL-Plus V6.1 (Bruker Analytical X-Ray Systems, Madison, WI).
All non-hydrogen atoms were refined with anisotropic thermal parameters.
Hydrogen atoms were placed with ideal positions and refined with isotropic
thermal parameters related to the parent carbon atom. CCDC
2
03757–203759. See http://www.rsc.org/suppdata/cc/b3/b301578e/ for
crystallographic data in .cif or other electronic format.
1
2
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3
The previously reported approach (ref. 7) for compound 2 is unsuitable
for the preparation of 1, because of decomposition of the fluorinated
enone 3 under the conditions of the Aldol reaction, and the less reactive
perfluorobenzyl Wittig salt for the ketone group in 3. See ESI for the
preparation of 1†.
Fig. 1 Offset stacking of the perfluorophenyl rings in the crystal structure of
compound 1.
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1
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