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2,3,4,5,6-Pentafluorophenol (pFp), unlike phenol, forms cocrystals with the weak heteroaromatic base phenazine (phz). Two types of cocrystals were prepared, (I) with a high content of pFp, 2,3,4,5,6-pentafluorophenol-phenazine (5/1), 5C
6HF
5O·C
12H
8N
2, and (II) with a 2:1 pFp-phz molar ratio, 2,3,4,5,6-pentafluorophenol-phenazine (2/1), 2C
6HF
5O·C
12H
8N
2. In both forms, homostacks are formed by the heterocyclic base and phenol molecules and no aryl-perfluoroaryl stacking interactions occur. The arrangement of the molecules in the crystal of (I) is determined by strong O-H
N and O-H
O hydrogen bonds, weak O-H
F, C-H
F and C-H
O interactions,
-
stacking interactions between the phz molecules and C-F
F interactions within the pFp stacks. Among the specific interactions in (II) are a strong O-H
N hydrogen bond, weak C-H
F interactions and
-
stacking interactions between the phz molecules. In (I) and (II), the heterocyclic molecules are located around inversion centres and one of the symmetry-independent pFp molecules in (I) is disordered about an inversion centre. Remarkably, similar structural fragments consisting of six pFp stacks can be identified in cocrystal (I) and in the known orthorhombic polymorph of pFp with
Z' = 3 [Gdaniec (2007).
CrystEngComm,
9, 286-288].
Supporting information
CCDC references: 846635; 846636
Phenazine (phz) and 2,3,4,5,6-pentafluorophenol (pFp) were purchased from
Aldrich. Yellow rhomboid cocrystals of (I) were obtained by dissolving phz in
molten pFp or by adding phenazine to a solution of a ten molar excess of pFp
in n-heptane. Needle-shaped crystals of the more stable form, (II),
were obtained from an n-heptane solution containing phz and pFp in a
1:2 molar ratio. Form (II) was also obtained by slow decomposition of (I).
All H atoms bonded to C atoms were placed in calculated positions, with C—H =
0.95 Å, and were refined as riding on their carrier atoms, with
Uiso(H) = 1.2Ueq(C). The H atoms of the O—H groups, except
for H2C in (I), were located in electron-density difference maps and
freely refined. In (I), atoms O2C and F2C were given an
occupancy of 0.5 and were refined as having identical coordinates and
displacement parameters. Atom H2C was located in an electron-density
difference map and the O2C—H2C distance constrained to 0.85 Å. It was refined as riding on O2C, with Uiso(H) =
1.2Ueq(O)
For both compounds, data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); 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) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
(I) 2,3,4,5,6-pentafluorophenol–phenazine (5/1)
top
Crystal data top
5C6HF5O·C12H8N2 | F(000) = 1088 |
Mr = 1100.54 | Dx = 1.842 Mg m−3 |
Monoclinic, P21/n | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2yn | Cell parameters from 1638 reflections |
a = 16.1015 (7) Å | θ = 3.4–56.6° |
b = 4.5223 (2) Å | µ = 1.82 mm−1 |
c = 27.4753 (12) Å | T = 130 K |
β = 97.315 (4)° | Prism, yellow |
V = 1984.35 (15) Å3 | 0.2 × 0.05 × 0.03 mm |
Z = 2 | |
Data collection top
Oxford SuperNova diffractometer | 4098 independent reflections |
Radiation source: Nova Cu X-ray Source | 3460 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.035 |
ω scans | θmax = 76.6°, θmin = 3.2° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | h = −20→19 |
Tmin = 0.671, Tmax = 1.000 | k = −5→4 |
13006 measured reflections | l = −33→34 |
Refinement top
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0645P)2 + 0.593P] where P = (Fo2 + 2Fc2)/3 |
4098 reflections | (Δ/σ)max < 0.001 |
342 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
Crystal data top
5C6HF5O·C12H8N2 | V = 1984.35 (15) Å3 |
Mr = 1100.54 | Z = 2 |
Monoclinic, P21/n | Cu Kα radiation |
a = 16.1015 (7) Å | µ = 1.82 mm−1 |
b = 4.5223 (2) Å | T = 130 K |
c = 27.4753 (12) Å | 0.2 × 0.05 × 0.03 mm |
β = 97.315 (4)° | |
Data collection top
Oxford SuperNova diffractometer | 4098 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 3460 reflections with I > 2σ(I) |
Tmin = 0.671, Tmax = 1.000 | Rint = 0.035 |
13006 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.115 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.08 | Δρmax = 0.27 e Å−3 |
4098 reflections | Δρmin = −0.26 e Å−3 |
342 parameters | |
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 | x | y | z | Uiso*/Ueq | Occ. (<1) |
N1 | 0.46750 (9) | 0.0873 (3) | 0.04301 (5) | 0.0265 (3) | |
C2 | 0.53374 (10) | −0.0948 (4) | 0.04505 (6) | 0.0263 (3) | |
C3 | 0.57197 (12) | −0.2024 (4) | 0.09113 (6) | 0.0345 (4) | |
H3 | 0.5506 | −0.1460 | 0.1204 | 0.041* | |
C4 | 0.63905 (12) | −0.3859 (5) | 0.09324 (7) | 0.0402 (5) | |
H4 | 0.6643 | −0.4569 | 0.1242 | 0.048* | |
C5 | 0.43300 (10) | 0.1837 (4) | −0.00133 (6) | 0.0260 (3) | |
C6 | 0.36263 (11) | 0.3749 (4) | −0.00517 (7) | 0.0338 (4) | |
H6 | 0.3398 | 0.4343 | 0.0235 | 0.041* | |
C7 | 0.32796 (12) | 0.4731 (5) | −0.04998 (7) | 0.0397 (4) | |
H7 | 0.2810 | 0.6018 | −0.0523 | 0.048* | |
O1A | 0.41726 (8) | 0.2525 (3) | 0.12785 (4) | 0.0326 (3) | |
H1A | 0.4259 (19) | 0.186 (7) | 0.0983 (12) | 0.086 (10)* | |
F2A | 0.31296 (7) | −0.1673 (3) | 0.07556 (4) | 0.0383 (3) | |
F3A | 0.16114 (7) | −0.2883 (2) | 0.10186 (4) | 0.0363 (3) | |
F4A | 0.10460 (7) | 0.0113 (2) | 0.17736 (4) | 0.0372 (3) | |
F5A | 0.20255 (6) | 0.4366 (2) | 0.22530 (3) | 0.0328 (2) | |
F6A | 0.35776 (6) | 0.5436 (2) | 0.20135 (3) | 0.0310 (2) | |
C1A | 0.33918 (10) | 0.1912 (4) | 0.13791 (6) | 0.0251 (3) | |
C2A | 0.28644 (11) | −0.0171 (4) | 0.11310 (6) | 0.0270 (4) | |
C3A | 0.20859 (11) | −0.0785 (4) | 0.12605 (6) | 0.0276 (4) | |
C4A | 0.18002 (10) | 0.0710 (4) | 0.16426 (6) | 0.0269 (3) | |
C5A | 0.23054 (11) | 0.2843 (4) | 0.18903 (6) | 0.0255 (3) | |
C6A | 0.30897 (10) | 0.3388 (4) | 0.17637 (5) | 0.0243 (3) | |
O1B | 0.55409 (9) | 0.4472 (4) | 0.18868 (5) | 0.0427 (4) | |
H1B | 0.5079 (19) | 0.374 (7) | 0.1768 (11) | 0.076 (9)* | |
F2B | 0.46806 (7) | 0.0542 (3) | 0.24287 (4) | 0.0418 (3) | |
F3B | 0.51478 (8) | −0.0064 (3) | 0.34095 (4) | 0.0488 (3) | |
F4B | 0.64597 (10) | 0.3099 (3) | 0.38614 (4) | 0.0608 (4) | |
F5B | 0.73003 (8) | 0.6878 (3) | 0.33262 (5) | 0.0586 (4) | |
F6B | 0.68262 (7) | 0.7523 (3) | 0.23533 (5) | 0.0472 (3) | |
C1B | 0.57390 (11) | 0.4058 (4) | 0.23734 (6) | 0.0301 (4) | |
C2B | 0.53249 (11) | 0.2137 (4) | 0.26516 (6) | 0.0303 (4) | |
C3B | 0.55610 (12) | 0.1797 (4) | 0.31484 (7) | 0.0334 (4) | |
C4B | 0.62270 (13) | 0.3403 (5) | 0.33746 (7) | 0.0381 (4) | |
C5B | 0.66516 (12) | 0.5306 (4) | 0.31077 (7) | 0.0377 (4) | |
C6B | 0.64082 (11) | 0.5635 (4) | 0.26092 (7) | 0.0328 (4) | |
F1C | 0.47372 (8) | 0.5849 (3) | 0.42814 (4) | 0.0514 (3) | |
F2C | 0.63056 (8) | 0.8047 (3) | 0.45430 (5) | 0.0492 (3) | 0.50 |
O2C' | 0.63056 (8) | 0.8047 (3) | 0.45430 (5) | 0.0492 (3) | 0.50 |
H1C | 0.6131 | 0.6577 | 0.4366 | 0.059* | 0.50 |
F3C | 0.65595 (7) | 1.2258 (3) | 0.52524 (4) | 0.0489 (3) | |
C1C | 0.48623 (12) | 0.7905 (4) | 0.46366 (6) | 0.0368 (4) | |
C2C | 0.56587 (12) | 0.9018 (5) | 0.47641 (7) | 0.0381 (4) | |
C3C | 0.57900 (12) | 1.1134 (5) | 0.51284 (7) | 0.0364 (4) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0285 (7) | 0.0316 (7) | 0.0203 (6) | 0.0017 (6) | 0.0065 (5) | −0.0015 (6) |
C2 | 0.0286 (8) | 0.0298 (8) | 0.0210 (7) | −0.0004 (7) | 0.0053 (6) | −0.0011 (6) |
C3 | 0.0366 (9) | 0.0458 (11) | 0.0217 (8) | 0.0042 (8) | 0.0063 (7) | 0.0028 (8) |
C4 | 0.0389 (10) | 0.0532 (12) | 0.0283 (9) | 0.0108 (9) | 0.0031 (8) | 0.0088 (9) |
C5 | 0.0285 (8) | 0.0293 (8) | 0.0208 (7) | −0.0008 (7) | 0.0054 (6) | −0.0008 (6) |
C6 | 0.0338 (9) | 0.0387 (10) | 0.0307 (9) | 0.0068 (8) | 0.0107 (7) | −0.0006 (8) |
C7 | 0.0339 (9) | 0.0476 (12) | 0.0380 (10) | 0.0127 (9) | 0.0068 (8) | 0.0054 (9) |
O1A | 0.0302 (6) | 0.0483 (8) | 0.0204 (6) | −0.0017 (6) | 0.0072 (5) | −0.0072 (5) |
F2A | 0.0457 (6) | 0.0421 (6) | 0.0280 (5) | 0.0015 (5) | 0.0079 (4) | −0.0155 (5) |
F3A | 0.0405 (6) | 0.0303 (5) | 0.0356 (5) | −0.0048 (5) | −0.0057 (4) | −0.0058 (4) |
F4A | 0.0307 (5) | 0.0434 (6) | 0.0389 (6) | −0.0039 (5) | 0.0095 (4) | 0.0029 (5) |
F5A | 0.0389 (6) | 0.0368 (6) | 0.0248 (5) | 0.0026 (5) | 0.0125 (4) | −0.0057 (4) |
F6A | 0.0368 (5) | 0.0339 (6) | 0.0222 (5) | −0.0058 (4) | 0.0034 (4) | −0.0079 (4) |
C1A | 0.0293 (8) | 0.0287 (8) | 0.0173 (7) | 0.0021 (7) | 0.0028 (6) | 0.0020 (6) |
C2A | 0.0362 (9) | 0.0277 (8) | 0.0169 (7) | 0.0059 (7) | 0.0025 (6) | −0.0039 (6) |
C3A | 0.0338 (9) | 0.0239 (8) | 0.0233 (8) | −0.0003 (7) | −0.0032 (6) | −0.0008 (6) |
C4A | 0.0282 (8) | 0.0281 (8) | 0.0247 (8) | 0.0013 (7) | 0.0042 (6) | 0.0060 (7) |
C5A | 0.0341 (8) | 0.0255 (8) | 0.0175 (7) | 0.0050 (7) | 0.0058 (6) | 0.0015 (6) |
C6A | 0.0313 (8) | 0.0248 (8) | 0.0162 (7) | −0.0002 (7) | 0.0002 (6) | −0.0002 (6) |
O1B | 0.0375 (7) | 0.0640 (10) | 0.0263 (6) | −0.0116 (7) | 0.0023 (5) | 0.0065 (6) |
F2B | 0.0355 (6) | 0.0452 (7) | 0.0440 (6) | −0.0116 (5) | 0.0019 (5) | 0.0006 (5) |
F3B | 0.0589 (8) | 0.0465 (7) | 0.0436 (7) | 0.0014 (6) | 0.0169 (6) | 0.0170 (5) |
F4B | 0.0814 (10) | 0.0699 (9) | 0.0277 (6) | 0.0060 (8) | −0.0068 (6) | −0.0002 (6) |
F5B | 0.0544 (8) | 0.0534 (8) | 0.0613 (8) | −0.0111 (6) | −0.0182 (6) | −0.0138 (7) |
F6B | 0.0375 (6) | 0.0473 (7) | 0.0573 (7) | −0.0118 (5) | 0.0077 (5) | 0.0095 (6) |
C1B | 0.0271 (8) | 0.0350 (9) | 0.0284 (8) | 0.0004 (7) | 0.0050 (7) | 0.0011 (7) |
C2B | 0.0282 (8) | 0.0309 (9) | 0.0320 (9) | −0.0005 (7) | 0.0040 (7) | −0.0008 (7) |
C3B | 0.0396 (10) | 0.0293 (9) | 0.0331 (9) | 0.0057 (8) | 0.0111 (8) | 0.0054 (7) |
C4B | 0.0488 (11) | 0.0389 (10) | 0.0250 (8) | 0.0095 (9) | −0.0020 (8) | −0.0017 (8) |
C5B | 0.0350 (9) | 0.0335 (10) | 0.0417 (10) | 0.0012 (8) | −0.0062 (8) | −0.0079 (8) |
C6B | 0.0296 (8) | 0.0304 (9) | 0.0386 (9) | −0.0009 (7) | 0.0059 (7) | 0.0015 (8) |
F1C | 0.0619 (8) | 0.0515 (7) | 0.0385 (6) | −0.0129 (6) | −0.0022 (6) | −0.0084 (6) |
F2C | 0.0435 (7) | 0.0571 (9) | 0.0483 (8) | −0.0037 (6) | 0.0113 (6) | −0.0021 (7) |
O2C' | 0.0435 (7) | 0.0571 (9) | 0.0483 (8) | −0.0037 (6) | 0.0113 (6) | −0.0021 (7) |
F3C | 0.0392 (6) | 0.0590 (8) | 0.0453 (7) | −0.0174 (6) | −0.0065 (5) | 0.0062 (6) |
C1C | 0.0448 (11) | 0.0369 (10) | 0.0266 (9) | −0.0068 (8) | −0.0039 (8) | 0.0042 (7) |
C2C | 0.0387 (10) | 0.0438 (11) | 0.0307 (9) | −0.0027 (9) | 0.0003 (8) | 0.0081 (8) |
C3C | 0.0351 (9) | 0.0404 (10) | 0.0309 (9) | −0.0103 (8) | −0.0068 (7) | 0.0098 (8) |
Geometric parameters (Å, º) top
N1—C2 | 1.343 (2) | C3A—C4A | 1.376 (2) |
N1—C5 | 1.345 (2) | C4A—C5A | 1.384 (2) |
C2—C3 | 1.421 (2) | C5A—C6A | 1.374 (2) |
C2—C5i | 1.433 (2) | O1B—C1B | 1.348 (2) |
C3—C4 | 1.357 (3) | O1B—H1B | 0.84 (3) |
C3—H3 | 0.9500 | F2B—C2B | 1.345 (2) |
C4—C7i | 1.418 (3) | F3B—C3B | 1.337 (2) |
C4—H4 | 0.9500 | F4B—C4B | 1.349 (2) |
C5—C6 | 1.419 (2) | F5B—C5B | 1.341 (2) |
C5—C2i | 1.433 (2) | F6B—C6B | 1.340 (2) |
C6—C7 | 1.360 (3) | C1B—C6B | 1.383 (3) |
C6—H6 | 0.9500 | C1B—C2B | 1.383 (2) |
C7—C4i | 1.418 (3) | C2B—C3B | 1.378 (3) |
C7—H7 | 0.9500 | C3B—C4B | 1.376 (3) |
O1A—C1A | 1.350 (2) | C4B—C5B | 1.369 (3) |
O1A—H1A | 0.89 (3) | C5B—C6B | 1.384 (3) |
F2A—C2A | 1.3491 (18) | F1C—C1C | 1.344 (2) |
F3A—C3A | 1.3404 (19) | F2C—C2C | 1.345 (2) |
F4A—C4A | 1.3374 (19) | F2C—H1C | 0.8501 |
F5A—C5A | 1.3360 (18) | F3C—C3C | 1.343 (2) |
F6A—C6A | 1.3450 (18) | C1C—C3Cii | 1.372 (3) |
C1A—C2A | 1.388 (2) | C1C—C2C | 1.381 (3) |
C1A—C6A | 1.389 (2) | C2C—C3C | 1.381 (3) |
C2A—C3A | 1.374 (2) | C3C—C1Cii | 1.372 (3) |
| | | |
C2—N1—C5 | 118.06 (14) | C6A—C5A—C4A | 120.14 (15) |
N1—C2—C3 | 119.90 (15) | F6A—C6A—C5A | 119.34 (14) |
N1—C2—C5i | 121.09 (15) | F6A—C6A—C1A | 118.75 (14) |
C3—C2—C5i | 119.01 (16) | C5A—C6A—C1A | 121.90 (15) |
C4—C3—C2 | 119.95 (16) | C1B—O1B—H1B | 115 (2) |
C4—C3—H3 | 120.0 | O1B—C1B—C6B | 117.72 (16) |
C2—C3—H3 | 120.0 | O1B—C1B—C2B | 124.44 (16) |
C3—C4—C7i | 121.01 (17) | C6B—C1B—C2B | 117.83 (16) |
C3—C4—H4 | 119.5 | F2B—C2B—C3B | 119.40 (16) |
C7i—C4—H4 | 119.5 | F2B—C2B—C1B | 118.88 (15) |
N1—C5—C6 | 119.90 (15) | C3B—C2B—C1B | 121.71 (17) |
N1—C5—C2i | 120.85 (15) | F3B—C3B—C4B | 120.16 (17) |
C6—C5—C2i | 119.25 (15) | F3B—C3B—C2B | 120.55 (17) |
C7—C6—C5 | 119.88 (16) | C4B—C3B—C2B | 119.30 (17) |
C7—C6—H6 | 120.1 | F4B—C4B—C5B | 120.04 (19) |
C5—C6—H6 | 120.1 | F4B—C4B—C3B | 119.73 (19) |
C6—C7—C4i | 120.90 (18) | C5B—C4B—C3B | 120.24 (17) |
C6—C7—H7 | 119.5 | F5B—C5B—C4B | 120.49 (18) |
C4i—C7—H7 | 119.5 | F5B—C5B—C6B | 119.51 (19) |
C1A—O1A—H1A | 112 (2) | C4B—C5B—C6B | 120.00 (17) |
O1A—C1A—C2A | 124.50 (15) | F6B—C6B—C1B | 119.75 (17) |
O1A—C1A—C6A | 118.85 (15) | F6B—C6B—C5B | 119.33 (17) |
C2A—C1A—C6A | 116.63 (15) | C1B—C6B—C5B | 120.92 (17) |
F2A—C2A—C3A | 118.96 (15) | C2C—F2C—H1C | 107.1 |
F2A—C2A—C1A | 118.94 (15) | F1C—C1C—C3Cii | 120.52 (18) |
C3A—C2A—C1A | 122.10 (15) | F1C—C1C—C2C | 119.01 (19) |
F3A—C3A—C2A | 119.72 (15) | C3Cii—C1C—C2C | 120.47 (19) |
F3A—C3A—C4A | 120.08 (16) | F2C—C2C—C1C | 120.94 (19) |
C2A—C3A—C4A | 120.19 (15) | F2C—C2C—C3C | 119.85 (18) |
F4A—C4A—C3A | 120.63 (16) | C1C—C2C—C3C | 119.21 (19) |
F4A—C4A—C5A | 120.35 (15) | F3C—C3C—C1Cii | 119.84 (18) |
C3A—C4A—C5A | 119.02 (16) | F3C—C3C—C2C | 119.84 (19) |
F5A—C5A—C6A | 120.30 (15) | C1Cii—C3C—C2C | 120.32 (18) |
F5A—C5A—C4A | 119.56 (15) | | |
Symmetry codes: (i) −x+1, −y, −z; (ii) −x+1, −y+2, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···N1 | 0.89 (3) | 1.79 (3) | 2.6693 (18) | 167 (3) |
O1B—H1B···O1A | 0.84 (3) | 1.93 (3) | 2.7358 (19) | 159 (3) |
O2C′—H1C···F4B | 0.85 | 2.21 | 2.948 (2) | 146 |
C6—H6···F2Aiii | 0.95 | 2.37 | 3.209 (2) | 147 |
C7—H7···F2C/O2Civ | 0.95 | 2.49 | 3.350 (2) | 151 |
C4—H4···F5Bv | 0.95 | 2.52 | 3.349 (2) | 145 |
C4—H4···O1Bvi | 0.95 | 2.70 | 3.199 (2) | 114 |
C3—H3···O1Bvi | 0.95 | 2.62 | 3.158 (2) | 116 |
Symmetry codes: (iii) x, y+1, z; (iv) x−1/2, −y+3/2, z−1/2; (v) −x+3/2, y−3/2, −z+1/2; (vi) x, y−1, z. |
(II) 2,3,4,5,6-pentafluorophenol–phenazine (2/1)
top
Crystal data top
2C6HF5O·C12H8N2 | F(000) = 548 |
Mr = 548.34 | Dx = 1.715 Mg m−3 |
Monoclinic, P21/n | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2yn | Cell parameters from 766 reflections |
a = 4.9045 (3) Å | θ = 3.5–36.7° |
b = 17.1342 (10) Å | µ = 1.53 mm−1 |
c = 12.6397 (6) Å | T = 130 K |
β = 90.931 (5)° | Needle, yellow |
V = 1062.03 (10) Å3 | 0.4 × 0.02 × 0.02 mm |
Z = 2 | |
Data collection top
Oxford SuperNova diffractometer | 2186 independent reflections |
Radiation source: Nova Cu X-ray Source | 1939 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.039 |
ω scans | θmax = 76.4°, θmin = 4.4° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | h = −5→6 |
Tmin = 0.366, Tmax = 1.000 | k = −20→21 |
10876 measured reflections | l = −15→15 |
Refinement top
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)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.11 | w = 1/[σ2(Fo2) + (0.0693P)2 + 0.4475P] where P = (Fo2 + 2Fc2)/3 |
2186 reflections | (Δ/σ)max = 0.001 |
176 parameters | Δρmax = 0.22 e Å−3 |
0 restraints | Δρmin = −0.29 e Å−3 |
Crystal data top
2C6HF5O·C12H8N2 | V = 1062.03 (10) Å3 |
Mr = 548.34 | Z = 2 |
Monoclinic, P21/n | Cu Kα radiation |
a = 4.9045 (3) Å | µ = 1.53 mm−1 |
b = 17.1342 (10) Å | T = 130 K |
c = 12.6397 (6) Å | 0.4 × 0.02 × 0.02 mm |
β = 90.931 (5)° | |
Data collection top
Oxford SuperNova diffractometer | 2186 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 1939 reflections with I > 2σ(I) |
Tmin = 0.366, Tmax = 1.000 | Rint = 0.039 |
10876 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.11 | Δρmax = 0.22 e Å−3 |
2186 reflections | Δρmin = −0.29 e Å−3 |
176 parameters | |
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 | x | y | z | Uiso*/Ueq | |
N1 | 0.5692 (3) | 0.47309 (8) | 0.60219 (10) | 0.0280 (3) | |
C2 | 0.3726 (3) | 0.52675 (9) | 0.58729 (12) | 0.0277 (3) | |
C3 | 0.2287 (4) | 0.55680 (10) | 0.67487 (13) | 0.0339 (4) | |
H3 | 0.2709 | 0.5389 | 0.7444 | 0.041* | |
C4 | 0.0303 (4) | 0.61123 (11) | 0.65930 (15) | 0.0391 (4) | |
H4 | −0.0649 | 0.6311 | 0.7184 | 0.047* | |
C5 | 0.6965 (3) | 0.44559 (9) | 0.51709 (12) | 0.0279 (3) | |
C6 | 0.9056 (4) | 0.38864 (10) | 0.52960 (14) | 0.0333 (4) | |
H6 | 0.9533 | 0.3699 | 0.5982 | 0.040* | |
C7 | 1.0369 (4) | 0.36105 (10) | 0.44369 (16) | 0.0388 (4) | |
H7 | 1.1754 | 0.3227 | 0.4525 | 0.047* | |
O1A | 0.7405 (3) | 0.43417 (8) | 0.80095 (10) | 0.0376 (3) | |
H1A | 0.686 (6) | 0.4419 (16) | 0.735 (2) | 0.067 (8)* | |
F2A | 0.3504 (2) | 0.33406 (6) | 0.71111 (7) | 0.0406 (3) | |
F3A | −0.0011 (2) | 0.25622 (6) | 0.83397 (9) | 0.0419 (3) | |
F4A | 0.0300 (2) | 0.27108 (7) | 1.04879 (9) | 0.0473 (3) | |
F5A | 0.4192 (3) | 0.36459 (8) | 1.13705 (8) | 0.0514 (3) | |
F6A | 0.7618 (2) | 0.44587 (6) | 1.01470 (8) | 0.0410 (3) | |
C1A | 0.5628 (3) | 0.39347 (9) | 0.85879 (12) | 0.0294 (4) | |
C2A | 0.3664 (4) | 0.34346 (10) | 0.81657 (12) | 0.0306 (4) | |
C3A | 0.1879 (4) | 0.30303 (9) | 0.87859 (13) | 0.0318 (4) | |
C4A | 0.2037 (4) | 0.31034 (10) | 0.98751 (14) | 0.0342 (4) | |
C5A | 0.4003 (4) | 0.35782 (11) | 1.03161 (13) | 0.0347 (4) | |
C6A | 0.5757 (4) | 0.39901 (10) | 0.96887 (13) | 0.0313 (4) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0297 (7) | 0.0321 (7) | 0.0223 (6) | −0.0029 (5) | 0.0007 (5) | 0.0024 (5) |
C2 | 0.0279 (8) | 0.0308 (8) | 0.0244 (7) | −0.0041 (6) | 0.0017 (6) | −0.0007 (6) |
C3 | 0.0344 (9) | 0.0405 (9) | 0.0270 (8) | −0.0045 (7) | 0.0041 (7) | −0.0049 (6) |
C4 | 0.0374 (10) | 0.0416 (9) | 0.0386 (9) | −0.0030 (7) | 0.0097 (7) | −0.0106 (7) |
C5 | 0.0300 (8) | 0.0288 (7) | 0.0248 (7) | −0.0041 (6) | 0.0001 (6) | 0.0002 (6) |
C6 | 0.0317 (9) | 0.0326 (8) | 0.0355 (9) | −0.0009 (7) | −0.0013 (7) | 0.0026 (7) |
C7 | 0.0337 (9) | 0.0337 (9) | 0.0491 (10) | 0.0000 (7) | 0.0024 (8) | −0.0046 (7) |
O1A | 0.0381 (7) | 0.0476 (7) | 0.0269 (6) | −0.0088 (5) | −0.0021 (5) | 0.0097 (5) |
F2A | 0.0495 (7) | 0.0502 (6) | 0.0220 (5) | −0.0069 (5) | −0.0031 (4) | 0.0001 (4) |
F3A | 0.0415 (6) | 0.0410 (6) | 0.0430 (6) | −0.0095 (5) | −0.0028 (5) | −0.0004 (5) |
F4A | 0.0480 (7) | 0.0553 (7) | 0.0391 (6) | −0.0073 (5) | 0.0125 (5) | 0.0108 (5) |
F5A | 0.0631 (8) | 0.0699 (8) | 0.0215 (5) | −0.0063 (6) | 0.0063 (5) | −0.0031 (5) |
F6A | 0.0454 (6) | 0.0453 (6) | 0.0322 (5) | −0.0064 (5) | −0.0055 (5) | −0.0046 (4) |
C1A | 0.0305 (8) | 0.0312 (8) | 0.0265 (8) | 0.0028 (6) | 0.0013 (6) | 0.0037 (6) |
C2A | 0.0355 (9) | 0.0333 (8) | 0.0229 (7) | 0.0035 (7) | −0.0010 (6) | 0.0016 (6) |
C3A | 0.0323 (9) | 0.0303 (8) | 0.0327 (9) | 0.0004 (6) | −0.0003 (7) | 0.0003 (6) |
C4A | 0.0347 (9) | 0.0363 (9) | 0.0317 (8) | 0.0024 (7) | 0.0081 (7) | 0.0060 (7) |
C5A | 0.0401 (10) | 0.0415 (9) | 0.0226 (8) | 0.0055 (7) | 0.0031 (7) | 0.0006 (6) |
C6A | 0.0336 (9) | 0.0329 (8) | 0.0274 (8) | 0.0015 (6) | −0.0018 (6) | −0.0019 (6) |
Geometric parameters (Å, º) top
N1—C5 | 1.338 (2) | O1A—C1A | 1.342 (2) |
N1—C2 | 1.343 (2) | O1A—H1A | 0.88 (3) |
C2—C3 | 1.419 (2) | F2A—C2A | 1.3437 (18) |
C2—C5i | 1.437 (2) | F3A—C3A | 1.343 (2) |
C3—C4 | 1.360 (3) | F4A—C4A | 1.341 (2) |
C3—H3 | 0.9500 | F5A—C5A | 1.3395 (19) |
C4—C7i | 1.419 (3) | F6A—C6A | 1.340 (2) |
C4—H4 | 0.9500 | C1A—C2A | 1.390 (2) |
C5—C6 | 1.422 (2) | C1A—C6A | 1.395 (2) |
C5—C2i | 1.437 (2) | C2A—C3A | 1.372 (2) |
C6—C7 | 1.356 (3) | C3A—C4A | 1.383 (2) |
C6—H6 | 0.9500 | C4A—C5A | 1.373 (3) |
C7—C4i | 1.419 (3) | C5A—C6A | 1.374 (3) |
C7—H7 | 0.9500 | | |
| | | |
C5—N1—C2 | 118.14 (14) | C1A—O1A—H1A | 113.7 (19) |
N1—C2—C3 | 120.26 (15) | O1A—C1A—C2A | 124.30 (15) |
N1—C2—C5i | 120.83 (15) | O1A—C1A—C6A | 119.27 (15) |
C3—C2—C5i | 118.90 (16) | C2A—C1A—C6A | 116.41 (15) |
C4—C3—C2 | 119.99 (16) | F2A—C2A—C3A | 118.61 (15) |
C4—C3—H3 | 120.0 | F2A—C2A—C1A | 118.94 (15) |
C2—C3—H3 | 120.0 | C3A—C2A—C1A | 122.46 (15) |
C3—C4—C7i | 121.14 (16) | F3A—C3A—C2A | 120.26 (15) |
C3—C4—H4 | 119.4 | F3A—C3A—C4A | 119.94 (15) |
C7i—C4—H4 | 119.4 | C2A—C3A—C4A | 119.80 (16) |
N1—C5—C6 | 119.82 (15) | F4A—C4A—C5A | 120.74 (16) |
N1—C5—C2i | 121.02 (15) | F4A—C4A—C3A | 120.23 (17) |
C6—C5—C2i | 119.16 (15) | C5A—C4A—C3A | 119.03 (16) |
C7—C6—C5 | 120.05 (16) | F5A—C5A—C4A | 119.46 (16) |
C7—C6—H6 | 120.0 | F5A—C5A—C6A | 119.73 (16) |
C5—C6—H6 | 120.0 | C4A—C5A—C6A | 120.80 (15) |
C6—C7—C4i | 120.76 (17) | F6A—C6A—C5A | 119.11 (14) |
C6—C7—H7 | 119.6 | F6A—C6A—C1A | 119.41 (15) |
C4i—C7—H7 | 119.6 | C5A—C6A—C1A | 121.47 (16) |
Symmetry code: (i) −x+1, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···N1 | 0.88 (3) | 1.85 (3) | 2.7192 (18) | 172 (3) |
C4—H4···F5Aii | 0.95 | 2.54 | 3.441 (2) | 158 |
C6—H6···F2Aiii | 0.95 | 2.47 | 3.276 (2) | 142 |
Symmetry codes: (ii) −x, −y+1, −z+2; (iii) x+1, y, z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | 5C6HF5O·C12H8N2 | 2C6HF5O·C12H8N2 |
Mr | 1100.54 | 548.34 |
Crystal system, space group | Monoclinic, P21/n | Monoclinic, P21/n |
Temperature (K) | 130 | 130 |
a, b, c (Å) | 16.1015 (7), 4.5223 (2), 27.4753 (12) | 4.9045 (3), 17.1342 (10), 12.6397 (6) |
β (°) | 97.315 (4) | 90.931 (5) |
V (Å3) | 1984.35 (15) | 1062.03 (10) |
Z | 2 | 2 |
Radiation type | Cu Kα | Cu Kα |
µ (mm−1) | 1.82 | 1.53 |
Crystal size (mm) | 0.2 × 0.05 × 0.03 | 0.4 × 0.02 × 0.02 |
|
Data collection |
Diffractometer | Oxford SuperNova diffractometer | Oxford SuperNova diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.671, 1.000 | 0.366, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13006, 4098, 3460 | 10876, 2186, 1939 |
Rint | 0.035 | 0.039 |
(sin θ/λ)max (Å−1) | 0.631 | 0.630 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.115, 1.08 | 0.043, 0.126, 1.11 |
No. of reflections | 4098 | 2186 |
No. of parameters | 342 | 176 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.27, −0.26 | 0.22, −0.29 |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···N1 | 0.89 (3) | 1.79 (3) | 2.6693 (18) | 167 (3) |
O1B—H1B···O1A | 0.84 (3) | 1.93 (3) | 2.7358 (19) | 159 (3) |
O2C'—H1C···F4B | 0.85 | 2.21 | 2.948 (2) | 146 |
C6—H6···F2Ai | 0.95 | 2.37 | 3.209 (2) | 147 |
C7—H7···F2C/O2Cii | 0.95 | 2.49 | 3.350 (2) | 151 |
C4—H4···F5Biii | 0.95 | 2.52 | 3.349 (2) | 145 |
C4—H4···O1Biv | 0.95 | 2.70 | 3.199 (2) | 114 |
C3—H3···O1Biv | 0.95 | 2.62 | 3.158 (2) | 116 |
Symmetry codes: (i) x, y+1, z; (ii) x−1/2, −y+3/2, z−1/2; (iii) −x+3/2, y−3/2, −z+1/2; (iv) x, y−1, z. |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1A—H1A···N1 | 0.88 (3) | 1.85 (3) | 2.7192 (18) | 172 (3) |
C4—H4···F5Ai | 0.95 | 2.54 | 3.441 (2) | 158 |
C6—H6···F2Aii | 0.95 | 2.47 | 3.276 (2) | 142 |
Symmetry codes: (i) −x, −y+1, −z+2; (ii) x+1, y, z. |
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Phenazine (phz), a diazaaromatic weak base, is considered to be a good supramolecular substrate as it can easily form complexes via metal coordination, hydrogen bonding and halogen bonding. The recognition process of phz can also occur via the use of weaker interactions involving its aromatic π system and C—H groups, thus making prediction of the stoichiometry and packing mode of its complexes more difficult. This fact is best illustrated by the molecular complexes formed by phz with polyphenols. Cocrystallization of phz with hydroquinone (HQ) and naphthalene-1,5-diol affords cocrystals in a 2:1 molar ratio, and cocrystals of stoichiometry 3:1 are formed with biphenyl-4,4'-diol (Thalladi et al., 2000), i.e. the stoichiometry of these cocrystals does not conform with simple considerations of the hydrogen-bond requirements of the cocrystal components. In turn, with phloroglucinol (phl) three nonsolvated crystalline forms of phz–phl molar ratio 2:1, 7:4 and 3:2 are obtained (Sarma et al., 2008), and only in this last cocrystal are the numbers of donor O—H groups and N-atom acceptors balanced. Importantly, all the above cocrystals share similar structural features, namely the main network is constructed from phz stacks and the phenolic molecules are accommodated in channels, where they interact with phz by O—H···N hydrogen bonds, weak nonclassical hydrogen bonds and edge-to-face aromatic interactions.
Edge-to-face interactions are of primary importance in the formation of these channel-type structures (Thalladi et al., 2000; Kadzewski & Gdaniec, 2006). Altering these interactions by lowering the electron density of the aromatic ring of the diphenol, through the exchange of C—H groups with C—F groups, destroys this channel-type structural motif and promotes the formation of mixed π-stacks (Czapik & Gdaniec, 2010), by analogy with the robust Ar—ArF packing motif found in arene–perfluoroarene systems (Collings et al., 2002, and references therein).
Structural and chemical information related to cocrystallization of phz with polyphenols is abundant in the literature. However, no information is available on cocrystallization attempts with phenol itself. As our crystallization efforts reveal, this is most probably due to the negative outcome of these experiments, as we too were unable to cocrystallize these two compounds, despite numerous trials and a variety of applied conditions. Instead, we were more successful with 2,3,4,5,6-pentafluorophenol (pFp), which is nearly five pKa units more acidic than phenol (5.50 for pFp versus 9.95 for phenol), and we obtained two types of pFp–phz cocrystals with component ratios 5:1, (I), and 2:1, (II). Form (I), which is highly unstable in air, was obtained when phenazine was dissolved in molten pFp (m.p. 305 K), or from an n-heptane solution containing phz and a large excess of pFp. The stable form, (II), was obtained when phz and pFp were dissolved in n-heptane in a 1:2 molar ratio. When crystals of (I) where immersed in a drop of perfluoropolyether, slow growth of (II) on the crystals of (I) was observed, with a complete transformation occurring overnight. The identitification of the crystals formed after this transformation as form (II) was determined by the measurement of the unit-cell parameters for a few single crystals resulting from the transformation.
The molecular structure of the molecules in cocrystal (I), together with the atom-numbering scheme, is shown in Fig. 1. The asymmetric unit of (I) consists of one-half of the centrosymmetric phz molecule and 2.5 molecules of pFp, labelled A, B and C. One of the pFp molecules is disordered about an inversion centre over two practically completely overlapping positions, i.e. the phenolic O atom and one of the F atoms are located with equal occupancy at the same position. Identification of the OH group of the disordered pFp molecule was based mostly on molecular geometric features, namely it was expected that the endocyclic angle at the C atoms attached to the electron-donating OH group would be smaller than 120° (Domenicano et al., 1975). As the C1C—C2C—C3C angle of 119.21 (19)° is significantly smaller than the remaining two angles [C1C—C3C—C2Ci = 120.32 (18)° and C3C—C1C—C2Ci = 120.42 (19)°; symmetry code: (i) -x + 1, -y + 2, -z + 1], it was concluded that the OH group is attached to atom C2C. In turn, analysis of the intermolecular contacts of the disordered pFp molecule indicated atoms C2C or C1C as the possible substitution sites. The two short intermolecular F1C···F3A(-x + 1/2, y + 1/2, -z + 1/2) and F2C···F4B contacts of 2.791 (2) and 2.948 (2) Å, respectively, might represent an O—H···F interaction. However, the latter, longer, contact appears to be more adequate for a generally weak O—H···F hydrogen bond, as the low propensity of organic fluorine to participate in classical hydrogen bonding is nowadays well recognized (Reichenbächer et al., 2005, and references therein). Location of the OH group in the remaining two pFp molecules was straightforward and confirmed by the analysis of pFp molecular geometry and intermolecular interactions.
The crystal packing of (I), viewed along the b axis, is shown in Fig. 2. The phz molecules are arranged via π–π interactions into stacks that are completely surrounded by eight stacks formed separately by the three symmetry-independent pFp molecules. All the stacks extend along [010] and the centroid-to-centroid distance between the benzene ring centroids for all pFp stacks is 4.5223 (2) Å, i.e. equal to the unit-cell parameter b. This value indicates significant slipping of the pFp molecules in the stacks and scant overlapping of their aromatic π-systems. Instead, to optimize electrostatic interactions, F atoms are located above and below the electron-defficient aromatic ring of pFp, with C—F···Cg distances in the range 3.264–3.309 Å for stacks composed of pFp molecules A and C, and 3.502–3.515 Å for stacks of B molecules. The stacks formed by phz molecules are also slipped, although in this case the slipping leads to an overlap of the π-systems of the electron-deficient pyrazine fragment and the electron-rich benzene fragment, with a centroid-to-centroid distance of 3.791 Å. However, the slipping of phz molecules in the stack is too small to expose one of the phz benzene rings for aryl–perfluoroaryl interactions, and the Ar—ArF synthon is not observed in (I). Strong O—H···N and O—H···O hydrogen bonds connect the phz molecules and pFp molecules A and B into centrosymmetric heteropentamers, with A molecules acting as donors in an O—H···N interaction and as acceptors in an O—H···O hydrogen bond (Table 1 and Fig. 2). Molecule A, which forms a dihedral angle of 72.25 (8)° with the phz molecule, is additionally involved in a C—H···F interaction with another phz molecule (Table 1), thus bridging two neighbouring molecules in the phz stack. Each of the phz C—H groups forms a short contact with the electronegative O or F atoms of the pFp molecules (Table 1).
Owing to the high pFp content in phz–pFp (5/1) cocrystal, (I), we decided to check whether any similar structural motif could be identified between the crystal packing of pFp molecules in this cocrystal and in the polymorphic forms of pFp. In fact, as shown in Fig. 3, in the orthorhombic P212121 pFp polymorph (Gdaniec, 2007), which like (I) contains three symmetry-independent molecules, a group of six pFp stacks with an arrangement strongly resembling that of the six stacks in (I) can be identified. The stacks in the orthorhombic polymorph are slightly more slipped than in (I), as the distance between the benzene ring centroids increases to 5.1398 (9) Å, i.e. it is ca 0.6 Å longer than in cocrystal (I). The arrangement of these stacks is mostly directed by close-packing forces and not by strong intermolecular interactions, as the helical hydrogen-bond motif observed in the orthorhombic polymorph of pFp is no longer present in (I), and the O—H···O interactions join only two pairs of stacks within this hexameric stack cluster.
The molecular structure of the molecules in (II) is shown in Fig. 4. The asymmetric unit of this (2/1) cocrystal consists of one-half of a phz molecule and one pFp molecule. The crystal components are connected into discrete heterotrimers via O—H···N hydrogen bonding (Table 2 and Fig. 5), and the stoichiometry of (II) agrees with that predicted from hydrogen-bonding considerations. The O—H···N hydrogen bond between the phenol molecule and the heteroaromatic base is longer in (II) than in (I), probably reflecting the absence of a cooperative effect on hydrogen bonding in the former. Nevertheless, the geometry of the O1A—H1A···N1 interaction in both cocrystals is in the range of hydrogen bonds formed by phz with strong carboxylic and dihalogenoanilic acids (Pedireddi et al., 1996; Senthil Kumar et al., 2002; Gdaniec & Połoński, 2007; Gotoh et al., 2007; Kumai et al., 2007). As in (I), the phz molecules in (II) are arranged into π-stacks extending along the a axis and are completely surrounded by stacks of pFp molecules (Fig. 5). The dihedral angles formed between the mean planes of the phz molecules and those of the pFp molecules in adjacent stacks are 83.48 (3) and 4.49 (8)°, respectively, with the pFp molecules in the latter case being virtually coplanar with the heteroaromatic base. In effect, the crystal structure of (II) can be seen as composed of slightly corrugated (001) molecular layers, composed of nearly parallel aromatic molecules (Fig. 5b), with face-to-face stacking interactions arranging the heterocyclic molecules into homostacks and C—H···F interactions directing the packing of pFp molecules relative to phz. As in (I), the Ar—ArF stacking synthon is not observed in this cocrystal, as the closest distance between the centroids of the fluorinated phenyl ring and the phz benzene ring is ca 4.597 Å.
In summary, in the 5:1 and 2:1 cocrystals formed by pFp and phz, each heterocyclic molecule is linked via strong O—H···N hydrogen bonds to two pFp molecules strongly inclined to the phz mean plane. The pFp and phz molecules form separate strongly slipped stacks and no aryl–perfluoroaryl interactions are observed. The absence of the Ar—ArF stacking synthon in the two crystalline forms is quite unexpected, given that this robust synthon is present in cocrystals formed by 2,3,5,6-tetrafluorohydroquinone with phz and quinoxaline (Czapik & Gdaniec, 2010), and in 1:1 cocrystals formed by phz with pentafluoroiodobenzene via C—I···N halogen bonds (Cinčić et al., 2008).