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π interactions are observed in the crystal packing. On the other hand, in (II), the pentafluorophenoxy moiety interacts closely with the Cl atom to form a folded conformation containing an intramolecular halogen–π interaction.Supporting information
 | Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270111008675/gd3379sup1.cif |
 | Structure factor file (CIF format) https://doi.org/10.1107/S0108270111008675/gd3379Isup2.hkl |
| Structure factor file (CIF format) https://doi.org/10.1107/S0108270111008675/gd3379IIsup3.hkl |
CCDC references: 829703; 829704
For related literature, see: Berryman et al. (2006); Dawson et al. (2010); Demeshko et al. (2004); Desiraju (1996); Doerksenm & Thakkar (1999); Hoog et al. (2004); Hori & Naganuma (2010); Hori et al. (2007); Howard et al. (1996); Patrick & Prosser (1960); Quiñonero et al. (2002); Schottel et al. (2008); Thalladi et al. (1998); Williams (1993).
Compounds (I) and (II) were prepared in one step using general procedures (Durmus et al., 2009). Typically, K2CO3 (11 g, 81 mol) was added in portions over a period of 2 h to a dry dimethylformamide solution (60 ml) of 4,5-dichlorophthalonitrile (4.0 g, 20 mol) and 2-phenoxyethanol (5.1 ml, 40 mol) under an N2 atmosphere. The reaction mixture was then stirred at 333 K for 2 d. The mixture was evaporated to remove the solvent and the residue was extracted by CHCl3. The product was further purified by column chromatography (silica gel, CHCl3/MeOH) and recycled gas-phase chromatography (CHCl3) to give (I) as a white powder. Compound (II) was obtained from 2-(pentafluorophenoxy)ethanol using the same procedure as (I). Each compound was crystallized from CHCl3 by the vapour diffusion of MeOH to give colourless crystals. Data for (I): yield 23%, m.p. 397–398 K; 1H NMR (400 MHz, CDCl3, TMS, δ, p.p.m.): 7.79 (s, Ar), 7.41 (s, Ar), 7.32 (t, J = 7.8 Hz, Ar), 7.01 (t, J = 7.8 Hz, Ar), 6.93 (d, J = 7.8 Hz, Ar), 4.54–4.51 (m, CH2), 4.44–4.41 (m, CH2); EI-MS: 298 m/z (M+); elemental analysis, calculated for C16H11ClN2O2: C 64.3, H 3.7, N 9.4%; found: C 64.2, H 3.7, N 9.4%. Data for (II): yield 32%, m.p. 405–207 K; 1H NMR (400 MHz, CDCl3, TMS, δ, p.p.m.): 7.80 (s, Ar), 7.31 (s, Ar), 4.62–4.60 (m, CH2), 4.49–4.47 (m, CH2); EI-MS: 388 m/z (M+); elemental analysis, calculated for C16H6ClF5N2O2: C 49.4, H 1.6, N 7.2%; found: C 49.4, H 1.5, N 7.1%.
All H atoms were placed in geometrically idealized positions and refined as riding, with aromatic C—H = 0.95 Å and aliphatic C—H = 0.99 Å, and with Uiso(H) = 1.2Ueq(C).
The anion–π interaction has been found and discussed as one of the most interesting topics regarding electrostatic interactions in the last decade. The provocative title of a paper, `Anion–π interactions: do they exist?', which was a theoretical study of the interaction reported by Quiñonero et al. (2002), attracted the interest of many chemists (Schottel et al., 2008). Since π-conjugated molecules show remarkable electrostatic interactions because of their quadrupole moments (i.e. negative charge of the aromatic centre), benzene molecules show cation–π, C—H···π and the sliding conformation of π–π interactions (Doerksenm & Thakkar, 1999). On the other hand, fluorinated compounds such as hexafluorobenzene have the opposite quadrupole moment (i.e. positive charge of the aromatic centre induced by the surrounding F atoms) and show the opposite electrostatic interactions, e.g. anion···C6F6 (anion–π), CF···C6F6 (CF–π) and the sliding conformation of C6F6···C6F6 (π–π) interactions. Several papers then demonstrated the existence of anion–π interactions between anion sources and aromatic moieties (Demeshko et al., 2004; de Hoog et al., 2004; Berryman et al., 2006; Dawson et al., 2010), which includes noncovalent π-interactions between lone-pair electrons of electronegative atoms (F, Cl, Br, O, S and N) and perfluorobenzene derivatives (Quiñonero et al., 2002). These studies of quadrupole moment and electrostatic interactions prompted us to compare them with the crystal structures of fluorinated compounds, which also show several unique electrostatic interactions in the crystalline state (Hori et al., 2007; Hori & Naganuma, 2010), e.g. the arene–perfluoroarene interaction (Patrick & Prosser, 1960; Williams, 1993) and C—H···F interactions (Desiraju, 1996; Thalladi et al., 1998). In this paper, we discuss the halogen–π interaction, classified as an anion–π interaction, between the pentafluorophenoxy group and Cl atoms in 4-chloro-5-[2-(pentafluorophenoxy)ethoxy]phthalonitrile, (II), in order to understand fluorine-substituted effects, given that no halogen–π interactions are observed in the nonfluorinated compound 4-chloro-5-(2-phenoxyethoxy)phthalonitrile, (I).
The molecular conformations of (I) and (II) are different (Fig. 1), viz. open in (I) and folded in (II), and the folded structure of (II) shows an apparently attractive interaction between atom Cl1 and the pentafluorophenoxy moiety (ring B). The Cl1···CgB distance in (II) is 3.7253 (12) Å, where CgB is the centroid of ring B. Two intramolecular aromatic rings (A and B) are linked by the ethoxy moiety, and significant conformational differences of trans–gauche–trans and trans–gauche–gauche conformations are observed in the C5/O1/C9/C10/O2/C11 ethoxy moiety of (I) and (II), respectively. The C9—C10—O2—C11 torsion angles in (I) and (II) are trans [173.89 (10)°] and gauche [77.06 (18)°], respectively. The thermodynamically unfavourable gauche–gauche conformation is realised in (II) because of the intramolecular interaction between atom Cl1 and ring B. The O1—C9—C10—O2 torsion angles have the same gauche configuration, viz. 75.96 (13)° in (I) and 71.99 (17)° in (II), and the C5—O1—C9—C10 torsion angles are trans, viz. 171.51 (11)° in (I) and 179.93 (13)° in (II). The dihedral angle between the aromatic rings (A and B) of (II) is 68.75 (4)°, which is smaller than the corresponding angle in (I) [70.89 (5)°]. The C4—Cl1 bond distance of 1.7256 (16) Å in (II) is slightly longer than that of 1.7168 (14) Å in (I), although the C10—O2 bond in (II) is longer than that in (I) [1.454 (2) versus 1.4309 (16) Å]. The C≡N bond distances in (I) and (II) are almost the same [C7≡N1 = 1.1458 (19) and C8≡N2 = 1.144 (2) Å for (I), and C7≡N1 = 1.144 (2) and C8≡N2 = 1.149 (2) Å for (II)]. The C5—O1 bond distances are also the same, i.e. 1.3535 (16) and 1.3524 (18) Å for (I) and (II), respectively.
In the crystal structure of (I), no π–π stacking is observed, but inversion-related pairs of molecules are linked by a C—H···π interaction (Fig. 2); atom H3 of ring A at (x, y, z) interacts closely with a phenoxy moiety at (-x + 2, -y + 1, -z + 1) [symmetry code (i)]. The intermolecular Cl1···Cl1i distance in the pair is short, at 3.274 (1) Å. The formation of the pair allows stabilization of the gauche configuration of O1/C9/C10/O2 to give the trans–gauche–trans conformation in (I). Further, the H atoms in ethoxy moieties C10—H10A and C10—H10B interact with rings Bii [symmetry code: (ii) -x + 1, -y, -z + 1] and Aiii [symmetry code: (iii) x, y - 1, z], respectively, through C—H···π interactions; H10A···CgBii = 2.59 Å [C10···CgBii = 3.477 (2) Å] and H10B···CgAiii = 2.71 Å [C10···CgAiii = 3.492 (2) Å]. Accordingly, the molecules are in a head-to-tail arrangement along the a axis and, further, they form zigzag arrangements along the c axis.
In (II), the molecules are aligned parallel to the a axis. In this direction, atom F5 in the pentafluorophenoxy group interacts with ethoxy atom H9B of a neighbouring molecule through a weak C—H···F contact (Howard et al., 1996), with F5···H9Biv = 2.51 Å [symmetry code: (iv) x - 1, y, z]. The F5···C5iv distance is also short, at 2.950 (2) Å. Because the pentafluorophenoxy groups are aligned in the same direction, the F substituents are located close to one another, with F1···F5v = 2.8625 (15) Å and F2···F4v = 2.8914 (17) Å [symmetry code: (v) x + 1, y, z]. Similarly, the molecules are aligned along the b axis and the F3···F4vi distance is short, at 2.7756 (17) Å [symmetry code: (vi) -x, -y, -z + 1]. No π–π stacking is observed in the crystal packing of (II).
In conclusion, the structures of (I) and (II) demonstrate that ring fluorination is associated with the folded structure of (II) through the halogen–π interaction. Since no strong intermolecular interactions are observed between the molecules in either structure, the halogen–π interaction may be the dominant driving force for the folding in (II).
For related literature, see: Berryman et al. (2006); Dawson et al. (2010); Demeshko et al. (2004); Desiraju (1996); Doerksenm & Thakkar (1999); Hoog et al. (2004); Hori & Naganuma (2010); Hori et al. (2007); Howard et al. (1996); Patrick & Prosser (1960); Quiñonero et al. (2002); Schottel et al. (2008); Thalladi et al. (1998); Williams (1993).
For both compounds, data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
![[Figure 1]](http://journals.iucr.org/c/issues/2011/05/00/gd3379/gd3379fig1thm.gif)
| Fig. 1. The molecular structures of (a) (I) and (b) (II), both at 100 K, showing the atom-labelling schemes. Displacement ellipsoids are drawn at the 50% probability level. |
![[Figure 2]](http://journals.iucr.org/c/issues/2011/05/00/gd3379/gd3379fig2thm.gif)
| Fig. 2. The pair of (I) formed through C—H···π interactions. The unit-cell outline and H atoms not involved in the motif shown have been omitted for clarity. [Symmetry code: (i) -x + 2, -y + 1, -z + 1.] |
| C16H11ClN2O2 | F(000) = 616 |
| Mr = 298.72 | Dx = 1.404 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 5581 reflections |
| a = 9.808 (4) Å | θ = 2.7–27.9° |
| b = 6.555 (3) Å | µ = 0.28 mm−1 |
| c = 22.018 (9) Å | T = 100 K |
| β = 93.259 (4)° | Prismatic, colourless |
| V = 1413.2 (10) Å3 | 0.20 × 0.10 × 0.10 mm |
| Z = 4 |
| Bruker APEXII CCD diffractometer | 3228 independent reflections |
| Radiation source: fine-focus sealed tube | 2744 reflections with I > 2σ(I) |
| Graphite monochromator | Rint = 0.029 |
| Detector resolution: 8.333 pixels mm-1 | θmax = 27.5°, θmin = 2.7° |
| φ and ω scans | h = −12→12 |
| Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | k = −8→8 |
| Tmin = 0.947, Tmax = 0.973 | l = −28→28 |
| 15329 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)] = 0.035 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.087 | H-atom parameters constrained |
| S = 1.04 | w = 1/[σ2(Fo2) + (0.0367P)2 + 0.8106P] where P = (Fo2 + 2Fc2)/3 |
| 3228 reflections | (Δ/σ)max = 0.001 |
| 190 parameters | Δρmax = 0.46 e Å−3 |
| 0 restraints | Δρmin = −0.56 e Å−3 |
| C16H11ClN2O2 | V = 1413.2 (10) Å3 |
| Mr = 298.72 | Z = 4 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 9.808 (4) Å | µ = 0.28 mm−1 |
| b = 6.555 (3) Å | T = 100 K |
| c = 22.018 (9) Å | 0.20 × 0.10 × 0.10 mm |
| β = 93.259 (4)° |
| Bruker APEXII CCD diffractometer | 3228 independent reflections |
| Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | 2744 reflections with I > 2σ(I) |
| Tmin = 0.947, Tmax = 0.973 | Rint = 0.029 |
| 15329 measured reflections |
| R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
| wR(F2) = 0.087 | H-atom parameters constrained |
| S = 1.04 | Δρmax = 0.46 e Å−3 |
| 3228 reflections | Δρmin = −0.56 e Å−3 |
| 190 parameters |
Experimental. IR (KBr disk, cm-1):3447, 3107, 2922, 2359, 2232, 1599, 1584, 1499, 1491, 1451, 1254, 1051, 758, 692, 532. |
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 | ||
| C1 | 0.74491 (14) | 0.9594 (2) | 0.31436 (6) | 0.0158 (3) | |
| C2 | 0.86918 (14) | 1.0586 (2) | 0.32848 (6) | 0.0175 (3) | |
| C3 | 0.95904 (14) | 0.9762 (2) | 0.37340 (7) | 0.0198 (3) | |
| H3 | 1.0439 | 1.0411 | 0.3835 | 0.024* | |
| C4 | 0.92400 (14) | 0.8000 (2) | 0.40310 (6) | 0.0188 (3) | |
| C5 | 0.79972 (13) | 0.6987 (2) | 0.38881 (6) | 0.0151 (3) | |
| C6 | 0.70992 (14) | 0.7809 (2) | 0.34416 (6) | 0.0154 (3) | |
| H6 | 0.6251 | 0.7157 | 0.3340 | 0.018* | |
| C7 | 0.64887 (14) | 1.0428 (2) | 0.26899 (6) | 0.0184 (3) | |
| C8 | 0.90211 (15) | 1.2475 (2) | 0.29898 (7) | 0.0215 (3) | |
| C9 | 0.64597 (13) | 0.4259 (2) | 0.40987 (6) | 0.0164 (3) | |
| H9A | 0.6280 | 0.4018 | 0.3658 | 0.020* | |
| H9B | 0.5713 | 0.5111 | 0.4246 | 0.020* | |
| C10 | 0.65352 (14) | 0.2262 (2) | 0.44356 (6) | 0.0157 (3) | |
| H10A | 0.5790 | 0.1349 | 0.4280 | 0.019* | |
| H10B | 0.7418 | 0.1583 | 0.4372 | 0.019* | |
| C11 | 0.65911 (13) | 0.0998 (2) | 0.54506 (6) | 0.0142 (3) | |
| C12 | 0.65391 (14) | 0.1413 (2) | 0.60719 (6) | 0.0170 (3) | |
| H12 | 0.6369 | 0.2762 | 0.6205 | 0.020* | |
| C13 | 0.67362 (14) | −0.0145 (2) | 0.64915 (6) | 0.0202 (3) | |
| H13 | 0.6693 | 0.0140 | 0.6913 | 0.024* | |
| C14 | 0.69975 (14) | −0.2132 (2) | 0.63016 (7) | 0.0206 (3) | |
| H14 | 0.7143 | −0.3194 | 0.6592 | 0.025* | |
| C15 | 0.70417 (14) | −0.2537 (2) | 0.56855 (7) | 0.0199 (3) | |
| H15 | 0.7216 | −0.3886 | 0.5553 | 0.024* | |
| C16 | 0.68337 (14) | −0.0984 (2) | 0.52585 (6) | 0.0172 (3) | |
| H16 | 0.6858 | −0.1277 | 0.4837 | 0.021* | |
| Cl1 | 1.03241 (4) | 0.70258 (6) | 0.459822 (19) | 0.03207 (12) | |
| N1 | 0.57125 (13) | 1.1075 (2) | 0.23319 (6) | 0.0255 (3) | |
| N2 | 0.92533 (15) | 1.4003 (2) | 0.27667 (6) | 0.0315 (3) | |
| O1 | 0.77600 (9) | 0.52762 (14) | 0.42099 (4) | 0.0168 (2) | |
| O2 | 0.64098 (10) | 0.26465 (14) | 0.50697 (4) | 0.0155 (2) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| C1 | 0.0185 (7) | 0.0164 (6) | 0.0128 (6) | 0.0037 (5) | 0.0022 (5) | 0.0004 (5) |
| C2 | 0.0198 (7) | 0.0157 (6) | 0.0177 (6) | 0.0014 (5) | 0.0066 (5) | 0.0029 (5) |
| C3 | 0.0140 (6) | 0.0198 (7) | 0.0257 (7) | −0.0015 (5) | 0.0024 (5) | 0.0052 (6) |
| C4 | 0.0129 (6) | 0.0214 (7) | 0.0218 (7) | 0.0015 (5) | −0.0010 (5) | 0.0067 (6) |
| C5 | 0.0151 (6) | 0.0148 (6) | 0.0159 (6) | 0.0017 (5) | 0.0041 (5) | 0.0022 (5) |
| C6 | 0.0157 (6) | 0.0165 (6) | 0.0141 (6) | −0.0002 (5) | 0.0014 (5) | −0.0006 (5) |
| C7 | 0.0225 (7) | 0.0169 (7) | 0.0162 (6) | 0.0001 (5) | 0.0032 (5) | 0.0015 (5) |
| C8 | 0.0216 (7) | 0.0217 (7) | 0.0214 (7) | 0.0015 (6) | 0.0044 (6) | 0.0033 (6) |
| C9 | 0.0138 (6) | 0.0171 (7) | 0.0179 (6) | −0.0028 (5) | −0.0010 (5) | 0.0018 (5) |
| C10 | 0.0178 (6) | 0.0151 (6) | 0.0142 (6) | −0.0018 (5) | 0.0012 (5) | −0.0004 (5) |
| C11 | 0.0117 (6) | 0.0147 (6) | 0.0164 (6) | −0.0021 (5) | 0.0016 (5) | 0.0019 (5) |
| C12 | 0.0163 (6) | 0.0168 (6) | 0.0181 (7) | −0.0009 (5) | 0.0020 (5) | −0.0022 (5) |
| C13 | 0.0198 (7) | 0.0254 (7) | 0.0154 (6) | −0.0036 (6) | 0.0018 (5) | 0.0002 (6) |
| C14 | 0.0199 (7) | 0.0202 (7) | 0.0217 (7) | −0.0025 (6) | 0.0009 (5) | 0.0069 (6) |
| C15 | 0.0200 (7) | 0.0144 (6) | 0.0257 (7) | −0.0008 (5) | 0.0040 (6) | 0.0004 (6) |
| C16 | 0.0191 (7) | 0.0162 (6) | 0.0165 (6) | −0.0029 (5) | 0.0033 (5) | −0.0011 (5) |
| Cl1 | 0.01731 (18) | 0.0337 (2) | 0.0436 (2) | −0.00739 (15) | −0.01191 (15) | 0.02295 (18) |
| N1 | 0.0283 (7) | 0.0268 (7) | 0.0212 (6) | 0.0018 (5) | −0.0010 (5) | 0.0067 (5) |
| N2 | 0.0389 (8) | 0.0229 (7) | 0.0337 (8) | −0.0009 (6) | 0.0105 (6) | 0.0087 (6) |
| O1 | 0.0140 (5) | 0.0162 (5) | 0.0198 (5) | −0.0031 (4) | −0.0014 (4) | 0.0065 (4) |
| O2 | 0.0193 (5) | 0.0128 (4) | 0.0145 (5) | 0.0000 (4) | 0.0018 (4) | 0.0002 (4) |
| C1—C6 | 1.3940 (19) | C9—H9B | 0.9900 |
| C1—C2 | 1.401 (2) | C10—O2 | 1.4309 (16) |
| C1—C7 | 1.4410 (19) | C10—H10A | 0.9900 |
| C2—C3 | 1.395 (2) | C10—H10B | 0.9900 |
| C2—C8 | 1.444 (2) | C11—O2 | 1.3735 (16) |
| C3—C4 | 1.380 (2) | C11—C16 | 1.3904 (19) |
| C3—H3 | 0.9500 | C11—C12 | 1.3984 (19) |
| C4—C5 | 1.408 (2) | C12—C13 | 1.383 (2) |
| C4—Cl1 | 1.7168 (14) | C12—H12 | 0.9500 |
| C5—O1 | 1.3535 (16) | C13—C14 | 1.396 (2) |
| C5—C6 | 1.3907 (19) | C13—H13 | 0.9500 |
| C6—H6 | 0.9500 | C14—C15 | 1.385 (2) |
| C7—N1 | 1.1458 (19) | C14—H14 | 0.9500 |
| C8—N2 | 1.144 (2) | C15—C16 | 1.393 (2) |
| C9—O1 | 1.4474 (16) | C15—H15 | 0.9500 |
| C9—C10 | 1.5046 (19) | C16—H16 | 0.9500 |
| C9—H9A | 0.9900 | ||
| C6—C1—C2 | 121.30 (12) | O2—C10—C9 | 108.84 (11) |
| C6—C1—C7 | 118.41 (13) | O2—C10—H10A | 109.9 |
| C2—C1—C7 | 120.28 (13) | C9—C10—H10A | 109.9 |
| C3—C2—C1 | 118.97 (13) | O2—C10—H10B | 109.9 |
| C3—C2—C8 | 120.16 (13) | C9—C10—H10B | 109.9 |
| C1—C2—C8 | 120.82 (13) | H10A—C10—H10B | 108.3 |
| C4—C3—C2 | 119.68 (13) | O2—C11—C16 | 124.58 (12) |
| C4—C3—H3 | 120.2 | O2—C11—C12 | 115.69 (12) |
| C2—C3—H3 | 120.2 | C16—C11—C12 | 119.72 (12) |
| C3—C4—C5 | 121.65 (13) | C13—C12—C11 | 119.87 (13) |
| C3—C4—Cl1 | 119.68 (11) | C13—C12—H12 | 120.1 |
| C5—C4—Cl1 | 118.66 (11) | C11—C12—H12 | 120.1 |
| O1—C5—C6 | 124.76 (12) | C12—C13—C14 | 120.65 (13) |
| O1—C5—C4 | 116.50 (12) | C12—C13—H13 | 119.7 |
| C6—C5—C4 | 118.72 (13) | C14—C13—H13 | 119.7 |
| C5—C6—C1 | 119.67 (13) | C15—C14—C13 | 119.24 (13) |
| C5—C6—H6 | 120.2 | C15—C14—H14 | 120.4 |
| C1—C6—H6 | 120.2 | C13—C14—H14 | 120.4 |
| N1—C7—C1 | 179.14 (16) | C14—C15—C16 | 120.63 (13) |
| N2—C8—C2 | 177.85 (16) | C14—C15—H15 | 119.7 |
| O1—C9—C10 | 107.41 (11) | C16—C15—H15 | 119.7 |
| O1—C9—H9A | 110.2 | C11—C16—C15 | 119.87 (13) |
| C10—C9—H9A | 110.2 | C11—C16—H16 | 120.1 |
| O1—C9—H9B | 110.2 | C15—C16—H16 | 120.1 |
| C10—C9—H9B | 110.2 | C5—O1—C9 | 117.97 (10) |
| H9A—C9—H9B | 108.5 | C11—O2—C10 | 116.22 (10) |
| C16H6ClF5N2O2 | F(000) = 776 |
| Mr = 388.68 | Dx = 1.728 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 5920 reflections |
| a = 5.8272 (13) Å | θ = 2.6–27.7° |
| b = 13.319 (3) Å | µ = 0.33 mm−1 |
| c = 19.380 (4) Å | T = 100 K |
| β = 96.544 (2)° | Prismatic, colourless |
| V = 1494.3 (6) Å3 | 0.24 × 0.10 × 0.08 mm |
| Z = 4 |
| Bruker APEXII CCD diffractometer | 3408 independent reflections |
| Radiation source: fine-focus sealed tube | 2890 reflections with I > 2σ(I) |
| Graphite monochromator | Rint = 0.027 |
| Detector resolution: 8.333 pixels mm-1 | θmax = 27.5°, θmin = 2.6° |
| φ and ω scans | h = −7→7 |
| Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | k = −17→17 |
| Tmin = 0.925, Tmax = 0.974 | l = −24→25 |
| 16533 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)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.088 | H-atom parameters constrained |
| S = 1.03 | w = 1/[σ2(Fo2) + (0.0382P)2 + 1.0883P] where P = (Fo2 + 2Fc2)/3 |
| 3408 reflections | (Δ/σ)max < 0.001 |
| 235 parameters | Δρmax = 0.43 e Å−3 |
| 0 restraints | Δρmin = −0.23 e Å−3 |
| C16H6ClF5N2O2 | V = 1494.3 (6) Å3 |
| Mr = 388.68 | Z = 4 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 5.8272 (13) Å | µ = 0.33 mm−1 |
| b = 13.319 (3) Å | T = 100 K |
| c = 19.380 (4) Å | 0.24 × 0.10 × 0.08 mm |
| β = 96.544 (2)° |
| Bruker APEXII CCD diffractometer | 3408 independent reflections |
| Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | 2890 reflections with I > 2σ(I) |
| Tmin = 0.925, Tmax = 0.974 | Rint = 0.027 |
| 16533 measured reflections |
| R[F2 > 2σ(F2)] = 0.034 | 0 restraints |
| wR(F2) = 0.088 | H-atom parameters constrained |
| S = 1.03 | Δρmax = 0.43 e Å−3 |
| 3408 reflections | Δρmin = −0.23 e Å−3 |
| 235 parameters |
Experimental. IR (KBr disk, cm-1): 3105, 2931, 2361, 2241, 2230, 1589, 1524, 1514, 1497, 1395, 1310, 1275, 1263, 1071, 993, 980, 905, 789, 534. |
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 | ||
| C1 | 0.8254 (3) | 0.27727 (12) | 0.27255 (8) | 0.0182 (3) | |
| C2 | 0.8091 (3) | 0.17269 (12) | 0.26444 (8) | 0.0185 (3) | |
| C3 | 0.6456 (3) | 0.11995 (12) | 0.29730 (8) | 0.0190 (3) | |
| H3 | 0.6328 | 0.0491 | 0.2923 | 0.023* | |
| C4 | 0.5020 (3) | 0.17142 (12) | 0.33720 (8) | 0.0180 (3) | |
| C5 | 0.5150 (3) | 0.27615 (12) | 0.34450 (8) | 0.0172 (3) | |
| C6 | 0.6782 (3) | 0.32895 (12) | 0.31177 (8) | 0.0181 (3) | |
| H6 | 0.6890 | 0.3999 | 0.3162 | 0.022* | |
| C7 | 1.0028 (3) | 0.33312 (12) | 0.24306 (8) | 0.0199 (3) | |
| C8 | 0.9638 (3) | 0.12052 (12) | 0.22354 (9) | 0.0210 (3) | |
| C9 | 0.3848 (3) | 0.42571 (12) | 0.39501 (8) | 0.0186 (3) | |
| H9A | 0.3615 | 0.4617 | 0.3501 | 0.022* | |
| H9B | 0.5400 | 0.4427 | 0.4183 | 0.022* | |
| C10 | 0.2010 (3) | 0.45551 (13) | 0.44015 (8) | 0.0210 (3) | |
| H10A | 0.1853 | 0.5295 | 0.4396 | 0.025* | |
| H10B | 0.0512 | 0.4267 | 0.4204 | 0.025* | |
| C11 | 0.2175 (3) | 0.32331 (12) | 0.52643 (8) | 0.0188 (3) | |
| C12 | 0.3881 (3) | 0.27177 (13) | 0.56812 (9) | 0.0213 (3) | |
| C13 | 0.3618 (3) | 0.17320 (14) | 0.58745 (9) | 0.0233 (4) | |
| C14 | 0.1595 (3) | 0.12251 (12) | 0.56594 (9) | 0.0234 (4) | |
| C15 | −0.0159 (3) | 0.17253 (13) | 0.52634 (9) | 0.0226 (4) | |
| C16 | 0.0125 (3) | 0.27144 (13) | 0.50756 (8) | 0.0201 (3) | |
| Cl1 | 0.30422 (7) | 0.10616 (3) | 0.37969 (2) | 0.02216 (11) | |
| F1 | 0.58648 (17) | 0.31911 (8) | 0.59067 (5) | 0.0289 (2) | |
| F2 | 0.53286 (19) | 0.12730 (8) | 0.62754 (6) | 0.0318 (3) | |
| F3 | 0.1311 (2) | 0.02670 (8) | 0.58397 (6) | 0.0318 (3) | |
| F4 | −0.21748 (18) | 0.12623 (8) | 0.50688 (6) | 0.0308 (3) | |
| F5 | −0.16755 (17) | 0.31781 (8) | 0.47097 (5) | 0.0264 (2) | |
| N1 | 1.1470 (3) | 0.37862 (11) | 0.22243 (8) | 0.0258 (3) | |
| N2 | 1.0870 (3) | 0.07993 (12) | 0.19061 (8) | 0.0272 (3) | |
| O1 | 0.36507 (19) | 0.31921 (8) | 0.38395 (6) | 0.0188 (2) | |
| O2 | 0.2528 (2) | 0.42182 (9) | 0.51158 (6) | 0.0222 (3) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| C1 | 0.0187 (8) | 0.0204 (8) | 0.0156 (7) | 0.0007 (6) | 0.0018 (6) | 0.0014 (6) |
| C2 | 0.0192 (8) | 0.0207 (8) | 0.0156 (7) | 0.0031 (6) | 0.0012 (6) | −0.0019 (6) |
| C3 | 0.0221 (8) | 0.0169 (8) | 0.0176 (7) | 0.0011 (6) | 0.0008 (6) | −0.0011 (6) |
| C4 | 0.0184 (7) | 0.0190 (8) | 0.0167 (7) | −0.0015 (6) | 0.0023 (6) | 0.0006 (6) |
| C5 | 0.0175 (7) | 0.0189 (8) | 0.0151 (7) | 0.0030 (6) | 0.0013 (6) | −0.0009 (6) |
| C6 | 0.0212 (8) | 0.0161 (7) | 0.0168 (7) | 0.0009 (6) | 0.0016 (6) | −0.0002 (6) |
| C7 | 0.0239 (8) | 0.0186 (8) | 0.0175 (8) | 0.0032 (7) | 0.0034 (6) | −0.0011 (6) |
| C8 | 0.0226 (8) | 0.0199 (8) | 0.0203 (8) | −0.0014 (6) | 0.0018 (7) | −0.0018 (6) |
| C9 | 0.0205 (8) | 0.0145 (7) | 0.0215 (8) | 0.0021 (6) | 0.0051 (6) | 0.0027 (6) |
| C10 | 0.0262 (8) | 0.0186 (8) | 0.0189 (8) | 0.0047 (7) | 0.0059 (6) | 0.0026 (6) |
| C11 | 0.0234 (8) | 0.0186 (8) | 0.0156 (7) | 0.0020 (6) | 0.0077 (6) | −0.0003 (6) |
| C12 | 0.0185 (8) | 0.0268 (9) | 0.0194 (8) | −0.0008 (6) | 0.0053 (6) | 0.0009 (7) |
| C13 | 0.0254 (9) | 0.0269 (9) | 0.0186 (8) | 0.0089 (7) | 0.0068 (7) | 0.0045 (7) |
| C14 | 0.0347 (10) | 0.0171 (8) | 0.0203 (8) | 0.0011 (7) | 0.0117 (7) | 0.0008 (6) |
| C15 | 0.0243 (8) | 0.0246 (9) | 0.0199 (8) | −0.0044 (7) | 0.0075 (7) | −0.0060 (7) |
| C16 | 0.0222 (8) | 0.0225 (8) | 0.0157 (7) | 0.0051 (6) | 0.0023 (6) | −0.0013 (6) |
| Cl1 | 0.0239 (2) | 0.0186 (2) | 0.0253 (2) | −0.00235 (15) | 0.00838 (15) | 0.00136 (15) |
| F1 | 0.0204 (5) | 0.0367 (6) | 0.0292 (6) | −0.0042 (4) | 0.0008 (4) | 0.0055 (5) |
| F2 | 0.0305 (6) | 0.0356 (6) | 0.0295 (6) | 0.0126 (5) | 0.0050 (5) | 0.0121 (5) |
| F3 | 0.0493 (7) | 0.0180 (5) | 0.0298 (6) | −0.0011 (5) | 0.0123 (5) | 0.0020 (4) |
| F4 | 0.0305 (6) | 0.0320 (6) | 0.0301 (6) | −0.0102 (5) | 0.0048 (4) | −0.0075 (5) |
| F5 | 0.0233 (5) | 0.0297 (6) | 0.0250 (5) | 0.0037 (4) | −0.0024 (4) | 0.0009 (4) |
| N1 | 0.0286 (8) | 0.0257 (8) | 0.0243 (8) | −0.0001 (6) | 0.0079 (6) | 0.0006 (6) |
| N2 | 0.0286 (8) | 0.0269 (8) | 0.0271 (8) | 0.0008 (6) | 0.0082 (6) | −0.0050 (6) |
| O1 | 0.0216 (6) | 0.0156 (5) | 0.0205 (6) | 0.0015 (4) | 0.0073 (5) | −0.0012 (4) |
| O2 | 0.0301 (6) | 0.0187 (6) | 0.0181 (6) | −0.0001 (5) | 0.0044 (5) | 0.0004 (5) |
| C1—C6 | 1.392 (2) | C9—H9B | 0.9900 |
| C1—C2 | 1.404 (2) | C10—O2 | 1.454 (2) |
| C1—C7 | 1.443 (2) | C10—H10A | 0.9900 |
| C2—C3 | 1.395 (2) | C10—H10B | 0.9900 |
| C2—C8 | 1.444 (2) | C11—O2 | 1.364 (2) |
| C3—C4 | 1.384 (2) | C11—C12 | 1.389 (2) |
| C3—H3 | 0.9500 | C11—C16 | 1.392 (2) |
| C4—C5 | 1.403 (2) | C12—F1 | 1.3455 (19) |
| C4—Cl1 | 1.7256 (16) | C12—C13 | 1.379 (2) |
| C5—O1 | 1.3524 (18) | C13—F2 | 1.3396 (19) |
| C5—C6 | 1.392 (2) | C13—C14 | 1.381 (3) |
| C6—H6 | 0.9500 | C14—F3 | 1.3383 (19) |
| C7—N1 | 1.144 (2) | C14—C15 | 1.378 (3) |
| C8—N2 | 1.149 (2) | C15—F4 | 1.342 (2) |
| C9—O1 | 1.4373 (19) | C15—C16 | 1.382 (2) |
| C9—C10 | 1.511 (2) | C16—F5 | 1.3475 (19) |
| C9—H9A | 0.9900 | ||
| C6—C1—C2 | 120.93 (15) | O2—C10—C9 | 112.73 (13) |
| C6—C1—C7 | 118.37 (15) | O2—C10—H10A | 109.0 |
| C2—C1—C7 | 120.64 (14) | C9—C10—H10A | 109.0 |
| C3—C2—C1 | 119.32 (14) | O2—C10—H10B | 109.0 |
| C3—C2—C8 | 120.66 (15) | C9—C10—H10B | 109.0 |
| C1—C2—C8 | 120.01 (15) | H10A—C10—H10B | 107.8 |
| C4—C3—C2 | 119.59 (15) | O2—C11—C12 | 118.91 (15) |
| C4—C3—H3 | 120.2 | O2—C11—C16 | 124.56 (15) |
| C2—C3—H3 | 120.2 | C12—C11—C16 | 116.31 (15) |
| C3—C4—C5 | 121.30 (15) | F1—C12—C13 | 118.42 (15) |
| C3—C4—Cl1 | 119.75 (13) | F1—C12—C11 | 119.27 (15) |
| C5—C4—Cl1 | 118.94 (12) | C13—C12—C11 | 122.31 (16) |
| O1—C5—C6 | 124.20 (14) | F2—C13—C12 | 119.60 (16) |
| O1—C5—C4 | 116.59 (14) | F2—C13—C14 | 120.34 (16) |
| C6—C5—C4 | 119.21 (14) | C12—C13—C14 | 120.06 (16) |
| C1—C6—C5 | 119.64 (15) | F3—C14—C15 | 120.03 (16) |
| C1—C6—H6 | 120.2 | F3—C14—C13 | 120.94 (16) |
| C5—C6—H6 | 120.2 | C15—C14—C13 | 119.03 (16) |
| N1—C7—C1 | 177.14 (18) | F4—C15—C14 | 120.28 (16) |
| N2—C8—C2 | 179.29 (19) | F4—C15—C16 | 119.44 (16) |
| O1—C9—C10 | 107.18 (13) | C14—C15—C16 | 120.26 (16) |
| O1—C9—H9A | 110.3 | F5—C16—C15 | 117.78 (15) |
| C10—C9—H9A | 110.3 | F5—C16—C11 | 120.27 (15) |
| O1—C9—H9B | 110.3 | C15—C16—C11 | 121.94 (15) |
| C10—C9—H9B | 110.3 | C5—O1—C9 | 117.18 (12) |
| H9A—C9—H9B | 108.5 | C11—O2—C10 | 118.56 (13) |
Experimental details
| (I) | (II) | |
| Crystal data | ||
| Chemical formula | C16H11ClN2O2 | C16H6ClF5N2O2 |
| Mr | 298.72 | 388.68 |
| Crystal system, space group | Monoclinic, P21/c | Monoclinic, P21/c |
| Temperature (K) | 100 | 100 |
| a, b, c (Å) | 9.808 (4), 6.555 (3), 22.018 (9) | 5.8272 (13), 13.319 (3), 19.380 (4) |
| β (°) | 93.259 (4) | 96.544 (2) |
| V (Å3) | 1413.2 (10) | 1494.3 (6) |
| Z | 4 | 4 |
| Radiation type | Mo Kα | Mo Kα |
| µ (mm−1) | 0.28 | 0.33 |
| Crystal size (mm) | 0.20 × 0.10 × 0.10 | 0.24 × 0.10 × 0.08 |
| Data collection | ||
| Diffractometer | Bruker APEXII CCD | Bruker APEXII CCD |
| Absorption correction | Empirical (using intensity measurements) (SADABS; Sheldrick, 1996) | Empirical (using intensity measurements) (SADABS; Sheldrick, 1996) |
| Tmin, Tmax | 0.947, 0.973 | 0.925, 0.974 |
| No. of measured, independent and observed [I > 2σ(I)] reflections | 15329, 3228, 2744 | 16533, 3408, 2890 |
| Rint | 0.029 | 0.027 |
| (sin θ/λ)max (Å−1) | 0.649 | 0.649 |
| Refinement | ||
| R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.087, 1.04 | 0.034, 0.088, 1.03 |
| No. of reflections | 3228 | 3408 |
| No. of parameters | 190 | 235 |
| H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
| Δρmax, Δρmin (e Å−3) | 0.46, −0.56 | 0.43, −0.23 |
Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
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The anion–π interaction has been found and discussed as one of the most interesting topics regarding electrostatic interactions in the last decade. The provocative title of a paper, `Anion–π interactions: do they exist?', which was a theoretical study of the interaction reported by Quiñonero et al. (2002), attracted the interest of many chemists (Schottel et al., 2008). Since π-conjugated molecules show remarkable electrostatic interactions because of their quadrupole moments (i.e. negative charge of the aromatic centre), benzene molecules show cation–π, C—H···π and the sliding conformation of π–π interactions (Doerksenm & Thakkar, 1999). On the other hand, fluorinated compounds such as hexafluorobenzene have the opposite quadrupole moment (i.e. positive charge of the aromatic centre induced by the surrounding F atoms) and show the opposite electrostatic interactions, e.g. anion···C6F6 (anion–π), CF···C6F6 (CF–π) and the sliding conformation of C6F6···C6F6 (π–π) interactions. Several papers then demonstrated the existence of anion–π interactions between anion sources and aromatic moieties (Demeshko et al., 2004; de Hoog et al., 2004; Berryman et al., 2006; Dawson et al., 2010), which includes noncovalent π-interactions between lone-pair electrons of electronegative atoms (F, Cl, Br, O, S and N) and perfluorobenzene derivatives (Quiñonero et al., 2002). These studies of quadrupole moment and electrostatic interactions prompted us to compare them with the crystal structures of fluorinated compounds, which also show several unique electrostatic interactions in the crystalline state (Hori et al., 2007; Hori & Naganuma, 2010), e.g. the arene–perfluoroarene interaction (Patrick & Prosser, 1960; Williams, 1993) and C—H···F interactions (Desiraju, 1996; Thalladi et al., 1998). In this paper, we discuss the halogen–π interaction, classified as an anion–π interaction, between the pentafluorophenoxy group and Cl atoms in 4-chloro-5-[2-(pentafluorophenoxy)ethoxy]phthalonitrile, (II), in order to understand fluorine-substituted effects, given that no halogen–π interactions are observed in the nonfluorinated compound 4-chloro-5-(2-phenoxyethoxy)phthalonitrile, (I).
The molecular conformations of (I) and (II) are different (Fig. 1), viz. open in (I) and folded in (II), and the folded structure of (II) shows an apparently attractive interaction between atom Cl1 and the pentafluorophenoxy moiety (ring B). The Cl1···CgB distance in (II) is 3.7253 (12) Å, where CgB is the centroid of ring B. Two intramolecular aromatic rings (A and B) are linked by the ethoxy moiety, and significant conformational differences of trans–gauche–trans and trans–gauche–gauche conformations are observed in the C5/O1/C9/C10/O2/C11 ethoxy moiety of (I) and (II), respectively. The C9—C10—O2—C11 torsion angles in (I) and (II) are trans [173.89 (10)°] and gauche [77.06 (18)°], respectively. The thermodynamically unfavourable gauche–gauche conformation is realised in (II) because of the intramolecular interaction between atom Cl1 and ring B. The O1—C9—C10—O2 torsion angles have the same gauche configuration, viz. 75.96 (13)° in (I) and 71.99 (17)° in (II), and the C5—O1—C9—C10 torsion angles are trans, viz. 171.51 (11)° in (I) and 179.93 (13)° in (II). The dihedral angle between the aromatic rings (A and B) of (II) is 68.75 (4)°, which is smaller than the corresponding angle in (I) [70.89 (5)°]. The C4—Cl1 bond distance of 1.7256 (16) Å in (II) is slightly longer than that of 1.7168 (14) Å in (I), although the C10—O2 bond in (II) is longer than that in (I) [1.454 (2) versus 1.4309 (16) Å]. The C≡N bond distances in (I) and (II) are almost the same [C7≡N1 = 1.1458 (19) and C8≡N2 = 1.144 (2) Å for (I), and C7≡N1 = 1.144 (2) and C8≡N2 = 1.149 (2) Å for (II)]. The C5—O1 bond distances are also the same, i.e. 1.3535 (16) and 1.3524 (18) Å for (I) and (II), respectively.
In the crystal structure of (I), no π–π stacking is observed, but inversion-related pairs of molecules are linked by a C—H···π interaction (Fig. 2); atom H3 of ring A at (x, y, z) interacts closely with a phenoxy moiety at (-x + 2, -y + 1, -z + 1) [symmetry code (i)]. The intermolecular Cl1···Cl1i distance in the pair is short, at 3.274 (1) Å. The formation of the pair allows stabilization of the gauche configuration of O1/C9/C10/O2 to give the trans–gauche–trans conformation in (I). Further, the H atoms in ethoxy moieties C10—H10A and C10—H10B interact with rings Bii [symmetry code: (ii) -x + 1, -y, -z + 1] and Aiii [symmetry code: (iii) x, y - 1, z], respectively, through C—H···π interactions; H10A···CgBii = 2.59 Å [C10···CgBii = 3.477 (2) Å] and H10B···CgAiii = 2.71 Å [C10···CgAiii = 3.492 (2) Å]. Accordingly, the molecules are in a head-to-tail arrangement along the a axis and, further, they form zigzag arrangements along the c axis.
In (II), the molecules are aligned parallel to the a axis. In this direction, atom F5 in the pentafluorophenoxy group interacts with ethoxy atom H9B of a neighbouring molecule through a weak C—H···F contact (Howard et al., 1996), with F5···H9Biv = 2.51 Å [symmetry code: (iv) x - 1, y, z]. The F5···C5iv distance is also short, at 2.950 (2) Å. Because the pentafluorophenoxy groups are aligned in the same direction, the F substituents are located close to one another, with F1···F5v = 2.8625 (15) Å and F2···F4v = 2.8914 (17) Å [symmetry code: (v) x + 1, y, z]. Similarly, the molecules are aligned along the b axis and the F3···F4vi distance is short, at 2.7756 (17) Å [symmetry code: (vi) -x, -y, -z + 1]. No π–π stacking is observed in the crystal packing of (II).
In conclusion, the structures of (I) and (II) demonstrate that ring fluorination is associated with the folded structure of (II) through the halogen–π interaction. Since no strong intermolecular interactions are observed between the molecules in either structure, the halogen–π interaction may be the dominant driving force for the folding in (II).