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The crystal structure of penta­fluoro­benzo­nitrile, C7F5N, has been determined by in-situ crystal growth from the liquid at 268 K. The structure is identical to that of the isocyanide, crystallizing in Cmca with the mol­ecule lying on a mirror plane bisecting the C6F5 ring and the cyano group. CN...F interactions are not observed in the structure.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801002641/wn6003sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801002641/wn6003Isup2.hkl
Contains datablock I

CCDC reference: 159853

Key indicators

  • Single-crystal X-ray study
  • T = 180 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.036
  • wR factor = 0.108
  • Data-to-parameter ratio = 12.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
CHEMS_02 Please check that you have entered the correct _publ_requested_category classification of your compound; FI or CI or EI for inorganic; FM or CM or EM for metal-organic; FO or CO or EO for organic. From the CIF: _publ_requested_category EO From the CIF: _chemical_formula_sum :C7 F5 N1 PLAT_371 Alert C Long C(sp2)-C(sp1) Bond C(1) - C(2) = 1.43 Ang. PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 1 N1 -C1 -C2 -C3 -89.90100.00 1.555 1.555 1.555 1.555 PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 2 N1 -C1 -C2 -C3 90.00100.00 1.555 1.555 1.555 12.655
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
4 Alert Level C = Please check

Comment top

Halogen–cyano interactions have been utilized in supramolecular synthons for crystal engineering (Desiraju & Harlow, 1989). For the heavier halogens (X = I, Br) the CN···X interaction is strongly structure-directing. We have recently investigated a series of perfluoro-aromatics of general formula, para-XC6F4CN. For the heavier halogens (X = Cl, Br, I), the compounds are solids at room temperature, whereas C6F5CN, (I), is a liquid (m.p. = 275.4 K; Fluorochem). The crystal was grown in a 0.4 mm capillary tube (GLAS) at 268 K, cooled with an Oxford Cryosystems Cryostream (Cosier & Glazer, 1986), and cooled further to 180 K for data collection.

Compound (I) is isostructural with the isocyanide, C6F5NC (Lentz & Preugschat, 1993), crystallizing in the orthorhombic space group Cmca with the molecule lying on a mirror plane bisecting the C6F5 ring and the cyano group (Figure 2). Compound (I) does not exhibit CN···F-type interactions. Instead, neighbouring molecules adopt a coplanar arrangement in which the F atom para to the cyano group is located over the centroid of the adjacent aromatic ring [d(F···centroid) = 3.263 Å]. The cyanide group aproaches the opposite face in a direction approximately perpendicular to the plane of the aromatic ring [d(N···centroid) = 3.071 Å] (Fig. 3). This interaction with the π-electron density of the phenyl ring presumably accommodates the complementary electronic demands of both the electronegative F and sp-hybridized N atoms.

It is interesting to note that the melting point of the isocyanide, C6F5NC, is some 10° higher than that of (I) (m.p. = 286 K) (Lentz & Preugschat, 1993). This suggests that the NC···π interactions in the isocyanide are stronger than the CN···π interactions in (I).

Experimental top

Pentafluorobenzonitrile was obtained from Lancaster and crystallized in a 0.4 mm capillary tube at 268 K, cooled with an Oxford Cryosystems Cryostream cooler.

Computing details top

Data collection: COLLECT (Nonius BV, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Sheldrick, 1993); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular unit showing displacement ellipsoids at the 50% probability level (XP; Sheldrick, 1993).
[Figure 2] Fig. 2. Projection on to (100) showing the overall packing arrangement in (I) (CAMERON; Watkin et al., 1996).
[Figure 3] Fig. 3. The structural motif observed in (I) (CAMERON; Watkin et al., 1996). F···π and CN···π interactions are indicated by dotted lines.
Pentafluorobenzonitrile top
Crystal data top
C7F5NDx = 1.911 Mg m3
Mr = 193.08Melting point: 268 K
Orthorhombic, CmcaMo Kα radiation, λ = 0.71073 Å
a = 7.6864 (5) ÅCell parameters from 2861 reflections
b = 9.5175 (3) Åθ = 1.0–27.5°
c = 18.3480 (12) ŵ = 0.21 mm1
V = 1342.25 (13) Å3T = 180 K
Z = 8Cylinder, colourless
F(000) = 7520.35 mm (radius)
Data collection top
KappaCCD
diffractometer
732 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.052
Horizonally-mounted graphite crystal monochromatorθmax = 27.5°, θmin = 2.2°
Detector resolution: 9 pixels mm-1h = 09
CCD scansk = 1212
4072 measured reflectionsl = 2323
820 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.037 w = 1/[σ2(Fo2) + (0.0592P)2 + 0.5299P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.108(Δ/σ)max < 0.001
S = 1.12Δρmax = 0.25 e Å3
819 reflectionsΔρmin = 0.24 e Å3
68 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.016 (4)
Crystal data top
C7F5NV = 1342.25 (13) Å3
Mr = 193.08Z = 8
Orthorhombic, CmcaMo Kα radiation
a = 7.6864 (5) ŵ = 0.21 mm1
b = 9.5175 (3) ÅT = 180 K
c = 18.3480 (12) Å0.35 mm (radius)
Data collection top
KappaCCD
diffractometer
732 reflections with I > 2σ(I)
4072 measured reflectionsRint = 0.052
820 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03768 parameters
wR(F2) = 0.1080 restraints
S = 1.12Δρmax = 0.25 e Å3
819 reflectionsΔρmin = 0.24 e Å3
Special details top

Experimental. Crystal grown in situ at 268 K in a 0.4 mm capillary.

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 on F2 for ALL reflections except for 1 with very negative F2 or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating _R_factor_obs 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
xyzUiso*/Ueq
F30.19431 (11)0.13388 (9)0.65670 (5)0.0411 (3)
F40.19455 (12)0.09958 (10)0.57154 (5)0.0450 (3)
F50.50000.21505 (12)0.53032 (7)0.0459 (4)
N10.50000.3606 (2)0.73871 (10)0.0479 (5)
C10.50000.2619 (2)0.70317 (10)0.0325 (4)
C20.50000.1383 (2)0.65861 (9)0.0257 (4)
C30.3447 (2)0.07690 (13)0.63639 (7)0.0273 (3)
C40.3441 (2)0.04187 (13)0.59347 (7)0.0295 (4)
C50.50000.1014 (2)0.57246 (9)0.0298 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F30.0277 (5)0.0426 (5)0.0531 (6)0.0058 (3)0.0084 (4)0.0006 (4)
F40.0378 (5)0.0462 (6)0.0510 (6)0.0153 (4)0.0104 (4)0.0009 (4)
F50.0697 (9)0.0305 (7)0.0374 (7)0.0000.0000.0114 (5)
N10.0715 (13)0.0343 (9)0.0380 (10)0.0000.0000.0081 (7)
C10.0419 (10)0.0266 (8)0.0290 (9)0.0000.0000.0011 (7)
C20.0313 (9)0.0223 (8)0.0235 (8)0.0000.0000.0020 (6)
C30.0263 (7)0.0268 (6)0.0288 (6)0.0023 (4)0.0023 (5)0.0048 (5)
C40.0302 (7)0.0297 (7)0.0287 (7)0.0072 (5)0.0045 (5)0.0035 (5)
C50.0434 (11)0.0233 (8)0.0229 (9)0.0000.0000.0022 (6)
Geometric parameters (Å, º) top
F3—C31.3299 (15)C2—C31.390 (2)
F4—C41.3360 (14)C2—C3i1.3905 (15)
F5—C51.330 (2)C3—C41.378 (2)
N1—C11.144 (3)C4—C51.381 (2)
C1—C21.432 (2)C5—C4i1.381 (2)
N1—C1—C2180.0 (2)F4—C4—C3120.82 (11)
C3—C2—C3i118.3 (2)F4—C4—C5119.60 (12)
C3—C2—C1120.83 (8)C3—C4—C5119.57 (12)
C3i—C2—C1120.83 (8)F5—C5—C4i119.75 (8)
F3—C3—C4119.46 (11)F5—C5—C4119.75 (8)
F3—C3—C2119.51 (12)C4i—C5—C4120.5 (2)
C4—C3—C2121.02 (11)
N1—C1—C2—C390.100C2—C3—C4—F4179.20 (12)
N1—C1—C2—C3i90.100F3—C3—C4—C5179.85 (13)
C3i—C2—C3—F3179.78 (9)C2—C3—C4—C50.3 (2)
C1—C2—C3—F30.1 (2)F4—C4—C5—F50.4 (2)
C3i—C2—C3—C40.0 (2)C3—C4—C5—F5179.19 (13)
C1—C2—C3—C4179.94 (14)F4—C4—C5—C4i178.82 (9)
F3—C3—C4—F40.6 (2)C3—C4—C5—C4i0.7 (3)
Symmetry code: (i) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC7F5N
Mr193.08
Crystal system, space groupOrthorhombic, Cmca
Temperature (K)180
a, b, c (Å)7.6864 (5), 9.5175 (3), 18.3480 (12)
V3)1342.25 (13)
Z8
Radiation typeMo Kα
µ (mm1)0.21
Crystal size (mm)0.35 (radius)
Data collection
DiffractometerKappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4072, 820, 732
Rint0.052
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.108, 1.12
No. of reflections819
No. of parameters68
Δρmax, Δρmin (e Å3)0.25, 0.24

Computer programs: COLLECT (Nonius BV, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP (Sheldrick, 1993), SHELXL97.

 

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