2,3,4,5,6-Penta­fluoro­aniline

In the title compound, C₆H₂F₅N, the N atom of the amino group deviates by 0.19 (2) Å from the plane of its bonded atoms and thus has slightly pyramidal sp² hybridization. The crystal packing is governed largely by N—H...F inter­actions and inter­action of F atoms with the perfluoro­phenyl ring (C—F...π_F = 3.21 and 3.25 Å). Inter­molecular N—H...F hydrogen bonds link mol­ecules into polar sheets parallel to the (100) plane.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.025
• wR factor = 0.065
• Data-to-parameter ratio = 5.8

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT089_ALERT_3_B Poor Data / Parameter Ratio (Zmax .LT. 18) .....       5.83

Author Response: the low data/parameter ratio results from the fact that it is a noncentrosymmetric structure of perfluorinated compound for which Friedel pairs were merged.

Alert level C
PLAT150_ALERT_1_C Volume as Calculated Differs from that Given ...     604.30 Ang-3

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.47
           From the CIF: _reflns_number_total                688
           Count of symmetry unique reflns          695
           Completeness (_total/calc)             98.99%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Structural study of pentafluoroaniline, (I), originates from our interest in diverse interaction observed in fluorinated compounds [e.g. X(O,N,C)—H···F, F···perfluorophenyl, phenyl-perfluorophenyl] that can be exploited for crystal engineering. The crystal structure of two monofluorinated anilines have been reported recently (Chopra et al., 2006) showing no intermolecular N—H···N and N—H···F interactions as cohesive force of the crystal. No hydrogen bonds were also found in decafluorodiphenylamine structure (Grzegorczyk & Gdaniec, 2006). Hydrogen bonding to covalently bound fluorine was a subject of several reports and nowadays low propensity of 'organic' fluorine to participate in classical hydrogen bonding is well recognized (Reichenbächer et al., 2005).

The molecule of (I) is shown in Fig. 1. A l l C—F distances are within the range 1.338 (2)–1.342 (2) Å. The amino group is slightly piramidalized, N atom of the amino group deviates by 0.19 (2) Å from the plane of its substituents, and thus the N atom hybridization is intermediate between sp² and sp³. The C1—N1 bond of 1.376 (3) Å is substantially shorter than that observed in the 1:2 pentafluoroaniline - pentafluorophenol cocrystal [1.410 (5) Å; Gdaniec, 2007]. In the latter case the amino nitrogen, which acted as an acceptor of hydrogen bonding from the phenolic OH group, had the sp³ hybridization.

The crystal packing of (I) is governed largely by N—H···F interactions and interaction of fluorine atoms with perfluorophenyl rings. The N—H···F interactions correspond to relatively strong bonding as indicated by the H···F distances and N—H···F angles (Table 1). These hydrogen bonds assemble molecules of (I) into polar sheets parallel to the (001) plane (Fig. 2a). The F···F intermolecular contacts are all longer than 3.084 (2) Å. The pentafluorophenyl rings of molecules related by an n-glide plane are arranged into stacks parallel to the [101] direction.These stacks exhibit large offset which brings atoms F2 and F6 directly above and below the centroid of the electron-defficient phenyl ring, with F···centroid distances of 3.21 and 3.25 Å, respectively (Fig. 2 b). Similar F···pentafluorophenyl ring interactions were observed in decafluorodiphenylamine (Grzegorczyk & Gdaniec, 2006).

Related literature

For related literature on the structure of the pentafluoroaniline cocrystal and of some other fluorinated anilines, see: Gdaniec (2007), Chopra et al. (2006), Grzegorczyk & Gdaniec (2006); for a review on fluorine atom interactions, see Reichenbächer et al. (2005).

S2. Experimental

Pentafluoroaniline was purchased from Alfa Aesar. Single crystal used for this study was obtained by recrystallization from n-heptane at 277 K. It was mounted in a cryoloop and flash-cooled to 100 K

S3. Refinement

The H atoms of the amino group were located in electron-density difference maps and were freely refined. In the absence of significant anomalous scattering effects, Friedel pairs were averaged.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation (Siemens, 1989). Mercury, Version 1.4 (Macrae et al., 2006); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. : Molecular structure of (I) with displacement ellipsoids shown at the 50% probability level.
	Fig. 2. : Crystal structure of (I): (a) (001) sheet of molecules viewed down the z axis with N—H···F hydrogen bonds shown as dashed lines and (b) F···pentafluorophenyl ring interactions (F···ring centroid distances are given in Å)

2,3,4,5,6-Pentafluoroaniline

Crystal data

C6H2F5N	F(000) = 360
Mr = 183.09	Dx = 2.012 Mg m^−3
Monoclinic, Cc	Melting point: 306 K
Hall symbol: C -2yc	Mo Kα radiation, λ = 0.71073 Å
a = 7.591 (2) Å	Cell parameters from 1580 reflections
b = 13.311 (2) Å	θ = 4–25°
c = 6.4023 (14) Å	µ = 0.23 mm^−1
β = 110.90 (2)°	T = 100 K
V = 604.3 (2) Å^3	Block, colorless
Z = 4	0.4 × 0.4 × 0.4 mm

Data collection

Kuma KM4CCD κ geometry diffractometer	682 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.014
Graphite monochromator	θmax = 27.5°, θmin = 4.6°
ω scans	h = −9→9
2423 measured reflections	k = −14→17
688 independent reflections	l = −6→8

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.025	All H-atom parameters refined
wR(F^2) = 0.065	w = 1/[σ^2(Fo^2) + (0.0435P)^2 + 0.2882P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
688 reflections	Δρmax = 0.28 e Å^−3
118 parameters	Δρmin = −0.17 e Å^−3
2 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.023 (3)

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.

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.4464 (3)	0.90222 (15)	0.6239 (4)	0.0201 (5)
F2	0.70684 (17)	0.76715 (11)	0.5825 (2)	0.0194 (3)
F3	0.6465 (2)	0.56639 (11)	0.5710 (2)	0.0235 (4)
F4	0.3236 (2)	0.49224 (11)	0.6051 (3)	0.0236 (4)
F5	0.06082 (18)	0.62247 (10)	0.6494 (2)	0.0213 (3)
F6	0.1169 (2)	0.82310 (11)	0.6457 (2)	0.0206 (3)
C1	0.4132 (3)	0.80038 (18)	0.6127 (4)	0.0142 (5)
C2	0.5454 (3)	0.73180 (18)	0.5952 (4)	0.0149 (4)
C3	0.5158 (3)	0.62946 (17)	0.5912 (4)	0.0156 (5)
C4	0.3526 (3)	0.59154 (18)	0.6096 (4)	0.0164 (5)
C5	0.2195 (3)	0.6579 (2)	0.6307 (4)	0.0161 (5)
C6	0.2493 (3)	0.75991 (17)	0.6305 (4)	0.0154 (5)
H2	0.341 (7)	0.939 (3)	0.608 (7)	0.047 (11)*
H1	0.522 (5)	0.924 (3)	0.568 (6)	0.025 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0221 (10)	0.0125 (10)	0.0274 (11)	−0.0006 (8)	0.0110 (10)	0.0010 (8)
F2	0.0139 (6)	0.0219 (7)	0.0240 (7)	−0.0031 (6)	0.0087 (6)	0.0001 (6)
F3	0.0205 (7)	0.0192 (7)	0.0333 (9)	0.0070 (6)	0.0127 (6)	0.0011 (6)
F4	0.0276 (9)	0.0126 (7)	0.0329 (8)	−0.0017 (6)	0.0136 (7)	0.0000 (6)
F5	0.0170 (7)	0.0224 (7)	0.0275 (8)	−0.0047 (6)	0.0115 (6)	−0.0005 (6)
F6	0.0184 (7)	0.0200 (7)	0.0260 (7)	0.0049 (6)	0.0112 (6)	0.0005 (6)
C1	0.0151 (13)	0.0140 (10)	0.0128 (8)	−0.0006 (9)	0.0043 (9)	0.0003 (8)
C2	0.0118 (9)	0.0190 (12)	0.0135 (10)	−0.0014 (9)	0.0041 (8)	0.0009 (8)
C3	0.0151 (11)	0.0158 (11)	0.0160 (10)	0.0039 (8)	0.0056 (9)	0.0001 (8)
C4	0.0188 (12)	0.0140 (10)	0.0151 (9)	−0.0014 (9)	0.0046 (9)	0.0004 (8)
C5	0.0140 (10)	0.0196 (11)	0.0146 (11)	−0.0036 (9)	0.0052 (8)	−0.0004 (9)
C6	0.0140 (11)	0.0173 (11)	0.0146 (10)	0.0018 (10)	0.0049 (8)	0.0012 (9)

Geometric parameters (Å, º)

N1—C1	1.376 (3)	F6—C6	1.341 (3)
N1—H2	0.91 (4)	C1—C2	1.390 (3)
N1—H1	0.83 (4)	C1—C6	1.397 (3)
F2—C2	1.342 (3)	C2—C3	1.379 (3)
F3—C3	1.341 (3)	C3—C4	1.381 (3)
F4—C4	1.339 (3)	C4—C5	1.384 (3)
F5—C5	1.338 (3)	C5—C6	1.377 (3)
C1—N1—H2	113 (3)	C2—C3—C4	120.3 (2)
C1—N1—H1	118 (2)	F4—C4—C3	120.3 (2)
H2—N1—H1	118 (3)	F4—C4—C5	120.8 (2)
N1—C1—C2	121.8 (2)	C3—C4—C5	118.9 (2)
N1—C1—C6	121.8 (2)	F5—C5—C6	120.1 (2)
C2—C1—C6	116.3 (2)	F5—C5—C4	119.7 (2)
F2—C2—C3	119.4 (2)	C6—C5—C4	120.2 (2)
F2—C2—C1	118.4 (2)	F6—C6—C5	119.4 (2)
C3—C2—C1	122.2 (2)	F6—C6—C1	118.47 (19)
F3—C3—C2	119.9 (2)	C5—C6—C1	122.1 (2)
F3—C3—C4	119.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2···F3^i	0.91 (4)	2.20 (4)	3.086 (3)	162 (4)
N1—H1···F4^ii	0.83 (4)	2.40 (4)	3.146 (2)	151 (3)

Symmetry codes: (i) x−1/2, y+1/2, z; (ii) x+1/2, y+1/2, z.