1,4-Bis(fluoro-meth-yl)benzene.

The title compound, C(8)H(8)F(2), lies across a crystallographic inversion centre. The structure features short C⋯F [2.8515 (18) Å] and F⋯F [2.490 (4) Å] contacts, which are significantly shorter than the sum of the van der Waals radii of these atoms. The F atom and methyl-ene H atoms are disordered over two positions with a site-occupancy ratio of 0.633 (3):0.367 (3). In the crystal structure, inter-molecular C-H⋯F inter-actions link neighboring mol-ecules into infinite chains along the b axis. In addition, C-H⋯π inter-actions link these mol-ecules along [10], forming a two-dimensional network parallel to (101).

Related literature

For the structures of compounds with non-linear properties, see, for example: Chantrapromma et al. (2006 ▶); Fun et al. (2008 ▶); Patil et al. (2007 ▶).

Experimental

Crystal data

C8H8F2

M = 143.15

Monoclinic,

a = 6.1886 (2) Å

b = 5.0152 (2) Å

c = 10.4750 (4) Å

β = 95.107 (2)°

V = 323.82 (2) Å3

Z = 2

Mo Kα radiation

μ = 0.12 mm−1

T = 100.0 (1) K

0.55 × 0.24 × 0.14 mm

Data collection

Bruker APEXII CCD area-detector diffractometer

Absorption correction: multi-scan (; Bruker, 2005 ▶) T min = 0.935, T max = 0.982

11592 measured reflections

1591 independent reflections

1343 reflections with I > 2σ(I)

R int = 0.029

Refinement

R[F 2 > 2σ(F 2)] = 0.074

wR(F 2) = 0.251

S = 1.18

1591 reflections

64 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.67 e Å−3

Δρmin = −0.59 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809003730/bq2122sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809003730/bq2122Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C8H8F2	F(000) = 148
Mr = 143.15	Dx = 1.458 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3653 reflections
a = 6.1886 (2) Å	θ = 2.5–34.7°
b = 5.0152 (2) Å	µ = 0.12 mm−1
c = 10.4750 (4) Å	T = 100 K
β = 95.107 (2)°	Needle, colourless
V = 323.82 (2) Å3	0.55 × 0.24 × 0.14 mm
Z = 2

Bruker APEXII CCD area-detector diffractometer	1591 independent reflections
Radiation source: fine-focus sealed tube	1343 reflections with I > 2σ(I)
graphite	Rint = 0.029
φ and ω scans	θmax = 36.6°, θmin = 3.7°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −10→10
Tmin = 0.935, Tmax = 0.982	k = −7→8
11592 measured reflections	l = −17→17

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)] = 0.074	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.251	H atoms treated by a mixture of independent and constrained refinement
S = 1.18	w = 1/[σ2(Fo2) + (0.1441P)2 + 0.1329P] where P = (Fo2 + 2Fc2)/3
1591 reflections	(Δ/σ)max < 0.001
64 parameters	Δρmax = 0.67 e Å−3
0 restraints	Δρmin = −0.59 e Å−3

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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	Occ. (<1)
F1A	0.9163 (2)	0.5267 (3)	0.72717 (12)	0.0219 (3)	0.633 (3)
F1B	0.6221 (4)	0.4849 (5)	0.6008 (3)	0.0260 (6)	0.367 (3)
C4	0.8122 (2)	0.4155 (2)	0.63866 (12)	0.0204 (3)
H4C	0.7640	0.5505	0.5776	0.025*	0.633 (3)
H4D	0.6847	0.3437	0.6718	0.025*	0.633 (3)
H4A	0.8129	0.3600	0.7274	0.025*	0.367 (3)
H4B	0.9052	0.5709	0.6369	0.025*	0.367 (3)
C1	0.7876 (2)	0.0844 (3)	0.46363 (13)	0.0222 (3)
C2	0.9095 (2)	0.1998 (2)	0.56704 (11)	0.0194 (3)
C3	1.1209 (2)	0.1184 (3)	0.60446 (12)	0.0217 (3)
H1	0.620 (4)	0.159 (6)	0.431 (2)	0.037 (6)*
H3	1.207 (4)	0.205 (5)	0.682 (2)	0.026 (5)*

	U11	U22	U33	U12	U13	U23
F1A	0.0227 (6)	0.0216 (6)	0.0215 (6)	0.0012 (4)	0.0030 (4)	−0.0057 (4)
F1B	0.0216 (10)	0.0244 (11)	0.0324 (12)	0.0115 (8)	0.0045 (8)	−0.0018 (8)
C4	0.0224 (5)	0.0170 (5)	0.0227 (5)	0.0024 (4)	0.0064 (4)	0.0013 (4)
C1	0.0204 (5)	0.0220 (5)	0.0243 (5)	0.0030 (4)	0.0023 (4)	0.0001 (4)
C2	0.0208 (5)	0.0176 (5)	0.0204 (5)	0.0020 (3)	0.0048 (4)	0.0013 (4)
C3	0.0207 (5)	0.0217 (6)	0.0226 (5)	0.0016 (4)	0.0007 (4)	−0.0006 (4)

F1A—C4	1.2162 (18)	C4—H4A	0.9699
F1A—H4A	1.0529	C4—H4B	0.9700
F1A—H4B	0.9681	C1—C2	1.3900 (18)
F1B—C4	1.257 (3)	C1—C3i	1.3916 (19)
F1B—H4C	0.9881	C1—H1	1.13 (3)
F1B—H4D	1.0739	C2—C3	1.3927 (18)
C4—C2	1.4754 (17)	C3—C1i	1.3916 (19)
C4—H4C	0.9600	C3—H3	1.02 (2)
C4—H4D	0.9600
C4—F1A—H4A	50.0	C2—C4—H4A	108.0
C4—F1A—H4B	51.2	H4C—C4—H4A	144.6
H4A—F1A—H4B	101.2	H4D—C4—H4A	58.7
C4—F1B—H4C	48.9	F1A—C4—H4B	51.1
C4—F1B—H4D	47.9	F1B—C4—H4B	108.2
H4C—F1B—H4D	96.7	C2—C4—H4B	108.0
F1A—C4—F1B	122.09 (16)	H4C—C4—H4B	64.6
F1A—C4—C2	120.74 (12)	H4D—C4—H4B	144.8
F1B—C4—C2	117.11 (16)	H4A—C4—H4B	107.3
F1A—C4—H4C	107.2	C2—C1—C3i	119.09 (12)
F1B—C4—H4C	50.8	C2—C1—H1	121.3 (14)
C2—C4—H4C	107.2	C3i—C1—H1	119.6 (14)
F1A—C4—H4D	107.0	C1—C2—C3	121.91 (12)
F1B—C4—H4D	56.0	C1—C2—C4	118.92 (11)
C2—C4—H4D	107.1	C3—C2—C4	119.17 (12)
H4C—C4—H4D	106.8	C1i—C3—C2	119.00 (12)
F1A—C4—H4A	56.2	C1i—C3—H3	120.6 (14)
F1B—C4—H4A	107.9	C2—C3—H3	120.4 (14)
C3i—C1—C2—C3	0.1 (2)	F1A—C4—C2—C3	1.96 (19)
C3i—C1—C2—C4	179.75 (11)	F1B—C4—C2—C3	179.18 (17)
F1A—C4—C2—C1	−177.73 (13)	C1—C2—C3—C1i	−0.1 (2)
F1B—C4—C2—C1	−0.5 (2)	C4—C2—C3—C1i	−179.75 (11)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4D···F1Aii	0.96	2.04	2.8515 (18)	141
C4—H4B···Cg1iii	0.97	2.84	3.5148 (12)	128
C4—H4C···Cg1iii	0.96	2.64	3.5148 (12)	144

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4D⋯F1Ai	0.96	2.04	2.8515 (18)	141
C4—H4B⋯Cg1ii	0.97	2.84	3.5148 (12)	128
C4—H4C⋯Cg1ii	0.96	2.64	3.5148 (12)	144

Symmetry codes: (i) ; (ii) . Cg1 is the centroid of the C1–C3/C1A–C3A benzene ring.