(E,E)-N1,N4-Bis(2,6-difluoro­benzyl­idene)butane-1,4-diamine

Khaledi Sardashti, M.; Kia, R.; Clegg, W.; Harrington, R.W.

doi:10.1107/S1600536811044801

organic compounds

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ISSN: 2056-9890

Volume 67| Part 11| November 2011| Page o3108

doi:10.1107/S1600536811044801

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(E,E)-N¹,N⁴-Bis(2,6-difluorobenzylidene)butane-1,4-diamine

Mohammad Khaledi Sardashti,^a ^* Reza Kia,^b William Clegg ^c and Ross W. Harrington ^c

^aDepartment of Chemistry, Faculty of Science, Islamic Azad University, Shahrekord Branch, Box 166, Tehran, Iran, ^bDepartment of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran, and ^cSchool of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, England
^*Correspondence e-mail: khaledi1974@yahoo.com

(Received 24 October 2011; accepted 26 October 2011; online 29 October 2011)

The asymmetric unit of the title compound, C₁₈H₁₆F₄N₂, comprises two half crystallographically independent potentially bidentate Schiff base ligands, with an inversion centre located at the mid-point of the central C—C bond. The crystal packing is stabilized by intermolecular C—H⋯F and π–π interactions [centroid–centroid distance = 3.8283 (11) Å].

Related literature

For background to the synthesis and structural variations of Schiff base ligands and their complexes, see: Granovski et al. (1993 ); Elmali et al. (2000 ).

Experimental

Crystal data

C₁₈H₁₆F₄N₂
M_r = 336.33
Triclinic, $[P \overline 1]$
a = 6.4672 (8) Å
b = 8.9296 (12) Å
c = 14.4939 (19) Å
α = 104.956 (2)°
β = 94.474 (2)°
γ = 93.679 (2)°
V = 803.10 (18) Å³
Z = 2
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 150 K
0.34 × 0.30 × 0.20 mm

Data collection

Bruker SMART 1K CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.962, T_max = 0.977
5828 measured reflections
2819 independent reflections
2394 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.100
S = 1.11
2819 reflections
218 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯F3ⁱ	0.95	2.43	3.137 (2)	131
C7—H7⋯F1ⁱⁱ	0.95	2.54	3.378 (2)	148
C12—H12⋯F2	0.95	2.42	3.192 (2)	138
Symmetry codes: (i) x+1, y+1, z; (ii) -x, -y+2, -z+1.

Data collection: SMART (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; 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 and PLATON (Spek,2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811044801/su2336sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811044801/su2336Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811044801/su2336Isup3.cml

checkCIF report

Comment top

Schiff base ligands are among the most prevalent ligands in the field of coordination chemistry. Metal derivatives of Schiff bases have been studied extensively, and Ni^II and Cu^II complexes play a major role in both synthetic and structural research (Elmali et al., 2000; Granovski et al., 1993).

The asymmetric unit of the title compound comprises two half crystallographically independent Schiff base molecules; A (including N1) and B (including N2), see Fig. 1. Each molecule lies about an inversion centre, which is located in the middle of the central C—C bond (Fig. 1). In both molecules the aromatic ring and the imine segment (C—N═C) are approximately coplanar [dihedral angle 14.9 (2)° for molecule A and 3.4 (2)° for molecule B]. These two essentially planar units are linked by a step formed by the four CH₂ groups, so that they are strictly parallel by inversion symmetry but not coplanar.

The crystal packing is stabilized by intermolecular C—H···F interactions (Fig. 2 and Table 1), and by ring stacking of the benzene rings of the two independent molecules [centroid···centroid distance 3.8283 (11) Å, dihedral angle 2.33 (8)°].

Related literature top

For background to the synthesis and structural variations of Schiff base ligands and their complexes, see: Granovski et al. (1993); Elmali et al. (2000).

Experimental top

The title compound was synthesized by mixing 2,4-difluorobenzaldehyde (4 mmol) and butylenediamine (2 mmol) in chloroform (20 ml). After stirring for 2 h, the solution was filtered and the resulting yellow solid was crystallized from ethanol, giving single crystals suitable for X-ray diffraction.

Computing details top

Data collection: SMART (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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) and PLATON (Spek,2009).

Figures top

	Fig. 1. The molecular structure of the two indpendent molecules of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering scheme [Symmetry codes for suffix A: -x, -y + 1, -z + 1 for molecule A, and -x, -y, -z + 2 for molecule B].
	Fig. 2. The crystal packing, viewed down the a axis, showing the intermolecular C—H···F hydrogen bonds (dashed lines), which link the molecules to form a three-dimensional network.

(E,E)-N¹,N⁴-Bis(2,6- difluorobenzylidene)butane-1,4-diamine top

Crystal data top

C₁₈H₁₆F₄N₂	Z = 2
M_r = 336.33	F(000) = 348
Triclinic, P1	D_x = 1.391 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.4672 (8) Å	Cell parameters from 4637 reflections
b = 8.9296 (12) Å	θ = 2.9–28.3°
c = 14.4939 (19) Å	µ = 0.12 mm⁻¹
α = 104.956 (2)°	T = 150 K
β = 94.474 (2)°	Block, colourless
γ = 93.679 (2)°	0.34 × 0.30 × 0.20 mm
V = 803.10 (18) Å³

Data collection top

Bruker SMART 1K CCD area-detector diffractometer	2819 independent reflections
Radiation source: fine-focus sealed tube	2394 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
Detector resolution: 8.33 pixels mm^-1	θ_max = 25.0°, θ_min = 2.4°
ω scans	h = −7→7
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −10→10
T_min = 0.962, T_max = 0.977	l = −16→17
5828 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.037	H-atom parameters constrained
wR(F²) = 0.100	w = 1/[σ²(F_o²) + (0.0437P)² + 0.2616P] where P = (F_o² + 2F_c²)/3
S = 1.11	(Δ/σ)_max < 0.001
2819 reflections	Δρ_max = 0.25 e Å⁻³
218 parameters	Δρ_min = −0.17 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0064 (19)

Crystal data top

C₁₈H₁₆F₄N₂	γ = 93.679 (2)°
M_r = 336.33	V = 803.10 (18) Å³
Triclinic, P1	Z = 2
a = 6.4672 (8) Å	Mo Kα radiation
b = 8.9296 (12) Å	µ = 0.12 mm⁻¹
c = 14.4939 (19) Å	T = 150 K
α = 104.956 (2)°	0.34 × 0.30 × 0.20 mm
β = 94.474 (2)°

Data collection top

Bruker SMART 1K CCD area-detector diffractometer	2819 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2394 reflections with I > 2σ(I)
T_min = 0.962, T_max = 0.977	R_int = 0.019
5828 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	0 restraints
wR(F²) = 0.100	H-atom parameters constrained
S = 1.11	Δρ_max = 0.25 e Å⁻³
2819 reflections	Δρ_min = −0.17 e Å⁻³
218 parameters

Special details top

Experimental. The low-temperature data were collected with the Oxford Cyrosystems Cryostream 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.1808 (2)	0.73556 (16)	0.64201 (10)	0.0304 (3)
N2	0.1964 (2)	0.08666 (15)	0.86448 (9)	0.0280 (3)
F1	0.19530 (16)	1.11574 (12)	0.54522 (8)	0.0423 (3)
F2	0.57474 (16)	0.85519 (11)	0.73666 (7)	0.0392 (3)
F3	0.14208 (16)	0.33304 (13)	0.78309 (9)	0.0486 (3)
F4	0.76402 (16)	0.30222 (12)	0.96638 (8)	0.0424 (3)
C1	0.3727 (2)	1.10083 (19)	0.59734 (11)	0.0274 (4)
C2	0.5378 (3)	1.21002 (19)	0.60645 (12)	0.0327 (4)
H2	0.5284	1.2924	0.5764	0.039*
C3	0.7184 (3)	1.1967 (2)	0.66064 (12)	0.0323 (4)
H3	0.8348	1.2707	0.6677	0.039*
C4	0.7309 (2)	1.07689 (19)	0.70447 (12)	0.0290 (4)
H4	0.8539	1.0686	0.7425	0.035*
C5	0.5610 (2)	0.96960 (18)	0.69179 (11)	0.0260 (4)
C6	0.3742 (2)	0.97517 (17)	0.63782 (10)	0.0236 (3)
C7	0.1858 (2)	0.86668 (18)	0.62385 (11)	0.0262 (4)
H7	0.0593	0.8975	0.5995	0.031*
C8	−0.0223 (3)	0.6452 (2)	0.62406 (12)	0.0353 (4)
H8A	−0.1286	0.7057	0.6011	0.042*
H8B	−0.0627	0.6257	0.6847	0.042*
C9	−0.0163 (3)	0.49050 (19)	0.54960 (12)	0.0324 (4)
H9A	0.0978	0.4343	0.5706	0.039*
H9B	−0.1488	0.4263	0.5459	0.039*
C10	0.3370 (2)	0.38982 (19)	0.82192 (12)	0.0285 (4)
C11	0.4160 (3)	0.52544 (19)	0.80426 (12)	0.0335 (4)
H11	0.3351	0.5768	0.7664	0.040*
C12	0.6160 (3)	0.58532 (19)	0.84294 (12)	0.0336 (4)
H12	0.6728	0.6790	0.8316	0.040*
C13	0.7339 (3)	0.51022 (19)	0.89783 (12)	0.0331 (4)
H13	0.8712	0.5509	0.9245	0.040*
C14	0.6470 (3)	0.37536 (18)	0.91265 (12)	0.0275 (4)
C15	0.4472 (2)	0.30737 (17)	0.87626 (11)	0.0245 (3)
C16	0.3732 (2)	0.15886 (18)	0.89413 (11)	0.0261 (4)
H16	0.4662	0.1137	0.9310	0.031*
C17	0.1558 (3)	−0.06100 (18)	0.88829 (12)	0.0298 (4)
H17A	0.2825	−0.0846	0.9229	0.036*
H17B	0.1225	−0.1454	0.8284	0.036*
C18	−0.0243 (2)	−0.05570 (17)	0.95036 (11)	0.0248 (3)
H18A	−0.1474	−0.0238	0.9176	0.030*
H18B	−0.0605	−0.1615	0.9571	0.030*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0337 (8)	0.0262 (7)	0.0285 (7)	−0.0040 (6)	0.0007 (6)	0.0044 (6)
N2	0.0307 (8)	0.0286 (7)	0.0266 (7)	−0.0016 (6)	0.0052 (6)	0.0109 (6)
F1	0.0344 (6)	0.0431 (6)	0.0530 (7)	−0.0030 (5)	−0.0134 (5)	0.0260 (5)
F2	0.0374 (6)	0.0374 (6)	0.0489 (6)	0.0016 (4)	−0.0052 (5)	0.0257 (5)
F3	0.0304 (6)	0.0456 (6)	0.0743 (8)	−0.0077 (5)	−0.0171 (5)	0.0333 (6)
F4	0.0352 (6)	0.0387 (6)	0.0568 (7)	−0.0022 (4)	−0.0143 (5)	0.0255 (5)
C1	0.0260 (8)	0.0301 (8)	0.0258 (8)	0.0033 (7)	−0.0027 (6)	0.0084 (7)
C2	0.0371 (10)	0.0287 (9)	0.0350 (9)	−0.0022 (7)	0.0009 (7)	0.0155 (7)
C3	0.0289 (9)	0.0348 (9)	0.0318 (9)	−0.0058 (7)	0.0035 (7)	0.0081 (7)
C4	0.0230 (8)	0.0350 (9)	0.0283 (8)	0.0023 (7)	0.0009 (7)	0.0075 (7)
C5	0.0308 (9)	0.0254 (8)	0.0241 (8)	0.0054 (7)	0.0048 (7)	0.0092 (6)
C6	0.0265 (8)	0.0231 (8)	0.0200 (7)	0.0018 (6)	0.0043 (6)	0.0029 (6)
C7	0.0260 (8)	0.0274 (8)	0.0242 (8)	0.0016 (6)	0.0019 (6)	0.0053 (6)
C8	0.0376 (10)	0.0330 (9)	0.0333 (9)	−0.0093 (8)	0.0081 (8)	0.0069 (7)
C9	0.0382 (10)	0.0260 (8)	0.0323 (9)	−0.0096 (7)	0.0027 (7)	0.0098 (7)
C10	0.0240 (8)	0.0277 (8)	0.0334 (9)	0.0004 (7)	−0.0009 (7)	0.0088 (7)
C11	0.0392 (10)	0.0287 (9)	0.0349 (9)	0.0038 (7)	−0.0034 (8)	0.0142 (7)
C12	0.0421 (10)	0.0228 (8)	0.0365 (9)	−0.0041 (7)	0.0004 (8)	0.0116 (7)
C13	0.0301 (9)	0.0285 (9)	0.0382 (10)	−0.0053 (7)	−0.0045 (7)	0.0087 (7)
C14	0.0278 (9)	0.0261 (8)	0.0297 (8)	0.0048 (7)	−0.0007 (7)	0.0100 (7)
C15	0.0262 (8)	0.0229 (8)	0.0250 (8)	0.0031 (6)	0.0055 (6)	0.0062 (6)
C16	0.0271 (9)	0.0269 (8)	0.0269 (8)	0.0058 (7)	0.0049 (7)	0.0101 (7)
C17	0.0370 (9)	0.0243 (8)	0.0284 (9)	−0.0009 (7)	0.0064 (7)	0.0076 (7)
C18	0.0281 (8)	0.0212 (7)	0.0246 (8)	−0.0053 (6)	−0.0003 (6)	0.0080 (6)

Geometric parameters (Å, º) top

N1—C7	1.264 (2)	C8—H8B	0.990
N1—C8	1.465 (2)	C9—C9ⁱ	1.520 (3)
N2—C16	1.262 (2)	C9—H9A	0.990
N2—C17	1.460 (2)	C9—H9B	0.990
F1—C1	1.3568 (18)	C10—C11	1.376 (2)
F2—C5	1.3492 (18)	C10—C15	1.396 (2)
F3—C10	1.3504 (19)	C11—C12	1.384 (2)
F4—C14	1.3562 (18)	C11—H11	0.950
C1—C2	1.373 (2)	C12—C13	1.382 (2)
C1—C6	1.394 (2)	C12—H12	0.950
C2—C3	1.385 (2)	C13—C14	1.370 (2)
C2—H2	0.950	C13—H13	0.950
C3—C4	1.382 (2)	C14—C15	1.394 (2)
C3—H3	0.950	C15—C16	1.473 (2)
C4—C5	1.379 (2)	C16—H16	0.950
C4—H4	0.950	C17—C18	1.522 (2)
C5—C6	1.398 (2)	C17—H17A	0.990
C6—C7	1.474 (2)	C17—H17B	0.990
C7—H7	0.950	C18—C18ⁱⁱ	1.520 (3)
C8—C9	1.523 (2)	C18—H18A	0.990
C8—H8A	0.990	C18—H18B	0.990

C7—N1—C8	116.31 (15)	H9A—C9—H9B	107.8
C16—N2—C17	116.69 (14)	F3—C10—C11	117.55 (14)
F1—C1—C2	117.90 (14)	F3—C10—C15	118.52 (14)
F1—C1—C6	117.45 (14)	C11—C10—C15	123.92 (15)
C2—C1—C6	124.65 (15)	C10—C11—C12	118.54 (15)
C1—C2—C3	118.21 (15)	C10—C11—H11	120.7
C1—C2—H2	120.9	C12—C11—H11	120.7
C3—C2—H2	120.9	C13—C12—C11	120.70 (15)
C4—C3—C2	120.62 (16)	C13—C12—H12	119.7
C4—C3—H3	119.7	C11—C12—H12	119.7
C2—C3—H3	119.7	C14—C13—C12	118.07 (16)
C5—C4—C3	118.57 (15)	C14—C13—H13	121.0
C5—C4—H4	120.7	C12—C13—H13	121.0
C3—C4—H4	120.7	F4—C14—C13	117.68 (15)
F2—C5—C4	117.69 (14)	F4—C14—C15	117.52 (14)
F2—C5—C6	118.30 (14)	C13—C14—C15	124.80 (15)
C4—C5—C6	123.98 (15)	C14—C15—C10	113.96 (14)
C1—C6—C5	113.95 (14)	C14—C15—C16	119.93 (14)
C1—C6—C7	119.55 (14)	C10—C15—C16	126.07 (15)
C5—C6—C7	126.46 (14)	N2—C16—C15	125.39 (15)
N1—C7—C6	124.53 (15)	N2—C16—H16	117.3
N1—C7—H7	117.7	C15—C16—H16	117.3
C6—C7—H7	117.7	N2—C17—C18	111.32 (13)
N1—C8—C9	111.07 (14)	N2—C17—H17A	109.4
N1—C8—H8A	109.4	C18—C17—H17A	109.4
C9—C8—H8A	109.4	N2—C17—H17B	109.4
N1—C8—H8B	109.4	C18—C17—H17B	109.4
C9—C8—H8B	109.4	H17A—C17—H17B	108.0
H8A—C8—H8B	108.0	C18ⁱⁱ—C18—C17	113.13 (16)
C9ⁱ—C9—C8	112.91 (17)	C18ⁱⁱ—C18—H18A	109.0
C9ⁱ—C9—H9A	109.0	C17—C18—H18A	109.0
C8—C9—H9A	109.0	C18ⁱⁱ—C18—H18B	109.0
C9ⁱ—C9—H9B	109.0	C17—C18—H18B	109.0
C8—C9—H9B	109.0	H18A—C18—H18B	107.8

F1—C1—C2—C3	179.14 (15)	F3—C10—C11—C12	−179.66 (15)
C6—C1—C2—C3	−0.9 (3)	C15—C10—C11—C12	−0.5 (3)
C1—C2—C3—C4	−0.2 (3)	C10—C11—C12—C13	0.2 (3)
C2—C3—C4—C5	1.0 (2)	C11—C12—C13—C14	0.0 (3)
C3—C4—C5—F2	−178.75 (14)	C12—C13—C14—F4	179.83 (15)
C3—C4—C5—C6	−0.8 (2)	C12—C13—C14—C15	0.1 (3)
F1—C1—C6—C5	−178.90 (13)	F4—C14—C15—C10	179.92 (14)
C2—C1—C6—C5	1.2 (2)	C13—C14—C15—C10	−0.3 (2)
F1—C1—C6—C7	−0.8 (2)	F4—C14—C15—C16	−2.0 (2)
C2—C1—C6—C7	179.26 (15)	C13—C14—C15—C16	177.79 (16)
F2—C5—C6—C1	177.68 (13)	F3—C10—C15—C14	179.69 (14)
C4—C5—C6—C1	−0.3 (2)	C11—C10—C15—C14	0.5 (2)
F2—C5—C6—C7	−0.2 (2)	F3—C10—C15—C16	1.7 (2)
C4—C5—C6—C7	−178.22 (15)	C11—C10—C15—C16	−177.44 (16)
C8—N1—C7—C6	179.47 (14)	C17—N2—C16—C15	178.58 (14)
C1—C6—C7—N1	166.67 (15)	C14—C15—C16—N2	−179.69 (15)
C5—C6—C7—N1	−15.5 (2)	C10—C15—C16—N2	−1.8 (3)
C7—N1—C8—C9	119.39 (16)	C16—N2—C17—C18	118.07 (16)
N1—C8—C9—C9ⁱ	−66.7 (2)	N2—C17—C18—C18ⁱⁱ	−66.8 (2)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···F3ⁱⁱⁱ	0.95	2.43	3.137 (2)	131
C7—H7···F1^iv	0.95	2.54	3.378 (2)	148
C12—H12···F2	0.95	2.42	3.192 (2)	138

Symmetry codes: (iii) x+1, y+1, z; (iv) −x, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₈H₁₆F₄N₂
M_r	336.33
Crystal system, space group	Triclinic, P1
Temperature (K)	150
a, b, c (Å)	6.4672 (8), 8.9296 (12), 14.4939 (19)
α, β, γ (°)	104.956 (2), 94.474 (2), 93.679 (2)
V (Å³)	803.10 (18)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.34 × 0.30 × 0.20

Data collection
Diffractometer	Bruker SMART 1K CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.962, 0.977
No. of measured, independent and observed [I > 2σ(I)] reflections	5828, 2819, 2394
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.100, 1.11
No. of reflections	2819
No. of parameters	218
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.17

Computer programs: SMART (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek,2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···F3ⁱ	0.95	2.43	3.137 (2)	131
C7—H7···F1ⁱⁱ	0.95	2.54	3.378 (2)	148
C12—H12···F2	0.95	2.42	3.192 (2)	138

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

Acknowledgements

MK thanks the Islamic Azad University, Shahrkord Branch, for the support of this work. WC and RWH thank the EPSRC (UK) for equipment funding.

References

Bruker (2005). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Elmali, A., Zeyrek, C. T., Elerman, Y. & Svoboda, I. (2000). Acta Cryst. C56, 1302–1304. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Granovski, A. D., Nivorozhkin, A. L. & Minkin, V. I. (1993). Coord. Chem. Rev. 126, 1–69. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta. Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar