(E,E)-N,N-Bis(2,6-difluoro-benzyl-idene)butane-1,4-diamine.

The asymmetric unit of the title compound, C(18)H(16)F(4)N(2), 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 inter-molecular C-H⋯F and π-π inter-actions [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 = 336.33

Triclinic,

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[F 2 > 2σ(F 2)] = 0.037

wR(F 2) = 0.100

S = 1.11

2819 reflections

218 parameters

H-atom parameters constrained

Δρmax = 0.25 e Å−3

Δρmin = −0.17 e Å−3

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 ▶).

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811044801/su2336sup1.cif

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

Supplementary material file. DOI: 10.1107/S1600536811044801/su2336Isup3.cml

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

C18H16F4N2	Z = 2
Mr = 336.33	F(000) = 348
Triclinic, P1	Dx = 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

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

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(Fo2) + (0.0437P)2 + 0.2616P] where P = (Fo2 + 2Fc2)/3
S = 1.11	(Δ/σ)max < 0.001
2819 reflections	Δρmax = 0.25 e Å−3
218 parameters	Δρmin = −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)

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.

	x	y	z	Uiso*/Ueq
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*

	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)

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)

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···F1iv	0.95	2.54	3.378 (2)	148
C12—H12···F2	0.95	2.42	3.192 (2)	138

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) ; (ii) .