N,N′-Bis[4-(trifluoro­meth­yl)benzyl­idene]butane-1,4-diamine

The title compound, C₂₀H₁₈F₆N₂, a Schiff base, was synthesized by the reaction of 1,4-diamino­butane and 4-(trifluoro­meth­yl)benzaldehyde in chloro­form solution and was crystallized from a mixture of ethanol and dichloro­methane (1:1). It lies across a crystallographic inversion centre. The crystal packing is stabilized by C—H...F hydrogen bonds and π–π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.048
• wR factor = 0.130
• Data-to-parameter ratio = 17.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT031_ALERT_4_C Refined Extinction Parameter within Range ......       2.67 Sigma
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C10
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1B    ..  F2      ..       2.64 Ang.
PLAT482_ALERT_4_C Small D-H..A Angle Rep for C5     ..  N1      ..      96.60 Deg.

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

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

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Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2001); software used to prepare material for publication: SHELXTL and local programs.

N,N'-Bis[4-(trifluoromethyl)benzylidene]butane-1,4-diamine

Crystal data

C20H18F6N2	F(000) = 412
Mr = 400.36	Dx = 1.429 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.0107 (16) Å	Cell parameters from 5528 reflections
b = 9.8541 (14) Å	θ = 2.3–28.2°
c = 8.6457 (13) Å	µ = 0.13 mm^−1
β = 97.266 (2)°	T = 150 K
V = 930.5 (2) Å^3	Needle, colourless
Z = 2	0.40 × 0.40 × 0.20 mm

Data collection

Bruker SMART 1K CCD area-detector diffractometer	2233 independent reflections
Radiation source: fine-focus sealed tube	1930 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
thin–slice ω scans	θmax = 28.3°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −14→14
Tmin = 0.951, Tmax = 0.975	k = −13→13
7930 measured reflections	l = −11→11

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters not defined
R[F^2 > 2σ(F^2)] = 0.048	w = 1/[σ^2(Fo^2) + (0.0546P)^2 + 0.5677P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.130	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.62 e Å^−3
2233 reflections	Δρmin = −0.47 e Å^−3
128 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.008 (3)
Primary atom site location: structure-invariant direct methods	Absolute structure: direct methods
Secondary atom site location: difference Fourier map

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
F1	0.86376 (11)	0.45527 (13)	0.4359 (2)	0.0874 (6)
F2	0.86324 (11)	0.63264 (18)	0.57845 (14)	0.0699 (5)
F3	0.88920 (10)	0.65049 (13)	0.34219 (14)	0.0534 (3)
N1	0.26168 (11)	0.60794 (13)	0.11012 (15)	0.0302 (3)
C1	0.06754 (13)	0.49162 (15)	0.03096 (17)	0.0289 (3)
H1A	0.1096	0.4444	−0.0482	0.035*
H1B	0.0752	0.4344	0.1258	0.035*
C2	0.12979 (13)	0.62782 (16)	0.0699 (2)	0.0325 (3)
H2A	0.1143	0.6894	−0.0209	0.039*
H2B	0.0955	0.6701	0.1587	0.039*
C3	0.30888 (13)	0.63977 (14)	0.24629 (17)	0.0275 (3)
H3	0.2582	0.6769	0.3167	0.033*
C4	0.44052 (13)	0.62075 (14)	0.29868 (16)	0.0248 (3)
C5	0.51224 (14)	0.53847 (15)	0.21434 (16)	0.0276 (3)
H5	0.4751	0.4909	0.1251	0.033*
C6	0.63664 (14)	0.52585 (15)	0.25993 (17)	0.0293 (3)
H6	0.6852	0.4707	0.2017	0.035*
C7	0.69042 (14)	0.59468 (15)	0.39209 (17)	0.0282 (3)
C8	0.62012 (15)	0.67388 (16)	0.47878 (18)	0.0318 (3)
H8	0.6572	0.7194	0.5696	0.038*
C9	0.49523 (14)	0.68647 (15)	0.43237 (17)	0.0296 (3)
H9	0.4468	0.7402	0.4921	0.035*
C10	0.82603 (15)	0.58230 (17)	0.4377 (2)	0.0349 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
F1	0.0366 (6)	0.0342 (6)	0.1846 (18)	0.0086 (5)	−0.0128 (8)	0.0088 (8)
F2	0.0410 (6)	0.1268 (13)	0.0384 (6)	0.0074 (7)	−0.0085 (5)	−0.0083 (7)
F3	0.0351 (6)	0.0724 (8)	0.0530 (7)	−0.0101 (5)	0.0071 (5)	0.0127 (6)
N1	0.0252 (6)	0.0314 (6)	0.0344 (7)	−0.0054 (5)	0.0054 (5)	−0.0025 (5)
C1	0.0266 (7)	0.0287 (7)	0.0306 (7)	−0.0029 (6)	0.0005 (6)	0.0000 (6)
C2	0.0259 (7)	0.0311 (8)	0.0402 (8)	−0.0035 (6)	0.0032 (6)	−0.0014 (6)
C3	0.0281 (7)	0.0244 (7)	0.0316 (7)	−0.0027 (5)	0.0097 (6)	−0.0023 (5)
C4	0.0290 (7)	0.0220 (6)	0.0243 (6)	−0.0022 (5)	0.0068 (5)	0.0012 (5)
C5	0.0327 (7)	0.0265 (7)	0.0239 (7)	−0.0014 (6)	0.0054 (5)	−0.0032 (5)
C6	0.0324 (7)	0.0279 (7)	0.0288 (7)	0.0031 (6)	0.0089 (6)	−0.0005 (5)
C7	0.0295 (7)	0.0254 (7)	0.0294 (7)	−0.0008 (5)	0.0031 (6)	0.0063 (5)
C8	0.0369 (8)	0.0308 (7)	0.0265 (7)	−0.0017 (6)	0.0001 (6)	−0.0041 (6)
C9	0.0347 (8)	0.0275 (7)	0.0273 (7)	0.0012 (6)	0.0071 (6)	−0.0054 (5)
C10	0.0330 (8)	0.0325 (8)	0.0384 (8)	−0.0002 (6)	0.0021 (6)	0.0053 (6)

Geometric parameters (Å, º)

F1—C10	1.320 (2)	C3—H3	0.9500
F2—C10	1.330 (2)	C4—C9	1.394 (2)
F3—C10	1.3277 (19)	C4—C5	1.3995 (19)
N1—C3	1.265 (2)	C5—C6	1.382 (2)
N1—C2	1.4630 (19)	C5—H5	0.9500
C1—C1^i	1.525 (3)	C6—C7	1.395 (2)
C1—C2	1.525 (2)	C6—H6	0.9500
C1—H1A	0.9900	C7—C8	1.384 (2)
C1—H1B	0.9900	C7—C10	1.500 (2)
C2—H2A	0.9900	C8—C9	1.388 (2)
C2—H2B	0.9900	C8—H8	0.9500
C3—C4	1.475 (2)	C9—H9	0.9500
C3—N1—C2	117.82 (13)	C6—C5—H5	119.7
C1^i—C1—C2	111.92 (15)	C4—C5—H5	119.7
C1^i—C1—H1A	109.2	C5—C6—C7	119.51 (13)
C2—C1—H1A	109.2	C5—C6—H6	120.2
C1^i—C1—H1B	109.2	C7—C6—H6	120.2
C2—C1—H1B	109.2	C8—C7—C6	120.61 (14)
H1A—C1—H1B	107.9	C8—C7—C10	120.63 (14)
N1—C2—C1	109.85 (12)	C6—C7—C10	118.76 (14)
N1—C2—H2A	109.7	C7—C8—C9	119.67 (14)
C1—C2—H2A	109.7	C7—C8—H8	120.2
N1—C2—H2B	109.7	C9—C8—H8	120.2
C1—C2—H2B	109.7	C8—C9—C4	120.44 (13)
H2A—C2—H2B	108.2	C8—C9—H9	119.8
N1—C3—C4	121.78 (13)	C4—C9—H9	119.8
N1—C3—H3	119.1	F1—C10—F3	106.39 (16)
C4—C3—H3	119.1	F1—C10—F2	107.68 (16)
C9—C4—C5	119.22 (14)	F3—C10—F2	104.79 (14)
C9—C4—C3	120.05 (13)	F1—C10—C7	112.23 (14)
C5—C4—C3	120.73 (13)	F3—C10—C7	112.18 (13)
C6—C5—C4	120.51 (13)	F2—C10—C7	113.05 (14)
C3—N1—C2—C1	−117.61 (15)	C10—C7—C8—C9	178.49 (14)
C1^i—C1—C2—N1	−173.00 (15)	C7—C8—C9—C4	−0.5 (2)
C2—N1—C3—C4	178.71 (13)	C5—C4—C9—C8	2.0 (2)
N1—C3—C4—C9	163.95 (14)	C3—C4—C9—C8	−177.19 (13)
N1—C3—C4—C5	−15.2 (2)	C8—C7—C10—F1	133.35 (17)
C9—C4—C5—C6	−2.1 (2)	C6—C7—C10—F1	−47.2 (2)
C3—C4—C5—C6	177.05 (13)	C8—C7—C10—F3	−106.92 (17)
C4—C5—C6—C7	0.7 (2)	C6—C7—C10—F3	72.53 (18)
C5—C6—C7—C8	0.8 (2)	C8—C7—C10—F2	11.3 (2)
C5—C6—C7—C10	−178.63 (13)	C6—C7—C10—F2	−169.23 (14)
C6—C7—C8—C9	−1.0 (2)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···N1	0.95	2.61	2.875 (2)	97
C1—H1B···F2^ii	0.99	2.65	3.582 (2)	158

Symmetry code: (ii) −x+1, −y+1, −z+1.