N,N′-Bis(4-chloro-3-fluoro­benzyl­idene)ethane-1,2-diamine

Kia, R.; Fun, H.-K.

doi:10.1107/S1600536808033916

organic compounds

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ISSN: 2056-9890

Volume 64| Part 11| November 2008| Page o2169

doi:10.1107/S1600536808033916

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N,N′-Bis(4-chloro-3-fluorobenzylidene)ethane-1,2-diamine

Reza Kia ^a and Hoong-Kun Fun ^a ^*

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 13 October 2008; accepted 17 October 2008; online 22 October 2008)

The asymmetric unit of the title Schiff base compound, C₁₆H₁₂Cl₂F₂N₂, contains one half of the centrosymmetric molecule. Molecules related by translation along the a axis form stacks with short intermolecular C⋯C distances of 3.429 (3) Å. The crystal packing also exhibits short intermolecular Cl⋯F contacts of 3.087 (1) Å.

Related literature

For a related structure, see Fun & Kia (2008 ). For general background, see: Pal et al. (2005 ); Calligaris & Randaccio (1987 ); Hou et al. (2001 ); Ren et al. (2002 ); Allen et al. (1987 ).

Experimental

Crystal data

C₁₆H₁₂Cl₂F₂N₂
M_r = 341.18
Monoclinic, P 2₁ /n
a = 4.6542 (1) Å
b = 23.1343 (6) Å
c = 6.9961 (2) Å
β = 107.063 (2)°
V = 720.12 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.47 mm⁻¹
T = 100.0 (1) K
0.51 × 0.05 × 0.04 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.795, T_max = 0.983
17372 measured reflections
2139 independent reflections
1705 reflections with I > 2σ(I)
R_int = 0.054

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.113
S = 1.07
2139 reflections
100 parameters
H-atom parameters constrained
Δρ_max = 0.99 e Å⁻³
Δρ_min = −0.34 e Å⁻³

Table 1
Selected interatomic distances (Å)

Cl1⋯F1ⁱ	3.087 (1)
C3⋯C6ⁱⁱ	3.429 (3)
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) x+1, y, z.

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); 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 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808033916/cv2465sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808033916/cv2465Isup2.hkl

checkCIF report

Comment top

Schiff bases are one of most prevalent mixed-donor ligands in the field of coordination chemistry. There has been growing interest in Schiff base ligands, mainly because of their wide application in the field of biochemistry, synthesis and catalysis (Pal et al., 2005; Hou et al., 2001; Ren et al., 2002). Many Schiff base complexes have been structurally characterized, but only a relatively small number of free Schiff bases have been characterized (Calligaris & Randaccio, 1987). As an extension of our work (Fun & Kia, 2008) on the structural characterization of Schiff base ligands, the title compound (I) is reported here.

The molecule of the title compound, (I) (Fig. 1), lies across a crystallographic inversion centre and adopts an E configuration with respect to the azomethine C═N bond. The bond lengths and angles are within normal ranges (Allen et al., 1987) and are comparable with those in the related structure (Fun & Kia, 2008). The planar units are parallel by symmetry but extend in opposite directions from the dimethylene bridge. The interesting feature of the crystal structure is the short intermolecular Cl···F interaction (Table 1) with the distance of 3.087 (1) Å, which is shorter than the sum of the van der Waals radii of these atoms. The molecules related by translation along the a axis form stacks with short intermolecular C···C distances of 3.429 (3) Å (Table 1).

Related literature top

For a related structure, see Fun & Kia (2008). For general background, see: Pal et al. (2005); Calligaris & Randaccio (1987); Hou et al. (2001); Ren et al. (2002); Allen et al. (1987).

Experimental top

The synthetic method has been described earlier (Fun & Kia, 2008). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.

Computing details top

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

Figures top

Fig. 1. The molecular structure of (I) with atom labels and 50% probability displacement ellipsoids [symmetry code: (A) -x, -y, -z + 1].

N,N'-Bis(4-chloro-3-fluorobenzylidene)ethane-1,2-diamine top

Crystal data top

C₁₆H₁₂Cl₂F₂N₂	F(000) = 348
M_r = 341.18	D_x = 1.573 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3479 reflections
a = 4.6542 (1) Å	θ = 3.2–30.0°
b = 23.1343 (6) Å	µ = 0.47 mm⁻¹
c = 6.9961 (2) Å	T = 100 K
β = 107.063 (2)°	Needle, colourless
V = 720.12 (3) Å³	0.51 × 0.05 × 0.04 mm
Z = 2

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2139 independent reflections
Radiation source: fine-focus sealed tube	1705 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.054
ϕ and ω scans	θ_max = 30.2°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −6→6
T_min = 0.795, T_max = 0.983	k = −32→32
17372 measured reflections	l = −9→9

Refinement top

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.113	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0465P)² + 0.6198P] where P = (F_o² + 2F_c²)/3
2139 reflections	(Δ/σ)_max < 0.001
100 parameters	Δρ_max = 0.99 e Å⁻³
0 restraints	Δρ_min = −0.34 e Å⁻³

Crystal data top

C₁₆H₁₂Cl₂F₂N₂	V = 720.12 (3) Å³
M_r = 341.18	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 4.6542 (1) Å	µ = 0.47 mm⁻¹
b = 23.1343 (6) Å	T = 100 K
c = 6.9961 (2) Å	0.51 × 0.05 × 0.04 mm
β = 107.063 (2)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2139 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	1705 reflections with I > 2σ(I)
T_min = 0.795, T_max = 0.983	R_int = 0.054
17372 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.113	H-atom parameters constrained
S = 1.07	Δρ_max = 0.99 e Å⁻³
2139 reflections	Δρ_min = −0.34 e Å⁻³
100 parameters

Special details top

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.

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

	x	y	z	U_iso*/U_eq
Cl1	0.77503 (10)	0.17566 (2)	−0.30608 (7)	0.01931 (14)
F1	0.6479 (3)	0.24323 (5)	0.0088 (2)	0.0285 (3)
N1	0.0845 (4)	0.04180 (7)	0.2962 (2)	0.0165 (3)
C1	0.4139 (4)	0.17032 (8)	0.1460 (3)	0.0170 (4)
H1A	0.3865	0.1959	0.2417	0.020*
C2	0.5544 (4)	0.18819 (8)	0.0072 (3)	0.0178 (4)
C3	0.6002 (4)	0.15091 (8)	−0.1355 (3)	0.0162 (4)
C4	0.5045 (4)	0.09402 (8)	−0.1403 (3)	0.0166 (4)
H4A	0.5381	0.0684	−0.2340	0.020*
C5	0.3581 (4)	0.07550 (8)	−0.0045 (3)	0.0158 (4)
H5A	0.2890	0.0376	−0.0100	0.019*
C6	0.3139 (4)	0.11314 (8)	0.1400 (3)	0.0146 (3)
C7	0.1624 (4)	0.09406 (8)	0.2865 (3)	0.0153 (4)
H7A	0.1227	0.1210	0.3742	0.018*
C8	−0.0692 (4)	0.02721 (8)	0.4438 (3)	0.0154 (4)
H8A	−0.2811	0.0208	0.3775	0.019*
H8B	−0.0510	0.0590	0.5372	0.019*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0208 (2)	0.0198 (2)	0.0212 (2)	−0.00002 (17)	0.01230 (17)	0.00367 (18)
F1	0.0397 (7)	0.0162 (6)	0.0378 (8)	−0.0075 (5)	0.0242 (6)	−0.0041 (5)
N1	0.0177 (7)	0.0177 (8)	0.0162 (8)	−0.0006 (6)	0.0082 (6)	0.0024 (6)
C1	0.0184 (8)	0.0155 (9)	0.0192 (9)	−0.0001 (7)	0.0088 (7)	−0.0015 (7)
C2	0.0175 (8)	0.0138 (8)	0.0241 (10)	−0.0015 (6)	0.0093 (7)	0.0016 (7)
C3	0.0135 (8)	0.0185 (9)	0.0185 (9)	0.0003 (7)	0.0077 (7)	0.0048 (7)
C4	0.0168 (8)	0.0165 (9)	0.0171 (9)	0.0003 (7)	0.0061 (7)	−0.0004 (7)
C5	0.0173 (8)	0.0131 (8)	0.0185 (9)	−0.0008 (6)	0.0073 (7)	0.0017 (7)
C6	0.0139 (7)	0.0152 (8)	0.0155 (8)	0.0006 (6)	0.0057 (6)	0.0027 (7)
C7	0.0147 (8)	0.0169 (9)	0.0152 (9)	0.0003 (6)	0.0057 (7)	0.0012 (7)
C8	0.0164 (8)	0.0155 (8)	0.0165 (9)	0.0003 (6)	0.0081 (7)	0.0020 (7)

Geometric parameters (Å, º) top

Cl1—C3	1.7274 (19)	C4—C5	1.389 (3)
F1—C2	1.345 (2)	C4—H4A	0.9300
N1—C7	1.270 (2)	C5—C6	1.395 (3)
N1—C8	1.458 (2)	C5—H5A	0.9300
C1—C2	1.383 (3)	C6—C7	1.472 (3)
C1—C6	1.399 (3)	C7—H7A	0.9300
C1—H1A	0.9300	C8—C8ⁱ	1.524 (4)
C2—C3	1.383 (3)	C8—H8A	0.9700
C3—C4	1.387 (3)	C8—H8B	0.9700

Cl1···F1ⁱⁱ	3.087 (1)	C3···C6ⁱⁱⁱ	3.429 (3)

C7—N1—C8	117.74 (17)	C4—C5—H5A	119.7
C2—C1—C6	118.90 (18)	C6—C5—H5A	119.7
C2—C1—H1A	120.5	C5—C6—C1	119.56 (17)
C6—C1—H1A	120.5	C5—C6—C7	121.36 (16)
F1—C2—C3	118.59 (17)	C1—C6—C7	119.08 (17)
F1—C2—C1	119.72 (17)	N1—C7—C6	121.70 (18)
C3—C2—C1	121.70 (17)	N1—C7—H7A	119.2
C2—C3—C4	119.55 (17)	C6—C7—H7A	119.2
C2—C3—Cl1	119.73 (14)	N1—C8—C8ⁱ	109.64 (18)
C4—C3—Cl1	120.72 (15)	N1—C8—H8A	109.7
C3—C4—C5	119.63 (18)	C8ⁱ—C8—H8A	109.7
C3—C4—H4A	120.2	N1—C8—H8B	109.7
C5—C4—H4A	120.2	C8ⁱ—C8—H8B	109.7
C4—C5—C6	120.65 (17)	H8A—C8—H8B	108.2

C6—C1—C2—F1	178.99 (16)	C4—C5—C6—C1	1.0 (3)
C6—C1—C2—C3	−0.5 (3)	C4—C5—C6—C7	−179.29 (16)
F1—C2—C3—C4	−179.76 (16)	C2—C1—C6—C5	0.2 (3)
C1—C2—C3—C4	−0.2 (3)	C2—C1—C6—C7	−179.57 (16)
F1—C2—C3—Cl1	0.1 (2)	C8—N1—C7—C6	−178.90 (15)
C1—C2—C3—Cl1	179.65 (14)	C5—C6—C7—N1	4.9 (3)
C2—C3—C4—C5	1.4 (3)	C1—C6—C7—N1	−175.37 (17)
Cl1—C3—C4—C5	−178.50 (14)	C7—N1—C8—C8ⁱ	−133.5 (2)
C3—C4—C5—C6	−1.7 (3)

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

Experimental details

Crystal data
Chemical formula	C₁₆H₁₂Cl₂F₂N₂
M_r	341.18
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	4.6542 (1), 23.1343 (6), 6.9961 (2)
β (°)	107.063 (2)
V (Å³)	720.12 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.47
Crystal size (mm)	0.51 × 0.05 × 0.04

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.795, 0.983
No. of measured, independent and observed [I > 2σ(I)] reflections	17372, 2139, 1705
R_int	0.054
(sin θ/λ)_max (Å⁻¹)	0.708

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.113, 1.07
No. of reflections	2139
No. of parameters	100
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.99, −0.34

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Selected interatomic distances (Å) top

Cl1···F1ⁱ

3.087 (1)

C3···C6ⁱⁱ

3.429 (3)

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

Acknowledgements

HKF and RK thank the Malaysian government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for the award of a post-doctoral research fellowship. We acknowledge Professor A. L. Spek for providing us with a symmetry operation code.

References

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