N,N′-Bis(4-bromo­benzyl­idene)butane-1,4-diamine

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

doi:10.1107/S1600536808028122

organic compounds

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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Page o1894

doi:10.1107/S1600536808028122

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N,N′-Bis(4-bromobenzylidene)butane-1,4-diamine

Hoong-Kun Fun,^a ^* Hadi Kargar ^b ‡ and Reza Kia ^a

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bDepartment of Chemistry, School of Science, Payame Noor University (PNU), Ardakan, Yazd, Iran
^*Correspondence e-mail: hkfun@usm.my

(Received 30 August 2008; accepted 3 September 2008; online 6 September 2008)

The molecule of the title Schiff base compound, C₁₈H₁₈Br₂N₂, lies across a crystallographic inversion centre and adopts an E configuration with respect to the C=N bond. In the crystal structure, molecules are linked into chains along [201] through intermolecular Br⋯Br interactions [3.3747 (3) Å], which are significantly shorter than the sum of the van der Waals radii for Br atoms (3.70 Å). The crystal structure is further stabilized by π–π stacking interactions [centroid–centroid distance 3.6811 (11) Å].

Related literature

For halogen–halogen interactions, see: Ramasubbu et al. (1986 ); Brammer et al. (2003 ). For the crystal structures of related compounds, see: Fun et al. (2008 ); Fun, Kia & Kargar (2008a ,b ); Fun & Kia (2008a ,b ). For bond-length data, see: Allen et al. (1987 ). For hydrogen-bondong motifs, see: Bernstein et al. (1995 ). For background, see: Casellato & Vigato (1977 ).

Experimental

Crystal data

C₁₈H₁₈Br₂N₂
M_r = 422.16
Monoclinic, P 2₁ /c
a = 11.2612 (5) Å
b = 9.5213 (4) Å
c = 8.2645 (4) Å
β = 100.040 (3)°
V = 872.56 (7) Å³
Z = 2
Mo Kα radiation
μ = 4.64 mm⁻¹
T = 100.0 (1) K
0.52 × 0.23 × 0.08 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.192, T_max = 0.688
15460 measured reflections
3843 independent reflections
2600 reflections with I > 2σ(I)
R_int = 0.037

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.092
S = 1.02
3843 reflections
136 parameters
All H-atom parameters refined
Δρ_max = 0.68 e Å⁻³
Δρ_min = −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 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808028122/rz2242sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808028122/rz2242Isup2.hkl

checkCIF report

Comment top

The condensation of primary amines with carbonyl compounds yields Schiff bases (Casellato & Vigato, 1977) that are still one of the most prevalent mixed-donor ligand in coordination chemistry. In the past two decades, the synthesis, structure and properties of Schiff base complexes have stimulated much interest for their noteworthy contributions in single molecule-based magnetism, materials science, catalysis of many reactions like carbonylation, hydroformylation, reduction, oxidation, epoxidation and hydrolysis (Casellato & Vigato 1977). As an extension of our work (Fun et al., 2008; Fun, Kia & Kargar 2008a,b; Fun & Kia 2008a,b) on the structural characterization of Schiff base ligands, the title compound is reported here.

The molecule of the title compound (Fig 1), lies across a crystallographic inversion centre and adopts an E configuration with respect to the C═N bond. The bond lengths (Allen et al., 1987) and angles are within normal ranges. The asymmetric unit of the compound is composed of one-half of the molecule. The imino group is coplanar with the benzene ring. Within the molecule, the planar units are parallel but extend in opposite directions from the methylene bridge. An interesting feature of the crystal structure is the short Br···Br [3.3747 (3) Å] interaction (Fig. 2), which is significantly shorter than the sum of the van der Waals radii for two Br atoms (3.70 Å). The directionality of these interactions, C—X···X—C (X = halogens), has been attributed to anisotropic van der Waals radii for terminally bound halogens or ascribed to donor–acceptor interactions involving a lone pair donor orbital on one halogen and a C—X σ^* acceptor orbital on the other (Ramasubbu et al., 1986; Brammer et al., 2003). In the crystal structure, molecules are linked into chains along the [201] direction through the short intermolecular Br···Br interactions (Fig. 2). In addition, the crystal structure is further stabilized by π–π interaction (Fig. 3) with centroid-to-centroid distance of 3.6811 (11) Å, perpendicular interplanar distance of 3.3617 (8) Å, and centroid···centroid offset of 1.4997 (5) Å.

Related literature top

For halogen–halogen interactions, see: Ramasubbu et al. (1986); Brammer et al. (2003). For the crystal structures of related compounds, see: Fun et al. (2008); Fun, Kia & Kargar (2008a,b); Fun & Kia (2008a,b). For bond-length data, see: Allen et al. (1987). For hydrogen-bondong motifs, see: Bernstein et al. (1995). For related literature, see: Casellato & Vigato (1977).

Experimental top

The synthetic method has been described earlier (Fun, Kia & Kargar, 2008b). 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 the title compound with atom labels and 50% probability ellipsoids for non-H atoms. The suffix A corresponds to symmetry code (-x, -y + 1, -z).
	Fig. 2. The crystal packing of the title compound viewed down the b axis, showing molecules linked into chains along the [201] direction by short intermolecular Br···Br interactions.
	Fig. 3. The crystal packing of the title compound viewed down the b-axis, showing the π–π stacking arrangement of molecules.

N,N'-Bis(4-bromobenzylidene)butane-1,4-diamine top

Crystal data top

C₁₈H₁₈Br₂N₂	F(000) = 420
M_r = 422.16	D_x = 1.607 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5047 reflections
a = 11.2612 (5) Å	θ = 2.8–33.0°
b = 9.5213 (4) Å	µ = 4.64 mm⁻¹
c = 8.2645 (4) Å	T = 100 K
β = 100.040 (3)°	Plate, colourless
V = 872.56 (7) Å³	0.52 × 0.23 × 0.08 mm
Z = 2

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3843 independent reflections
Radiation source: fine-focus sealed tube	2600 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.037
ϕ and ω scans	θ_max = 35.0°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −10→18
T_min = 0.192, T_max = 0.688	k = −15→15
15460 measured reflections	l = −13→13

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.092	All H-atom parameters refined
S = 1.02	w = 1/[σ²(F_o²) + (0.0376P)² + 0.4289P] where P = (F_o² + 2F_c²)/3
3843 reflections	(Δ/σ)_max = 0.001
136 parameters	Δρ_max = 0.68 e Å⁻³
0 restraints	Δρ_min = −0.59 e Å⁻³

Crystal data top

C₁₈H₁₈Br₂N₂	V = 872.56 (7) Å³
M_r = 422.16	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 11.2612 (5) Å	µ = 4.64 mm⁻¹
b = 9.5213 (4) Å	T = 100 K
c = 8.2645 (4) Å	0.52 × 0.23 × 0.08 mm
β = 100.040 (3)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3843 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2600 reflections with I > 2σ(I)
T_min = 0.192, T_max = 0.688	R_int = 0.037
15460 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	0 restraints
wR(F²) = 0.092	All H-atom parameters refined
S = 1.02	Δρ_max = 0.68 e Å⁻³
3843 reflections	Δρ_min = −0.59 e Å⁻³
136 parameters

Special details top

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

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Br1	0.863352 (18)	0.42295 (2)	0.45375 (3)	0.03180 (8)
N1	0.26074 (15)	0.39137 (18)	0.1162 (2)	0.0234 (3)
C1	0.50731 (18)	0.31392 (19)	0.4478 (2)	0.0208 (4)
C2	0.63137 (18)	0.3255 (2)	0.4915 (3)	0.0240 (4)
C3	0.69332 (18)	0.40815 (19)	0.3962 (2)	0.0222 (4)
C4	0.63436 (18)	0.4810 (2)	0.2596 (2)	0.0216 (4)
C5	0.50998 (17)	0.4680 (2)	0.2182 (2)	0.0200 (3)
C6	0.44549 (16)	0.38295 (19)	0.3101 (2)	0.0184 (3)
C7	0.31505 (17)	0.3638 (2)	0.2606 (2)	0.0204 (3)
C8	0.13050 (18)	0.3707 (2)	0.0806 (3)	0.0261 (4)
C9	0.06720 (18)	0.5093 (2)	0.0273 (3)	0.0245 (4)
H1	0.462 (2)	0.260 (3)	0.514 (3)	0.028 (6)*
H2	0.679 (2)	0.273 (3)	0.586 (3)	0.028 (6)*
H4	0.678 (2)	0.540 (3)	0.209 (3)	0.032 (7)*
H5	0.470 (2)	0.515 (3)	0.130 (3)	0.024 (6)*
H7	0.276 (2)	0.330 (2)	0.341 (3)	0.018 (5)*
H8A	0.113 (2)	0.300 (3)	−0.016 (3)	0.023 (6)*
H8B	0.1034 (19)	0.336 (2)	0.172 (3)	0.016 (5)*
H9A	0.111 (3)	0.550 (3)	−0.053 (4)	0.034 (7)*
H9B	0.092 (3)	0.576 (3)	0.111 (3)	0.033 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.01994 (10)	0.03249 (12)	0.04155 (14)	−0.00088 (8)	0.00144 (8)	−0.00353 (9)
N1	0.0197 (7)	0.0250 (8)	0.0255 (8)	0.0015 (6)	0.0042 (6)	0.0006 (6)
C1	0.0261 (9)	0.0185 (8)	0.0185 (8)	−0.0004 (7)	0.0055 (7)	0.0000 (7)
C2	0.0273 (9)	0.0214 (8)	0.0220 (9)	0.0017 (7)	0.0012 (7)	−0.0003 (7)
C3	0.0221 (8)	0.0208 (8)	0.0237 (9)	0.0000 (7)	0.0041 (7)	−0.0045 (7)
C4	0.0248 (9)	0.0185 (8)	0.0230 (9)	−0.0022 (7)	0.0088 (7)	−0.0014 (7)
C5	0.0239 (9)	0.0175 (7)	0.0194 (9)	0.0003 (7)	0.0060 (7)	0.0009 (7)
C6	0.0204 (8)	0.0156 (7)	0.0196 (8)	0.0008 (6)	0.0048 (6)	−0.0013 (6)
C7	0.0213 (8)	0.0190 (8)	0.0224 (9)	−0.0001 (7)	0.0080 (7)	0.0014 (7)
C8	0.0201 (9)	0.0286 (10)	0.0301 (11)	−0.0004 (7)	0.0055 (8)	0.0020 (8)
C9	0.0200 (8)	0.0248 (9)	0.0285 (10)	−0.0005 (7)	0.0034 (7)	0.0018 (8)

Geometric parameters (Å, º) top

Br1—C3	1.896 (2)	C5—C6	1.398 (3)
N1—C7	1.270 (2)	C5—H5	0.91 (2)
N1—C8	1.458 (3)	C6—C7	1.466 (3)
C1—C2	1.385 (3)	C7—H7	0.92 (2)
C1—C6	1.391 (3)	C8—C9	1.527 (3)
C1—H1	0.95 (3)	C8—H8A	1.04 (2)
C2—C3	1.385 (3)	C8—H8B	0.93 (2)
C2—H2	1.00 (3)	C9—C9ⁱ	1.512 (4)
C3—C4	1.391 (3)	C9—H9A	0.97 (3)
C4—C5	1.388 (3)	C9—H9B	0.94 (3)
C4—H4	0.90 (3)

C7—N1—C8	117.69 (18)	C1—C6—C7	120.26 (18)
C2—C1—C6	120.93 (19)	C5—C6—C7	120.70 (17)
C2—C1—H1	120.3 (15)	N1—C7—C6	122.12 (18)
C6—C1—H1	118.7 (15)	N1—C7—H7	123.0 (14)
C3—C2—C1	118.83 (18)	C6—C7—H7	114.8 (14)
C3—C2—H2	118.2 (15)	N1—C8—C9	110.13 (18)
C1—C2—H2	122.9 (15)	N1—C8—H8A	107.3 (13)
C2—C3—C4	121.89 (18)	C9—C8—H8A	108.9 (13)
C2—C3—Br1	119.12 (14)	N1—C8—H8B	110.2 (13)
C4—C3—Br1	118.99 (15)	C9—C8—H8B	109.9 (14)
C5—C4—C3	118.31 (19)	H8A—C8—H8B	110.3 (19)
C5—C4—H4	123.6 (17)	C9ⁱ—C9—C8	112.2 (2)
C3—C4—H4	117.8 (17)	C9ⁱ—C9—H9A	116.2 (16)
C4—C5—C6	120.99 (18)	C8—C9—H9A	106.1 (16)
C4—C5—H5	119.6 (16)	C9ⁱ—C9—H9B	116.7 (18)
C6—C5—H5	119.4 (16)	C8—C9—H9B	107.8 (16)
C1—C6—C5	119.02 (17)	H9A—C9—H9B	96 (2)

Symmetry code: (i) −x, −y+1, −z.

Experimental details

Crystal data
Chemical formula	C₁₈H₁₈Br₂N₂
M_r	422.16
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	11.2612 (5), 9.5213 (4), 8.2645 (4)
β (°)	100.040 (3)
V (Å³)	872.56 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.64
Crystal size (mm)	0.52 × 0.23 × 0.08

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.192, 0.688
No. of measured, independent and observed [I > 2σ(I)] reflections	15460, 3843, 2600
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.807

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.092, 1.02
No. of reflections	3843
No. of parameters	136
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.68, −0.59

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

Footnotes

‡Additional correspondence author: tel.: +98-352-7220011 ext. 157, fax: 98-352-7228110, e-mail: hkargar@pnu.ac.ir.

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 postdoctoral research fellowship. HK thanks PNU for financial support.

References

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