N,N′-Bis(4-bromo­benzyl­idene)ethane-1,2-diamine

Fun, H.-K.; Mirkhani, V.; Kia, R.; Vartooni, A.R.

doi:10.1107/S1600536808019594

organic compounds

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ISSN: 2056-9890

Volume 64| Part 8| August 2008| Pages o1374-o1375

doi:10.1107/S1600536808019594

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N,N′-Bis(4-bromobenzylidene)ethane-1,2-diamine

Hoong-Kun Fun,^a ^* Valiollah Mirkhani,^b ‡ Reza Kia ^a and Akbar Rostami Vartooni ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bChemistry Department, University of Isfahan, Isfahan, 81746-73441, Iran
^*Correspondence e-mail: hkfun@usm.my

(Received 26 June 2008; accepted 27 June 2008; online 5 July 2008)

The molecule of the title Schiff base compound, C₁₆H₁₄Br₂N₂, lies across a crystallographic inversion centre and adopts an E configuration with respect to the azomethine C=N bond. The imino group is coplanar with the aromatic ring. Within the molecule, the planar units are parallel, but extend in opposite directions from the dimethylene bridge. The crystal structure is stabilized by intermolecular C—H⋯π interactions and Br⋯Br [3.6307 (4) Å] short contacts.

Related literature

For the values of bond lengths, see Allen et al. (1987 ). For related structures see, for example: Fun, Kargar & Kia (2008 ); Fun, Kia & Kargar (2008 ); Habibi et al. (2007 ); Calligaris & Randaccio, (1987 ). For information on Schiff base complexes and their applications, see, for example: Kia, Mirkhani, Harkema & van Hummel (2007 ); Kia, Mirkhani, Kalman & Deak (2007 ); Amirnasr et al. (2002 ); Pal et al. (2005 ); Hou et al. (2001 ); Ren et al. (2002 ).

Experimental

Crystal data

C₁₆H₁₄Br₂N₂
M_r = 394.11
Monoclinic, P 2₁ /c
a = 13.8417 (5) Å
b = 7.4796 (3) Å
c = 7.1531 (3) Å
β = 95.692 (1)°
V = 736.91 (5) Å³
Z = 2
Mo Kα radiation
μ = 5.49 mm⁻¹
T = 100.0 (1) K
0.45 × 0.24 × 0.03 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker 2005 ) T_min = 0.189, T_max = 0.853
10096 measured reflections
2148 independent reflections
1773 reflections with I > 2σ(I)
R_int = 0.048

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.069
S = 1.06
2148 reflections
99 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.73 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7A⋯Cg1	0.93	2.99	3.7143 (19)	136
Cg1 is the centroid of the C1–C6 benzene ring.

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/S1600536808019594/at2584sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808019594/at2584Isup2.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 (Kia et al., 2007a,b; Habibi et al., 2007; Amirnasr et al., 2002; 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. As an extension of our work (Fun et al., 2008a,b) on the structural characterization of Schiff base compounds, the title compound (I), (Fig. 1), 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). The asymmetric unit of the compound is composed of one-half of the molecule. The two planar units are parallel but extend in opposite directions from the methylene bridge. The interesting feature of the structure is Br···Brⁱ [symmetry code: (i) 2 - x, 1 - y, 1 - z] interactions with distance 3.6307 (4) Å. In the crystal structure, molecules (Fig. 2) are arranged into columns along the c axis by C—H···π interactions (Table 1).

Related literature top

For the values of bond lengths, see Allen et al. (1987). For related structures see, for example: Fun et al. (2008a,b); Habibi et al. (2007); Calligaris & Randaccio, (1987). For information on Schiff base complexes and their applications, see, for example, Kia et al. (2007a,b); Amirnasr et al. (2002); Pal et al. (2005); Hou et al. (2001); Ren et al. (2002). For related literature, see: Fun, Kargar & Kia (2008); Fun, Kia & Kargar (2008); Kia, Mirkhani, Harkema & van Hummel (2007); Kia, Mirkhani, Kalman & Deak (2007). Cg1 is the centroid of the C1–C6 benzene ring.

Experimental top

The synthetic method has been described earlier (Fun et al., 2008a,b). 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 and PLATON (Spek, 2003).

Figures top

	Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms [symmetry code for a: -x, 0.5 + y, 0.5 - z].
	Fig. 2. The crystal packing, showing column arrangement of the molecules along the c-axis. The Br···Br contacts are shown as dashed lines.

N,N'-Bis(4-bromobenzylidene)ethane-1,2-diamine top

Crystal data top

C₁₆H₁₄Br₂N₂	F(000) = 388
M_r = 394.11	D_x = 1.776 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3320 reflections
a = 13.8417 (5) Å	θ = 3.1–31.6°
b = 7.4796 (3) Å	µ = 5.49 mm⁻¹
c = 7.1531 (3) Å	T = 100 K
β = 95.692 (1)°	Block, colourless
V = 736.91 (5) Å³	0.45 × 0.24 × 0.03 mm
Z = 2

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2148 independent reflections
Radiation source: fine-focus sealed tube	1773 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.048
ϕ and ω scans	θ_max = 30.0°, θ_min = 3.0°
Absorption correction: multi-scan (SADABS; Bruker 2005)	h = −19→19
T_min = 0.189, T_max = 0.853	k = −10→9
10096 measured reflections	l = −10→10

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.069	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.0291P)² + 0.1298P] where P = (F_o² + 2F_c²)/3
2148 reflections	(Δ/σ)_max = 0.001
99 parameters	Δρ_max = 0.73 e Å⁻³
0 restraints	Δρ_min = −0.45 e Å⁻³

Crystal data top

C₁₆H₁₄Br₂N₂	V = 736.91 (5) Å³
M_r = 394.11	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 13.8417 (5) Å	µ = 5.49 mm⁻¹
b = 7.4796 (3) Å	T = 100 K
c = 7.1531 (3) Å	0.45 × 0.24 × 0.03 mm
β = 95.692 (1)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2148 independent reflections
Absorption correction: multi-scan (SADABS; Bruker 2005)	1773 reflections with I > 2σ(I)
T_min = 0.189, T_max = 0.853	R_int = 0.048
10096 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.069	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.73 e Å⁻³
2148 reflections	Δρ_min = −0.45 e Å⁻³
99 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
Br1	0.901280 (16)	0.57354 (3)	−0.36941 (3)	0.02279 (8)
N1	0.57142 (14)	0.4729 (2)	0.2936 (2)	0.0199 (4)
C1	0.67242 (16)	0.5432 (3)	−0.0377 (3)	0.0185 (4)
H1A	0.6068	0.5727	−0.0490	0.022*
C2	0.72773 (16)	0.5762 (2)	−0.1849 (3)	0.0187 (4)
H2A	0.7001	0.6316	−0.2937	0.022*
C3	0.82508 (15)	0.5259 (3)	−0.1685 (3)	0.0172 (4)
C4	0.86807 (16)	0.4432 (2)	−0.0085 (3)	0.0183 (4)
H4A	0.9327	0.4073	−0.0005	0.022*
C5	0.81247 (16)	0.4149 (2)	0.1402 (3)	0.0179 (4)
H5A	0.8408	0.3615	0.2496	0.021*
C6	0.71515 (16)	0.4652 (2)	0.1284 (3)	0.0169 (4)
C7	0.65967 (17)	0.4292 (2)	0.2901 (3)	0.0185 (4)
H7A	0.6909	0.3717	0.3944	0.022*
C8	0.52516 (17)	0.4197 (3)	0.4604 (3)	0.0202 (4)
H8A	0.4726 (17)	0.323 (3)	0.418 (3)	0.025 (6)*
H8B	0.5700 (17)	0.359 (3)	0.553 (3)	0.014 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.02663 (14)	0.02485 (12)	0.01759 (12)	−0.00239 (9)	0.00569 (9)	0.00236 (8)
N1	0.0245 (9)	0.0218 (8)	0.0134 (8)	0.0011 (7)	0.0025 (7)	0.0012 (6)
C1	0.0196 (10)	0.0176 (10)	0.0178 (10)	0.0016 (7)	−0.0005 (8)	−0.0006 (7)
C2	0.0250 (11)	0.0172 (9)	0.0131 (9)	0.0030 (8)	−0.0015 (8)	0.0005 (7)
C3	0.0231 (11)	0.0143 (8)	0.0143 (9)	−0.0018 (8)	0.0024 (8)	−0.0009 (7)
C4	0.0193 (10)	0.0164 (9)	0.0188 (9)	−0.0014 (7)	0.0006 (8)	−0.0018 (7)
C5	0.0239 (11)	0.0148 (9)	0.0144 (9)	−0.0008 (8)	−0.0008 (8)	0.0002 (7)
C6	0.0249 (11)	0.0122 (8)	0.0135 (9)	−0.0011 (7)	0.0013 (8)	−0.0026 (6)
C7	0.0265 (11)	0.0155 (9)	0.0132 (9)	−0.0012 (8)	0.0002 (8)	−0.0010 (7)
C8	0.0231 (11)	0.0215 (10)	0.0167 (10)	0.0002 (8)	0.0050 (8)	0.0021 (8)

Geometric parameters (Å, º) top

Br1—C3	1.8987 (19)	C4—C5	1.389 (3)
N1—C7	1.267 (3)	C4—H4A	0.9300
N1—C8	1.464 (3)	C5—C6	1.393 (3)
C1—C2	1.384 (3)	C5—H5A	0.9300
C1—C6	1.400 (3)	C6—C7	1.475 (3)
C1—H1A	0.9300	C7—H7A	0.9300
C2—C3	1.393 (3)	C8—C8ⁱ	1.526 (4)
C2—H2A	0.9300	C8—H8A	1.05 (2)
C3—C4	1.383 (3)	C8—H8B	0.97 (2)

C7—N1—C8	116.51 (18)	C4—C5—H5A	119.4
C2—C1—C6	120.0 (2)	C6—C5—H5A	119.4
C2—C1—H1A	120.0	C5—C6—C1	119.23 (18)
C6—C1—H1A	120.0	C5—C6—C7	118.59 (18)
C1—C2—C3	119.43 (19)	C1—C6—C7	122.15 (19)
C1—C2—H2A	120.3	N1—C7—C6	123.10 (19)
C3—C2—H2A	120.3	N1—C7—H7A	118.5
C4—C3—C2	121.58 (18)	C6—C7—H7A	118.5
C4—C3—Br1	119.00 (15)	N1—C8—C8ⁱ	109.9 (2)
C2—C3—Br1	119.42 (15)	N1—C8—H8A	107.5 (13)
C3—C4—C5	118.43 (19)	C8ⁱ—C8—H8A	108.8 (13)
C3—C4—H4A	120.8	N1—C8—H8B	112.2 (12)
C5—C4—H4A	120.8	C8ⁱ—C8—H8B	113.6 (13)
C4—C5—C6	121.22 (19)	H8A—C8—H8B	104.4 (18)

C6—C1—C2—C3	2.1 (3)	C4—C5—C6—C7	179.13 (17)
C1—C2—C3—C4	0.1 (3)	C2—C1—C6—C5	−2.6 (3)
C1—C2—C3—Br1	−179.35 (14)	C2—C1—C6—C7	179.26 (17)
C2—C3—C4—C5	−1.7 (3)	C8—N1—C7—C6	176.96 (18)
Br1—C3—C4—C5	177.70 (14)	C5—C6—C7—N1	178.68 (18)
C3—C4—C5—C6	1.2 (3)	C1—C6—C7—N1	−3.2 (3)
C4—C5—C6—C1	1.0 (3)	C7—N1—C8—C8ⁱ	129.5 (3)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···Cg1	0.93	2.99	3.7143 (19)	136

Experimental details

Crystal data
Chemical formula	C₁₆H₁₄Br₂N₂
M_r	394.11
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	13.8417 (5), 7.4796 (3), 7.1531 (3)
β (°)	95.692 (1)
V (Å³)	736.91 (5)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	5.49
Crystal size (mm)	0.45 × 0.24 × 0.03

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker 2005)
T_min, T_max	0.189, 0.853
No. of measured, independent and observed [I > 2σ(I)] reflections	10096, 2148, 1773
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.069, 1.06
No. of reflections	2148
No. of parameters	99
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.73, −0.45

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···Cg1	0.93	2.99	3.7143 (19)	136

Footnotes

‡Additional correspondence author: e-mail: mirkhani@sci.ui.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 a post-doctoral research fellowship. VM and ARV thank the University of Isfahan for financial support. VM and ARV thank Dr Reza Kia for the manuscript preparation.

References

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