organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

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

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 ππ stacking inter­actions [centroid–centroid distance 3.6811 (11) Å].

Related literature

For halogen–halogen inter­actions, see: Ramasubbu et al. (1986[Ramasubbu, N., Parthasathy, R. & Murry-Rust, P. (1986). J. Am. Chem. Soc. 108, 4308-4314.]); Brammer et al. (2003[Brammer, L., Espallargas, M. E. & Adams, H. (2003). CrystEngComm, 5, 343-345.]). For the crystal structures of related compounds, see: Fun et al. (2008[Fun, H.-K., Kargar, H. & Kia, R. (2008). Acta Cryst. E64, o1308.]); Fun, Kia & Kargar (2008a[Fun, H.-K., Kia, R. & Kargar, H. (2008a). Acta Cryst. E64, o1335.],b[Fun, H.-K., Kia, R. & Kargar, H. (2008b). Acta Cryst. E64, o1855.]); Fun & Kia (2008a[Fun, H.-K. & Kia, R. (2008a). Acta Cryst. E64, m1081-m1082.],b[Fun, H.-K. & Kia, R. (2008b). Acta Cryst. E64, m1116-m1117.]). For bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-S19.]). For hydrogen-bondong motifs, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]). For background, see: Casellato & Vigato (1977[Casellato, U. & Vigato, P. A. (1977). Coord. Chem. Rev. 23, 31-50.]).

[Scheme 1]

Experimental

Crystal data
  • C18H18Br2N2

  • Mr = 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[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.192, Tmax = 0.688

  • 15460 measured reflections

  • 3843 independent reflections

  • 2600 reflections with I > 2σ(I)

  • Rint = 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

  • Δρmax = 0.68 e Å−3

  • Δρmin = −0.59 e Å−3

Data collection: APEX2 (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]).

Supporting information


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 CN 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 ππ 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.

Refinement top

All hydrogen atoms were located from the difference Fourier map and refined freely.

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
[Figure 1] 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).
[Figure 2] 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.
[Figure 3] Fig. 3. The crystal packing of the title compound viewed down the b-axis, showing the ππ stacking arrangement of molecules.
N,N'-Bis(4-bromobenzylidene)butane-1,4-diamine top
Crystal data top
C18H18Br2N2F(000) = 420
Mr = 422.16Dx = 1.607 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5047 reflections
a = 11.2612 (5) Åθ = 2.8–33.0°
b = 9.5213 (4) ŵ = 4.64 mm1
c = 8.2645 (4) ÅT = 100 K
β = 100.040 (3)°Plate, colourless
V = 872.56 (7) Å30.52 × 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 tube2600 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
ϕ and ω scansθmax = 35.0°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 1018
Tmin = 0.192, Tmax = 0.688k = 1515
15460 measured reflectionsl = 1313
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.092All H-atom parameters refined
S = 1.02 w = 1/[σ2(Fo2) + (0.0376P)2 + 0.4289P]
where P = (Fo2 + 2Fc2)/3
3843 reflections(Δ/σ)max = 0.001
136 parametersΔρmax = 0.68 e Å3
0 restraintsΔρmin = 0.59 e Å3
Crystal data top
C18H18Br2N2V = 872.56 (7) Å3
Mr = 422.16Z = 2
Monoclinic, P21/cMo Kα radiation
a = 11.2612 (5) ŵ = 4.64 mm1
b = 9.5213 (4) ÅT = 100 K
c = 8.2645 (4) Å0.52 × 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)
Tmin = 0.192, Tmax = 0.688Rint = 0.037
15460 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.092All H-atom parameters refined
S = 1.02Δρmax = 0.68 e Å3
3843 reflectionsΔρmin = 0.59 e Å3
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
xyzUiso*/Ueq
Br10.863352 (18)0.42295 (2)0.45375 (3)0.03180 (8)
N10.26074 (15)0.39137 (18)0.1162 (2)0.0234 (3)
C10.50731 (18)0.31392 (19)0.4478 (2)0.0208 (4)
C20.63137 (18)0.3255 (2)0.4915 (3)0.0240 (4)
C30.69332 (18)0.40815 (19)0.3962 (2)0.0222 (4)
C40.63436 (18)0.4810 (2)0.2596 (2)0.0216 (4)
C50.50998 (17)0.4680 (2)0.2182 (2)0.0200 (3)
C60.44549 (16)0.38295 (19)0.3101 (2)0.0184 (3)
C70.31505 (17)0.3638 (2)0.2606 (2)0.0204 (3)
C80.13050 (18)0.3707 (2)0.0806 (3)0.0261 (4)
C90.06720 (18)0.5093 (2)0.0273 (3)0.0245 (4)
H10.462 (2)0.260 (3)0.514 (3)0.028 (6)*
H20.679 (2)0.273 (3)0.586 (3)0.028 (6)*
H40.678 (2)0.540 (3)0.209 (3)0.032 (7)*
H50.470 (2)0.515 (3)0.130 (3)0.024 (6)*
H70.276 (2)0.330 (2)0.341 (3)0.018 (5)*
H8A0.113 (2)0.300 (3)0.016 (3)0.023 (6)*
H8B0.1034 (19)0.336 (2)0.172 (3)0.016 (5)*
H9A0.111 (3)0.550 (3)0.053 (4)0.034 (7)*
H9B0.092 (3)0.576 (3)0.111 (3)0.033 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.01994 (10)0.03249 (12)0.04155 (14)0.00088 (8)0.00144 (8)0.00353 (9)
N10.0197 (7)0.0250 (8)0.0255 (8)0.0015 (6)0.0042 (6)0.0006 (6)
C10.0261 (9)0.0185 (8)0.0185 (8)0.0004 (7)0.0055 (7)0.0000 (7)
C20.0273 (9)0.0214 (8)0.0220 (9)0.0017 (7)0.0012 (7)0.0003 (7)
C30.0221 (8)0.0208 (8)0.0237 (9)0.0000 (7)0.0041 (7)0.0045 (7)
C40.0248 (9)0.0185 (8)0.0230 (9)0.0022 (7)0.0088 (7)0.0014 (7)
C50.0239 (9)0.0175 (7)0.0194 (9)0.0003 (7)0.0060 (7)0.0009 (7)
C60.0204 (8)0.0156 (7)0.0196 (8)0.0008 (6)0.0048 (6)0.0013 (6)
C70.0213 (8)0.0190 (8)0.0224 (9)0.0001 (7)0.0080 (7)0.0014 (7)
C80.0201 (9)0.0286 (10)0.0301 (11)0.0004 (7)0.0055 (8)0.0020 (8)
C90.0200 (8)0.0248 (9)0.0285 (10)0.0005 (7)0.0034 (7)0.0018 (8)
Geometric parameters (Å, º) top
Br1—C31.896 (2)C5—C61.398 (3)
N1—C71.270 (2)C5—H50.91 (2)
N1—C81.458 (3)C6—C71.466 (3)
C1—C21.385 (3)C7—H70.92 (2)
C1—C61.391 (3)C8—C91.527 (3)
C1—H10.95 (3)C8—H8A1.04 (2)
C2—C31.385 (3)C8—H8B0.93 (2)
C2—H21.00 (3)C9—C9i1.512 (4)
C3—C41.391 (3)C9—H9A0.97 (3)
C4—C51.388 (3)C9—H9B0.94 (3)
C4—H40.90 (3)
C7—N1—C8117.69 (18)C1—C6—C7120.26 (18)
C2—C1—C6120.93 (19)C5—C6—C7120.70 (17)
C2—C1—H1120.3 (15)N1—C7—C6122.12 (18)
C6—C1—H1118.7 (15)N1—C7—H7123.0 (14)
C3—C2—C1118.83 (18)C6—C7—H7114.8 (14)
C3—C2—H2118.2 (15)N1—C8—C9110.13 (18)
C1—C2—H2122.9 (15)N1—C8—H8A107.3 (13)
C2—C3—C4121.89 (18)C9—C8—H8A108.9 (13)
C2—C3—Br1119.12 (14)N1—C8—H8B110.2 (13)
C4—C3—Br1118.99 (15)C9—C8—H8B109.9 (14)
C5—C4—C3118.31 (19)H8A—C8—H8B110.3 (19)
C5—C4—H4123.6 (17)C9i—C9—C8112.2 (2)
C3—C4—H4117.8 (17)C9i—C9—H9A116.2 (16)
C4—C5—C6120.99 (18)C8—C9—H9A106.1 (16)
C4—C5—H5119.6 (16)C9i—C9—H9B116.7 (18)
C6—C5—H5119.4 (16)C8—C9—H9B107.8 (16)
C1—C6—C5119.02 (17)H9A—C9—H9B96 (2)
Symmetry code: (i) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC18H18Br2N2
Mr422.16
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)11.2612 (5), 9.5213 (4), 8.2645 (4)
β (°) 100.040 (3)
V3)872.56 (7)
Z2
Radiation typeMo Kα
µ (mm1)4.64
Crystal size (mm)0.52 × 0.23 × 0.08
Data collection
DiffractometerBruker SMART APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.192, 0.688
No. of measured, independent and
observed [I > 2σ(I)] reflections
15460, 3843, 2600
Rint0.037
(sin θ/λ)max1)0.807
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.092, 1.02
No. of reflections3843
No. of parameters136
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)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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