Synthesis and supramolecular structure of 3,3′-Dibromo-1,1′- [butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene

Article abstract of DOI:10.14233/ajchem.2013.13826

The compound, 3,3′-dibromo-1,1′-[butane-1,4- diyldioxybis(nitrilo-methylidyne)]dibenzene with the molecular formula C ₁₈H₁₈N₂O₂Br₂, was synthesized by the reaction of 3-bromobenzaldehyde with 1,4-bis(aminooxy) butane in ethanol. The molecule lies across a crystallographic inversion centre (symmetry code: -x, -y, -z) and adopts an extended form. Within the molecule, the two aromatic rings are aligned with the angle of 5.57(3)°, but extend in opposite directions from the tetramethylene bridge. In the crystal structure, weak intermolecular C-H···Ο hydrogen bonds and C-H···π stacking interactions link the title molecules into an infinite 3D supramolecular network structure.

Full text of DOI:10.14233/ajchem.2013.13826

Asian Journal of Chemistry; Vol. 25, No. 6 (2013), 3387-3389
http://dx.doi.org/10.14233/ajchem.2013.13826
Synthesis and Supramolecular Structure of
3,3'-Dibromo-1,1'-[butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene
*
YIN-XIA SUN , WEI-SHENG MENG, QING-YING LAN, XIAO-YAN ZHANG, FEI-XIA MA and DA-SENG WANG
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*Corresponding author: E-mail: sun_yinxia@163.com
(Received: 3 April 2012;
Accepted: 21 December 2012)
AJC-12594
The compound, 3,3'-dibromo-1,1'-[butane-1,4-diyldioxybis(nitrilo-methylidyne)]dibenzene with the molecular formula C18H18N2O2Br2,
was synthesized by the reaction of 3-bromobenzaldehyde with 1,4-bis(aminooxy) butane in ethanol. The molecule lies across a crystallographic
inversion centre (symmetry code: -x, -y, -z) and adopts an extended form. Within the molecule, the two aromatic rings are aligned with the
angle of 5.57(3)º, but extend in opposite directions from the tetramethylene bridge. In the crystal structure, weak intermolecular C-H···Ο
hydrogen bonds and C-H···π stacking interactions link the title molecules into an infinite 3D supramolecular network structure.
Key Words: Bisoxime compound, Synthesis, Supramolecular structure.
points were measured by the use of a microscopic melting
point apparatus made in Beijing Taike Instrument Limited
Company and the thermometer was uncorrected.
INTRODUCTION
Salen-type compounds are one of most prevalent mixed-
donor ligands in the field of coordination chemistry1-3. They
play an important role in the development of coordination
chemistry related to catalysis and enzymatic reactions,
magnetism and supramolecular architectures. In the past few
years, salen-type compounds have been used widely as ligands
in the formation of transition metal complexes4,5. Many salen-
type complexes have been structurally characterized, but only
a relatively small number of free salen-type bisoxime comp-
ounds have been characterized. As an extension of our work6-8,
we report here the synthesis and crystal structure of a new
salen-type bisoxime compound 3,3'-dibromo-1,1'-[butane-1,4-
diyldioxybis(nitrilomethylidyne)]dibenzene.
General procedure: 3,3'-Dibromo-1,1'-[butane-1,4-
diyldioxybis(nitrilomethylidyne)]dibenzene was synthesized
according to an analogous method reported earlier7,8. To an
ethanolic solution (2 mL) of 3-bromobenzaldehyde (407.7 mg,
2.13 mmol) was added an ethanolic solution (3 mL) of 1,4-
bis(aminooxy)butane (128.1 mg, 1.07 mmol). The mixture
solution was stirred at 328 K for 4 h. When cooled to room
temperature, the precipitate was filtered and washed succes-
sively with ethanol and ethanol-hexane (1:4), respectively. The
product was dried under vacuum to yield 94.8 mg of the title
compound. Yield, 19.6 %. m.p. 323.5-325.5 K. Anal. calcd.
(%) for C18H18N2O2Br2: C, 47.60; H, 3.99; N, 6.17. Found (%):
C, 47.42; H, 3.83; N, 6.00. IR (KBr, νmax, cm-1): C=N, 1625
and C-O, 1176. 1H NMR (400 MHz, CDCl3): 2.05 (t, J = 4.0
Hz, 4H, CH2), 4.22 (t, J = 4.0 Hz, 4H, CH2-O), 6.86 (d, J = 4.0
Hz, 2H, PhH), 6.95 (s, 2H, PhH), 7.22 (s, 2H, PhH), 7.36 (d,
J = 4.0 Hz, 2H, PhH), 8.03 (s, 2H, N=CH). Colourless needle-
shaped single crystals suitable for X-ray diffraction studies
were obtained after several weeks by slow evaporation from a
methanol-acetonitrile mixed solution of 3,3'-dibromo-1,1'
-[butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene.
X-Ray structure determination: The single crystal of
the title compound, with approximate dimensions of 0.48 mm
× 0.38 mm × 0.30 mm was placed on a Bruker Smart 1000
diffractmeter equipped withApex CCD area detector. The diff-
raction data were collected using a graphite monochromated
EXPERIMENTAL
3-Bromobenzaldehyde was purchased from Alfa Aesar
and used without further purification. 1,4-Bis(aminooxy)butane
was synthesized according to an analogous method reported
earlier6. The other reagents and solvents were analytical grade
reagents from Tianjin Chemical Reagent Factory. C, H and N
analyses were carried out with a GmbH VariuoEL V3.00 au-
tomatic elemental analyzer. IR spectra in the range 4000-400
cm-1 were recorded on aVERTEX70 FT-IR spectrophotometer
using KBr pellets. The 1H NMR spectra were recorded on a
Mercury-400BB spectrometer at room temperature using
CDCl3 as solvent. X-Ray single crystal structure was deter-
mined on a Bruker Smart APEX CCD area detector. Melting

3388 Sun et al.
Asian J. Chem.
MoKα radition (γ = 0.71073 Å) at 298(2) K. The structure was
solved by using the program SHELXS-979 and Fourier diffe-
rence techniques and refined by full-matrix least-squares
method on F2 using SHELXL-9710. Details of the data collection
and refinements of title compound are given in Table-1. The
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were added theoretically. CCDC: 696136.
Fig. 1. Molecule structure of the title compound
TABLE-1
CRYSTAL DATA AND REFINEMENT PARAMETERS
FOR THE TITLE COMPOUND
conformation in which two benzaldoxime moieties are well
separated from each other with a crystallographic inversion
center (symmetry code: -x, -y, -z). Within the molecule, the
two aromatic rings are aligned with the angle of 5.57(3)º, but
extend in opposite directions from the tetramethylene bridge.
In the crystal structure, C-H···π(Ph) stacking interactions
and weak intermolecular C-H···O hydrogen bonds link the
neighboring molecules into an infinite three-dimensional
supramolecular network structure. The title molecules are linked
by a pair of intermolecular C9-H9···πcentroid (C13-C18) hydrogen
bond interactions into a 1D infinite zigzag chain along the
c-axis. Furthermore, this linkage is further stabilized by a pair
intermolecular C16-H16···πcentroid (C6-C11) hydrogen bond inter-
actions to form an infinite 2D crapy layer parallel to the
bc-plane (Fig. 2). The intermolecular C-H···πcentroid separations
are ca. 3.214 Å for C16-H16···πcentroid (C6-C11) and ca. 3.231 Å
for C9-H9···πcentroid (C13-C18), respectively (Table-3) and lie in the
accepted distance range for this type of contacts11. In addition,
the adjacent crapy layers are further linked by the intermole-
cular C18-H18···O2 hydrogen bonds between the oxime
oxygen atom and the methylene groups of the benzene ring. It
is noteworthy that an infinite helices chain along the b-axis is
formed by the C18-H18···O2 hydrogen bond interactions (Figs.
3 and 4). To sum up, with the help of intermolecular C-H···O
and C-H···π hydrogen-bonding interactions, the crystal
packing shows a self-assembling 3D supramolecular network
structure.
Empirical formula
Formula weight
Temperature
C18H18N2O2Br2
454.16
298(2) K
Wavelength
0.71073 Å
Crystal system
Space group
Monoclinic
P2(1)/c
Cell dimensions
a = 11.9330(16) Å, b = 4.8703(5)
Å, c = 32.423(3) Å β = 99.706(2)
Volume
1857.4(4) Å3
Z
4
Density (calculated)
Absorption coefficient
F(000)
1.624 mg/m3
4.377 mm-1
904
Index ranges
-14 ≤ h ≤ 11, -5 k ≤ 5, -38 ≤ l ≤ 34
8610/3256 [R(int) = 0.0505]
3256
3256/0/217
1.005
R1 = 0.0766, wR2 = 0.1515
0.524 and -0.538 e. Å
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness of fit indicator
R [I > 2σ(I)]
Largest diff. peak and hole
RESULTS AND DISCUSSION
X-Ray crystallographic analysis revealed the crystal
structure of title compound. And the structure is shown in
Fig. 1. Selected bond distances and angles are listed in Table-2.
The crystal structure of the title compound is built up by only
the C18H18N2O2Br2 molecules and all bond lengths and angles
are in normal ranges6,7. The molecule assumes an extended
TABLE-2
SELECTED BOND LENGTHS (Å) AND ANGLES (º) FOR THE TITLE COMPOUND
Bond
Br(1)-C(8)
N(1)-C(5)
N(2)-C(12)
O(1)-C(1)
C(1)-C(2)
C(3)-C(4)
C(6)-C(7)
Lengths
1.901(8)
1.253(9)
1.265(9)
1.438(8)
1.520(10)
1.510(9)
1.376(10)
1.387(10)
1.376(11)
108.6(7)
109.7(6)
106.6(6)
110.7(6)
122.2(8)
121.0(7)
118.7(8)
119.6(6)
118.0(8)
117.7(9)
Bond
C(9)-C(10)
C(12)-C(13)
C(13)-C(18)
C(15)-C(16)
C(17)-C(18)
Br(2)-C(15)
N(1)-O(1)
Lengths
1.368(12)
1.480(10)
1.413(9)
1.387(11)
1. 383(10)
1.861(7)
1.419(7)
1.422(8)
–
119.8(7)
118.0(7)
118.9(8)
121.8(6)
119.0(8)
111.1(6)
108.3(5)
112.3(7)
108.4(6)
120.8(7)
Bond
O(2)-C(4)
C(2)-C(3)
C(5)-C(6)
C(6)-C(11)
C(8)-C(9)
C(10)-C(11)
C(13)-C(14)
Lengths
1.419(8)
1.524(10)
93(11)
1.411(11)
1.380(11)
1.342(11)
1.372(9)
1.386(10)
–
118.2(8)
121.0(8)
119.4(6)
123.5(9)
120.1(7)
122.2(7)
120.5(7)
119.3(6)
121.9(8)
119.9(7)
C(7)-C(8)
N(2)-O(2)
C(14)-C(15)
C(16)-C(17)
C(5)-N(1)-O(1)
N(1)-O(1)-C(1)
O(1)-C(1)-C(2)
C(4)-C(3)-C(2)
N(1)-C(5)-C(6)
C(7)-C(6)-C(5)
C(6)-C(7)-C(8)
C(9)-C(8)-Br(1)
C(10)-C(9)-C(8)
C(10)-(11)-C(6)
–
–
C(14)-C(13)-C(18)
C(18)-C(13)-C(12)
C(14)-C(15)-C(16)
C(16)-C(15)-Br(2)
C(16) -C(17)-C(18)
C(12)-N(2)-O(2)
C(4)-O(2)-N(2)
C(1)-C(2)-C(3)
O(2)-C(4)-C(3)
C(7)-C(6)-C(11)
C(11)-C(6)-C(5)
C(9)-C(8)-C(7)
C(7)-C(8)-Br(1)
C(11)-C(10)-C(9)
N(2)-C(12)-C(13)
C(14)-C(13)-C(12)
C(13)-C(14)-C(15)
C(14)-C(15)-Br(2)
C(17)-C(16)-C(15
C(17)-C(18)-C(13)

Vol. 25, No. 6 (2013)
Synthesis of 3,3'-Dibromo-1,1'-[butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene 3389
Fig. 2. View of the 1D supramolecular zigzag chain and 2D crapy layers within the title compound (hydrogen atoms, except those forming hydrogen bonds,
are omitted for clarity)
TABLE-3
HYDROGEN-BONDING DATA [Å, º]
D-H···A
d(D-H)
d(H···A)
d(D···A)
∠D-H···A
C18-H18···O2
C16-H16···Cg1a
C9-H9···Cg2b
0.93
0.93
0.93
2.51
3.21
3.23
3.417(3)
4.012(4)
4.008(4)
161
146
143
aCg1 is the C6–C11 ring centroids. bCg2 is the C13–C18 ring
centroid.
ACKNOWLEDGEMENTS
The authors thank Young Scholars Science Foundation
of Lanzhou Jiaotong University (2011007) for financial support
of this work.
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Fig. 4. Helix chain linked by C18-H18···O2 hydrogen bonds. For clarity,
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omitted