Synthesis and crystal structure of 6-Ethoxy-4',6'-dibromo-2,2'- [ethylenedioxybis(nitrilomethylidyne)]diphenol

Article abstract of DOI:10.14233/ajchem.2013.14363

The title compound, 6-ethoxy-4',6'-dibromo-2,2'- [ethylenedioxybis(nitrilomethylidyne)]diphenol with the molecular formula C ₁₈H₁₈Br₂N₂O₅, adopts an L-shaped configuration, in which the benzene units are approximately perpendicular, making a dihedral angle of 76.39(3)°. Intramolecular H-bonds are formed between the OH groups and the N atoms. In the crystal structure, each molecule links other molecules into an infinite three-dimensional supramolecular structure by intermolecular C-H...O and C-H...p hydrogen bond interactions.

Full text of DOI:10.14233/ajchem.2013.14363

Asian Journal of Chemistry; Vol. 25, No. 9 (2013), 5039-5041
http://dx.doi.org/10.14233/ajchem.2013.14363
Synthesis and Crystal Structure of
6-Ethoxy-4',6'-dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol
1,*
1
2
2
2
1
XIN-WEN LIU , JUN-JIANG WU , YU-JIE ZHANG , GANG LI , LI WANG and XIU-YAN DONG
1School of Biological Science and Chemistry, Tianshui Normal University, Tianshui 741001, P.R. China
2School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
*Corresponding author: E-mail: liuxwts@126.com
(Received: 24 July 2012;
Accepted: 18 March 2013)
AJC-13132
The title compound, 6-ethoxy-4',6'-dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol with the molecular formula
C18H18Br2N2O5, adopts an L-shaped configuration, in which the benzene units are approximately perpendicular, making a dihedral angle
of 76.39(3)º. Intramolecular H-bonds are formed between the OH groups and the N atoms. In the crystal structure, each molecule links other
molecules into an infinite three-dimensional supramolecular structure by intermolecular C-H···O and C-H···π hydrogen bond interactions.
Key Words: Asymmetric salen-type bisoxime, Synthesis, Crystal structure.
structure was determined on a Bruker Smart 1000 CCD area
detector. Melting points were measured by the use of a micro-
scopic melting point apparatus made in Beijing Taike Instrument
Limited Company and the thermometer was uncorrected.
General procedure: 6-Ethoxy-4',6'-dibromo-2,2'-
[ethylenedioxybis(nitrilomethylidyne)]diphenol was synthesized
according to an analogous method reported earlier9.
1,2-Bis(aminooxy)ethane was synthesized by a reported
method10. Yield 75.2 %. Anal. calcd. (%) for C2H8N2O2: C,
26.08; H, 8.76; N, 30.42. Found (%): C, 25.99; H, 8.92; N,
30.35.
3-Ethoxysalicylaldehyde O-(1-ethyloxyamide)oxime:A
solution of 1,2-bis(aminooxy)ethane (368.2 mg, 4 mmol) in
ethanol (20 mL) was added to a solution of 3-ethoxy-2-
hydroxybenzaldehyde (332.1 mg, 2 mmol) in ethanol (20 mL),
the mixture was heated at 328-333 K for 4 h and concentrated
under reduced pressure. The residue was purified by column
chromatography (SiO2, chloroform/ethyl acetate, 50:3) to
afford 284.0 mg crystals of the product. Yield 59.2 %. m.p.
336-337 K.Anal. calcd. (%) for C11H16N2O4: C, 54.99; H, 6.71;
N, 11.66. Found (%): C, 54.92; H, 6.75; N, 11.69.
6-Ethoxy-4',6'-dibromo-2,2'-[ethylenedioxybis(nitrilo-
methylidyne)]diphenol: A solution of 3-ethoxy salicy-
laldehyde O-(1-ethyloxyamide)oxime (240.3 mg, 1 mmol) in
ethanol (20 mL) was added to a solution of 3,5-dibromo-2-
hydroxybenzaldehyde (279.2 mg, 1 mmol) in ethanol (20 mL)
and the mixture was heated at 328-333 K for 6 h. After cooling
to room temperature, white precipitates were collected on a
suction filter to give 407.6 mg white powder of the title
INTRODUCTION
Salen-type compounds constitute an important class of
ligands which have been extensively investigated in coordi-
nation chemistry1. The development of their bisoxime
analogues and complexes can provide new topologies for
functional materials, in which coordination forms and func-
tionality are significant variables2. Mainly due to their facile
synthesis and easily tunable steric, electronic and catalytic
properties can be used to acquire non-linear optical materials3,
biological systems4, interesting magnetic properties5. They are
also useful in constructing supramolecular structures6. Thus,
new materials can be produced by using these compounds,
which seem to be suitable candidates for further chemical
modifications7,8. Herein, we report on the synthesis and crystal
structure of 6-ethoxy-4',6'-dibromo-2,2'-[ethylenedioxy
bis(nitrilomethylidyne)]diphenol.
EXPERIMENTAL
3,5-Dibromo-2-hydroxybenzaldehyde and 3-ethoxy-2-
hydroxy benzaldehyde were purchased from Alfa Aesar and
used without further purification. The other reagents and
solvents were analytical grade reagents from Tianjin Chemical
Reagent Factory. C, H and N analyses were carried out with a
GmbHVariuoELV3.00 automatic elemental analyzer. IR spectra
in the range 4000-400 cm-1 were recorded on a VERTEX70
FT-IR spectrophotometer using KBr pellets. The H NMR
spectra were recorded on a Mercury-400BB spectrometer at
room temperature using CDCl3 as solvent. X-Ray single crystal
1

5040 Liu et al.
Asian J. Chem.
TABLE-1
CRYSTAL DATA AND STRUCTURE
REFINEMENT FOR THE TITLE COMPOUND
compound. Yield: 81.2 %. m.p. 396-398 K. Anal. calcd. (%)
for C18H18N2O5Br2: C, 43.05; H, 3.61; N, 5.58. Found (%): C,
43.01; H, 2.93; N, 5.61.
Colourless needle-like single crystals suitable for X-ray
diffraction studies were obtained after about one month by
slow evaporation from a ethanol/acetone (1:1) solution of the
title compound.
X-Ray structure determination: The single crystal of
the title compound, with approximate dimensions of 0.32 mm
× 0.10 mm × 0.06 mm was placed on a Bruker Smart 1000
diffractmeter equipped withApex CCD area detector. The diff-
raction data were collected using a graphite monochromated
MoKα radition (λ = 0.71073 Å) at 298(2) K. The structure
was solved by using the program SHELXS-97 and Fourier
difference techniques and refined by full-matrix least-squares
method on F2 using SHELXL-97. Details of the data collection
and refinements of the title compound are given in Table-1.
The non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were added theoretically. CCDC: 891145.
Empirical formula
C18H18N2O5Br2
502.16
298(2) K
0.71073 Å
Monoclinic
C2/c
a = 14.760(1) Å, b = 12.969(1) Å,
Formula weight
Temperature
Wavelength
Crystal system
Space group
Cell dimensions
c = 20.905(2), Å β = 100.871(1)º
Volume
Z
Density (calculated)
Absorption coefficient
F(000)
3929.9(6) Å3
8
1.697 mg/m3
4.157 mm-1
2000
Index ranges
-17 ≤ h ≤ 17, -7 ≤ k ≤ 15, -24 ≤ l ≤ 24
9261/3460 [R(int) = 0.0781]
1160
3460/0/246
1.059
R1 = 0.0463, wR2 = 0.0851
0.809 and -0.873 e Å-3
Reflections collected/unique
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 the title compound. The structure is shown in Fig.
1 and packing arrangement of the unit cell is shown in Fig. 2.
Selected bond distances and angles are listed in Table-2. The
structure of the title compound consists of discrete C18H18N2O5Br2
molecule, in which all bond lengths and angles are in normal
ranges. The molecule is disposed about an L-shaped configu-
ration, in which the benzene units are approximately perpen-
dicular, making a dihedral angle of 76.39(3)º. There are two
weak intramolecular O-H···N hydrogen bonds involving the
hydroxyl groups and adjacent N atoms. In the crystal structure,
intermolecular C-H···O and C-H···π hydrogen bonds link the
molecules, forming an infinite three-dimensional supramolecular
Fig. 1. Molecule structure of the title compound with atom numbering
scheme. Displacement ellipsoids for non-hydrogen atoms are drawn
at the 30 % probability level
structure11-15
.
TABLE-2
SELECTED BOND DISTANCES (Å) AND ANGLES (º) FOR THE TITLE COMPOUND
Bond
Br(1)-C(8)
Br(2)-C(6)
N(1)-C(3)
N(1)-O(1)
N(2)-C(10)
N(2)-O(2)
O(1)-C(1)
Lengths
1.838(13)
1.870(14)
1.275(15)
1.401(12)
1.283(15)
1.399(12)
1.435(14)
1.421(15)
1.314(13)
1.349(14)
Angles
Bond
O(5)-C(13)
O(5)-C(17)
C(1)-C(2)
C(3)-C(4)
C(4)-C(5)
C(4)-C(9)
C(5)-C(6)
C(6)-C(7)
C(7)-C(8)
C(8)-C(9)
Bond
Lengths
1.365(15)
1.409(14)
1.512(16)
1.434(16)
1.388(16)
1.402(16)
1.406(16)
1.388(17)
1.385(16)
1.385(16)
Angles
Bond
C(10)-C(11)
C(11)-C(12)
C(11)-C(16)
C(12)-C(13)
C(13)-C(14)
C(14)-C(15)
C(15)-C(16)
Lengths
1.459(18)
1.358(17)
1.441(19)
1.374(17)
1.381(17)
1.381(19)
1.317(18)
1.499(18)
–
O(2)-C(2)
O(3)-C(5)
O(4)-C(12)
C(17)-C(18)
–
–
–
Bond
Bond
Angles
C(3)-N(1)-O(1)
C(10)-N(2)-O(2)
N(1)-O(1)-C(1)
N(2)-O(2)-C(2)
C(13)-O(5)-C(17)
O(1)-C(1)-C(2)
O(2)-C(2)-C(1)
N(1)-C(3)-C(4)
C(5)-C(4)-C(9)
C(5)-C(4)-C(3)
C(9)-C(4)-C(3)
O(3)-C(5)-C(4)
110.3(11)
112.6(11)
109.7(10)
109.4(9)
118.0(11)
113.5(11)
108.5(10)
117.3(13)
119.5(12)
124.7(13)
115.8(12)
121.9(12)
O(3)-C(5)-C(6)
C(4)-C(5)-C(6)
C(7)-C(6)-C(5)
C(7)-C(6)-Br(2)
C(5)-C(6)-Br(2)
C(8)-C(7)-C(6)
C(9)-C(8)-C(7)
C(9)-C(8)-Br(1)
C(7)-C(8)-Br(1)
C(8)-C(9)-C(4)
N(2)-C(10)-C(11)
C(12)-C(11)-C(16)
119.8(12)
118.3(12)
121.2(13)
120.6(9)
118.2(10)
120.9(13)
117.8(12)
122.7(10)
119.3(11)
122.4(12)
120.0(13)
119.7(14)
C(12)-C(11)-C(10)
C(16)-C(11)-C(10)
O(4)-C(12)-C(11)
O(4)-C(12)-C(13)
C(11)-C(12)-C(13)
O(5)-C(13)-C(13)
O(5)-C(13)-C(14)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
C(16)-C(15)-C(14)
C(15)-C(16)-C(11)
O(5)-C(17)-C(18)
121.8(14)
118.4(14)
123.7(14)
116.2(12)
120.1(13)
116.6(12)
123.7(14)
119.5(13)
120.0(14)
121.5(15)
119.0(14)
106.1(12)

Vol. 25, No. 9 (2013)
Synthesis of 6-Ethoxy-4',6'-dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol 5041
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