New Fe(III) complex with 8-(4-chlorophenyl)-3-butyl-3H-imidazo[4′,5′:3,4]benzo[1,2-c]isoxazol-5-amine (5-AIBI) ligand: Synthesis, spectroscopic characterization and DFT calculations

Article abstract of DOI:10.1016/j.molstruc.2016.10.015

The new heterocyclic ligand 8-(4-chlorophenyl)-3-butyl-3H-imidazo[4′,5′:3,4]benzo [1,2-c]isoxazol-5-amine (5-AIBI) was synthesized from the reduction of 3-butyl-8-(4-chlorophenyl)-5-nitro-3H-imidazo[4′,5′:3,4]benzo[1,2-c]isoxazole in high yield. The coord

Full text of DOI:10.1016/j.molstruc.2016.10.015

Journal of Molecular Structure 1130 (2017) 55e61
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Journal of Molecular Structure
journal homepage: http://www.elsevier.com/locate/molstruc
New Fe(III) complex with 8-(4-chlorophenyl)-3-butyl-3H-imidazo
[40,50:3,4]benzo[1,2-c]isoxazol-5-amine (5-AIBI) ligand: Synthesis,
spectroscopic characterization and DFT calculations
Zahra Agheli, Mehdi Pordel*, S. Ali Beyramabadi
Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
a r t i c l e i n f o
a b s t r a c t
The new heterocyclic ligand 8-(4-chlorophenyl)-3-butyl-3H-imidazo[40,50:3,4]benzo [1,2-c]isoxazol-5-
amine (5-AIBI) was synthesized from the reduction of 3-butyl-8-(4-chlorophenyl)-5-nitro-3H-imidazo
[40,50:3,4]benzo[1,2-c]isoxazole in high yield. The coordination ability of the ligand with some cations
was examined by spectrophotometric method at rt condition. Results showed that only the absorption
spectra of the Fe3þe5-AIBI complex show a high redshift of the absorption maximum in the aqueous
ethanol solution. The effect of pH on the absorption spectrum of the green irone5-AIBI complex was also
investigated. In addition, density functional theory (DFT) calculations are performed to provide the
optimized geometries, structural parameters, calculated chemical shifts and vibrational frequencies of
the investigated Fe(III) complex.
Article history:
Received 8 July 2016
Received in revised form
1 October 2016
Accepted 5 October 2016
Available online 6 October 2016
Keywords:
3H-imidazo[40,50:3,4]benzo[1,2-c]isoxazole
Coordination chemistry
Iron(III) complex
© 2016 Published by Elsevier B.V.
Density functional theory
Absorption spectra
1. Introduction
been reported and well characterized. In a review of the literature
of isoxazole-metal complexes [10], the binding characteristics of
Coordination complexes are used as catalysts for a diverse range
of organic reactions such as polymerization [1], hydrogenation [2],
oxygen-, nitrogen- and carbon-atom transfer to alkenes [3], cross-
coupling reactions [4], Lewis acid catalysts in organic synthesis
[5], electrochemical reactions [6], etc. Also, the interaction of
transition metal ions with biological molecules provides one of the
most fascinating areas of coordination chemistry. There are many
metal complexes that can use as drugs and chemotherapeutic
agents. Farrell concentrates on Pt anticancer drugs and, particularly,
the differing interactions of mono-, di- and trinuclear complexes
with DNA and the differing antitumor effects this may produce [7].
On the other hand, isoxazoles and fused isoxazoles are an
important class of heterocyclic pharmaceuticals and bioactive
compounds because of their considerable and wide spectrum of
biological activities, including potent and selective antagonism of
the NMDA receptor [8] and anti-HIV activity [9]. Isoxazole-metal
complexes are often postulated as intermediates in reactions of
considerable synthetic utility, for example the reductive ring
opening of isoxazoles. Several isoxazole-metal complexes have
the isoxazoles in the complexes have been examined, and some
tentative conclusions regarding the regularity of isoxazole
complexation behavior have been discussed. Also, it has been
pointed that the behavior of the aminoisoxazoles was seen to be
fairly well in the isoxazole-metal complexes.
Taking this body of research into consideration, we have syn-
thesized a new heterocyclic ligand 8-(4-chlorophenyl)-3-butyl-3H-
imidazo[40,50:3,4]benzo[1,2-c]isoxazol-5-amine (5-AIBI) in high
yield and the coordination ability of the ligand with some cations
such as Cr3þ, Ba2þ, Zn2þ, Hg2þ, Fe3þ, Ni2þ, Al3þ, Co2þ, Mn2þ, Pb2þ
,
Sr2þ and Cu2þ was examined by spectrophotometric method at rt
condition. The stoichiometry of the Fe(III)eligand complex were
obtained by using the Job's method. Furthermore, density func-
tional theory (DFT) calculations are performed to provide the
optimized geometries and structural parameters of the investigated
Fe(III) complex.
2. Experimental
2.1. Equipment and materials
* Corresponding author.
E-mail address: mehdipordel58@mshdiau.ac.ir (M. Pordel).
Melting points were measured on an Electrothermal type-9100
http://dx.doi.org/10.1016/j.molstruc.2016.10.015
0022-2860/© 2016 Published by Elsevier B.V.

56
Z. Agheli et al. / Journal of Molecular Structure 1130 (2017) 55e61
melting-point apparatus. The FT-IR (as KBr discs) spectra were
obtained on a Tensor 27 spectrometer and only noteworthy ab-
sorptions are listed. The 13C NMR (100 MHz) and 1H NMR
(400 MHz) were recorded on a Bruker Avance DRX-400 spec-
trometer. Chemical shifts are reported in ppm downfield from TMS
as internal standard; coupling constant J is given in Hz. The mass
spectrum was recorded on a Varian Mat, CH-7 at 70 eV and ESI mass
spectrum was measured using a Waters Micromass ZQ spectrom-
eter. Elemental analysis was performed on a Thermo Finnigan Flash
EA microanalyzer. Absorption spectra were recorded on Varian 50-
bio UV-Visible spectrophotometer. UV-vis scans were recorded
from 200 to 1000 nm. All measurements were carried out at room
temperature. Compounds 1[11], 3[12] and 4[13] were obtained
according to the published methods. Other reagents were
commercially available. Adjustment of pH was made with acetic
acid, phosphoric acid, boric acid and their potassium salts. Sodium
perchlorate was added to give a constant ionic strength of 0.1 M.
5.01; N, 16.34.
2.4. Synthesis of complex
To the yellow solution of ligand 5-AIBI (200 mg, 588.2 mM) in
aqueous ethanolic solution (20 mL, EtOH, H2O, 10:90) iron (III)
chloride (47.6 mg, 294.1 M) was added, resulting in color change to
deep green. The reaction was carried out for another 1 h. The
complex was isolated by evaporation of the solvent and washed
with acetonitrile.
m
[Fe(5-AIBI)2] Cl3$2(H2O): was obtained as a dark green powder.
mp > 300 ꢁC (decomp). 1H NMR (DMSO-d6):
d
0.75 (t, J ¼ 7.0 Hz, 3H,
CH3), 1.14e1.22 (m, 2H, CH2), 1.34e1.42 (m, 2H, CH2), 4.30 (t,
J ¼ 7.0 Hz, 2H, NCH2), 5.63 (br s, 2H, NH2), 7.48 (s, 1H, Ar H), 7.52 (d,
J ¼ 9.0 Hz, 2H, Ar H), 7.94 (s, 1H, Ar H), 8.97 (d, J ¼ 9.0 Hz, 2H, Ar H)
ppm; 13C NMR (CDCl3):
d 13.3, 19.5, 31.8, 45.4, 97.2, 108.1, 127.3,
126.5, 128.3, 129.7, 131.6, 132.7, 135.8, 136.2, 155.0, 162.3 ppm. IR
(KBr): 3436, 3302 cmꢂ1 (NH2), ESI-MS (þ) m/z (%): 736 [Fe(5-
AIBI)2]3þ. Anal. Calcd for C36H38Cl5FeN8O4 (879.85): C, 49.14; H,
4.35; N, 12.74. Found: C, 48.81; H, 4.31; N, 12.49.
2.2. Computational methods
All of the calculations have been performed using the DFT
method with the B3LYP functional [14] as implemented in the
Gaussian 03 program package [15]. The 6-311 þ G(d,p) basis sets
were employed except for the Fe atom where the LANL2DZ basis
sets were used with considering its effective core potential. Ge-
ometry of the Fe complex was fully optimized, which was
confirmed to have no imaginary frequency of the Hessian. Geom-
etry optimization and frequency calculation simulate the properties
in the gas/solution phases.
. The fully-optimized geometry was confirmed to has no imag-
inary frequency of the Hessian. Also, the calculation were done in
both states of the Fe(III) complex, the high spin and low spin.
Obviously, the solvent plays an important role in chemical re-
actions. In this work, the solute-solvent interactions have been
investigated using one of the self-consistent reaction field methods,
i.e., the sophisticated Polarizable Continuum Model (PCM) [16]. In
both of the gas phase and ethanolic solution, the zero-point-energy
(ZPE) corrections were made to calculate energies.
3. Results and discussion
The processes to obtain the desired new ligand are depicted in
Scheme 1. In the first place, the commercially available 5-nitro-1H-
benzimidazole was alkylated with n-butyl bromide in KOH and
DMF to give 1-butyl-5-nitro-1H-benzimidazole (1) at rt [11]. 3-
Butyl-8-(4-chlorophenyl)-3H-imidazo [40,50:3,4]benzo[1,2-c]iso-
xazoles (3) was obtained from the reaction of 1-butyl-5-nitro-1H-
benzimidazole 1 with (4-chlorophenyl)acetonitrile (2) in basic
MeOH solution [12]. Regioselective nitration of compound 3 was
carried out using a mixture of sulfuric and potassium nitrate and
led to the formation of 3-butyl-8-(4-chlorophenyl)-5-nitro-3H-
imidazo[40,50:3,4]benzo[1,2-c]isoxazole 4 in high yield [13]. Finally,
reduction of 4 in EtOH by SnCl2, gave the new 8-(4-chlorophenyl)-
3-butyl-3H-imidazo[40,50:3,4]benzo[1,2-c]isoxazol-5-amine (5) in
high yield. The NOESY spectrum of the compound 4 and 1H NMR
and 13C NMR spectra of compound 5 can be found in Supporting
Information (Figures S1eS3 and Table S1).
2.3. General procedure for the synthesis of 5 from 4
Structural assignments of the new compound 5 were based on
its spectral and microanalytical (C, H, and N) data. In the 1H NMR
spectrum of compound 5 there is an exchangeable peak at
SnCl2$2H2O (4.52 g, 20.0 mmol) was added to a solution of 4
(1.0 g, 2.70 mmol) in ethanol (20 mL). The reaction mixture was
refluxed for 2 h until the reaction was complete as indicated by TLC
analysis. The solvent was removed under reduced pressure and the
crude residue was partitioned between ethyl acetate and 2M KOH.
The aqueous layer was extracted with further portions of ethyl
acetate (3 ꢀ 50 mL) and the combined organic extracts were
washed with brine (2 ꢀ 50 mL) and water (3 ꢀ 100 mL), dried
(MgSO4) and concentrated under reduced pressure. The crude
residue was subjected to flash silica gel column chromatography
(40% ethyl acetate in hexanes) yielding 8-(4-chlorophenyl)-3-
butyl-3H-imidazo[40,50:3,4]benzo[1,2-c]isoxazol-5-amine 5 (85%).
8-(4-chlorophenyl)-3-butyl-3H-imidazo[40,50:3,4]benzo [1,2-c]iso-
d
4.38 ppm assignable to NH2 group protons. Also, there are two
doublet signals (
¼ 8.83 and 7.54 ppm) and two singlet signals
¼ 7.68 and 6.47 ppm) attributed to six protons of aromatic rings.
In addition, 15 different carbon atom signals are observed in the 13
d
(d
C
NMR spectrum of compound 5. Moreover, the IR spectrum of
compound 5 in KBr revealed a broad absorption band at 3455 cmꢂ1
assignable to NH2 group. All this evidence taken in conjunction
with molecular ion peak at m/z 342 [Mþ2]þ support the structure
of ligand 5.
The coordination ability of the 8-(4-chlorophenyl)-3-butyl-3H-
imidazo[40,50:3,4] benzo[1,2-c]isoxazol-5-amine (5-AIBI) dissolved
in EtOH was studied with some cations such as Cr3þ, Ba2þ, Zn2þ
,
xazol-5-amine (5) was obtained as
a
yellow powder. mp
Hg2þ, Fe3þ, Ni2þ, Al3þ, Co2þ, Mn2þ, Pb2þ, Sr2þ and Cu2þ by using a
UV-vis spectrophotometer at rt condition. Results revealed that
only the absorption spectra of the Fe3þe5-AIBI complex show a
high redshift of the absorption maximum in dilute (1 ꢀ 10ꢂ4 M)
aqueous ethanolic solution and color change to deep green.
The absorption spectra of the ligand (5-AIBI) and iron (III)e5-
AIBI complex are shown in Fig. 1. As seen, the spectrum of
irone5-AIBI complex has an absorption maximum at 740 nm at
which the ligand has no absorbance. So wavelength 740 nm has
179e182 ꢁC. 1H NMR (CDCl3):
d
0.96 (t, J ¼ 7.2 Hz, 3H, CH3),
1.33e1.41 (m, 2H, CH2), 1.79e1.89 (m, 2H, CH2), 4.10 (t, J ¼ 7.2 Hz,
2H, NCH2), 4.38 (br s, 2H, NH2), 6.48 (s, 1H, Ar H), 7.54 (d, J ¼ 9.0 Hz,
2H, Ar H), 7.67 (s, 1H, Ar H), 8.83 (d, J ¼ 9.0 Hz, 2H, Ar H) ppm; 13
C
NMR (CDCl3):
d 13.6, 19.9, 32.3, 45.1, 94.3, 108.9, 126.1, 126.9, 128.4,
129.2, 130.7, 131.7, 135.5, 137.2, 153.4, 161.9 ppm. IR (KBr): 3455,
3302 cmꢂ1 (NH2), MS (m/z) 342 (Mþþ2). Anal. Calcd for
C
18H17ClN4O (340.8): C, 63.44; H, 5.03; N, 16.44. Found: C, 63.29; H,

Z. Agheli et al. / Journal of Molecular Structure 1130 (2017) 55e61
57
Scheme 1. Synthesis of the new ligand 5.
can be clearly seen, the absorption of the irone5-AIBI complex
remains constant between pH and and then gradually
2
4
decreased. The absorption of the irone5-AIBI complex decreases at
pH < 1 by protonation in the ligand and drops sharply at pH > 10.0
with the formation of a precipitate of iron hydroxide.
In order to confirm the stoichiometry of the Fe(III)e5-AIBI
complex spectrophotometric measurements were performed by
using the Job's method [18]. Nine aqueous ethanolic mixtures of 5-
AIBI (0.6 mM) and iron (III) chloride (0.6 mM) were prepared in
appropriate buffer at 25 ꢁC. Sodium perchlorate was added to give a
constant ionic strength of 0.1 M. The volumes of 5-AIBI solution
used varied from 9 to 1 mL and those of iron (III) chloride solution
from 1 to 9 mL; total volume was always 10 ml. The absorption
spectra of the complex achieved immediately after mixing the
ligand and iron (III) chloride solutions. The absorption spectra of
the nine aqueous ethanolic mixtures of 5-AIBI and iron (III) chloride
can be found in Fig. 3.
The stoichiometry of the complex formed between Fe3þ cation
and the ligand was obtained by Job's method of continuous varia-
tion. The Job's plot (Fig. 3) reached a maximum value at a mole
fraction of 0.33, which confirmed that molar ratio between Fe(III)
ions and 5-AIBI in the complex is 1:2.
Fig. 1. The absorption spectra of the ligand (5-AIBI) and iron(III)e5-AIBI complex in
aqueous ethanolic solution (1 ꢀ 10ꢂ4 M).
been used in all subsequent measurements of absorbance. An
efficient charge transfer of electron from p-orbital on ligand to iron
(III)' d-orbital can be considered as the main reason for the color of
the complex described as Ligand to-Metal charge transfer (LMCT)
[17].
Moreover, microanalysis of the irone5-AIBI complex
(C36H38Cl5FeN8O4) and molecular ion peak at m/z 736 ([Fe(5-
The effect of pH on the absorption spectrum of the irone5-AIBI
complex was also investigated. The dependence of the UV-Vis ab-
sorption of the irone5-AIBI complex on pH is depicted in Fig. 2. As it
Fig. 3. Job's curve of equimolar solutions for 5-AIBI e Fe3þ complex in aqueous
Fig. 2. The effect of pH on the absorption spectrum of the irone5-AIBI complex.
ethanolic solution.

58
Z. Agheli et al. / Journal of Molecular Structure 1130 (2017) 55e61
AIBI)2]3þ) strongly support the structure of the new complex [Fe(5-
AIBI)2] Cl3$2(H2O).
atoms is shown in Fig. 4 in two different views. In addition, the
structure of the complex can be found in Supporting Information
(Scheme S1). Some of the calculated structural parameters of the
Fe(III) complex are gathered in Table 1.
Except of the butyl group, the 5-AIBI ligands are planar. The
aromatic rings of the ligand are in a same plane. Also, both of the
ligands are in a same plane forming a square plane of the octahedral
complex. Two other positions of the complex are filled by two H2O
molecules, which are Trans to each other. The H2O ligands are
perpendicular to the square plane of the complex. The FeeO and
FeeN Lengths bonds are listed in Table 1. As seen, the bonds be-
tween the Fe3þ ion and nitrogen atoms of the isoxazole rings and
amino group (FeeN1 and FeeN4 bonds) are the shortest ones.
Based on the reported literature [19] and our experimental re-
sults, an octahedral geometry was proposed for the Fe(III) complex
of the investigated ligand. In the optimized geometry of the com-
plex, the 5-AIBI ligand acts as a bidentate ligand, coordinates to the
Fe(III) via nitrogen atom of the amine group (eNH2) and nitrogen
atom of the isoxazole ring. Geometry of the complex was optimized
in both of the gas phase and the PCM model, where the ethanol was
the used solvent. In addition, optimized geometry and frequency
calculations were done in both of the possible states of the com-
plex, high spin and low spin.
The optimized geometry of the complex with labeling of its
Fig. 4. The optimized geometry of the Fe(III) complex in two different views.

Z. Agheli et al. / Journal of Molecular Structure 1130 (2017) 55e61
59
Table 1
Selected structural parameters of the investigated Fe(III) complex.
3.1. NMR spectra
The DFT computed 1H and 13C NMR chemical shifts (
d) of the
Bond
Bond length (pm) Angle
(ꢁ)
Dihedral angle
N1-N7-N4-N8
(ꢁ)
investigated Fe(III) complex are gathered in Table 2 together with
the experimental values for comparison. The atoms are numbered
as in Fig. 4. Both of the High and low spin states of the complex are
explored theoretically.
As seen in Table 2, the DFT calculated chemical shifts of the high
spin complex are closer to the experimental ones in comparison
with the low spin form. Good agreement between the calculated
chemical shifts of the high spin state of the complex and the
experimental data confirms suitability of the high spin form, which
is more stable than the high spin form of the complex, too.
Fe-N1
Fe-N4
Fe-N7
Fe-N8
Fe-O3
Fe-O4
N1-O1
O1-C2
C2-C1
C1-C3
C3-C4
C2-C9
C1-C7
C7-N2
N2-C8
C8-N3
195.7
195.7
211.5
211.8
243.2
242.7
139.0
137.1
141.4
141.5
141.0
142.7
141.8
135.6
132.1
136.7
N1-Fe-N7 82.0
N1-Fe-N4 179.7 N1-N7-N4-Fe
N7-Fe-N8 179.6 O1-N1-Fe-O3
ꢂ0.6
ꢂ0.2
93.1
N1-Fe-N8 97.9
N4-Fe-N7 98.1
N1-Fe-O3 90.0
N1-Fe-O4 89.4
N7-Fe-O3 88.0
N7-Fe-O4 92.1
O3-Fe-O4 179.3 C3-N1-O1-C2
Fe-N7-C4 109.3 O1-C2-C9-C10
N7-C4-C3 112.6 O1-C2-C1-C7
C3-N1-Fe 114.7 C3-C1-C7-N2
Fe-O1-N1 120.3 C6-C7-N2-C8
C3-N1-O1 106.2 N2-C8- N3-C29
O1-N1-Fe-O4
O1-N1-Fe-N7
C4-N7-Fe-O3
C4-N7-Fe-N4
C4-C3-N1-O1
C3-N1-Fe-N8
86.8
ꢂ178.9
91.4
ꢂ179.1
0.3
178.5
0.2
ꢂ0.3
ꢂ179.1
ꢂ179.3
ꢂ0.2
178.3
3.2. Vibrational spectroscopy
N1-O1-C2 109.7 C10-C12-C14-Cl1 ꢂ180.0
N3-C29 148.0
C4-N7
C4-C5
O1-C2-C9 117.2 N7-C3-C4-C1
C2-C1-C7 140.8 C5-C6-N3-C8
C1-C7-N2 131.8 C3-C4-C17-C18
179.7
1179.2
ꢂ0.3
Herein, the vibrational modes of the titled Fe complex were
analyzed by comparing the experimental and DFT-computed IR
spectra. Assignment of the selected-vibrational frequencies is
gathered in Table 3. There is good agreement between the experi-
mental and DFT-calculated frequencies of the high spin complex,
confirming suitability of its optimized geometry. The obtained re-
sults could be useful in identification of similar compounds, too.
In the 3600-2000 cmꢂ1 spectral region of the IR spectra,
146.2
137.5
C14-Cl1 174.5
C7-N2-C8 104.9 N3-C29-C30-C31 178.3
The high spin state of the complex is more stable than the low
spin state. Their energy difference is 79.64 and 64.04 kJ. Molꢂ1 in
the gas phase and PCM model, respectively.
Table 2
Experimental and DFT computed 1H and13C NMR chemical shifts of the investigated complex in DMSO solution,
d [ppm].
1H NMR
13C NMR
Theo.
Theo.
Exp.
8.97
Exp.
Low spin
Atom position
High spin
Low spin
Atom position
High spin
d
Atom position
d
d
Atom position
d
H10
H4
H2
H8
H1
H7
H9
H3
H6
9.92
9.91
8.85
8.85
8.62
8.62
8.58
8.57
8.47
8.47
8.24
8.24
5.63
5.62
5.06
5.02
4.64
4.63
4.39
4.38
2.04
2.04
1.88
1.88
1.83
1.83
1.81
1.8
H4
H10
H2
H8
H3
H9
H6
H12
H5
H11
H1
9.97
9.97
8.72
8.72
8.64
8.64
8.42
8.42
8.22
8.22
7.86
7.86
4.5
C2
166.9
166.9
C14
C28
C16
C2
C8
C22
C3
C17
C7
C21
C11
C25
C6
C20
C13
C27
C12
C26
C10
C24
C9
C23
C19
C5
C4
C18
C1
C15
C29
C33
C30
C34
C31
C35
C32
C36
165.5
165.5
161.9
161.9
161.9
161.9
153.4
153.4
153.4
153.4
137.2
137.2
137.2
137.2
137.2
137.2
137.2
137.2
137.2
137.2
135.5
135.5
130.7
130.7
126.9
126.9
126.1
126.1
108.9
108.9
45.1
C16
C28
C14
C17
C3
C22
C8
C21
C7
166.29
166.12
172.05
172.01
160.89
160.82
149.3
149.26
145.72
145.63
145.5
145.48
141.86
141.85
140.37
140.33
136.27
136.19
129.53
129.43
127.68
127.63
125.32
125.18
116.71
116.65
54.98
163.14
163.13
159.87
159.86
157.58
157.58
149.57
149.55
145.85
145.85
144.04
144.02
141.57
141.56
140.16
140.16
136.13
136.13
129.61
129.61
126.13
126.12
118.74
118.72
115.51
115.51
54.62
7.94
7.52
H12
H5
7.48
5.63
C20
C6
H11
H17
H29
H18
H28
H19
H31
H20
H30
H22
H33
H23
H35
H27
H37
H32
H21
H24
H34
H38
H26
H25
H36
H16
H14
H15
H13
H7
H19
H31
H20
H30
H17
H29
H14
H15
H13
H16
H18
H28
H22
H33
H23
H35
H27
H37
H24
H34
H21
H32
H26
H38
H25
H36
C25
C11
C27
C13
C26
C12
C24
C10
C23
C9
4.5
4.17
4.17
3.79
3.79
3.5
4.10
3.5
3.44
3.43
2.89
2.89
1.91
1.91
1.79
1.79
1.76
1.76
1.66
1.66
1.26
1.26
1.19
1.19
1.06
1.06
4.10
C5
C19
C18
C4
C15
C1
C33
C29
C30
C34
C35
C31
C32
C36
1.34e1.42
1.78
1.78
1.26
1.25
1.15
1.15
ꢂ1.08
ꢂ1.12
ꢂ1.17
ꢂ1.2
1.14e1.22
54.97
40.78
40.78
26.24
26.16
16.76
16.76
54.62
40.64
40.63
26.05
26.04
16.71
16.71
45.1
32.3
32.3
19.9
19.9
13.6
13.6
0.75

60
Z. Agheli et al. / Journal of Molecular Structure 1130 (2017) 55e61
Table 3
Selected experimental and calculated IR vibrational frequencies (cmꢂ1) of the Fe complex.
Experimental frequency
Calculated frequency
Intensity (km.molꢂ1
)
Vibrational assignment
502 (w)
629 (w)
836 (m)
945 (w)
511
642
832
906
920
972, 969
1012
1037
1046, 1057
1083
46
172
70
ysym(Fe-N)
yasym(Fe-N)
dop(Aromatic hydrogens)
dwagging of the eCH2 moieties
Breathing of the aromatic rings
166
1123
186, 211
106
929
1083, 1278
147
35
1014 (m)
1038 (s)
y
y
y
y
(N1-O1, N4-O2)þ
y
(C-C) aliphatic
(C4-N7, C18-N8)
(C29-N3, C33-N6)þ
y
(C-Cl) þ (C-O)
y
(C-Cl) þ yasym(C2-O1-N1, C16-O2-N4)
1092 (s)
ysym(CeC) aliphatic
1109
dip(Aromatic hydrogens)
1131 (m, sh)
1152
1172
1208
1239
1277
1316
1395
1413
369
702
206
662
115
2738
1526
824
74
y
y
y
y
(C4-N7, C18-N8, C2-O1, C16-O2)
(C2-C9, C16-C23)
(C2-O1, C16-O2)
(C29-N3, C33-N6)
1206 (m)
1267 (m)
yasym(C7-N2-C8, C21-N5-C22)
1313 (m)
1370 (s)
1457 (vs)
y
y
y
(C29-N3, C33-N6)
(C]C, C]N) of the aromatic rings
(C]C, C]N) of the aromatic rings
1439
doscissoring of the methyl groups
1458
1473
182
83
doscissoring of the eCH2 moieties
yasym(CeC) of the benzene rings involving the eCl substituent
1491 (vs, sh)
1556 (vs)
1487
1524
1547
1566
1580
1584
2901, 2985
2914
2924e2993
3056e3095
3120
65
1978
3986
1076
235
42
65,11
40
4e42
9e33
74
y(C]C, C]N) of the aromatic rings
1594 (s, sh)
doscissoring of the H2O ligands
doscissoring of the eNH2 moieties
ysym(CeH) of the eCH2 moieties
ysym(CeH) of the methyl groups
yasym(CeH) of the eCH2 moieties
2872 (w)
2931(m)
2958 (m)
3058 (w)
y(CeH) aromatic
y(C8-H2, C22-H8)
3374 (m,br)
3450 (m,br)
3320
3374
3632
3719
63
68
134
5
ysym(OeH) of the eNH2 moieties
yasym(OeH) of the eNH2 moieties
ysym(OeH) of the H2O ligands
yasym(OeH) of the H2O ligands
Abbreviation: op, out-of-plane; ip, in-plane; w, weak; m, medium; s, strong; vs, very strong; br, broad; sh, shoulder.
overlapping of stretching vibrations of the OeH, CeH and NeH
bonds with each other results in a band broadening [20e22]. The
deconvolution of this region is given in Table 3. As seen, the most
intensive band is related to the stretching vibrations of the OeH
bonds of the H2O ligands.
Also, a great attempt to obtain an appropriate single crystal of
the complex for crystallography in is in progress and will soon be
reported elsewhere.
Appendix A. Supplementary data
In combination with other vibrations, the C]C and C]N
stretching vibrations of the aromatic rings cause to very strong
bands in the 1600-1450 cmꢂ1 spectral region of the IR spectrum of
the complex.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.molstruc.2016.10.015.
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