Synthesis and crystal structures of salen-type Cu(II) and Ni(II) Schiff base complexes: application in [3+2]-cycloaddition and A3-coupling reactions

Article abstract of DOI:10.1039/c8nj01718b

The synthesis of two new salen-type Schiff base complexes of the type [Cu(L)]·0.5H₂O, 1, and [Ni(L)], 2, from the reaction of a 6,6′-[(1E,1′E)-(cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene)bis(3-(diethylamino)phenol)] salen-type Schiff base ligand (H₂L) with Cu(OAc)₂·H₂O and Ni(OAc)₂·4H₂O in methanol at room temperature, respectively, is described. The complexes are isolated as coloured crystalline solids and characterized by elemental analysis, FT-IR spectroscopy, UV-visible spectroscopy and single crystal X-ray diffraction studies. The paramagnetic nature of complex 1, having g_iso = 2.076, was confirmed by EPR studies, which indicated a distorted square planar geometry of the complex. In contrast to this, the nickel complex was found to be diamagnetic in nature and it was additionally characterized by ¹H NMR. The crystal structures of complexes 1 and 2 confirm the distorted square planar geometry of both the complexes. Complex 1 was found to be a better catalyst for the synthesis of a series of 5-substituted 1H-tetrazoles from nitriles and sodium azide via [3+2]-cycloaddition and for the A³-coupling reaction of aldehydes, secondary amines and terminal alkynes with a low catalyst loading (0.7 and 0.9 mol%, respectively) as compared to complex 2. Complex 1 is novel in the sense that, being a homogeneous catalyst, it can be recovered almost quantitatively in both reactions and recycled up to four times to afford good yields of the corresponding products.

Full text of DOI:10.1039/c8nj01718b

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Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
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Pl Ne ae swe Jd oo u nr no at l ao dfj Cu sh te mm ai sr tgr iyn s
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DOI: 10.1039/C8NJ01718B
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ARTICLE
Synthesis and crystal structures of salen-type Cu(II) and
Ni(II) Schiff base complexes: Application in [3+2]-
3
Cycloaddition and A -coupling reactions
Received 00th January 20xx,
Accepted 00th January 20xx
a
a
b
a*
Bhumika Agrahari , Samaresh Layek , Rakesh Ganguly , Devendra D. Pathak
DOI: 10.1039/x0xx00000x
The synthesis of two new salenꢀtype Schiff base complexes of the type [Cu(L)].0.5H
from the reaction of 6,6’ꢀ[(1E,1’E)ꢀ(cyclohexaneꢀ1,2ꢀdiylbis(azanylylidene))bis(methanylylidene)bis(3ꢀ
diethylamino)phenol)] salenꢀtype Schiff base ligand (H L) with Cu(OAc) .H O and Ni(OAc) .4H O in methanol at room
2
O, 1, and [Ni(L)], 2, are described
www.rsc.org/
(
2
2
2
2
2
temperature, respectively. The complexes are isolated as coloured crystalline solids and characterized by elemental analysis,
FTIR, UVꢀvisible spectroscopy and single crystal Xꢀray diffraction studies. The paramagnetic nature of the complex 1 was
confirmed by EPR studies, having giso= 2.076 which indicated a distorted square planar geometry of the complex. Contrary
1
to this, the nickel complex was found to be diamagnetic in nature and it was additionally characterized by H NMR. The
crystal structures of complex 1 and 2 confirm the distorted square planar geometry of both the complexes. The complex 1
was found to be a better catalyst for the synthesis of series of 5ꢀsubstituted 1Hꢀtetrazoles from nitriles and sodium azide via
3
[
3+2]ꢀcycloaddition and in A ꢀcoupling reaction of aldehydes, secondary amines and terminal alkynes with low catalyst
loading (0.7 and 0.9 mol % respectively) as compared to complex 2. The complex 1 is novel in the sense that, being a
homogeneous catalyst, it can be recovered almost quantitatively in both reactions and recycled up to four times to afford
good
yields
of
the
corresponding
products.
1
6
17
18
19
such as Zn(OTf)
Cu (OTf)
Fe(OAc)
AgNO3, 25Fe
BF ꢀOEt
Introduction
2,
2
2,
2,
3
2,
2
0
21
22
Cu(NO2
3
)
2
.3H
2
O,
Cu(II), Zn/Al hydrotalcite, CoY zeolites, γꢀFe O
29
Cu(OAc)
2
,
3
O
4
@SiO
2
/salen
nanoꢀ
3
24
26
2
3,
The tetradentate Schiff base, salenꢀtype ligand and their complexes
have allured much interest since Jacobsen’s discovery of chiral
manganese(III) salen Schiff base catalysts in the asymmetric
27
28
ZnO/Co
microporous
3
O
4
,
nanoꢀCuFe
molecular
2
O
4,
NiꢀFerrite NPs , AlPOꢀ5
30
sieves,
PdꢀSMTU@boehmite
32
31
nanoparticles, and [Pd SBT@MCM41] etc. Majority of the
methods suffers from one or more drawbacks such as long reaction
time, high catalyst loading, elevated temperature, low yields, tedious
workup of the reaction mixture etc.
Multiꢀcomponent reactions (MCRs) are another very
powerful tool in the armoury of an organic chemist for the synthesis
of complex organic compounds via a oneꢀpot methodology . An
attractive example of MCRs is the A ‐coupling reaction.
Propargylamines, the final product of an A ꢀcoupling reaction, are
important intermediates for the synthesis of many nitrogenꢀ
containing natural products and potential therapeutic molecules such
as lꢀDeprenil and PF960IN (Fig. 1). Due to the versatile
applications, propargylamine have been usually prepared by the
nucleophillic attack of lithium acetylides and Grignard reagents on
imines or their derivatives. However, these methods have certain
limitations such as moisture sensitivity and the requirement for
stringent reaction conditions. Various homogenous
heterogeneous
propargylamines. However, recovery and recyclability of most of the
homogeneous catalysts is still an issue. Therefore, there is a
considerable scope for design and development of structurally well
characterized, robust, and recyclable catalysts for this reaction.
1
epoxidation of unfunctionalised olefins in 1990s. SalenꢀSchiff base
transition metal complexes have been extensively studied because of
their prospective use as catalysts in a wide range of CꢀC and CꢀN
bond formation reactions such as cyclopropanations, aziridination,
asymmetric cycloaddition reactions, and A ꢀcoupling etc. Among
different type of reactions, CꢀN bond formation reactions mediated
by salenꢀtype transition metal complexes has attracted much interest
3
2
33
3
34
3
in recent decade. The construction of the CꢀN bonds of aromatic
compounds is particularly important to medicinal chemists.
3
4
Nitrogen containing heterocyclic moiety is an integral part of several
natural products and many synthetic organic compounds exhibiting
35
5
ꢀ7
interesting biological activities.
Among various heterocycles
reported, tetrazoles are very important class of compounds8.
Tetrazoles have been used as ligands in coordination chemistry,
36
9
stabilizers in photographic industry, linkers for selective covalent
attachment of synthetic groups to biopolymers, antihypertensive
and antiviral drugs and ligating aryl thiotetrazolyl acetanilides with
1
0
11
37ꢀ46
and
12
47ꢀ53
catalysts have been reported for the synthesis of
13
HIVꢀ1 reverse transcriptase.
Due to wide applications of tetrazoles and their
derivatives, concerted efforts have been directed towards the
development new synthetic methodologies. Among them, [3+2]ꢀ
cycloaddition, first reported by Hantzsch and Vagt, is the most
widely used procedure to
1
4
access 5ꢀsubstituted 1Hꢀtetrazoles from sodium azide and organic
1
5
nitriles. Numerous catalysts have been reported for this reaction;
l-Deprenil
PF960IN
Fig. 1 Propargylamine moiety containing drugs
In continuation of our ongoing research interest in the synthesis,
structural characterization and catalytic applications of transition

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ARTICLE
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5
4ꢀ58
metal complexes in organic synthesis,
we herein describe the mL). The catalyst (0.7 mol %) was added to the reaction mixture and
o
synthesis and characterization of two new salenꢀtype Schiff base allowed to react at 110 C for 4ꢀ6 h. The progress of the reaction was
complexes [Cu(L)].0.5H O, 1 and [Ni(L)], 2 and their application in monitored by TLC. After completion, the reaction mixture was
2
the synthesis of 5ꢀsubstituted 1Hꢀtetrazoles and propargylamines.
cooled down to room temperature and recrystallized salen Cu(II)
was removed by filtration and the filtrate was treated with HCl (2N,
1
0ml) and then with ethyl acetate (3x10 mL). The resultant organic
Experimental
layer was separated, washed with water and dried over Na SO .The
2
4
solvent was removed under reduced pressure to give crude product
which was purified by column chromatography using petroleum
ether/ethyl acetate (1:4) as an eluent. Products were characterized by
Materials and instrumentations
1
13
All reagents and solvents for the synthesis and analysis were
purchased from Merck and Sigma Aldrich and used as received
without further purifications.
H and C NMR studies.
General procedure for the synthesis of propargylamines
FTIR spectra were recorded on a Perkin Elmer Spectrometer in the
ꢀ
1
range of 400ꢀ4000 cm using KBr pellets. Electronic absorption A mixture of aldehyde (1.0 mmol), secondary amine (1.0 mmol),
spectra were recorded on a Shimadzu UVꢀ1800 Spectrophotometer alkyne (1.2 mmol) and catalyst (0.9 mol %) was stirred in a 25ꢀmL
in the wave length range of 200ꢀ900 nm. The Cyclic Voltammetry roundꢀbottomed flask at 80 °C for 5ꢀ8 hrs in toluene (5ꢀmL). The
(
CV) analysis were performed on a CHI660C electrochemical progress of the reaction was monitored by TLC. After completion,
analyzer under oxygenꢀfree conditions. The CV studies were the reaction mixture was cooled down to room temperature and
ꢀ3
performed on [Cu(L)].0.5H O complex (10 M) using 0.1 M recrystallized salen Cu(II) was removed by filtration and then
2
[
nBu N][ClO ] as a supporting electrolyte in DMF solvent at a scan solvent was removed under vacuum. The crude product was washed
4 4
ꢀ1
rate of 100 mV S . The threeꢀcomponent electrode consisted of a with water and extracted with ethyl acetate (3x10 mL). It was
glassy carbon working electrode, a SCE reference electrode, and purified by the column chromatography using silica gel and ethyl
platinum wire as counter electrode. The H and C NMR spectra of acetate: petroleum ether as an eluent. Products were characterized by
1
13
1
13
the isolated products were recorded on a Bruker AvIII HDꢀ400 MHz
H NMR and C NMR studies.
spectrometer in DMSOꢀd and CDCl using TMS as the internal
6
3
Standard. Melting points were recorded on a Yazawa micro melting Crystallographic studies
point apparatus.
The Xꢀray diffraction data were collected on a Bruker Kappa
General synthesis of Salen-type Schiff base complexes diffractometer at 203(2) K and 293 K equipped with a CCD detector,
M(L)].xH O
employing Mo K α radiation (λ = 0.71073 Å), with the SMART
[
2
6
0
suite of programs. All data were processed and corrected for
2
L was prepared by reported method. A methanolic Lorentz and polarization effects with SAINT and for absorption
59
The ligand H
solution of ligand H
clear solution of Cu(OAc)
Ni(OAc) .4H O (0.248 g, 1.0 mmol) in methanol (10 mL). The were refined (weighted least squares refinement on F ) to
6
1
2
L (0.464 g, 1.0 mmol) was added dropwise to a effects with SADABS. Structural solution and refinement were
62
2
2
.H O (0.200 g, 1.0 mmol) or carried out with the SHELXTL suite of programs. The structures
2
2
2
solution was stirred at room temperature for 8 h and resultant dark convergence. All the nonꢀhydrogen atoms in all the compounds were
brown for Cu(II) and reddish brown precipitate for Ni(II) complexes, refined anisotropically by fullꢀmatrix leastꢀsquares refinement. A
were filtered, washed with cold ethanol and dried in vacuum over summary of the crystallographic and refinement data of complexes
anhydrous CaCl . Single crystals suitable to Xꢀray crystallography are given in Table 1.
2
were grown over a period of two weeks on standing a concentrated
solution of the complex in DMF.
o
Complex [Cu(L)].0.5H
0.36 (EtOAc), Anal. Calc. for C28
.35; N, 10.47; O, 7.47. Found: C, 62.67; H, 7.48; N, 10.23; O, 7.28.
2
O 1: Yields: 0.481 g, 90 %, m.p = 286 C, R
f
2
Table 1 Crystal data and refinement parameters of [Cu(L)].0.5H O
=
4
H39 Cu N O2.50: C, 62.84; H, and [Ni(L)] complexes
7
ꢀ
1
CCDC
1576528
39 Cu N
535.17
203(2) K
0.71073 Å
Triclinic
Pꢀ1
1813608
C H N Ni O
28 38 4 2
FTIR (KBr), cm : 1584 ν (C=N), 2857ꢀ2931 ν (CH ), 1318
2
Empirical formula
Formula weight
Temperature
C
28
H
4
O
2
.
50
ν (C=Cring), 619 ν (CuꢀO), 512 ν (CuꢀN). UVꢀvis [λmax(nm)]: 346,
521.33
293(2) K
0.71073 Å
Monoclinic
P 2 /n
566.
o
Complex [Ni(L)] 2: Yields: 0.459 g, 88 %, m.p = 330 C, R
f
ꢀ
=0.57 Wavelength
Crystal system
Space group
(
EtOAc), Anal. Calc. for C28 H38 Ni N O : C, 64.51; H, 7.35; N,
4
2
1
1
10.75. Found: C, 64.39; H, 7.24; N, 10.89. FTIR (KBr), cm :1590
Unit cell dimensions
ν (C=N), 2857ꢀ2931 ν (CH
2
), 1325 ν (C=Cring), 523 ν (NiꢀO), 442 ν
a
b
c
α
β
γ
9.4610(11) Å
15.3673(17) Å
19.021(2) Å
92.716(3)°
12.0046(13)Å
8.5202(9)Å
26.095(2)Å
90°
1
0
(
NiꢀN). H NMR (CDCl
6.79 (d, J = 8 Hz, 2H, Ar H), 6.15 (d, J = 2 Hz, 2H, Ar H), 5.94
m, 2H, Ar H), 3.24 (q, J = 2 Hz, 8H, ꢀCH ), 2.90 (m, 2H,
cyclohexane ring), 2.29 (d, 2H, J = 6.8, cyclohexane), 1.78 (d, J
0.8, 2H, cyclohexane ring), 1.20 (m, 4H, cyclohexane
1.08 (t, 12H, J = 7.2 Hz, ꢀCH UVꢀvis [λmax(nm)]: 377,
3
, 25 C, 400 MHz): δ 7.03 (s, 2H, HꢀCN),
δ
(
δ
93.956(3)°
92.104(9)°
2
102.009(3)°
90°
δ
δ
3
3
Volume
2693.1(5) Å
2667.2(5) Å
=
δ
Z
4
4
ring),
δ
3
)
.
3
3
Density (calculated)
Absorption coefficient
1.320 mg/m
1.298 mg/m
0.759 mm
ꢀ1
ꢀ1
557.
0
.845 mm
F(000)
Crystal size
1136
1112
0.1 x 0.1 x 0.1 mm
3
0.420
x
0.140
x
0.080
General procedure for the synthesis of 5-substituted 1H-
3
mm
tetrazoles
Theta range for data
collection
1.357 to 26.173°
1.842 to 29.425°
A mixture of nitrile (1.0 mmol), and sodium azide (0.078g, 1.2 Index ranges
mmol) were placed in 25ꢀmL roundꢀbottomed flask in DMSO (5
ꢀ11<=h<=6,18<=k<=19,ꢀ
3<=l<=23
20273
ꢀ15<=h<=15,ꢀ7<=k<=10, ꢀ
33<=l<=35
14110
2
Reflections collected
2
| J. Name., 2012, 00, 1-3
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Completeness to theta
=
98.7 %
None
100 %
25.242°
Structure description of complex [Ni(L)], 2
Absorption correction
Semiꢀempirical
equivalents
from
Refinement method
Fullꢀmatrix leastꢀsquares Fullꢀmatrix leastꢀsquares The ORTEP diagram of the complex [Ni(L)] along with the atom
2
2
on F
10518 / 239 / 702
on F
6171/125/368
numbering scheme is depicted in Fig. 2(b). The crystal data and
structural refinement parameters are summarized in Table 1 and
selected bond lengths and bond angles are given in Table 1S.
Molecular structure of the complex revealed that nickel atom in the
Data / restraints /
parameters
2
0.936
1.014
Goodnessꢀofꢀfit on F
Final
I>2sigma(I)]
R indices (all data)
R
indices
R1
0.1363
R1
.1721
n/a
=
0.0709, wR2
0.1722, wR2
=
=
R1 =0.0541, wR2 =0.1138
2
complex [NiL] have distorted square planar .The ligand H L
[
=
R1 =0.1134, wR2 =0.1357
coordinate to Ni atom in tetradentate manner through two phenolate
oxygen and two imine nitrogen forming one five membered and two
six membered ring. In Ni(II) complex, Ni(1)ꢀO(1), Ni(1)ꢀO(2),
Ni(1)ꢀN(1) and Ni(1)ꢀN(2) bond length are 1.840(3), 1.856(3),
0
Extinction coefficient
Largest diff. peak and hole
n/a
ꢀ3
ꢀ3
0
.723 and ꢀ0.919 e.Å
0.567 and ꢀ0.285 e.Å
1
.851(4) and 1.850(3), respectively. The bond angles O(1)ꢀNi(1)ꢀ
O(2), O(1)ꢀNi(1)ꢀN(1), O(2)ꢀNi(1)ꢀN(1),O(1)ꢀNi(1)ꢀN(2) are
5.0(1),95.0(2), 176.5(2) and 178.0(2), respectively. The bond angle
Results and discussion
8
and bond length are in close agreement with the previously reported
Ni(II) complexes.
The Salenꢀtype Schiff base ligand 6,6’ꢀ[(1E,1’E)ꢀ(cyclohexaneꢀ1,2ꢀ
diylbis(azanylylidene))bis(methanylylidene)bis(3ꢀ
63
(
diethylamino)phenol)] (H
in 89 % yield by the reported method. The reaction of H
Cu(OAc) .H O and Ni(OAc) .4 H O in methanol at room
2
L) was synthesized as an offꢀwhite solid
60
2
L with
2
2
2
2
2
temperature afforded complexes [Cu(L)].0.5H O, 1, and [Ni(L)], 2,
as dark brown and red brown solids, respectively (Scheme1) in high
yields (88ꢀ90 % yields). The complexes were air stable, insoluble in
water and benzene, and soluble in other common organic solvents
such as CH Cl , CHCl , CH CN, DMF and DMSO. The complexes
2
2
3
3
were fully characterized by elemental analysis, FTIR, UVꢀvis and
single crystal Xꢀray diffraction studies. In addition, paramagnetic
nature of complex 1 was confirmed by EPR spectroscopy. The
complex 2 was found to be diamagnetic and it was also characterized
1
by H NMR.
(
2
a) [Cu(L)].0.5 H O
Scheme 1 Synthesis of complexes
X-ray crystallography
Diffraction quality crystals of complexes 1 and 2 were grown over a
period of two weeks on standing a concentrated solution of the
respective complex in DMF at room temperature. The structures of
the complexes have been elucidated by singleꢀcrystal Xꢀray
diffraction studies.
Structure description of complex [Cu(L)].0.5H
2
O, 1
(
b) [Ni(L)]
The ORTEP diagram of the complex [Cu(L)].0.5H O along with the
2
atom numbering scheme is depicted in Fig. 2(a). The crystal data and
structural refinement parameters are summarized in Table 1 and
selected bond lengths and bond angles are given in Table 1S. The
central copper(II) ion adopts a distorted square planar geometry,
ligated to two phenolate oxygen and two imine nitrogen of
tetradentate Salenꢀtype ligand forming one five membered and two
six membered ring. In Cu(II) complex, the bond length of Cu(1)ꢀ
O(1), Cu(1)ꢀO(2), Cu(1)ꢀN(1) and Cu(1)ꢀN(2) are 1.903(3),
Fig. 2 ORTEP diagram of (a) Cu(II) (Thermal ellipsoids are drawn
at the 50% probability level. Water molecule have been omitted for
Cu(II) complex) and, (b) Ni(II) Salenꢀtype Schiff base complexes
with the atom labelling scheme (Thermal ellipsoids are drawn at the
5
0% probability level.)
FTIR spectra of ligand and complexes 1 and 2 are shown in Fig.
3
3
ν
. The FTIR spectrum of free ligand shows characteristic bands at
1
.910(3), 1.925(4) and 1.928(4), respectively. The bond angles O(1)ꢀ
ꢀ1
298, 2850ꢀ2923 and 1620 cm corresponding to
(CH )cyclohexane and ν (C=N) of azomethine group, respectively.
2
However the FTIR spectra of complexes 1 and 2 showed band at
ν (OH),
Cu(1)ꢀO(2), O(1)ꢀCu(1)ꢀN(1), O(2)ꢀCu(1)ꢀN(1), O(1)ꢀCu(1)ꢀN(2)
are 90.17(15), 93.81(18),169.75(16), 165.92(16) respectively. The
bond angle and bond length are in close agreement to the other
6
4
ꢀ
1
ꢀ1
6
3
1584 cm and 1590 cm attributed to ν (C=N), respectively. A
square planar Cu(II) complex.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
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comparison of the spectra of free ligand with the complexes, hydroxybenzaldehyde moiety in the free ligand appeared as quartet
ꢀ
1
indicated that the
1
ν
(C=N) has been lowered by 36 cm for Complex and triplet at
δ
3.32 and
δ
1.14, respectively. The ꢀCH resonance of
3.14. The
ꢀ
1
and 30 cm for complex 2, supporting the coordination of the cyclohexane ring are recorded as multiplets at
azomethine nitrogen atom to Cu and Ni metal ions. The methylene resonances (ꢀCH ) of the cyclohexane ring were observed
δ
2
+
2+
65
2
1
disappearance of
ν
OH band in the FTIR spectra of both the in the range of
δ
1.94ꢀ1.42 as multiplets. A comparision of the H
ꢀ
1
complexes and appearance of two additional bands 619 and 512 cm
NMR spectrum of complex 2 with the free ligand indicated upfield
for ν (CuꢀO) and ν (CuꢀN) and 523 and 442 cm for ν (NiꢀO) and shift of the azomethine proton (CH=N) at
7.03 from 7.93. The
ν (NiꢀN) respectively, confirms the deprotonation of the ꢀOH group CH2 and CH protons of 4ꢀ(diethylamino)ꢀ2ꢀhydroxybenzaldehyde
ꢀ
1
δ
δ
3
and supports the coordination of phenolate oxygen atom to metal moiety in the complex 2 appeared as quartet and triplet at
δ
3.24 and
ions.
δ
1.08, respectively. The ꢀCH protons of cyclohexane ring is shifted
to upfield at
δ
2.90 and the methylene resonances (ꢀCH
2
) of
cyclohexane ring appeared in the range
of complex 2. The disappearance of ꢀOH proton signal in H NMR
spectrum of complex 2 confirms the deprotonation of ꢀOH group.
δ
1.78ꢀ1.06 in the spectrum
1
6
7
The catalytic activity of complexes 1 and 2 were screened for the
synthesis of 5ꢀsubstituted 1Hꢀtetrazoles and propargylamines
(
Scheme 2ꢀ3). Initially the catalytic studies were performed for
synthesis of tetrazoles choosing benzonitrile and sodium azide as a
model substrates. Various parameters such as catalyst loading,
solvent, temperature and time were studied and optimized. The
results are summarised in Table 2. When the reaction was carried out
o
in absence of catalyst in DMSO at 110 C, no product was obtained
even after 24 h (Table 2, entry 1). However, in presence of 0.4 mol
%
complex 1, 40 % yield of the product was obtained in 9h (Table 2,
2
Fig. 3 FTIR spectra of (a) Ligand (b) [Cu(L)].0.5H O, 1 and (c)
entry 2). Increasing catalyst loading to 0.7 mol %, resulted in 96 %
yield of the desired product in 4 h at 110 C (Table 2, entry 3).
[
Ni(L)], 2 complex
o
However further increase in catalyst loading to 1 mol % did not
improve the yield of the product (Table 2, entry 4). Therefore, 0.7
mol % of the catalyst loading was found to be optimum (Table 2,
entry 3). In order to find the best solvent, reaction was carried out in
The UVꢀvis spectra of the ligand and complexes 1 and 2 are
shown in Fig. S3. The UVꢀvis spectrum of the ligand shows peaks at
*
3
09 nm due to πꢀπ transition localised on the aromatic rings and a
*
low intensity band at 351 nm due to the nꢀπ excitation of the lone
pair on the imine nitrogen atom to the π* orbital on the C=N
fragment. However, a comparison of the UVꢀVis spectra of the
complexes with the ligand indicated a slight shift in the position and
intensity of this band at around 346 and 377 nm in complex 1 and
3 6 5 3
different solvents such as CH CN, C H CH , DMF and DMSO
(
Table 2). Among all the solvents used DMSO was found to be the
66
best solvent (Table 2, entry 3). The reaction was also carried out at
o
different temperatures, i.e. at 90, 110, 120, 140 C (Table 2, entries
o
9
ꢀ11). The best yield of the product was obtained at 110 C (Table 2,
3
19 and 359 nm in complex 2 respectively. The spectra of the Cu(II)
entry 3). Further, the effect of time was also investigated (Table 2)
and the best yield was obtained in 4 h (Table 2, entries 3, 12). The
reaction was also performed with complex 2 under optimized
conditions. Although the product was formed but in low yield (30
and Ni(II) complexes also shows an additional broad band at 566
2
2
1
and 557 nm due to dꢀd transitions assignable to B1ꢀ
→ A1g and
1
A
1ꢀ
→
A
2g respectively, suggesting the distorted square planar
67
geometry of the complexes.
%
) as compared to the complex 1 which may be due to the weaker
interaction of Ni ion with nitrile than Cu ion (Table 2, entry 5). The
best results were obtained with 0.7 mol % catalyst loading of
complex 1, at 110 C in DMSO in 4 h (Table 2, entry 3).
The Xꢀband EPR spectrum of the complex 1 recorded at room
temperature is shown in the Fig. 4. The EPR spectrum of the
powdered complex at 300 K, revealed an isotropic behaviour with
broad signal having giso= 2.076 with no hyperfine structure and
o
6
8
confirmed a distorted square planar geometry of the complex.
Scheme 2 Synthesis of 5ꢀsubstituted 1Hꢀtetrazoles
Scheme 3 Synthesis of propargylamines
Fig. 4 EPR spectrum of [Cu(L)].0.5H
2
O
1
Table 2 Optimization of reaction conditions for Synthesis of 5ꢀ
substituted 1Hꢀtetrazoles
The H NMR spectra of ligand and complex 2 are shown in Fig.
a
1
S1ꢀS2. The H NMR spectrum of H
singlet at 13.79 due to presence of OH proton. The azomethine
proton (CH=N) appeared at 7.93 as a singlet and the phenyl
protons of the free ligand are observed in the range of 6.89ꢀ6.03 as
multiplets. The CH and CH protons of 4ꢀ(diethylamino)ꢀ2ꢀ
2 3
L in CDCl showed one broad
δ
δ
δ
2
3
4
| J. Name., 2012, 00, 1-3
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DOI: 10.1039/C8NJ01718B
Journal Name
ARTICLE
b
Entry
Catalyst
Catalyst
loading
Solvent
Temperature
( C)
Time
(h)
Yield
(%)
o
(mol
%
)
1
2
3
4
5
6
7
8
9
ꢀ
ꢀ
DMSO
DMSO
DMSO
DMSO
DMSO
DMF
110
110
110
110
110
110
80
24
9
ꢀ
Cu(II)
Cu(II)
Cu(II)
Ni(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
0.4
0.7
1
40
96
96
30
70
30
35
75
96
96
96
4
4
0.7
0.7
0.7
0.7
0.7
0.7
0.7
0.7
4
4
CH
3
CN
CH
4
C
6
H
5
3
110
90
5
Scheme 4 A plausible reaction mechanism for the 5ꢀsubstituted 1Hꢀ
tetrazole
DMSO
DMSO
DMSO
DMSO
12
4
1
0
1
2
120
140
110
Table 3 The reaction of various benzonitrile with sodium azide
1
4
a,b
under optimized reaction conditions
1
8
a
3
Reaction conditions: Benzonitrile (1.0 mmol), NaN (1.2mmol).
Isolated yield.
b
With the optimized reaction conditions in hand, the scope of the
reaction was extended to a variety of substituted nitriles with sodium
azide. Aromatic nitriles bearing electron withdrawing group such as
ꢀ
COCH
3
2
, ꢀBr, ꢀCl, and ꢀNO results in higher yield (Table 3, entries
3
dꢀg, iꢀj) while nitriles bearing electron donating groups such as ꢀ
3
OCH and ꢀOH results in lower yield as compared to nitriles bearing
electron withdrawing groups (Table 3, entry 3bꢀc,h). This is due to
faster cycloaddition reaction of aromatic nitriles with electron
withdrawing substituents rather than the reaction of aromatic nitrile
compound with electron donating as the presence of electron
withdrawing group, increases the polarity of the cyanide group (ꢀI
6
9
effect), favouring the reaction
.
However, substituents at para and
meta position resulted in excellent yield (Table 3, entries 3c,i,j) as
compared to ortho substituent’s due to steric hindrance (Table 3,
1
entries 3h).The isolated products were fully characterized by H and
1
3
C NMR (Figure S9ꢀS17). A plausible mechanism for the reaction,
2
0,69
a
based on previous reports,
is suggested in Scheme 4. The
Reaction conditions: Benzonitrile (1.0 mmol), NaN
Isolated Yield
3
(1.2mmol).
b
proposed mechanism entails coordination of nitrogen atom of the
nitrile group to Cu(II) as the initial step to form complex I. The
complex I serves as an ideal template for the [3+2]ꢀcycloaddition
reaction between activated nitrile an azide. Interestingly, the
cycloaddition reaction in absence of the catalyst, did not proceed
Table 4 A comparison study of synthesized [Cu(L)].0.5H
complex with some of the previous reported catalysts for 5ꢀ
substituted 1Hꢀtetrazoles
2
O
o
even after prolong refluxing time at 110 C (Table 3, entry 1). This
2
+
Entry
Catalyst
Catalyst
loading
Temp
.
( C)
Time
(h)
Yield
s (%)
Reference
clearly indicates the role of Cu as a Lewis acid in the activation of
the nitrile. After [3+2]ꢀcycloaddition between the C≡N bond of
nitrile and azide, a fiveꢀmembered heterocyclic ring was formed (II).
Protonolysis of the intermediate II by 2 N HCl yielded the 5ꢀ
substituted 1Hꢀtetrazole III. In order to ascertain the efficiency of
the new catalysts, a comparison was made with some previously
o
(mol%)
1
2
AgNO
3
10
120
5ꢀ5.5
12
87
96
22
21
Cu(OAc)2
20
120
3
4
Salen complex
of Cu(II)
0.4
120
110
6ꢀ12
4ꢀ6
92
96
23
21ꢀ23
reported catalysts
(Table 4). The results indicate that the
[Cu(L)].0.5H
2
O
0.7
This work
complex 1 exhibited better catalytic activity as compared to other
reported catalyst. The complex 1 afforded products at low catalyst
loadings, in short reaction time, and high yields. Easy synthesis,
stability and recyclability of the homogenous catalyst are some of
the additional characteristics of the complex 1 that makes it a better
catalyst as compared to the reported catalysts.
To enhance the scope of our studies, [Cu(L)].0.5H
2
O, 1, was also
tested for the synthesis of propargylamines. Initially benzaldehyde,
piperdine and phenylacetylene were chosen as model substrates. The
results are summarized in Table 5. When the reaction was carried out
o
in the absence of the catalyst in toluene at 80 C for 24 h, no product
was obtained (Table 5, entry 1). However in presence of 0.5 mol %
of Cu(II) complex, 35% yield of desired product was obtained
(
Table 5, entry 2) in 9h. Further catalyst loading was increased to 0.7
mol % and 0.9 mol % resulted in 85 % and 93 % yield of the product
respectively, in 7 h in toluene (Table 5, entries 3ꢀ4). However no
significant improvement in yield was observed on increasing catalyst
loading to 1 mol % (Table 5, entry 5). Thus 0.9 mol % of catalyst
This journal is © The Royal Society of Chemistry 20xx
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ARTICLE
Journal Name
loading was found to be optimum (Table 5, entry 4). The effect of 0.46 V vs. SCE (E = 0.51 V, Ep/c = 0.41 V vs. SCE) corresponding
p/a
II
I
solvents was investigated in presence of the optimized catalyst to the Cu /Cu redox couple, supporting the formation of a Cu(I)
7
0
(
5
Table 5, entries 4ꢀ8). The best result was obtained in toluene (Table intermediate during the catalytic reaction. The irreversible peak at
, entry 4). When, the reaction was carried out without solvent, 50 % 1/2 = ꢀ1.39 V vs. SCE (Ep/a= ꢀ1.33 V, Ep/c= ꢀ1.45 V vs. SCE) is due
yield of the desirable product was obtained in 7h (Table 5, entry to ligand based reduction and one irreversible anodic peak at
E
5
9
9
).To investigate the effect of temperature, the reaction was potential 0.74 V vs. SCE is due to ligand based oxidation.
o o o
performed at RT, 50 C, 80 C and 100 C (Table 5, entries10ꢀ12)
and the best result was obtained at 80 C (Table 5, entry 4).
A plausible mechanism for reaction, based on previous reports
is suggested in Scheme 5. The A ꢀcoupling reaction proceeds by
o
47,48
3
Additionally, the effect of time was also investigated, maximum the activation of CꢀH bond of the terminal alkyne by the Cu(II)
yield obtained in 7h (Table 5, entry 4). The reaction was also carried complex. The copperꢀacetylide intermediate then reacted to the
out using 0.9 mol % of complex 2 as catalyst, resulted in low yield iminium ion prepared in situ from the aldehyde and the amine to
as compared to Cu(II) complex (Table 5, entry 13). The reason for afford the corresponding propargylamine.
this is may be due to the fact that Cu ions can form stronger
4
7
complexes with acetylenes than nickel. Thus, the best yield (93%)
was achieved in the presence of 0.9 mol% of Cu(II) catalyst in
o
C
6
H
5
CH
3
solvent at 80 C in 7 h (Table 5, entry 4).
Table 5 Optimization of reaction conditions for Synthesis of
a
propargylamines
Scheme 5 A plausible reaction mechanism for the propargylamines
A comparison was also made with some of the previous reported
3
catalysts for A ꢀcoupling reactions. The results indicate that the
complex 1 exhibited better catalytic activity as compared to some of
b
Entry
Catalyst
Catalyst
loading
Solvent
To emperature
( C)
Time
(h)
Yield
(%)
other reported catalyst in terms of catalyst loading, temperature and
(mol %)
37ꢀ39,47
1
2
3
4
5
6
7
8
9
ꢀ
ꢀ
C
C
C
C
C
6
6
6
6
6
H
H
H
H
H
5
5
5
5
5
CH
CH
CH
CH
CH
3
3
3
3
3
80
80
80
80
80
80
80
80
80
100
50
RT
80
80
80
24
9
7
7
7
7
7
7
7
7
8
10
7
10
8
ꢀ
time etc. (Table 7).
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Cu(II)
Ni(II)
Cu(II)
Cu(II)
0.5
0.7
0.9
1
35
85
93
93
50
55
80
50
90
75
30
25
93
93
Table 6 Synthesis of propargylamines from aldehydes, amines and
a,b
alkynes
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
DMF
OH
CN
C
2
H
5
CH
3
ꢀ
1
1
1
1
1
0
1
2
3
4
5
C
C
C
C
C
C
6
6
6
6
6
6
H
H
H
H
H
H
5
5
5
5
5
5
CH
CH
CH
CH
CH
CH
3
3
3
3
3
3
1
a
Reaction conditions: Aldehyde 1 (1mmol), Amine 2 (1mmol), Alkyne 3
(
1.2 mmol)
b
Isolated yield
The scope and applicability of the catalyst was examined to
various aldehyde, amines and alkynes under optimized conditions.
Aryl aldehyde with electron withdrawing groups such as ꢀBr, ꢀCl, ꢀ
CHO and ꢀNO , (Table 6, entries 4dꢀh) afforded high yields as
2
3
compared to electron donating groups such ꢀCH and ꢀOH (Table 6,
entries 4c,j). Aliphatic aldehyde such as formaldehyde also resulted
in good yield (Table 6, entry 4m). The reaction with secondary
cyclic amines, i.e. piperdine and morpholine also proceeded well to
afford the corresponding propargylamine in good yields (Table 6,
entries 4aꢀm) under optimized conditions. Attempts to isolate
products with aromatic amines, such as aniline and benzyl amine,
were unsuccessful presumably due to the low nucleophilicity of the
aromatic amines. Interestingly, 2ꢀthiophenecarbaxaldehyde also
reacted well to afford the corresponding propargylamine in 85 %
yields (Table 6, entry 4i). Reactions using substituted and
unsubstituted alkynes also afforded corresponding products in high
yields (Table 6, entries 4aꢀm). The isolated products were fully
1
13
characterized by H and C NMR (Figure S18ꢀS30).
a
Reaction conditions: Aldehyde 1 (1mmol), Amine 2 (1mmol), Alkyne 3
Further, the change of oxidation state was confirmed by Cyclic
(1.2 mmol)
Voltammetry (CV). The ꢀ CV studies were performed on
b
Isolated Yield
3
[
Cu(L)].0.5H O complex (10 M) using 0.1 M [nBu N][ClO ] as a
2
4
4
ꢀ
1
supporting electrolyte in DMF solvent at a scan rate of 100 mV S
Fig. S7). The CV plot showed one quasiꢀreversible peak at E1/2
(
=
6
| J. Name., 2012, 00, 1-3
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Journal Name
Table 7 A comparison study of synthesized [Cu(L)].0.5H
complex with some of the previous reported catalysts for A ꢀ
coupling reactions
ARTICLE
2
O
3
1
2
(a) C. Baleiza and H. Garcia, Chem. Rev., 2006, 106, 3987ꢀ4043.
(b) P. G. Cozzi, Chem. Soc. Rev., 2004, 33, 410ꢀ421.
(a) A. Gogoi, G. Sarmah, A. Dewan, U. Bora, Tetrahedron Lett., 2014,
55, 31ꢀ35.
(b) E. N. Jacobsen, F. Kakiuch, R. G. Konsler, J. F. Larrow and
M.Tokunaga, Tetrahedron Lett.,1997, 38, 773ꢀ776.
c) T. Niimi, T. Uchida, R. Irie and T. Katsuki, Tetrahedron Lett., 2000,
1, 3647ꢀ3651.
d) J. L. Liang, X. Q. Yu and C.M. Che, Chem. Commun., 2002, 124ꢀ
Entry
Catalyst
Catalyst
loading
Temp.
( C)
Time
(h)
Yields
(%)
Reference
o
(mol %)
1
CuI
Gold(III) salen
[Au(C^N)Cl
2
0.05
1
120
40
40
5
78
37
38(a)
39
(
4
(
(
2
3
4
24
24
2.5
94
82
95
2
]
Cu(ΙI)
salen
3
80
47
1
3
4
5
25.
complex
e) S. E. Schaus, J. Branalt and E. N. Jacobsen, J. Org. Chem., 1998, 63,
5
[Cu(L)].0.5H
2
O
0.9
80
5ꢀ8
93
This
work
403ꢀ405.
(a) J. Bariwal and E. V. Eycken, Chem. Soc. Rev., 2013, 42, 9283ꢀ9303.
b) Y. Liu, Q. Zhang, X. Ma, P. Liu , J. Xie, B. Dai and Z. Liu, Int. J.
(
Org. Chem., 2013, 3, 185ꢀ189.
(a) R. Hili and A. K. Yudin, Nat. Chem. Biol., 2006, 2, 284ꢀ287.
b) P. Y. S. Lam, S. Deudon, K. M. Averill, R. Li, M. Y. He, P. D.
Shong, and C. G. Clark, J. Am. Chem. Soc., 2000, 122, 7600ꢀ7601.
A. B. Pinkerton, J. M. Vernier, H. Schaffhauser, B. A. Rowe, U. C.
Campbell, D. E. Rodriguez, D. S. Lorrain, C. S. Baccei, L. P. Daggett,
and L. J. Bristow, J. Med. Chem., 2004, 47, 4595ꢀ4599.
(
Reusability of catalyst
Recovery and reusability of the catalyst were studied for both the
reactions under the optimized condition. A reaction of benzonitrile
and sodium azide in DMSO and benzaldehyde, piperdine and
6
7
G. Sandmann, C. Schneider, P. Z. Boger and C. Naturforsch, Bioscience,
1
996, 51, 534ꢀ538.
6 5 3
phenylacetylene in C H CH was chosen as a model reaction. After
A. B. Pinkerton, R. V. Cube, J. H. Hutchinson, B. A. Rowe, H.
Schaffhauser, X. Zhao, L. P. Daggett, J. M. Vernier, Bioorg. & Med.
Chem. Lett., 2004, 14, 5329ꢀ5332.
P. N. Gaponik, S. V. Voitekhovich and O. A. Ivashkevich, Russ. Chem.
Rev., 2006, 75, 507ꢀ539.
References cited therein: M. N. S. Rad, J. Braz. Chem. Soc., 2017, 28, 11ꢀ
0.
References cited therein: A. Xie, M. Cao, Y. Liu, L. Feng, X. Hu and W.
completion of the reaction, it was cooled down to room temperature
in open atmosphere and allowed to stand overnight. During this
period, the complex crystallized from the reaction mixture which can
be easily separated by simple filtration. The complex, after washing
with water and methanol, was dried and reused up to four time to
afford good yields of the product. A marginal decrease in the
catalytic activity of the complex 1 was observed from the first to
forth cycle (Fig. S4). The identity of the recovered catalyst was
8
9
1
1
2
0
1
Dong, Eur. J. Org. Chem.,2014, 436ꢀ 441.
V. A. Ostrovskii, R. E. Trifonov and E. A. Popova, Russ. Chem. Bull.,
f
confirmed by comparing its R value, melting point, FTIR (Fig. S5ꢀ
2
012, 61, 768ꢀ780.
S6) and cyclic voltammetry (Fig. S7) with the original complex.
12
E. Vieira, S. Huwyler, S. Jolidon, F. Knoflach, V. Mutel and J.
Wichmann,
Bioorg. Med. Chem. Lett., 2005, 15, 4628ꢀ4631.
A. Gagnon, S. Landry, R. Coulombe, A. Jakalian, I. Guse, B.
Thavonekham, P.R. Bonneau, C. Yoakim and B. Simoneau, Bioorg.
Conclusions
1
3
In conclusion, two new salenꢀtype Schiffꢀbase complexes
Med.
Chem. Lett., 2009, 19, 1199ꢀ1205.
[
2
Cu(L)].0.5H O 1 and [Ni(L)], 2, have been synthesized and
characterized by various spectroscopic techniques and structure of 14 J. Shie and J. Fang, J. Org. Chem., 2007, 72, 3141ꢀ3144.
the complexes confirmed by single crystal Xꢀray structure 15 A. Hantzsch and A. Vagt, Justus Liebig’s Ann. Chem., 1901, 314, 339ꢀ
3
69.
determination. The catalytic application of Cu(II) complex has been
1
6
S. Hajra, D. Sinha and M. Bhowmick, J. Org. Chem., 2007, 72, 1852ꢀ
1855.
L. Bosch and J. Vilarrasa, Angew. Chem. Int. Ed., 2007, 46, 3926ꢀ3930.
J. Bonnamour and C. Bolm, Chem. Eur. J., 2009, 15, 4543ꢀ4545.
A. Kumar, R. Narayanan and H. Shechter, J. Org. Chem., 1996, 61,
4462ꢀ4465.
demonstrated in the synthesis of 5ꢀsubstituted 1Hꢀtetrazoles (10
3
reactions) and A ꢀcoupling reactions (13 reactions). The reactions
1
1
1
7
8
9
proceeded smoothly at a low catalyst loading and the catalyst can be
recycled up to four times in both the reactions. The complex 2 was
not found to be a good catalyst for these reactions as low yields of
products were obtained with this complex.
20 C. Taoa, B. Wanga, L. Suna, J. Yia, D. Shia, J. Wanga and W. Liu, J.
Chem. Res., 2017, 41, 25ꢀ29.
2
2
2
1
2
3
C. M. M. Heravi, A. Fazeli, H. A. Oskooie, Y. S. Beheshtiha and H.
Valizadeh, Synlett, 2012, 23, 2927ꢀ2930.
P. Mani, A. K. Singh and S. K. Awasthi, Tetrahedron Lett, 2014, 55,
1879ꢀ1882.
F. Dehghani, A. R. Sardarian and M. Esmaeilpour, J. Organometal.
Chem.,
Acknowledgment
We are thankful to the SAIF Panjab University, Chandigarh and
IISER, Bhopal for providing help in the analysis of the samples and
we also grateful to NTU, Singapore for the single crystal Xꢀray
analysis. Bhumika Agrahari and Samaresh Layek acknowledges the
receipt of IIT (ISM), Dhanbad fellowship.
2
013, 743, 87ꢀ96.
M. L. Kantam, K. B. Shiva Kumar and K. J. Phani Raja, J. Mol. Catal. A,
006, 247, 186ꢀ188.
2
2
4
5
2
V. Rama, K. Kanagaraj and K. Pitchumani, J. Org. Chem., 2011, 76,
9090ꢀ9095.
G. Qi and Y. Dai, Chin. Chem. Lett., 2010, 21, 1029ꢀ1032.
Supporting Information
2
2
6
7
S. M. Agawane and J. M. Nagarkar, Catal. Sci. Technol., 2012, 2, 1324ꢀ
CCDC 1576528 and 1813608 contain the supplementary
crystallographic data for this paper. This data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223ꢀ336ꢀ033; or mail.
1
327.
B. Sreedhar, A. S. Kumar and D. Yada, Tetrahedron Lett. 2011, 52,
565ꢀ3569.
2
2
3
8
9
0
3
F. Abrishami, M. Ebrahimikia and F. Rafiee, App. Organomet. Chem.,
2015, 29, 730ꢀ735.
D. Kong, Y. Liu, J. Zhang, H. Li, X. Wang, G. Liu, B. Li and Z. Xu,
New
Reference
J. Chem., 2014, 38, 3078ꢀ3083.
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ARTICLE
Journal Name
3
3
3
3
1
2
3
4
M. Nikoorazm, A. G. Choghamarani, M. Ghobadi and S. Massahi, App.
Organomet. Chem., 2017, 31, 3848.
M. Esmaeilpour, J. Javidi and S. Zahmatkesh, App. Organomet. Chem.,
Transit. Met. Chem., 2009, 34, 905ꢀ914.
65 W. K. Dong, L. C. Zhu, Y. J. Dong, J. C. Ma and Y. Zhang, Polyhedron,
2016, 117, 148ꢀ154.
66 N. Kumar, A. K. Asatkar, S. Panda and S. S. Zade, Polyhedron, 2016,
2
016, 30, 897ꢀ904.
V.A. Peshkov, O. P. Pereshivko and E. V. V. d. Eycken, Chem Soc
Rev.,2012, 41, 3790ꢀ3807.
K. Lauder, A. Toscani, N. Scalacci and D. Castagnolo, Chem. Rev., 67 M. Barwiolek, E. Szlyk, T. M. Muzioł and T. Lis, Dalton Trans., 2011,
117,
718ꢀ728.
2
017,
40, 11012ꢀ11022.
1
17, 14091ꢀ14200.
68 V.T. Kasumov, Y. Yerli, A. Kutluay and M. Aslanoglu, Spectrochim
3
3
5
6
P. Li , S. Regati, H.C. Huang, H. D. Arman, B. Lin Chen and J. C. G. Z.,
Chinese Chemical Letters, 2015, 26, 6ꢀ10.
(a) T. Murai, Y. Mutoh, Y. Ohta, M. Murakami, J Am Chem Soc. 2004,
Acta
A Mol Biomol Spectrosc., 2013, 104, 203ꢀ212.
69 (a) B. Akhlaghinia and S. Rezazadeh, J. Braz. Chem. Soc.,2012, 23,
1
26, 5968ꢀ5969.
2197ꢀ
(b) R. Bloch, Chem Rev 1998, 98 1407ꢀ1438.
2203.
(
c)T. K. Saha and R. Das, ChemSelect, 2018, 3, 12206ꢀ12228.
(b) H. R. Pawar, A. P. Jakhade, and R. C. Chikate, Chem. Select, 2017,
2, 6949 ꢀ6956.
3
3
7
8
S. B. Park and H. Alper, Chem Commun., 2005, 1315ꢀ1317.
(a) V. K. Y. Lo, Y. Liu, M. K. Wong and C. M. Che, Org. Lett., 2006, 8, 70 (a) K. Majee, J. Patel, B. Das, and S. K. Padhi, Dalton Trans., 2017, 46,
1
(
529ꢀ1532.
b) R. Manikandan, P. Anitha, P. Viswanathamurthi, J. G. Malecki,
Polyhedron 2016, 119, 300ꢀ306.
c) S. Samai, G. C. Nandi, M. S. Singh, Tetrahedron Lett. 2010, 51,
555ꢀ5558.
14869ꢀ14879.
(b) A. Ercag, M. ꢁahin, A. Koca and E. Bozkurt, J. Coord. Chem., 2013,
66, 1635ꢀ1649.
(
5
3
4
4
9
0
1
V. K. Y. Lo, K. K. Y. Kung, M. K. Wong and C. M. Che, J. Organomet
Chem., 2009, 694, 583ꢀ591.
J. S Yadav, B. V. S Reddy, A. V. H. Gopal, K. S Patil, Tetrahedron Lett,
2
009, 50, 3493ꢀ3496.
E. Ramu, R. Varala, N. Sreelatha and S. R. Adapa, Tetrahedron Lett.,
007, 48, 7184ꢀ7190.
2
4
4
4
4
4
2
3
4
5
C. Wei, Z. Li and C. Li, J. Org. Lett., 2003, 5, 4473ꢀ4475.
C. Wei and C. J. Li, J. Am. Chem. Soc., 2003, 125, 9584ꢀ9585.
D. S. Raghuvanshi and K. N. Singh, Syn. Lett., 2011, 3, 373ꢀ377.
L. P. Hua and W. Lei, Chin. J. Chem., 2005, 23, 1076ꢀ1080.
6 Q. Zhang, J. X. Chen, W. X. Gao, J. C. Ding and H. Y. Wu, Appl.
Organometal. Chem., 2010, 24, 809ꢀ812.
4
4
7
M. Tajbaksh, M. Farhang, H. R. Mardani, R. Hosseinzadeh and Y.
Sarrafi,
Chinese J. Catal., 2013, 34, 2217ꢀ2222.
8
(a) S. Kumari, A. Shekhar and D. D. Pathak, RSC Adv., 2016, 6, 15340ꢀ
1
(
2
5344.
b) M. L. Kantam, S. Laha, J. Yadav, S. Bhargava, Tetrahedron Lett.,
008, 49, 3083ꢀ3086.
P. Li, L. Wang, Y. Zhang and M. Wang, Tetrahedron Lett., 2008, 49,
650ꢀ6654.
R. Mallampati and S. Valiyaveettil, ACS Sustain. Chem. Eng., 2014, 2,
55ꢀ859.
4
5
9
0
6
8
5
5
1
2
X. Zhang and A. Corma, Angew. Chem. Int. Ed., 2008, 47, 4358ꢀ4361.
B. J. Borah, S. J. Borah, K. Saikia and D. K. Dutta, Catal. Sci. Technol.,
2
014, 4, 4001ꢀ4009.
5
5
3
4
G. Bosica and R. Abdilla, J. Mol. Catal. A: Chem., 2017, 426, 542ꢀ549.
(a) B. Agrahari, S. Layek, S. Kumari, Anuradha, R. Ganguly and D. D.
Pathak, J. Mol. Struct., 2017, 1134, 85ꢀ90.
(b) S. Layek, S. Kumari, Anuradha, B. Agrahari, R. Ganguly and D. D.
Pathak, Inorg. Chim. Acta, 2016, 453, 735ꢀ741.
S. Layek, B. Agrahari, Anuradha, R. Ganguly and D. D. Pathak, J. Mol.
Struct., 2017, 1141, 428ꢀ435.
(a) S. Layek, Anuradha, B. Agrahari and D. D. Pathak, J. Organomet.
Chem.2017, 846,105ꢀ112.
5
5
5
6
(
b) S. Layek, B. Agrahari, S. Kumari, Anuradha and D. D. Pathak,
Catal.Lett., 2018, DOI:10.1007/s10562ꢀ018ꢀ2449ꢀ6.
B. Agrahari, S. Layek, S. Kumari, Anuradha, R. Ganguly and D. D.
Pathak,
5
7
Inorg. Chim. Acta, 2018, 471, 345ꢀ354.
5
5
8
9
Anuradha, S. Layek, B. Agrahari and D. D. Pathak, Chem. Select, 2017,
2
, 6865ꢀ6876.
J. Cheng, K. Wei, X. Ma, X. Zhou and H. Xiang, J. Phys. Chem., C
2
013,
117, 16552ꢀ16563.
6
6
0
1
SMART version 5.628; Bruker AXS Inc., Madison, WI, USA, 2001.
Sheldrick, G. M. SADABS; University of Gottingen, Gottingen,
Germany, 1996.
6
6
2
3
SHELXTL version 5.1; Bruker AXS Inc., Madison, WI, USA, 1997.
S. Meghdadi, M. Amirnasr, K. Mereiter, S. Motaharioour, M. Nasehi and
M. Bagheri, S. Abbasi, J. Coord. Chem., 2015, 68, 4055ꢀ4069.
N. S. Youssef, E. A. ElꢀZahany, B. N. Barsoum and A. M. A. ElꢀSeidy,
6
4
8
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Page 9 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C8NJ01718B
The synthesis of two new salen-type Schiff base complexes of the type [Cu(L)].0.5H O, 1,
2
and [Ni(L)], 2, and their application in the synthesis of 5-substituted 1H-tetrazoles and
propargylamines are described. The complex 1 is novel in the sense that, being a
homogeneous catalyst, it can be recovered almost quantitatively in both reactions by filtration
and recycled up to four times to afford good yields of the corresponding products.