Chemical fixation of CO2 into cyclic carbonates by azo-containing Schiff base metal complexes

Article abstract of DOI:10.1039/c5nj00571j

Two new ligands containing a -NN- group, 4-((E)-(4-bromophenyl)diazenyl)-2-((E)-(phenylimino)methyl)phenol (L¹H, 2), 4-((E)-(4-bromophenyl)diazenyl)-2-((E)-((4-ethylphenyl)imino)methyl)phenol (L²H, 3) and their metal complexes were synthesized. The synthesized metal complexes were used as catalysts for the chemical fixation of CO₂ into cyclic carbonates using epoxides which were used as both substrate and solvent. According to analytical, UV-visible and IR data, the metal complexes are formed by coordination of the N and O atoms of the ligands and the metal:ligand ratio was found to be 1:2 for all the complexes. The TG and DTA results showed that these complexes had good thermal stability. The molecular structures of ligand 2 (L¹H) and its Zn^II complex 4 (Zn(L¹)₂) were determined by single crystal X-ray diffraction studies. After choosing the most active catalyst (Zn(L¹)₂, 4), optimization studies were performed by changing various parameters. Ionic liquids have been found to have a positive effect and showed the most active performance with (bmim)PF₆ + Zn(L¹)₂ (4) as a binary catalytic system.

Full text of DOI:10.1039/c5nj00571j

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: E. Ispir, M. Ulusoy,
M. kiz, M. Aslanta, E. Aytar, S. Karabuga and Ö. Çelik, New J. Chem., 2015, DOI: 10.1039/C5NJ00571J.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/njc

Page 1 of 14
New Journal of Chemistry
Dynamic Article Links►
Journal Name
View Article Online
DOI: 10.1039/C5NJ00571J
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
Chemical fixation of CO into Cyclic Carbonates by azoꢀcontaining
2
Schiff Bases metal complexes
a
a
b
a
c
d
Mesut Đkiz, Esin Đspir, * Emine Aytar, ꢁemistan Karabuğa, Mehmet Aslantaꢂ, Ömer Çelik, Mahmut
Ulusoy
b
5
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
1
Two new ligands containing ꢀN=Nꢀ group, 4ꢀ((E)ꢀ(4ꢀbromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ(phenylimino)methyl)phenol (L H 2), 4ꢀ((E)ꢀ(4ꢀ
2
bromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ((4ꢀethylphenyl)imino)methyl)phenol (L H 3) and their metal complexes were synthesized. The
1
0
synthesized metal complexes were performed as catalysts for the chemical fixation of CO into cyclic carbonates using epoxides which
2
were used as both substrate and solvent. According to analytical, UVꢀvisible and IR data, the metal complexes are formed by
coordination of the N, O atoms of the ligands and metal:ligand ratio was found to 1:2 for all the complexes. TG and DTA results showed
1
II
1
that these complexes had good thermal stability. Molecular structures of the ligand (L H 2) and its Zn complex 4 (Zn(L ) )were
2
1
determined by single crystal Xꢀray diffraction studies. After choosing the best active catalyst (Zn(L ) 4), the optimization studies were
2
1
5
performed by changing various parameters. Ionic Liquid has been found to have a positive effect and showed the best active performance
1
with (bmim)PF + Zn(L ) 4 as binary catalytic system.
6
2
9
Keywords: Schiff Base complexes; azo compounds, catalysts, 45 CO2 and epoxides . In recent studies, it is mentioned that
carbon dioxide, cyclic carbonate, Xꢀray crystallography
transition metals Ni, Rh, Pd and Au can catalyze the same
13
reaction . The most distinctive advantages of the metal
complexes are their easy synthesis and good stability against
moisture and air. Metal complexes synthesized from these
mentioned metals and salycyliminederivates have also been
2
0
Introduction
5
5
6
6
7
0
5
0
5
0
5
ꢀ8
successfully applied as catalysts for this transformation . For
this purpose, the suitable ligand design for catalysts has been
shown to be beneficial for the synthesis of cyclic carbonates from
Fossil fuels which give CO as a byꢀproduct are the main sources
2
of energy despite of new different energy sources such as wind,
sun, geothermal etc.. Fossil fuel burning is the primary source of
CO and epoxides.
1
2
2
3
3
4
5
0
5
0
CO2 emission . CO is a renewable source of carbon and
2
Among the various ligands, Schiff base ligands have significant
importance because Schiff base ligands are potentially capable of
identified to be a naturally abundant, economic, recyclable and
nonꢀtoxic C1 building block in organic synthesis that can
14
forming stable complexes with metal ions . By attaching donor
2
, 3
occasionally replace toxic chemicals . Due to the great
atoms of Schiff bases, they can coordinate various metals and
stabilize them in different oxidation states; such complexes are
properties, chemical fixation of CO becomes more and more
2
4
important for decrease of carbon emission day by day .
15,16
used as catalysts in many important processes
. The N=N
The most important carbon dioxide fixation products are cyclic
carbonates which widely used as monomer for polymer synthesis,
17
bonds in azo compounds are good electron/hydrogen acceptors .
The molecule bears the azoimine (–N=N–C=N–) functional
group, and is an efficient pꢀacid system for stabilization of low
5ꢀ10
aprotic solvents, antifoam additives or plasticizers . Cyclic
carbonates can be synthesized via coupling reaction between CO2
and strained heterocycles, though hard reaction conditions and
18
oxidation state metal ions . Metal complexes of Schiff bases
have been extensively studied at scientific applications as
catalysts due to their attractive chemical and physical properties.
To the best of our knowledge, Schiff base metal complexes
containing azo group have not been used as catalysts for chemical
fixation of carbon dioxide.
Based on this background, we decided to synthesize new Schiff
base metal complexes having azo group with different transition
metals such as Ni, Cu, Co, Zn and Fe in this study. There are
various reported catalytic systems that are used in carbon dioxide
fixation reactions. Our aim was to use azo containing NOꢀdonor
1
1
often a suitable catalyst should be used . Therefore, a variety of
catalysts have been developed over the past 35 years for the
synthesis of cyclic carbonates from CO and epoxides under the
2
1
2
leadership of Inoue and coꢀworkers in the late 1960s .
Among the synthesized catalysts such as alkali metal salts,
transition metal complexes, Schiff Bases and ionic liquids, metal
complexes based on transition metal complexes have been of
great interest. We have found out that only a few metals such as
Al, Cr, Co, Mg, Li, Zn, Cu and Cd are effective for coupling of
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 |1

New Journal of Chemistry
Page 2 of 14
View Article Online
DOI: 10.1039/C5NJ00571J
Br
R
ligands for the synthesis of cyclic carbonates from CO2 and
N
N
N
epoxides and demonstrate that the azo group has got increasing
effect on the catalytic activity. Ni, Cu, Co, Zn and Fe
complexesof azo containing ligands have been prepared and
O
M
O
N
II
N
N
1
R
Br
5
characterized. In addition, a Zn complex of azo free form of L H
II
II
II
(
2) ligand13was prepared.These complexes were used as catalysts
M:Cu , Co , Ni , Zn
in direct synthesis cyclic carbonates from carbon dioxide with
various epoxides. Ligand and complex structures were confirmed
R: H (L
1
H), CH CH3 (L
2
2
H)
Br
1
13
by, FTIR, Hꢀ, Cꢀ NMR, UV/Vis spectroscopy and mass
spectrometry. Singleꢀcrystal Xꢀray analysis were performed for
N
N
N
H
2
O
10
O
Fe
1
1
O
ligand (L H 3) and its Zn complex 4 (Zn(L ) ). The analytical
Cl
2
N
N
N
data shows that the ratio of metal to ligand in the mononuclear
Schiff Base complexes is 1:2.
Br
X
Scheme 2 Proposed structures of metal complexes.
The structures of the complexes were further characterized by
FTIR, UVꢀvisible spectra and elemental analyses. The
experimental elemental analyses results of the complexes are in
good harmony with the theoretical values. The data show the
1
5
Result and Discussion
4
0
Synthesis and characterization
complexation ratio of formulae [M(L) ] is 1:2 [Metal : Ligand].
2
1
Single crystals of L H 2 and its Zn complex 4 which are shown in
1
2
45
Fig. 1 and Fig. 2 were grown from DMF solutions by slow
The Schiff base ligands, L H 2 and L H 3 were prepared by the
2
evaporation. Although the single crystals of the L H 3 and the
20
condensation
of
(E)ꢀ5ꢀ((4ꢀbromophenyl)diazenyl)ꢀ2ꢀ
with aniline or 4ꢀethylaniline,
hydroxybenzaldehyde
1
respectively, (1:1 molar ratio) in EtOH as shown in Scheme 1
The level of the purity of the ligands and the complexes was
II
II
I
checked by T.L.C. on silica gelꢀcoated plates. Zn 4, Co 5, Cu
I
II
III
1
II
II
II
25
6, Ni 7 and Fe 8 complexes of L H 2 and Zn 9, Co 10, Cu
II
2
1
1 and Ni 12 complexes of L H 3 were prepared.
NH
2
OH
OH
OH
ArN Cl
N
O
N
N
2
N
ii
N
O
i
1
Br
Br
L1H 2
other complexes were not isolated, the analytical and
spectroscopic data enables us to predict possible structures as
shown in Scheme 1 and 2.
PhNH
2
ii
2
H N
OH
N
OH
N
N
N
1
3
Br
50
L2H 3
1
Fig.1 The molecular structure of L H ligand 2, with atomic numbering
(i) HCl/NaNO2, 0ꢀ5 °C and (ii) Ethanol, 3 h, reflux.
scheme. The thermal ellipsoids are drawn at the 50% probability level.
Dashed lines indicate the intramolecular hydrogen bond.
30
Scheme 1 General synthesis of ligands
The ligands are stable at room temperature and soluble in
common organic solvents such as EtOH, MeOH, DMF and
CH Cl . The complexes are also stable at room temperature. The
2
2
complexes have oxygen and nitrogen atoms as π donors and the
metal ions allow π electronic delocalization as shown in
Scheme2.
35
1
55
Fig.2 The molecular structure of complex (Zn(L )
2
) 4, with atomic
numbering scheme. The thermal ellipsoids are drawn at the 50%
probability level.
1
In the mass spectrum of the L H ligand 2, the peak observed at
+
m/z: 380 can be assigned to the molecular ions [M] . The peaks at
+
60
m/z: 169 and 210 can be attributed to the [C H BrN] and
[
4
10
+
+
C H N O] fragments, respectively. The [M] molecular ion
13 10 2
2
|Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 14
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ00571J
2
II
peak for the L H ligand 3 is observed at m/z 407. The most
between 600 and 700 nm. Electronic spectra of the Cu 6, 11
6, 7
intense peak at m/z: 311 corresponds to [C H –N=N–C H – 60 complexes display bands at 642 and 639 nm . These values
6
4
6
3
+
II
N=CH–C H ꢀ C H ] which results from the loss of a Br atom
suggest square planar geometry for Cu complex.
6
4
2
5
II
and an OH group from the parent ligand. The mass spectra of
ligands are given in Fig. S3 (ESI†).
The H NMR spectra of the ligands are shown in Fig. S4 (ESI
In the H NMR spectra of the L H 2 and L H 3 ligands, the 65 4.7 and 4.5 B.M. reveal tetrahedral geometry around the Co ion
singlets in the 13.93–14.03ppm range can be attributed to the
proton of the first –OH group which is neighboring the
azomethine group . The H NMR resonance of azomethine
proton (CH=N) in ligands are observed at 8.76 and 8.78 ppm for
L H 2 and L H 3 respectively. The multiplets of the aromatic 70 five unpaired electrons.
protons were in the region of 8.04–7.15 and 8.11ꢀ7.16 ppm for Thermal behaviors of complexes were studied using TG. and
L H 2and L H 3 ligands . The quarted signal at 2.73 ppm and the
triplet signal at 1.30 ppm corresponded to –CH2 and –CH3
protons, respectively.
The observed magnetic moments of the Cu complexes are 1.9ꢀ
2.1 for Cu(L ) 6 and Cu(L ) 11 respectively which confirms that
2 2
the Cu complexes have squareꢀplanar geometry. The values of
1
2
5
0
5
0
5
0
5
0
5
0
5
1
II
†).
1
1
2
II
22
II
II
. Magnetic moments measurements of Ni 7, 12 and Zn 4, 9
metal complexes show that these complexes are diamagnetic,
indicating the square planar d ꢀ and d systems, as expected.
1
4
1
8
10
1
1
2
2
3
3
4
4
5
5
1
[Fe(L ) Cl(H O)] 8 complex have 4.7 BM value that is equal to
2
2
1
2
1
2
19
DTA. The thermal analyses were carried out in order to
demonstrate the existence of water molecules in complexes
[Co(L ) ].2H O 5 and [Fe(L ) Cl(H O)] 8. Thermal curves
1
1
2
2
2
2
The IR spectra of the ligands and their complexes were studied 75 obtained for most of the complexes were very similar in
and the free Schiff base ligands were compared with that of the
metal complexes in order to determine the linkage of Schiff base
character. The thermograms of complexes are shown in Fig. S5
1
1
(ESI†). Except for [Co(L ) ].2H O 5 and [Fe(L ) Cl(H O)] 8
2
2
2
2
ligands to the metal in the complexes. In the ligands and
complexes, all the complexes do not show any mass losses up to
1
o
complexes spectra, both ligands, [Co(L ) ].2H O
5
and
200 C, which prove that no water molecules are incorporated in
2
2
–1
1
1
[
Fe(L ) Cl(H O)] 8 exhibit bands at 3409–3425 cm and 3075– 80 complexes. The TG curve of [Co(L ) ].2H O 5 consists mainly
2
2
2
2
–1
20
o
3
038 cm that are assignable to ν(OH) and ν(ArꢀCH) . In the
of three steps in the range 23 ꢀ150, 150–700 and 700ꢀ1100 C.
1
complexes, the four coordination sites of metal ions were filled
by two donor nitrogen and oxygen atoms. Therefore, in the
The first estimated mass loss for [Co(L ) ].2H O 5 within the
2
2
o
temperature range of 23ꢀ150 C may be attributed to the loss of
absorbed water molecules . Some decomposition could be
1
1
26
complexes except for [Co(L ) ].2H O 5 and [Fe(L ) Cl(H O)] 8,
2
2
2
2
1
the ν(OH) vibration disappeared. In the [Co(L ) ].2H O 5 and 85 correlated with proper decomposition products. The last
Fe(L ) Cl(H O)] 8 complex spectra, the ν(OH) vibrations that
2
2
1
[
decomposition step is in air ended with metal oxide formation.
2
2
1
o
were attributed to the OH groups which were originating from
For [Fe(L ) Cl(H O)] 8 complex, the mass loss at 20ꢀ150 C
2 2
H O molecules (the presence was confirmed by elemental and
range is assigned to losses of solvent and absorbed water
2
ꢀ
1
thermal analyses as well). The main bands at 1621ꢀ1622 cm is
molecules. Besides, this % 2 of mass loss at the range of 150ꢀ
1
o
due to the vibration of the azomethine group (ꢀCH=Nꢀ) in L H 2 90 200 C is attributed to the one mol of coordinated water molecule
2
21
and L H 3 ligands . The characteristic bands of N=N group were
in the complex. All the other complexes have three
decomposition parts according to the losses of solvent and
absorbed water molecules, decomposition of ligands and metal
oxide formation, respectively. Therefore, these features
ꢀ
1
observed at 1567 cm for both ligands. Metal complexes show
significant differences at vibrations as distinct from ligands. After
complexation, the C=N stretching frequencies slightly shifted to
lower wave number region in comparison with free ligands. The 95 confirmed the thermal stability of complex.
lowering in frequencies of the C=N peak suggests the formation
ꢀ
of metalꢀligand bonds. In the ranges of 417ꢀ459 and 512ꢀ663 cm
Description of crystal structures
1
two complementary bands were assigned to stretching
2
2
vibrations ν(MꢀN) and ν(MꢀO) for the complexes .
1
The electronic absorption spectral data for complexes were
The L H ligand 3, crystallizes in a monoclinic system with the
and Z=4. Individually each benzene ring in the
obtained in DMF solutions at room temperature. There are 100 space group C
c
absorption bands between 642 and 211 nm for the ligands and
their metal complexes at the UV–visible spectra in DMF. The
chemical shift values (λmax) were determined by taking the
contrast between the absorption maxima of the metal complexes
molecule is almost planar. The C3, C12, and C18 atoms deviate
from the each benzene best plane by ꢀ0.100(3), 0.016(2), and
0.0065(2) Å. All bond lengths and angles in (C1ꢀC6), (C7ꢀC12),
and (C14ꢀC19) benzene rings have normal values; the weighted
and ligands. The spectra of the complexes that show intense 105 average ring bond distances (CꢀC) are 1.384(4), 1.395(4), and
bands in the highꢀenergy region can be assigned to the ligandꢀtoꢀ
1.384(4) Å, respectively. The whole molecule is not planar and
the P1/P2, P1/P3, and P2/P3 dihedral angles between the planes
of benzene rings, respectively, P1(C1ꢀC6), P2(C7ꢀC12), and
2
3
metal charge transition (LMCT) . The bands at λ 390 and 394
max
nm were assigned to n→π* transitions of the azomethine groups
1
2
o
in the L H 2 and L H 3 ligands. In the spectra of the complexes,
P3(C14ꢀC19) are 4.73(8), 47.85(7), and 45.39(7) . Besides the
the bands of the azomethine n→π* transitions shifted to lower 110 dihedral angle of P4/P5 between the planes of azo and
frequencies indicating the involment of the imine nitrogen atom
with the metal ion. The Co 5, 10 complexes show bands at 458ꢀ
azomethine
groups
[P4(C4/N1/N2/C7)
and
II
o
P5(C11/C13/N3/C14)] is 23.40(2) . The two benzene rings along
the N2=N1 displays trans configuration and the torsion angle of
4
01 and 552ꢀ 639 nm. This indicates tetrahedral geometry for the
II
o
Co 5, 10 complexes. In general, due to JahnꢀTeller distortion,
C4ꢀN1ꢀN2ꢀC7 is 179.3(2) . This angle is reported in literature as
II
o27
o28
o29
square planar Cu 6, 11 complexes give a broad absorption band 115 179.80(17) ,175.83 and 178.5(3) . The BrꢀC1, N1=N2, N2ꢀ
C7, and N1ꢀC4 bond lengths are seen in Table 1, which are
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |3

New Journal of Chemistry
Page 4 of 14
View Article Online
DOI: 10.1039/C5NJ00571J
3
0
1
1
values within normal ranges .
in Table 1 for L H 2 and Table 2 for Zn(L ) 4, respectively.
2
Selected bond lengths, bond angles and torsion angles are listed
o
o
1
Table 1 Some selected bond lengths [Å], bond angles [ ] and torsion angles [ ] for L H 2.
5
BrꢀC1
1.897(3)
.243(3)
OꢀC10
1.334(3)
1.425(3)
1.375(4)
1.282(3)
1.455(4)
114.5(2)
118.4(2)
122.1(2)
125.1(2)
121.8(2)
116.6(2)
179.3(2)
ꢀ146.7(2)
ꢀ179.83(19)
178.9(2)
ꢀ6.5(3)
1
N2ꢀC7
N2ꢀN1
C6ꢀC5
1.371(4)
1.426(3)
1.413(3)
114.4(2)
121.5(2)
119.7(3)
120.8(2)
115.3(2)
119.3(2)
ꢀ6.2(3)
C6ꢀC1
N1ꢀC4
N3ꢀC13
N3ꢀC14
C13ꢀC11
N1ꢀN2ꢀC7
N2ꢀN1ꢀC4
C13ꢀN3ꢀC14
C18ꢀC19ꢀC14
N3ꢀC13ꢀC11
C3ꢀC4ꢀN1
C15ꢀC14ꢀN3
C19ꢀC14ꢀN3
C5ꢀC4ꢀN1
OꢀC10ꢀC11
C12ꢀC7ꢀN2
C4ꢀN1ꢀN2ꢀC7
C13ꢀN3ꢀC14ꢀC15
BrꢀC1ꢀC2ꢀC3
C8ꢀC9ꢀC10ꢀO
OꢀC10ꢀC11ꢀC13
C10ꢀC11ꢀC13ꢀN3
N3ꢀC14ꢀC19ꢀC18
C6ꢀC1ꢀBr
N2ꢀN1ꢀC4ꢀC5
N1ꢀN2ꢀC7ꢀC8
C14ꢀN3ꢀC13ꢀC11
C2ꢀC3ꢀC4ꢀN1
C9ꢀC10ꢀC11ꢀC13
C13ꢀC11ꢀC12ꢀC7
N3ꢀC14ꢀC15ꢀC16
10.5(3)
ꢀ170.7(2)
ꢀ177.1(2)
172.8(2)
ꢀ171.2(2)
ꢀ176.8(2)
4.7(3)
175.5(2)
o
o
1
Table 2 Some selected bond lengths [Å], bond angles [ ] and torsion angles [ ] forZn(L )
2
4.
Br1ꢀC3
Zn1ꢀN3
N1ꢀN2
1.892(2)
Zn1ꢀO1
O1ꢀC10
N1ꢀC6
1.9265(14)
2.0046(16)
1.246(3)
1.303(2)
1.432(3)
1.297(2)
N2ꢀC7
1.425(3)
N3ꢀC13
N3ꢀC14
O1ꢀZn1ꢀO1
1.432(3)
i
120.43(9)
109.55(6)
122.69(9)
112.5(2)
i
O1ꢀZn1ꢀN3
O1ꢀZn1ꢀN3
C10ꢀO1ꢀZn1
N1ꢀN2ꢀC7
98.16(6)
i
N3 ꢀZn1ꢀN3
N2ꢀN1ꢀC6
124.25(13)
114.5(2)
C13ꢀN3ꢀZn1
C2ꢀC3ꢀBr1
118.73(14)
118.76(19)
116.80(16)
ꢀ1.64(16)
2.97(15)
C14ꢀN3ꢀZn1
121.19(12)
i
i
O1 ꢀZn1ꢀO1ꢀC10
N3 ꢀZn1ꢀO1ꢀC10
ꢀ130.68(15)
179.20(19)
ꢀ123.46(14)
ꢀ179.80(14)
ꢀ60.22(13)
173.1(2)
N3ꢀZn1ꢀO1ꢀC10
O1ꢀZn1ꢀN3ꢀC13
C6ꢀN1ꢀN2ꢀC7
i
O1 ꢀZn1ꢀN3ꢀC13
i
N3 ꢀZn1ꢀN3ꢀC13
122.54(15)
53.77(15)
ꢀ176.2(2)
ꢀ7.5(3)
O1ꢀZn1ꢀN3ꢀC14
i
i
O1 ꢀZn1ꢀN3ꢀC14
N3 ꢀZn1ꢀN3ꢀC14
Br1ꢀC3ꢀC2ꢀC1
N2ꢀN1ꢀC6ꢀC5
N2ꢀN1ꢀC6ꢀC1
N1ꢀN2ꢀC7ꢀC12
C12ꢀC11ꢀC10ꢀO1
Zn1ꢀN3ꢀC14ꢀC15
Zn1ꢀN3ꢀC13ꢀC11
173.4(2)
N1ꢀN2ꢀC7ꢀC8
ꢀ7.3(3)
ꢀ178.02(19)
17.3(2)
C13ꢀN3ꢀC14ꢀC15
Zn1ꢀN3ꢀC14ꢀC19
ꢀ165.52(19)
ꢀ162.48(15)
ꢀ2.8(3)
Symmetry code: (i: ꢀx, y, ꢀzꢀ3/2)
4
|Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 5 of 14
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ00571J
1
In the L H ligand 2, a strong OꢀH…N intramolecular hydrogen
bond is observed (Fig. 1) [O1…N3; 1.845(2) Å, O1ꢀH8…N3;
neighboring molecules in the unit cell (Table 3 and Fig. S1
(ESI†)). Moreover analysis of short ringꢀinteractions shows that a
o
1
47.00 ] (Table 3) which is in good agreement with values in 10 considerably Cg…Cg (π… π stacking) interaction is found
reported structures as 146.00
o31
o29
a
5
and 147.93 . The molecular
between Cg2…Cg2 as 4.631(13) Å [Cg2: ring (C7ꢀC12) and
packing of the structure is stabilized by a CꢀH…O intermolecular
hydrogen bond and six weak CꢀH π interactions between
symmetry code (a): x, ꢀy, ½+z].
o
1
1
2
Table 3 Hydrogen bond geometry (Å, ) of compoundsL H 2 and Zn(L ) 4.
b
ꢀ
DꢀH...A
DꢀH
0.82
H...A
1.845
D...A
DꢀH…A
147.00
Symmetry
1
L H 2
O1ꢀH8…N3
2.572(3)
3.692(3)
3.458(3)
x, y, z
1
Zn(L )
2
4
C16ꢀH16…Br1
C19ꢀH19…O1
0.93
0.93
2.863
2.572
149.00
159.00
ꢀ½+x, ½+y,ꢀ1+z
x, ꢀy, ½+z
CꢀH…π
1
L H 2
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.867
2.782
2.837
2.984
2.754
2.805
2.691
3.573(2)
3.471(2)
3.480(2)
3.573(2)
3.474(3)
3.534(3)
133.65
131.72
127.25
130.34
134.83
135.94
145.36
x, ꢀy, ꢀ½+z
x, 1ꢀy, ½+z
x, ꢀy, ꢀ½+z
x, 1ꢀy, ½+z
x, 1ꢀy, ꢀ½+z
x, ꢀy, ½+z
C3ꢀH2…R1
C6ꢀH3…R1
C9ꢀH6…R2
C12ꢀH7…R2
C15ꢀH9…R3
C18ꢀH12…R3
C15ꢀH15…R4
1
Zn(L )
2
4
3.496(2)
ꢀx, y, ꢀ½ꢀz
b
1
1
1
5
D: Donor, A: Acceptor, [R1: (C1ꢀC6), R2: (C7ꢀC12), R3: (C14ꢀC19) rings for L H 2] and [R4: (Zn1/O1/N3/C10ꢀC13) ring for Zn(L )
2
4].
1
The asymmetric unit of complex (Zn(L ) ) 4 contains oneꢀhalf 40 unit cell and listed in Table 3.
2
molecule with other half generated by an inversion centre which
Catalytic studies
lies at the midpoint of Zn1 atom [symmetry code: ꢀx, y, ꢀzꢀ3/2].
1
2
0
The Zn1 atom of complex (Zn(L ) ) 4 coordination geometry can
2
be described as a distorted tetrahedral arrangement and Zn1 atom
forms two sixꢀmembered chelate rings related to each other by
The carboxylation of epichlorohydrin with CO
corresponding cyclic carbonate (4ꢀ(chloromethyl)ꢀ1,3ꢀdioxolanꢀ
2
into
the twofold rotation axis passing through Zn1. The dihedral angle 45 2ꢀone) in the presence of 0.1% complexes were conducted in a
o
of between these chelate rings is approximately 80.14(6) , and the
Zn1ꢀO1 and Zn1ꢀN3 distances are 1.9265(14) and 2.0046(16) Å,
batchꢀwise operation under various conditions as shown in Table
4. The coupling of carbon dioxide and various epoxides catalyzed
by complexes were investigated under different reaction
conditions (Table 4, entries 1ꢀ9). Catalytic experiments were
2
3
3
5
0
5
3
0
close to normal values . The defined planes A(Zn1/O1/N3/C10ꢀ
C13), B(C7ꢀC12), C(Br/N1/N2/C1ꢀC7), and D(N3/C14ꢀC19) are
almost planar; the maximum deviations from their best planes are 50 carried out at optimized conditions, which were determined at our
32ꢀ35
0
.021(2), ꢀ0.011(2), ꢀ0.064(2) and ꢀ0.002(3) Å for atoms N3,
previous studies
. Five different types of organic bases were
C12, N1, and C16. The dihedral angles between these planes are
used as coꢀcatalysts. Also, two different types of ionic liquids
(IL) as catalysts were investigated. One is the 1ꢀButylꢀ3ꢀ
methylimidazolium iodide ((bmim)I) and the other one is 1ꢀ
o
1
.17(9), 15.36(7), 16.07(8), 14.49(9), 15.04(10), and 17.61(9) ,
respectively, for A/B, A/C, A/D, B/C, B/D, and C/D. In the
1
complex (Zn(L ) ) the two benzene rings of (C1ꢀC6) and (C7ꢀ 55 Butylꢀ3ꢀmethylimidazolium hexafluorophosphate ((bmim)PF
).
2
6
C12) adop a trans configuration with respect to N1=N2 double
o
bond and the torsion angle of C6ꢀN1ꢀN2ꢀC7 is 179.20(19) . The
molecules are linked by CꢀH…Br and CꢀH…O hydrogen bonds
forming a threeꢀdimensional network (Table 3 and Fig.S2
(ESI†)). Besides a weak CꢀH…π interaction are present in the
60
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |5

New Journal of Chemistry
Page 6 of 14
Dynamic Article Links►
Journal Name
View Article Online
DOI: 10.1039/C5NJ00571J
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
Table 4 Synthesis of ECHC (4ꢀ(chloromethyl)ꢀ1,3ꢀdioxalanꢀ2ꢀone) from ECH (2ꢀ(chloromethyl)oxirane) and CO
2
catalyzed by metal complexes.
O
1
0
.1 %, Zn(L ) (CAT.), 0.2 % DMAP
2
O
O
O
+
CO2
o
2
h, 100 C, 1.6 MPa
Cl
Cl
a
a
b
c
ꢀ1
Entry
Cat.
Yield
Selectivity
(%)
TON
TOF (h )
(%)
5
1
d
Blank
Zn(L )
2
4
4
9
6
11
7
3.0
92.0
98.2
99.3
97.4
97.4
98.4
98.6
98.5
98.9
97.2
30
15
1
1
2
3
4
5
6
7
8
9
Zn(L )
2
62.1
51.4
48.0
50.6
54.5
49.3
27.9
55.7
52.1
621
514
480
506
545
493
279
557
521
311
257
240
253
273
247
140
279
261
2
Zn(L )
2
1
Cu(L )
2
2
Cu(L )
2
10
1
Ni(L )
2
2
Ni(L )
2
12
].2H O 5
10
Cl(H O)] 8
1
[Co(L )
2
2
2
Co(L )
2
1
[Fe(L )
2
2
ꢀ
5
ꢀ2
ꢀ5
o
Reaction conditions: Cat.(4.5x10 mol), epichlorohydrin (4.5x10 mol),DMAP (9x10 mol), CO
2
(1.6 MPa), 100 C, 2 h.
d
a
ꢀ5
ꢀ2
o
15
2
Cat.(4.5x10 mol), epichlorohydrin (4.5x10 mol), CO (1.6 MPa), 100 C, 2 h.
Yield and selectivity of epichlorohydrin to corresponding cyclic carbonate were determined by GC.
Moles of cyclic carbonate produced per mole of catalyst.
The rates expressed in terms of the turnover frequency {TOF [mol of product (mol of catalyst h) ]=turnovers/h}
b
c
ꢀ1
1
20
The complexes, when used 4ꢀdimethylamino pyridine (DMAP) as 25 (Zn(L ) )bearing phenylimino group and DMAP showed best
2
coꢀcatalyst, showed highest catalytic activity and selectivity for
catalytic activity and selectivity (yield: 62.1% and selectivity:
the conversion of CO into cyclic carbonates using the epoxide
98.2%) for the coupling of CO and epichlorohydrin as substrate
2
2
derivatives which served as substrate and solvent. The complex 4
(Fig. 3).
1
00
8
6
4
2
0
0
0
0
0
yield (%)
selectivity (%)
Catalysts
30
1
ꢀ5
ꢀ2
o
*
Zn(L )
2
4 (4.5x10 mol), epichlorohydrin (4.5x10 mol), CO
2
(1.6 MPa), 100 C, 2 h.
Fig. 3The effects of catalysts for the formation of epichlorohydrin to corresponding cyclic carbonate at the same catalytic conditions.
This journal is © The Royal Society of Chemistry [year] [journal], [year], [vol], 00–00 |6

Page 7 of 14
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ00571J
1
Interestingly, excluding complex Zn(L )2 4, the activities of
(PO), styrene oxide (SO) and cyclohexene oxide (CHO)) were
catalysts were significantly low. Lots of parameters such as 15 used as both solvent and substrate under optimized reaction
solubility of complexes in epoxide, polarity, biphasic reaction
media, differences between catalysts and substrates could play a
role for this phenomenon.
conditions. As shown in Table 5, epichlorohydrin was found to be
the most reactive epoxide, while cyclohexene oxide exhibited the
lowest activity of the epoxides surveyed. This result may be due
5
to more electron donating substituents linked to C ꢀatom of these
2
20
epoxides (EB, SO, PO and CHO) which could be coordinated to
the metal centre and was responsible for the catalyst poisoning .
Synthesis of cyclic carbonates from other epoxides and CO2
35
The results of optimization conditions such as reaction
1
1
0
The above results indicate that complex Zn(L ) 4 is an efficient
temperature, epoxide, time and CO pressure were very similar
2
2
catalyst for the cycloaddition of CO to ECH. For investigation of
for both homogeneous and heterogeneous systems that were
2
36
the efficiency of the catalytic system, different epoxides 25 previously reported .
epichlorohydrin (ECH), 1,2ꢀepoxybutane (EB), Propylene oxide
(
1
Table 5The comparison of various epoxides to corresponding cyclic carbonates at the same catalytic conditions with Zn(L )
2
4 catalyst
a
a
a
a
Yield
%)
Selectivity
Yield
(%)
Selectivity
(%)
Entry
Product
Entry
Product
(
(%)
O
30
O
O
O
O
O
2
.4
1
3.3
99.0
4
95.8
Ph
O
O
35
O
O
O
O
7
2.5
2
3
62.1
98.2
73.2
5
0.6
Cl
O
40
O
O
4.2
45
a
Yield and selectivity of epichlorohydrin to corresponding Epichlorohydrin carbonate were determined by GC.
Reaction conditions: epoxides (4.5ꢁ10 mol), catalyst: Zn(L ) (4.5ꢁ10 mol), DMAP (9ꢁ10 mol), 100˚C, 1.6 MPa and 2 h.
2
b
ꢀ2
1
ꢀ5
ꢀ5
5
0
Pyridine based coꢀcatalyst systems (C H N and DMAP) were
5
5
Influence of bases on the ECHC (4ꢀ(chloromethyl)ꢀ1,3ꢀ
dioxolanꢀ2ꢀone) synthesis
found to be effective bases. Especially, DMAP which has Nꢀ
dimethyl amino moiety showed the best activity.The catalytic
efficiencies of these coꢀcatalysts were found to be in the
following order: CH CN < PPh3 <NEt3 <C H N < DMAP.
We also evaluated the effect of coꢀcatalyst on the catalytic
performance (Fig. 4). For this purpose, organic bases (DMAP (4ꢀ
65
3
5
5
5
5
40
Similar effect was observed in our previous papers . Blank
reaction was made to determine the effect of coꢀcatalyst (Table 4,
Blank run). Consequently, the necessity of base was observed as
shown in Fig. 4.
(dimethylamino)pyridine),
CH CN
(acetonitrile),
C H N
5 5
3
(
pyridine), NEt (triethylamine) and PPh (triphenylphosphine))
3
3
were used as coꢀcatalyst. Interestingly, the use of CH CN resulted
3
in the yield of 1.3%, and the yield remarkably increased up to
37
6
0
62.1% when DMAP was used as the base in high selectivity .
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |7

New Journal of Chemistry
Page 8 of 14
Dynamic Article Links►
Journal Name
View Article Online
DOI: 10.1039/C5NJ00571J
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
1
00
5
0
0
yield (%)
selectivity (%)
Bases
1
Fig. 4 Conversionand selectivity of 2ꢀ(chloromethyl)oxirane as effect the transformation of base at the same catalytic conditions with Zn(L )
2
4 catalyst.
10
4h. It is observed that the cycloaddition reaction proceeds rapidly
Optimization Studies
within the first 2 h, reaching an ECHC yield of 62.1%. Following
an increase in time from 0.5 to 4h, ECHC yield increased sharply
from 29.5 to 65.5% (Fig. 5). On this basis, the experiments to
assess other reaction parameters were performed for 2h.
1
5
Since the Zn(L ) 4 showed good catalytic activity, the effects of
2
reaction parameters (temperature, CO pressure, and time) were
2
examined using this catalytic system. Firstly, the effect of
reaction time on the ECHC yield was investigated. Fig. 5 shows
that the ECHC yield increased with reaction time up to a period
15
1
00
8
6
4
2
0
0
0
0
T = 100 ̊C
p(CO ) = 1.6 MPa
2
yield (%)
selectivity (%)
0
1
2
Time (h)
3
4
1
2
Fig. 5 Conversion and selectivity of ECH as a function of time with Zn(L ) 4 as catalyst.
from 11.9 to 91.8%. With increase of temperature from 125 to
The results shown in Fig. 6 clearly show that temperature has a 25 150˚C, ECHC yield slowly increased from 91.8 to 93.9% (Fig.
20
strong effect on the ECH conversion. When catalytic reactions
were conducted at 75, 100, 125, and 150˚C, the ECH conversions
were 11.9, 62.1, 91.8, and 93.9%, respectively. With increase of
temperature from 75 to 125˚C, ECHC yield increased sharply
13). This temperature and conversion relationship is attributed to
higher reactivity at a higher temperature. These types of catalysts
were found to be more reactive at high temperatures. As a result,
the temperature is required for these catalysts (Fig. 6).
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 |8

Page 9 of 14
New Journal of Chemistry
Dynamic Article Links►
Journal Name
View Article Online
DOI: 10.1039/C5NJ00571J
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
1
00
8
6
4
2
0
0
0
0
0
t = 2 h
p(CO ) = 1.6 MPa
2
yield (%)
selectivity (%)
5
0
75
100
125
150
o
Temperature ( C)
1
Fig. 6 Conversion and selectivity of ECH as a function of temperature with Zn(L )
2
4 as catalyst.
The effects of CO pressure were also investigated. As shown in 15 between ECH and catalysts, resulting in a decrease in ECH
2
5
Fig. 7, in the lowꢀpressure range (0.5ꢀ1.6 MPa), there has been a
rise in ECHC yield (from 32.4% to 62.1%) with an increase in
conversion. Thus, the best EC yield could be achieved at 1.6
MPa. According to the literature, this can be explained
qualitatively by the effect of pressure on the concentration of
initial CO pressure. But, further rise of pressure to 4 MPa results
2
4
1
in moderate decrease in ECHC yield (from 62.1% to 38.6%).
CO2 and epoxide in the two phases in the reaction systems . The
Similar effects of CO2 pressure on catalytic activity were 20 upper phase is the vapour phase, and bottom phase is the liquid
3
2
1
0
observed in our previous reports . In a catalytic reaction system,
phase. The reaction took place mainly in the liquid phase because
the catalyst was dispersed in the liquid phase. When the pressure
a higher CO pressure can effectively increase the solubility of
2
CO in ECH, enabling the reaction equilibrium to shift toward
was higher than 4 MPa, the CO concentration was too high and
2
2
carbonate formation. However, when CO2 pressure reached 4
inhibited the contact of ECH with the catalyst by a dilution
41ꢀ46
MPa, this high CO pressure may have retarded the interaction 25 effect
.
2
1
00
8
6
4
2
0
0
0
0
t = 2 h
T = 100 ̊C
Yield (%)
Selectivity (%)
0
1
2
3
4
Pressure (MPa)
1
2
Fig. 7 Conversion and selectivity of ECH as a function of pressure with Zn(L ) 4as catalyst.
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 |9

New Journal of Chemistry
Page 10 of 14
Dynamic Article Links►
Journal Name
View Article Online
DOI: 10.1039/C5NJ00571J
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
investigated. One is the (bmim)I (1ꢀbutylꢀ3ꢀmethylimidazolium
iodide) and the other one is (bmim)PF6 (1ꢀbutylꢀ3ꢀ
Synthesis of cyclic carbonates from EB and CO catalyzed by
metal complexes and ionic liquids.
2
10
methylimidazolium hegzafluorophosphate). The best active
1
complex compound (Zn(L ) 4) and ionic liquide’s ((bmim)I and
2
(
bmim)PF ) were used together as binary catalytic system and
The carboxylation of epoxybutane with CO into corresponding
6
2
their activities were investigated. Ionic liquids, metal complexes
and the binary catalytic system were compared for each catalytic
condition (Fig. 8).
5
cyclic carbonate (4ꢀethylꢀ1,3ꢀdioxolanꢀ2ꢀone) in the presence of
15
0
.1% catalyst system was conducted in a batchꢀwise operation
under various conditions as shown in Table 6, entries 1ꢀ5. In this
study, two different types of ionic liquids (IL) as catalysts were
Table6 Synthesis of EBHC (4ꢀethylꢀ1,3ꢀdioxolanꢀ2ꢀone) from EB (2ꢀethyloxirane) and CO
2
catalyzed by metal complexes and ionic liquids.
O
1
O
0.1 %, Zn(L ) , 0.1 % IL
2
O
O
+
CO2
o
2
h, 100 C, 1.6 MPa
20
a
a
b
c
ꢀ1
Entry
Cat.
Yield
%)
Selectivity
TON
621
TOF (h )
(
(%)
1
d
Zn(L )
2
4
62.1
98.2
97.0
99.0
91.8
94.6
311
43
1
2
3
4
5
(
bmim)I
85.0
83.6
89.7
94.3
85.0
83.6
89.7
94.3
(
bmim)PF
6
41.8
44.9
47.2
25
1
(
bmim)I+Zn(L )
2
4
1
(
bmim)PF
6
+Zn(L )
2
4
ꢀ
5
ꢀ5
ꢀ3
o
Reaction conditions: Cat.(4.5x10 mol), IL(4.5x10 mol), 1,2ꢀ epoxybutane (4.5x10 mol), CO
2
(1.6 MPa), 100 C, 2 h.
d
a
ꢀ5
ꢀ2
ꢀ5
o
3
0
5
2
Cat.(4.5x10 mol), 1,2ꢀ epoxybutane (4.5x10 mol),DMAP (9x10 mol),CO (1.6 MPa), 100 C, 2 h.
Yield and selectivity of epoxybutaneto corresponding epoxybutane carbonate were determined by GC.
Moles of cyclic carbonate produced per mole of catalyst.
The rates expressed in terms of the turnover frequency {TOF [mol of product (mol of catalyst h) ]=turnovers/h}
b
c
ꢀ1
3
1
00
5
0
0
Yield (%)
Selectivity (%)
Catalysts
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 |10

Page 11 of 14
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ00571J
Fig. 8 The effects of catalysts for the formation of epoxybutane to corresponding cyclic carbonate at the same catalytic conditions.
8
300 FTIR spectrophotometer. The electronic spectra in the 200–
900 nm range were obtained using DMF on a Hithachi Uꢀ3900
best catalytic activity and selectivity (yield: 94.3% and 25 spectrophotometer. Magnetic measurements were carried out by
1
The (bmim)PF + Zn(L ) 4 as binary catalytic system showed the
6
2
5
selectivity: 94.6%) for the coupling of CO2 and epoxybutane
Table 6, entry 5).The similar Salen type Zn(II) complex which
has not involved the azoꢀmoieties 13 has been prepared and tested
the Gouy method using MnCl as calibrant. ESI mass spectra
2
1
(
were recorded on a ESI/MS Tandem mass spectrometry. H and
13
C NMR spectra were recorded on a Varian ASꢀ400 MHz
at the same catalytic conditions to see the effectiveness of the
azoꢀmoieties. The %43.2 yield was achieved with 97.9% 30 The diffraction data for suitable single crystals of L H 3 ligand
selectivity. This result shows that, azoꢀmoiety has positive affect
to the catalytic system.
instrument and Bruker 600 MhzUltrashield TM in CDCl .
3
1
II
1
1
0
and its Zn complex 4 (Zn(L ) ) were collected using a Bruker
2
APEXꢀII CCD diffractometer equipped with a MoK radiation
α
source (λ=0.71073Å at 296 K). ω/2θ scan mode was employed
3
8
for data collection. The structures were solved by SHELXSꢀ97
35 and refined with SHELXLꢀ97
39
Experimental
software package. All nonꢀ
hydrogen atoms were assigned anisotropic displacement
parameters and refined positional constraints. The H atoms were
placed in geometrically idealized positions, with CꢀH distances of
1
5
Materials and measurements
1
1
0
.93 Å (aromatic) for L H2 and Zn(L ) 4, and 0.82 Å (hydroxyl)
2
All solvents were of reagent grade. The metal salts
1
40
for L H 2. Details of the data collection parameters and
crystallographic information for L H and Zn(L ) are given in
[
Zn(CH COO) H O,
Cu(CH COO) H O,
Ni(Cl) .6H O,
2 2
3
2
2
3
2
2
1
1
2
Co(CH COO) .4H O, Fe(Cl) .6H O],pꢀbromoaniline, aniline, 4ꢀ
3
2
2
3
2
Table 7.
ethylaniline and salicylaldehyde were obtained from Fluka.
Elemental analyses were carried out by The Scientific and
Technological Research Center of Đnönü University. IR spectra
2
4
0
5
–
1
were obtained using KBr discs (4000–400 cm ) on a Shimadzu
ı
1
Table 7 Crystal data and structure refinements for ligand (L H 2) and complex (Zn(L )
2
4).
ı
1
Properties
L H 2
2
Zn(L ) 4
Empirical Formula
Formula weight
C
19
H
13BrN
3
O
38 2 6 2
C H26Br N O Zn
379.23
823.84
Crystal system
Space group
Monoclinic
Cc
Monoclinic
C2/c
a = 37.4840(11) Å
b = 7.0935(2) Å
c = 6.2089(2) Å
a = 34.9897(7) Å
b = 8.3586(2) Å
c = 11.8489(3) Åo
β = 105.3030(10)
Unit cell dimensions
o
β = 97.497(2)
3
3
Volume
1636.79(8) Å
3342.52(13) Å
Z
4
8
3
3
Calculated density
Absorption coefficient
F(000)
1.539 Mg/m
1.637 Mg/m
ꢀ1
ꢀ1
2.522 mm
764
3.171 mm
1648
Crystal size
0.45 x 0.23 x 0.04 mm
0.45 x 0.25 x 0.10 mm
o
o
θ
range for data collection
2.19ꢀ26.37
2.41ꢀ30.27
ꢀ
46 ≤ h ≤ 46
ꢀ8 ≤ k ≤ 8
7 ≤ l ≤ 7
ꢀ49 ≤ h ≤ 47
ꢀ11 ≤ k ≤ 11ꢀ
16 ≤ l ≤ 16
Limiting indices
ꢀ
Reflections collected
9427
19157
Unique reflections
2858 [R(int) = 0.0323]
26.37 99.3 %
0.9059 and 0.3966
Fullꢀmatrix leastꢀsquares on F
2858 / 0 / 217
4951 [R(int)=0.0322]
30.27 99.0 %
0.7422 and 0.3295
Fullꢀmatrix leastꢀsquares on F
4951 / 0 / 222
Completeness to theta
Max. and min. Transmission
Refinement method
2
2
Data / restraints / parameters
2
Goodnessꢀofꢀfit on F
1.008
1.018
Final R indices [I>2σ(I)]
R indices (all data)
R
R
1
1
=0.0289,
=0.0334,
w
w
R
2
2
=0.0626
=0.0643
R
R
1
1
=0.0380,
=0.0729,
w
w
R
2
2
=0.0832
= 0.0945
R
R
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |11

New Journal of Chemistry
Page 12 of 14
View Article Online
DOI: 10.1039/C5NJ00571J
ꢀ3
ꢀ3
ꢂρmax and ꢂρmin
0.343 and ꢀ0.184 e. Å
0.662 and ꢀ0.515 Å
Selected bond lengths, bond angles and torsion angles are listed 55 408.30): C 61.70, H 4.41, N 10.28. Found (%): C 61.78, H 4.44,
1
1
ꢀ1
in Table 1 for L H 2 and Table 2 for Zn(L ) 4, respectively.
N 10.29. FTꢀIR (cm , KBr): 3445 (s), 3055 (s), 1622 (s), 1567
2
1
1
1
Hydrogen bonding geometries of L H 2 and Zn(L ) 4 are shown
in Table 3. The ORTEP drawings of the molecule indicating
atom numbering scheme with thermal ellipsoids at %50
(s). UVꢀVis (λ, nm): 234, 292, 346, 394. H NMR (600 MHz,
CDCl δppm): 14.03 (s, 1H), 8.78 (s, 1H), 8.11 – 8.01 (m, 2H),
7.83 – 7.75 (m, 2H), 7.70 – 7.62 (m, 2H), 7.29 (m, 4H), 7.16 (d, J
2
4
0
5
0
5
3
1
1
probability are given in Fig. 1 for L H 2 and Fig.4 for Zn(L ) 4. 60 = 8.7 Hz, 1H), 2.73 (q, J = 7.6 Hz, 2H), 1.30 (t, J = 7.6 Hz, 3H).
2
47
48
13
The PARST
and PLATON
programs were used for
C NMR (101 MHz, CDCl δppm): 164.52, 160.98, 151.38,
3
geometrical calculation and conformational features of the
molecules. Further experimental details have been deposited as
supplementary material at the Cambridge Crystallographic Data
Centre CCDC 1035285ꢀ1035286.
The yields of epoxides to corresponding cyclic carbonates were
determined by GC (Agilent 7820A) with HPꢀ5 MS column.
145.37, 145.21, 143.91, 132.30, 128.97, 128.03, 127.31, 124.75,
124.10, 121.13, 119.02, 118.28, 28.50, 15.56. MS m/z: 407 [M] .
+
1
65
Synthesis of (E)ꢀ2ꢀ((phenylimino)methyl)phenol13
(
E)ꢀ2ꢀ((phenylimino)methyl)phenol 13 was prepared according to
50
the literature .
1
2
5 mL 2ꢀhydroxybenzaldehyde (508.5 mg, 2.00mmol) solution in
Synthesis
hydroxybenzaldehyde 1
of
(E)ꢀ5ꢀ((4ꢀbromophenyl)diazenyl)ꢀ2ꢀ
methanol was added aniline (186.3 mg, 2 mmol) in methanol (5
mL) and refluxed for 8 hours. The solution was concentrated on
air by removing solvent for two days and crystallized to give (E)ꢀ
70
(
E)ꢀ5ꢀ((4ꢀbromophenyl)diazenyl)ꢀ2ꢀhydroxybenzaldehyde 1 was
2
ꢀ((phenylimino)methyl)phenol 13 as a yellow needle crystals.
4
9
20
prepared according to the reported procedure .
Yield: 5.5 g (83%). Anal. Calcd. (%) for C H NO (M= 197.2):
13
11
C 79.16, H 5.62, N 7.10. Found (%): C 78.93, H 5.71, N 7.05.
ꢀ
1
75
FTꢀIR (cm , KBr): 3430 (s), 3060 (s), 1600 (s),. UVꢀVis (λ,
nm): 275, 339, 393.
Synthesis
of
4ꢀ((E)ꢀ(4ꢀbromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ
1
(phenylimino)methyl)phenol 2 (L H )
2
3
3
4
5
0
5
0
4ꢀ((E)ꢀ(4ꢀbromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ(phenylimino)methyl)
phenol 2 (L H) (Scheme 1) was synthesized as follow; 10 mmol
General procedure for the synthesis of metal complexes
1
(3.05
g)
of
(E)ꢀ5ꢀ((4ꢀbromophenyl)diazenyl)ꢀ2ꢀ
1
2
3
8
8
9
9
0
5
0
5
L H 2 and L H 3 ligands (20 mmol) dissolved in 200 cm
hydroxybenzaldehyde 1 and 10 mmol (0.93 g) of aniline were
absolute EtOH was mixed with 10 mmol metal salts in 10
3
condensed by refluxing in 70 cm of absolute ethanol for 3 h. The
3
cm EtOH. The stirred mixture was refluxed for 24 h, then
solution was left at room temperature. 4ꢀ((E)ꢀ(4ꢀ
bromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ(phenylimino)methyl)phenol
3
evaporated to 15–20 cm in vacuum and left to cool to room
2
temperature. The compounds were precipitated after adding 5
was obtained as orange micro crystals; the micro crystals were
3
cm EtOH. The products were filtered in vacuum, washed with a
3
filtered off, washed with 10 cm of absolute ethanol and then
1
small amount of MeOH and water. Zn(L ) 4 recrystallized from
2
recrystallized from DMF. Yield: 7.8 g (79%). Anal. Calcd. (%)
DMF. The products are soluble in solvents such as CHCl , DMF
3
for C H BrN O (M= 380.24): C 60.00, H 3.69, N 11.05. Found
1
9
14
3
and DMSO.
ꢀ
1
(
%): C 60.02, H 3.71, N 11.05. FTꢀIR (cm , KBr): 3434 (s),
3
075 (s), 1621 (s), 1567 (s). UVꢀVis (λ, nm): 224, 277, 335, 390.
1
Zn(L )2 (4): Yield: 6.8 g (83%). Anal. Calcd. (%) for
1
H NMR (400 MHz, CDCl δppm): 13.93 (bs, 1H), 8.76 (s, 1H),
3
C H Br N O Zn (M= 823,84): C 55.43, H 3.15, N 10.19. Found
3
8
26
2
6
2
8
.04 (m, 2H), 7.79 (m, 2H), 7.66 (m, 2H), 7.47 (m, 2H), 7.34 (m,
ꢀ1
(
(
%): C55.40, H3.18, N 10.20. FTꢀIR (cm , KBr): 3038 (s), 1607
s), 1585 (s), 528 (w), 422 (w). UVꢀVis (λ, nm): 283, 333, 399,
1
3
3H), 7.15 (d, J = 8.8 Hz, 1H).
C NMR (101 MHz,
CDCl δppm): 164.4, 162.0, 151.3, 147.7, 145.4, 132.3, 129.6,
3
4
57.
1
3
28.2, 127.5, 127.4, 124.8, 124.1, 121.2, 118.9, 118.3. MS m/z:
80 [M] .
1
[Co(L ) ].2H O (5): Yield: 6.1 g (72%). Anal. Calcd. (%) for
+
2
2
C H Br N O Co (M= 853.42): C 53.48, H 3.54, and N 9.85.
3
8
30
2
6
4
ꢀ
1
Found (%): C 53.04, H 3.15, N 9.70. FTꢀIR (cm , KBr): 3412 (s),
3038 (s), 1613 (s), 1585 (s), 594 (w), 418 (w). UVꢀVis (λ, nm):
45
Synthesis
of
4ꢀ((E)ꢀ(4ꢀbromophenyl)diazenyl)ꢀ2ꢀ((E)ꢀ((4ꢀ
2
ethylphenyl)imino)methyl) phenol 3 (L H)
2
37, 279, 348, 366, 458, 552.
1
1
00 Cu(L )2 (6) : Yield: 6.7 g (81%). Anal. Calcd. (%) for
C H Br N O Cu (M= 822,01): C 55.74, H 3.45, N 10.22.
Found (%): C 55.52, H 3.19, N 10.22. FTꢀIR (cm , KBr): 3041
(s), 1602 (s), 1528 (s), 599 (w), 457 (w). UVꢀVis (λ, nm): 236,
3
8
26
2
6
2
1
0 mmol (3.05 g) of (E)ꢀ5ꢀ((4ꢀbromophenyl)diazenyl)ꢀ2ꢀ
ꢀ
1
hydroxybenzaldehyde 1 and 10 mmol (1.21 g) of 4ꢀethylaniline
were condensed by refluxing in 50 cm of absolute EtOH for 3 h.
The solution was left at room temperature. The product was
obtained as orange micro crystals; the micro crystals were filtered
off, washed with 10 cm of absolute ethanol and dried in air.
3
50
2
75, 335, 366, 425, 642.
1
1
05 Ni(L )2 (7) : Yield: 6.5 g (79%). Anal. Calcd. (%) for
3
C H Br N O Ni (M= 817,15): C 55.25, H 3.22, N 10.18. Found
3
8
26
2
6
2
ꢀ
1
(
%): C 55.85, H 3.21, N 10.28. FTꢀIR (cm , KBr): 3048 (s), 1601
Yield: 8.2 g (75%). Anal. Calcd. (%) forC H BrN O (M=
21
18
3
1
2
|Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 13 of 14
New Journal of Chemistry
View Article Online
DOI: 10.1039/C5NJ00571J
1
(s), 1595 (s), 515 (w), 459 (w). UVꢀVis (λ, nm): 283, 375, 490,
active catalyst has found to be Zn(L ) 4 which was characterized
2
5
39.
by single crystal Xꢀray analysis. Different parameters have been
investigated using this active complex as catalyst. From the
1
[Fe(L ) Cl(H O)] (8): Yield: 7.4 g (85%). Anal. Calcd. (%) for
2 2
C H Br N O Co (M= 867.77): C 52.46, H 3.27, N 9.58. Found 60 comparison of all these complexes, azo group has positive effect
3
8
28
2
6
3
ꢀ
1
5
0
5
0
5
0
(%): C 52.60, H 3.25, N 9.68. FTꢀIR (cm , KBr): 3403 (s), 3056
s), 1607 (s), 1599 (s), 589 (w), 425 (w). UVꢀVis (λ, nm): 270,
30, 350, 375, 610.
to the catalytic activity. Catalytic studies are summarized as
below:
1ꢀBest active epoxide is found to be ECH,
2ꢀBest active coꢀcatalyst as base is found to be DMAP,
(
3
2
Zn(L ) (9): Yield: 7.6 g (87%). Anal. Calcd. (%) for
2
C H Br N O Zn (M= 879,95): C 57.29, H 3.90, N 9.52. Found 65 3ꢀBest CO atmosphere pressure is found to be 1.6 MPa,
4
2
34
2
6
2
2
ꢀ
1
1
1
2
2
3
(%): C 57.33, H 3.92, N 9.55. FTꢀIR (cm , KBr): 3058 (s), 1609
s), 1579 (s), 587 (w), 418 (w). UVꢀVis (λ, nm): 276, 359, 414,
07.
4ꢀ125 ˚C is required for the catalytic conversion,
5ꢀ2 hours reaction time is enough for the coupling,
(
5
6ꢀIonic Liquid has been found to have a positive effect and
2
1
Co(L ) (10) : Yield: 6.5 g (75%). Anal. Calcd. (%) for
showed the best active performance with (bmim)PF + Zn(L ) 4as
2
6
2
C H Br N O Co (M= 873.50): C 57.60, H 3.92, N 9.60. Found 70 binary catalytic system.
4
2
34
2
6
2
ꢀ
1
(%): C 57.75, H 3.92, N 9.62. FTꢀIR (cm , KBr): 3062 (s), 1602
s), 1576 (s), 610 (w), 420 (w). UVꢀVis (λ, nm): 235, 280, 348,
66, 545.
7ꢀ Azo moiety increased the activity.
(
3
Acknowledgements
2
Cu(L ) (11): Yield: 7.5 g (85%). Anal. Calcd. (%) for
2
The authors are grateful to TÜBĐTAK (110T655) for research funds.
C H Br N O Cu (M= 878.11): C 57.21, H 3.95, N 9.23. Found
4
2
34
2
6
2
ꢀ
1
(%): C 57.45, H 3.90, N 9.37. FTꢀIR (cm , KBr): 3057 (s), 1592
s), 1575 (s), 663 (w), 420 (w). UVꢀVis (λ, nm): 237, 279, 346,
63, 401, 639.
Notes and references
a
(
3
75 Department of Chemistry, Kahramanmaraꢃ Sütçü Đmam University,
Kahramanmaraꢃ, 46050–9, Turkey
2
Ni(L ) (12) : Yield: 7.6 g (87%). Anal. Calcd. (%) for
2
b
Department of Chemistry, Harran University, ꢁanlıurfa, 63190, Turkey
C H Br N O Ni (M= 873.26): C 57.70, H 3.95, N 12.59. Found
c
4
2
34
2
6
2
Physics Department, Science and Arts Faculty, KahramanmaraꢂSütçü
ꢀ
1
(%): C 57.77, H 3.92, N 9.62. FTꢀIR (cm , KBr): 3035 (s), 1603
Đmam University, 46100 Kahramanmaraꢂ TURKEY.
d
(
3
s), 1594 (s), 512 (w), 417 (w). UVꢀVis (λ, nm): 234, 292, 346, 80 Science and Technology Application and Research Center, Dicle
94.
University, 21280 Diyarbakır TURKEY
*
Corresponding author: Tel.: +90(344)2801451, Eꢀmail:
Zn(4)2 (14) : Yield: 3.7
g (82). Anal. Calcd. (%) for
esinispir@gmail.com. (E. Đspir).
C H N O Zn (M= 457.83): C 68.21, H 4.40, N 6.12. Found
2
6
20
2
2
85
ꢀ
1
(
(
3
%): C 67.97, H 4.42, N 6.62. FTꢀIR (cm , KBr): 3033 (s), 1603
s), 1596 (s), 515 (w), 413 (w). UVꢀVis (λ, nm): 234, 293, 341,
94.
† Electronic supplementary information (EIS) available: Crystal packing
1
1
1
2
of the L H ligand and its complex (Zn(L ) ), mass spectrum of L H and
1 2
2
1
13
L H ligands, H and CꢀNMR spectrum of L H and L H ligands,
Thermograms of complexes, experimental details have been deposited as
supplementary material at the Cambridge Crystallographic Data Centre
CCDC 1035285ꢀ1035286.
90
3
5
General procedure for the cycloaddition of epoxides to CO2
3
A 50 cm stainless pressure reactor was charged with all of
1. M. Ozdemir, Inorg Chim Acta, 2014, 421, 1ꢀ9.
2. S. K. Sarkar, M. S. Jana, T. KumarMondal and C. Sinha, Appl
Organomet Chem, 2014, 28, 641ꢀ651.
ꢀ
5
ꢀ2
complexes (4.5ꢁ10 mol), epoxide (4.5ꢁ10 mol), and 4ꢀ
dimethylaminopyridine (DMAP) (9ꢁ10 mol). The reaction vessel
was placed under a constant pressure of carbon dioxide for 2 min
ꢀ
5
95
00
3
4
.
.
A. G. F. Shoair, J Coord Chem, 2012, 65, 3511ꢀ3518.
A. Kilic, M. Ulusoy, M. Durgun, Z. Tasci, I. Yilmaz and B.
Cetinkaya, Appl Organomet Chem, 2010, 24, 446ꢀ453.
4
0
to allow the system to equilibrate and CO was charged into the
2
autoclave with desired pressure then heated to the desired
temperature. The pressure was kept constant during the reaction.
The vessel was then cooled to 5ꢀ10 ºC in an ice bath after the
expiration of the desired time of reaction. The pressure was
released, then, the excess gases were vented. The yields of
5. M. A. Fuchs, C. Altesleben, T. A. Zevaco and E. Dinjus, Eur J Inorg
Chem, 2013, 2013, 4541ꢀ4545.
1
6
.
S. Iksi, A. Aghmiz, R. Rivas, M. D. Gonzalez, L. CuestaꢀAluja, J.
Castilla, A. Orejon, F. El Guemmout and A. M. MasdeuꢀBulto, J Mol
Catal aꢀChem, 2014, 383, 143ꢀ152.
4
5
7
8
9
.
.
.
S. Liang, H. Liu, T. Jiang, J. Song, G. Yang and B. Han Chem.
Commun., 2011, 47, 2131–2133.
W. Cheng, X. Chen, J. Sun, J. Wang, S. Zhang Catalysis Today, 2013,
epoxides to corresponding cyclic carbonates were determined by 105
GC (Agilent 7820A).
2
00, 117–124.
M. Ulusoy, A. Kilic, M. Durgun, Z. Tasci and B. Cetinkaya,
J
Organomet Chem, 2011, 696, 1372ꢀ1379.
Conclusions
110 10. K. Xu, J. G. Chen, KuanꢀWang, Z. W. Liu, J. Q. Jiang and Z. T. Liu,
J Macromol Sci A, 2014, 51, 589ꢀ597.
5
0
1
1
1
1. C. Martín, G. Fiorani and A. W. Kleij, ACS Catal., 2015, 5, 1353ꢀ
1370.
2. S. Inoue, H. Koinuma and T. Tsuruta, Journal of Polymer Science
Part B: Polymer Letters, 1969, 7, 287ꢀ292.
3. S. Kikuchi, S. Yoshida, Y. Sugawara, W. Yamada, H. M. Cheng, K.
Fukui, K. Sekine, I. Iwakura, T. Ikeno and T. Yamada, B Chem Soc
Jpn, 2011, 84, 698ꢀ717.
In this study we have reported the synthesis and characterization
of two novel ligands containing ꢀN=Nꢀ group, and their metal
complexes. In addition, a Zn complex of azo free form of L H
ligand 13 was prepared. The catalytic activity of the prepared
metal complexes has been examined for the chemical fixation of
CO2 to corresponding cyclic carbonates with epoxides. Best
1
115
5
5
14. E. Ispir, Dyes Pigments, 2009, 82, 13ꢀ19.
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 |13

New Journal of Chemistry
Page 14 of 14
View Article Online
DOI: 10.1039/C5NJ00571J
1
5. H. Atabey, E. Findik, H. Sari and M. Ceylan, Turk J Chem, 2014, 38,
09ꢀ120.
6. D. X. Huang, C. X. Wang and Y. B. Song, Russ J Gen Chem+, 2013,
3, 2361ꢀ2369.
17. S. Farhadi and S. Sepahvand, J Mol Catal aꢀChem, 2010, 318, 75ꢀ84.
1
1
8
5
0
5
0
5
0
5
0
5
0
5
0
5
1
8. P. Govindaswamy, C. Sinha and M. R. Kollipara, J Organomet
Chem, 2005, 690, 3465ꢀ3473.
1
9. M. Gulcan, S. Özdemir, A. Dündar, E. Đspir and M. Kurtoğlu,
Zeitschrift für anorganische und allgemeine Chemie, 2014, 640,
1754ꢀ1762.
1
1
2
2
3
3
4
4
5
5
6
6
2
2
0. ꢄ. Bitmez, K. Sayin, B. Avar, M. Köse, A. Kayraldız and M.
Kurtoğlu, J Mol Struct, 2014, 1076, 213ꢀ226.
1. A.ꢀN. M. A. Alaghaz, Y. A. Ammar, H. A. Bayoumi and S. A.
Aldhlmani, J Mol Struct, 2014, 1074, 359ꢀ375.
22. E. Peker and S. Serin, Synthesis and Reactivity in Inorganic and
MetalꢀOrganic Chemistry, 2004, 34, 859ꢀ872.
2
2
2
3. K. Ouari, S. Bendia, J. Weiss and C. Bailly, Spectrochim Acta A
,
2
015, 135, 624ꢀ631.
4. H. A. Bayoumi, A.ꢀN. M. Alaghaz and M. S. Aljahdali, Int. J.
Electrochem. Sci, 2013, 8, 9399ꢀ9413.
5. M. Gaber, Y. S. ElꢀSayed, K. ElꢀBaradie and R. M. Fahmy, J Mol
Struct, 2013, 1032, 185ꢀ194.
2
2
6. E. Ispir and S. Serin, J Therm Anal Calorim, 2008, 94, 281ꢀ288.
7. N. Karadayi, C. Albayrak, M. Odabasoglu and O. Buyukgungor, Acta
Crystallographica Section E, 2006, 62, o1727ꢀo1729.
2
2
8. W. Yang, X. L. You, Y. Zhong and D. C. Zhang, Dyes Pigments
007, 73, 317ꢀ321.
9. M. Aslantas, N. Kurtoglu, E. Sahin and M. Kurtoglu, Acta
Crystallographica Section E, 2007, 63, o3637.
,
2
30. F. H. Allen, O. Kennard, D. G. Watson, L. Brammer, A. G. Orpen
and R. Taylor, J Chem Soc Perk T 2, 1987, S1ꢀS19.
3
3
3
3
1. H. Dal, Y. Suzen and E. Sahin, Spectrochim Acta A, 2007, 67, 808ꢀ
14.
2. A. Kilic, M. V. Kilic, M. Ulusoy, M. Durgun, E. Aytar, M.
8
Dagdevren and I. Yilmaz, J Organomet Chem, 2014, 767, 150ꢀ159.
3. A. Kilic, M. Ulusoy, M. Durgun and E. Aytar, Inorg Chim Acta
,
2
014, 411, 17ꢀ25.
4. A. Kilic, M. Ulusoy, M. Durgun, E. Aytar, A. Keles, M. Dagdevren
and I. Yilmaz, J Coord Chem, 2014, 67, 2661ꢀ2679.
35. M. Ulusoy, E. Cetinkaya and B. Cetinkaya, Appl Organomet Chem
009, 23, 68ꢀ74.
6. Z. Tasci and M. Ulusoy, J Organomet Chem, 2012, 713, 104ꢀ111.
7. M. Ulusoy, O. Sahin, A. Kilic and O. Buyukgungor, Catal Lett, 2011,
41, 717ꢀ725.
38. G. M. Sheldrick, University of Göttingen: Germany, 1997.
,
2
3
3
1
3
4
4
9. G. M. Sheldrick, University of Göttingen: Germany, 1997.
0. L. Farrugia, Journal of Applied Crystallography, 1997, 30, 565.
1. J. Song, Z. Zhang, S. Hu, T. Wu, T. Jiang, B. Han, Green Chem,
2
009, 11, 1031ꢀ1036.
42. D. J. Darensbourg, R. M. Mackiewicz, D. R. Billodeaux,
Organometallics, 2005, 24, 144ꢀ148.
4
4
3. T. Lijima, T. Yamaguchi, Appl Catal A: General, 2008, 345, 12ꢀ17.
4. A. Kilic, M. Ulusoy, E. Aytar, M. Durgun, Journal of Industrial and
Engineering Chemistry, 2015, 24, 98ꢀ106.
45.C. JingꢀXian, J. Bi, D. WeiꢀLi, D. SenꢀLin, C. LiuꢀRen, C. ZongꢀJie,
L. ShengꢀLian, L. XuꢀBiao, T. XinꢀMan, A. ChakꢀTong, Appl Catal
A: General, 2014, 484, 26ꢀ32.
4
6.Y. Xie, Z. Zhang, T. Jiang, J. He, B. Han, T. Wu, K. Ding, Angew
Chem Int Ed, 2007, 46, 7255ꢀ7258.
47. M. Nardelli, Journal of Applied Crystallography, 1995, 28, 659.
4
4
8. A. Spek, Journal of Applied Crystallography, 2003, 36, 7ꢀ13.
9. M. Odabasoglu, C. Albayrak, R. Ozkanca, F. Z. Aykan and P.
Lonecke, J Mol Struct, 2007, 840, 71ꢀ89.
5
0. W. Rehman, F. Saman, I. Ahmad, Russian Journal of Coordination
Chemistry, 2008, 34, 678ꢀ682.
1
4
|Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]