Synthesis and crystal structures of two azido-bridged copper(II) complexes with schiff bases

Article abstract of DOI:10.1134/S1070328410121073

Two new end-on azido-bridged dinuclear copper(II) complexes with the formula [Cu(μ_1,1-N₃)₂(IEP)₂] (I) and [Cu(μ_1,1-N₃)₂(EMP)₂] (II), where IEP and EMP are the deproton

Full text of DOI:10.1134/S1070328410121073

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 1, pp. 40–44. © Pleiades Publishing, Ltd., 2011.
Synthesis and Crystal Structures of Two AzidoꢀBridged Copper(II)
1
Complexes with Schiff Bases
L. H. Wang
Key Laboratory for Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education,
Hubei Province, SouthꢀCentral University for Nationalities, Wuhan, 430074, PR. China
eꢀmail: wanglihua07@126.com
Received April 21, 2010
Abstract—Two new endꢀon azidoꢀbridged dinuclear copper(II) complexes with the formula
[
Cu(
μ
ꢀN ) (IEP)2] (
I
) and [Cu(
μ
ꢀN ) (EMP)2] (II), where IEP and EMP are the deprotoꢀ
1
,1
3 2
1,1 3 2
nated forms of 2ꢀ[1ꢀ(2ꢀisopropylaminoethylimino)ethyl]phenol and 2ꢀethoxyꢀ6ꢀ[(2ꢀmethylaminoethꢀ
ylimino)methyl]phenol, respectively, were synthesized. Both complexes were characterized by elemental
analyses and IR spectra. The crystal structures were determined by the Xꢀray diffraction. The crystal of
monoclinic: space group 2 / = 9.662(2), = 15.282(3), = 10.639(2) = 115.418(10)
= 2. The crystal of II is monoclinic: space group 2 / = 12.588(2), = 7.705(1), c
I
is
=
=
P
c,
a
b
c
Å,
β
°
, V
1
3
1
1
418.9(5)
4.481(2),
endꢀon azide groups. Each Cu atom is in a square pyramidal coordination. The Cu···Cu distances are
.230(2) Å in and 3.150(2) Å in II
Å
,
Z
P
n
,
a
b
1
3
β
= 91.736(5) , V = 1403.9(2) Å , Z = 2. The two Cu atoms in each complex are bridged by two
°
3
I
.
DOI: 10.1134/S1070328410121073
1
INTRODUCTION
EXPERIMENTAL
Materials and methods. Commercially available 2'ꢀ
hydroxyacetophenone, 3ꢀethoxysalicylaldehyde, Nꢀ
isopropylethylenediamine, and Nꢀmethylethylenediꢀ
amine of AR grade were available from Alfa Aesar.
Polynuclear complexes are of great interest in many
fields [1–3]. The main strategy for designing the polynuꢀ
clear complexes is to use suitable bridging groups. Azide is
a versatile bridging group, which can bind two and more Other solvents and reagents were made in China and
metal atoms in the (endꢀon), (endꢀtoꢀend),
1,1,1, used as obtained. C, H, and N elemental analyses were
μ
1
μ
1,3
μ
,1
performed with a PerkinElmer 240C elemental anaꢀ
lyzer. The IR spectra (KBr pellets) were measured with
a FTꢀIR 170ꢀSX (Nicolet) spectrophotometer.
μ
1,1,3, and many other modes, yielding various polynuclear
complexes [4–7]. Multidentate Schiff bases have been
widely used in the preparation of metal complexes [7–9].
In the present work, two new Schiff bases, 2ꢀ[1ꢀ(2ꢀ
isopropylaminoethylimino)ethyl]phenol
and 2ꢀethoxyꢀ6ꢀ[(2ꢀmethylaminoethylimino)meꢀ
Synthesis of HIEP. 2'ꢀHydroxyacetophenone
(
(
(
1.0 mmol, 0.136 g) and Nꢀisopropylethylenediamine
1.0 mmol, 0.102 g) were mixed in a methanol solution
30 ml). The mixture was stirred for 30 min at reflux, and
(HIEP)
thyl]phenol (HEMP), were synthesized. To our the solvent was evaporated to give a yellow oil of HIEP.
knowledge, no metal complexes derived from HIEP
and HEMP have been reported so far. We syntheꢀ For C H N O
13 20 2
sized and characterized two endꢀon azidoꢀbridged
anal. calcd., %: C, 70.9;
Found, %: C, 70.5;
H, 9.2;
H, 9.3;
N, 12.7.
N, 12.5.
dinuclear copper(II) complexes, [Cu( 1
μ
ꢀN ) (IEP) ] (
2
I
)
,1
3 2
and [Cu(μ1
ꢀN ) (EMP) ] (II
)
.
,1
3 2
2
Synthesis of HEMP. 3ꢀEthoxysalicylaldehyde
(1.0 mmol, 0.166 g) and Nꢀmethylethylenediamine
1.0 mmol, 0.074 g) were mixed in a methanol solution
30 ml). The mixture was stirred for 30 min at reflux,
H
N
(
(
N
H
OH
and the solvent was evaporated to give yellow oil of
HEMP.
N
N
O
OH
HIEP
For C H N O
2 18 2 2
1
HEMP
anal. calcd., %: C, 64.8;
Found, %: C, 64.5;
H, 8.2;
H, 8.2;
N, 12.6.
N, 12.8.
1
The article is published in the original.
40

SYNTHESIS AND CRYSTAL STRUCTURES OF TWO AZIDOꢀBRIDGED COPPER(II)
41
Table 1. Crystallographic and experiment data for the comꢀ Table 2. Coordinate bond lengths and bond angles for the
plexes
I
and II
*
complexes*
Bond
Value
d,
Å
Bond
d, Å
Parameter
I
II
I
M
649.7
653.7
Cu(1)–O(1)
Cu(1)–N(3)
Cu(1)–N(3)i
1.867(4) Cu(1)–N(1)
2.003(4) Cu(1)–N(2)
2.417(4)
1.955(4)
2.022(5)
Crystal size, mm
Crystal system
Space group
0.20
×
0.18
×
0.18 0.20
×
0.20 × 0.18
Monoclinic
2 /
Monoclinic
P
c
P
2 /
1
n
II
1
a,
b,
c,
Å
Å
Å
9.662(2)
15.282(3)
10.639(2)
115.418(10)
1418.9(5)
2
12.588(1)
Cu(1)–O(1)
Cu(1)–N(3)
Cu(1)–N(3)ii
1.907(3) Cu(1)–N(1)
1.989(3) Cu(1)–N(2)
2.510(4)
1.931(4)
2.051(4)
7.705(1)
14.481(2)
91.736(5)
1403.9(2)
2
β, deg
V, Å3
Angle
ω, deg
Angle
ω, deg
I
Z
, mm–1
O(1)Cu(1)N(1)
93.9(2) O(1)Cu(1)N(3)
89.3(2)
μ
Mo
1.543
1.565
N(1)Cu(1)N(3) 169.9(2) O(1)Cu(1)N(2) 177.5(2)
Tmin
0.748
0.745
N(1)Cu(1)N(2)
O(1)Cu(1)N(3)i
N(3)Cu(1)N(3)i 86.6(2) N(2)Cu(1)N(3)i 88.1(2)
86.1(2) N(3)Cu(1)N(2)
94.4(2) N(1)Cu(1)N(3)i 102.7(2)
90.3(2)
Tmax
0.769
0.766
Reflections/parameters
Independent reflections
7454/187
2809
6642/186
2363
II
F(000)
676
676
Goodnessꢀofꢀfit on F2
O(1)Cu(1)N(1)
N(1)Cu(1)N(3) 166.7(2) O(1)Cu(1)N(2) 174.5(2)
N(1)Cu(1)N(2) 84.8(2) N(3)Cu(1)N(2) 91.3(2)
O(1)Cu(1)N(3)ii 88.9(2) N(1)Cu(1)N(3)ii 100.5(2)
N(3)Cu(1)N(3)ii 91.9(2) N(2)Cu(1)N(3)ii 86.3(2)
93.5(2) O(1)Cu(1)N(3)
91.4(2)
0.977
0.967
R1 wR2 )*
,
(I
≥
2σ(I
0.0588, 0.1267
0.0986, 0.1513
0.0471, 0.1036
0.0765, 0.1157
R1, wR2 (all data)*
1
2
⎤
2
2
⎡
2
o
2
c
2
*
R = ∑||F | – |F ||/∑|F |, wR = Σw F − F
Σw F
o
( )
⎥
⎦
.
1
o
c
o
2
(
)
⎢
⎣
i
ii
*
Symmetry codes: 2 – x, – y, 2 – z; 1 – x, – y, – z.
Synthesis of [Cu( 1,1
methanolic solution (20 ml) of HIEP (0.5 mmol, evaporation of the solvents for a week. The isolated
.110 g) and sodium azide (0.5 mmol, 0.033 g) was crystals were washed three times with cold methanol
added a methanolic solution (5 ml) of Cu(ClO4)2
and dried in a vacuum over anhydrous CaCl2
µ
ꢀN ) (IEP)2] (I). To a stirred Xꢀray singleꢀcrystal analysis, were formed on the slow
3 2
0
⋅
.
7
H O (0.5 mmol, 0.194 g). The mixture was stirred for
2
3
0 min at room temperature to give a deep blue soluꢀ
For C H N O Cu
2
24
34 10
4
tion. Blue blockꢀshaped crystals of I, suitable for Xꢀray
anal. calcd., %: C, 44.1;
Found, %: C, 43.8;
H, 5.2;
H, 5.5;
N, 21.4.
N, 21.0.
singleꢀcrystal analysis, were formed on the slow evapꢀ
oration of the solvents for a week. The isolated crystals
were washed three times with cold methanol and dried
Xꢀray structure determination. Diffraction intensiꢀ
ties for the complexes were collected at 298(2) K using
a Bruker SMART APEX II CCD areaꢀdetector with
in a vacuum over anhydrous CaCl2
.
For C H N O Cu
2
26
38 10
2
Mo
K
radiation ( = 0.71073 Å). The collected data
λ
α
anal. calcd., %: C, 48.1;
Found, %: C, 48.6;
H, 5.9;
H, 6.1;
N, 21.6.
N, 21.3.
were reduced using the SAINT program [10], and
multiscan absorption corrections were performed
using the SADABS program [11]. The structures were
2
Synthesis of [Cu( 1,1
µ
ꢀN ) (EMP) ] (II)
.
To a stirred solved by direct methods and refined against
F
by fullꢀ
3 2
2
methanolic solution (20 ml) of HEMP (0.5 mmol, matrix leastꢀsquares methods using the SHELXTL
.111 g) and sodium azide (0.5 mmol, 0.033 g) was package [12]. All of the nonꢀhydrogen atoms were
added a methanolic solution (5 ml) of Cu(ClO4)2 refined anisotropically. The amino H atoms in both
H O (0.5 mmol, 0.194 g). The mixture was stirred complexes were located from difference Fourier maps
0
⋅
7
2
for 30 min at room temperature to give a deep blue and refined isotropically, with N–H distances
solution. Blue blockꢀshaped crystals of II, suitable for restrained to 0.90 Å. Other H atoms in the complexes
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 1
2011

42
WANG
Table 3. Geometric parameters of hydrogen bonds for comꢀ Centre (nos. 768497 (I) and 768498 (II); deposit@ccdc.
plexes I and II*
cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
Distance,
Å
Angle
D–H⋅⋅⋅A,
deg
Contact
D–H···A
D–H
H
⋅⋅⋅ D⋅⋅⋅A
A
To design and synthesize polynuclear structures of
metal complexes, the selection of ligands and the
bridging groups is important. We herein designed and
synthesized two new Schiff base ligands, HIEP and
HEMP. Both Schiff bases were readily synthesized
with high yields and purity, which can chelate to the
metal atoms through the phenolate O, imine N,
and/or amine N atoms. The azide is used as a bridging
group in the synthesis. Both complexes were readily
synthesized under the similar synthetic procedure.
I
N(2)–H(2)⋅⋅⋅O(1)i 0.90 2.40(2) 3.282(5) 167(6)
II
N(2)–H(2)⋅⋅⋅O(1)ii 0.90 2.25(2) 3.084(4) 155(4)
N(2)–H(2)⋅⋅⋅O(2)ii 0.90 2.58(4) 3.291(5) 137(4)
i
ii
The Schiff bases are yellow oils. They can be
diluted with methanol, ethanol, acetonitrile, and
chloroform. The blue blockꢀshaped crystals of the two
complexes are stable in air at room temperature, soluꢀ
ble in methanol, ethanol, and acetonitrile and insoluꢀ
ble in water.
*
Symmetry codes: 2 – x, – y, 2 – z; 1 – x, – y, – z.
were placed in calculated positions and constrained to
ride on their parent atoms. The crystallographic data
for the complexes are summarized in Table 1. Selected
bond lengths and angles are given in Table 2. Hydrogen
bonds are listed in Table 3.
In the IR spectra of the Schiff bases, the weak
–1
absorption bands at about 3450 cm are assigned to
the stretching vibration of the hydroxy groups, which
Crystallographic data for the two complexes have been is absent in the complexes. The weak and sharp bands
deposited with the Cambridge Crystallographic Data at about 3260 cm are assigned to the N–H stretching
–1
C(4)
C(5)
C(3)
O(1)
Cu(1A)
N(3
A)
C(6)
C(8)
C(2)
N(1)
C(1)
Cu(1)
N(3)
N(4)
C(7)
N(5)
C(9)
C(10)
N(2)
C(11)
C(13)
C(12)
Fig. 1. Molecular structure of
I at 30% ellipsoid.
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SYNTHESIS AND CRYSTAL STRUCTURES OF TWO AZIDOꢀBRIDGED COPPER(II)
43
C(9)
C(8)
C(10)
N(1)
N(2)
Cu(1)
C(7)
N(3A)
C(1)
C(6)
N(3)
N(4)
N(5)
Cu(1A)
O(1)
O(2)
C(2)
C(3)
C(5)
C(4)
C(11)
C(12)
Fig. 2. Molecular structure of II at 30% ellipsoid.
vibration. The strong absorption bands at 1621 cm–1 and with one N atom of an azide group, defining the
for HIEP and 1627 cm–1 for HEMP are assigned to the basal plane. The apical position of the square pyramid
azomethine groups, which are shifted to lower freꢀ
quencies in the complexes (1615 cm–1 for
and
618 cm–1 for II). The intense absorption bands of the
is occupied by one N atom of another azide group. The
values [13] are 0.127 for and 0.130 for II. The coorꢀ
dinate bond lengths and angles in both complexes are
comparable to each other and also comparable to
those observed in other similar copper(II) complexes
I
τ
I
1
–
1
azide groups in both complexes are at 2040 cm
.
The molecular structures of I and II are shown as
Figs. 1 and 2, respectively. Both complexes are two
endꢀon azidoꢀbridged centrosymmetric dinuclear
copper(II) compounds, with the inversion centers
[
7, 14–16].
The two [CuL] units (L is IEP for
I and EMP
lying at the midpoint of the two Cu atoms. The Cu···Cu for II) in each complex are linked not only by the
distances are 3.230(2) Å in and 3.150(2) Å in II
two endꢀon azide bridges, but also intermolecular
H···O hydrogen bonds. There were two N–H···O
I
.
N
⎯
Each Cu atom in the complexes is in a square pyraꢀ
midal coordination with one phenolate O, one imine hydrogen bonds in and four in II, which might lead
N, and one amine N atoms of one Schiff base ligand to the longer Cu···Cu distance in than that in II
I
I
.
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4
4
WANG
8. Garnovskii, A.D., Vasilchenko, I.S., Garnovskii, D.A.,
ACKNOWLEDGMENTS
et al., Russ. J. Gen. Chem., 2009, vol. 79, no. 12, p. 2776.
This work was supported by the Sciences Foundaꢀ
9
. Benetollo, F., Di Bernardo, P., Tamburini, S., et al.,
tion of the SouthꢀCentral University for Nationalities
no. Yzz02002).
Inorg. Chem. Commun., 2008, vol. 11, no. 3, p. 246.
(
1
1
1
0. SMART and SAINT, Software Reference Manuals,
Madison (WI, USA): Bruker AXS Analytic XꢀRay Sysꢀ
tems Inc., 2002.
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