In situ self-assemblyof 1D copper(II) coordination polymer containing EO azide and phenolate bridges: Crystal structure and magnetic properties

Full text of DOI:10.1246/bcsj.82.582

5
82
Bull. Chem. Soc. Jpn. Vol. 82, No. 5, 582–584 (2009)
Short Articles
O
C
OH
HO
decomposed
MeOH / H O
In Situ Self-Assembly of 1D
Copper(II) Coordination Polymer
Containing EO Azide and Phenolate
Bridges: Crystal Structure
N
N
HO
2
NH
(
L)
(L1)
NaN3 Cu2+
NH
and Magnetic Properties
O
N3
N3
Cu
Cu
Cu
Cu
O
N3
O
NH
NH
1
1
2
Zhiliang Liu,* Weihua Han, Caiming Liu,*
in situ assembling
1
1
2
Xiaowei Di, Jun Zhang, and Deqing Zhang
Scheme 1.
1College of Chemistry and Chemical Engineering,
Inner Mongolia University, Hohhot 010021, P. R. China
2Laboratory of Organic Solids, Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100080, P. R. China
Received October 27, 2008; E-mail: cezlliu@imu.edu.cn
A
novel one-dimensional copper(II) coordination
II
polymer with formula [Cu (L1)(N3)]n (1), has been prepared
via in situ self-assembly. Compound 1 consists of 1D
uniform chains in which the copper(II) ions are bridged by
end-on azide and an oxygen of salicylideneamine (L1).
Magnetic susceptibility measurement reveals the existence of
relatively strong ferromagnetic interactions in the 1D chain.
Figure 1. Perspective view showing the atomic labeling
scheme, metal coordination environment and the topology
of the chain.
assembly of coordination polymers. In the majority of the
cases, different chelated organic ligands have been used for this
9
,10
purpose.
The design and construction of coordination polymers have
In this paper, we report the syntheses, structure, and
magnetic properties of a novel 1D mixed bridges (EO-azide
and oxygen of salicylideneamine) copper(II) compound 1.
been a field of rapid growth in materials chemistry because of
their fascinating structures and applications as new materials.
For studies of the molecule-based magnets, coordination
polymers have aroused wide interests of the experimental and
theoretical chemists.1 The growing interest in this field is
motivated by the ability of metalloligand coordination to
provide a simple route to the controlled assembly of 1D, 2D,
and 3D coordination polymers.2 One of the points to be
seriously considered for the preparation of these materials is the
selection of the appropriate paramagnetic metal ions, bridging
ligands, and suitable synthesis methods.4
II
Compound 1, of formula [Cu (L )(N )] , consists of 1D
1
3 n
uniform chains. Ferromagnetic interactions are existed in the
1D compound.
Single crystals of compound 1 were obtained by slow
11­13
diffusion in an H-shaped tube.
During the reaction, N,N¤-
,3
disalicylideneurea (L) decomposed into salicylideneamine
(L ) and compound 1 was obtained via in situ self-assembly
1
(Scheme 1).
,5
The crystal structure of compound 1 was determined by X-
1
4
The pseudohalide azide has been demonstrated to be not
only an extremely versatile ligand but also an excellent
magnetic coupler. Thus, a large number of azide-bridged
coordination polymers have been synthesized and magneto-
structurally characterized.6 In general, the very common
bridging modes observed for the azido linker are end-to-end
ray diffraction analysis. Figure 1 shows the building unit
drawing of the 1D chain. Table 1 shows the selected bond
lengths/¡ and angles/°.
The coordination geometry around copper(II) ion is the
distorted square pyramidal: CuN O . The basal plane for
3
2
copper(II) ion consists of the nitrogen atom of EO-azide N(1)
and N(1A), oxygen atom of salicylideneamine O(1), and the
nitrogen atom of the imine N(4). The axial coordination site of
copper(II) is occupied by the oxygen atom of salicylideneamine
O(1A) [Symmetry transformations used to generate equivalent
atoms: ¹x + 3/2, y, z + 1/2], and the bond length of apical
bond: Cu(1)­O(1A) is 2.416(2) ¡, which is much longer than
the equatorial bond distances 1.918(2) ¡ for Cu(1)­O(1). All
the O­Cu­O, O­Cu­N, or N­Cu­N angles are deviation from a
few degrees of 90 or 180°. The copper(II) ion and the four
equatorially bound atoms are coplanar. The equatorially
(
EE) and end-on (EO). The former one is mainly known as an
antiferromagnetic coupler (AF) with a few exceptions where
some systems have been shown the formation of EE azido
7
bridged ferromagnetic materials. EO mode can mediate both
ferro- and antiferromagnetic interactions depending on the M­
8
N­M bond angle.
On the other hand, one-dimensional metal­azido systems are
important because of the possibility of enhancement of the bulk
magnetic interactions. The introduction of a second hybrid
ligand to a metal­azido system is important to control the
Published on the web May 13, 2009; doi:10.1246/bcsj.82.582

Z. Liu et al.
Bull. Chem. Soc. Jpn. Vol. 82, No. 5 (2009)
583
Table 1. Selected Bond Lengths/¡ and Bond Angles/° for
Compound 1
Crystal structural analysis shows that 1D magnetic chain is
formed in the crystal lattice of compound 1. The magnetic data
of compound 1 can be well fitted with a 1D magnetic chain
model. The inter-chain spin­spin interaction is treated simply
with mean-field theory. Accordingly, the temperature depen-
dence of the magnetic susceptibility of compound 1 was fitted
to eqs 1 and 2,
a)
Cu(1)­O(1)
Cu(1)­N(1A)
Cu(1)­O(1A)
1.918(2) Cu(1)­N(4)
1.968(3) Cu(1)­N(1)
2.416(2)
1.934(3)
1.983(3)
1
5
O(1)­Cu(1)­N(4)
N(4)­Cu(1)­N(1A)
N(4)­Cu(1)­N(1)
O(1)­Cu(1)­O(1A)
N(1)­Cu(1)­O(1A)
92.31(11) O(1)­Cu(1)­N(1A)
90.84(12) O(1)­Cu(1)­N(1)
160.11(12) N(1)­Cu(1)­N(1A)
101.17(11) N(4)­Cu(1)­O(1A)
71.27(11) N(1)­Cu(1)­O(1A)
171.93(12)
82.77(11)
96.66(12)
92.35(10)
107.50(11)
ꢀ
ꢁ
2
3
2
2
Ng ¢
N
D
»chain
¼
ð1Þ
4
kT
2
3
3
N ¼ 1:0 þ 5:7979916y þ 16:902653y þ 29:376885y
Cu(1)­O(1A)­Cu(1A) 95.15(2) Cu(1)­N(1A)­Cu(1A) 109.02(71)
4
5
þ 29:832959y þ 14:036918y
a) Symmetry transformations used to generate equivalent atoms:
2
D ¼ 1:0 þ 2:7979916y þ 7:0086780y þ 8:6538644y
¹
x + 3/2, y, z + 1/2.
4
þ 4:5743114y
y ¼ J=2kT
g = 2.09
»chain
»M
¼
ð2Þ
-
1
2
J = 39.48 cm
0.6
2
0
0
0
.04
.02
.00
1 ꢀ ð2zJ=Ng ¢ Þ»
chain
-1
zJ = -0.90 cm
where J is referred to as the magnetic exchange constant
within the 1D chain and zJ represents the inter-chain spin­spin
0
0
0
.4
.2
.0
¹
1
interaction. The best fitting leads to g = 2.09, J = 39.48 cm ,
¹
1
and zJ = ¹0.90 cm , showing that the intra-chain spin­spin
interaction is relatively strongly ferromagnetic, while the inter-
chain spin­spin interaction is weakly antiferromagnetic.
It has been widely cited that the interaction through an EO
azido bridge is ferromagnetic for lower Cu­N­Cu angles and
antiferromagnetic for higher angles. The critical angle is 104°
0
100
200
300
T / K
16
according to empirical analyses and 108° according to a den-
1
7
sity functional study. It appears that the ferromagnetic coupl-
ing in 1, with a Cu­N­Cu angle of 109.02°, disagrees with the
above trends. Furthermore, comparing to double EO azido
Figure 2. Plots of »MT and »M vs. T for compound 1; the
solid line represents the best fitting with eqs 1 and 2.
1
8
coordination plane suffers a small tetrahedral distortion as
indicated by deviations of the relevant atoms (the deviations
from the average planes are 0.2264 ¡) and the deviation of
Cu(1) from the least-square plane is 0.0937 ¡. The neighboring
copper(II) ions are connected by nitrogen atoms of EO-azide
and oxygen atoms of salicylideneamine and the 1D uniform
chain is formed. The separation between the neighboring
copper(II) ions through the mixed bridges is 3.2168(8) ¡. It
is interesting to note that the phenoxo-oxygen atom assumes
an asymmetric apical­basal disposition between neighboring
copper(II) ions, i.e., the same oxygen bridge resides on the
apical position of one copper but in the basal plane of the
neighboring copper, with the apical Cu­O distance (Cu(1)­
O(1A) = 2.416(2) ¡) being significantly longer than the basal
one (Cu(1)­O(1) = 1.918(2) ¡). In the lattice, the chains run
along the c direction and there is no evident indication of
interchain ³­³ interactions.
bridging mode in the literatures, the mixed bridges containing
an EO azide and phenoxo-oxygen in 1, mediate relatively
strong ferromagnetic interaction. The ferromagnetic interaction
may work through the phenoxo-oxygen because of orthogo-
nality of magnetic orbitals among neighboring copper(II) ions.
In summary, we report for the synthesis, crystal structure,
and magnetic properties of a novel 1D copper(II) coordination
II
polymer of formula [Cu (L )(N )] (1). Compound 1 consists
1
3 n
of 1D uniform chain and there exists relatively strong
ferromagnetic interaction in the chain. It should be pointed
out that compound 1 is interesting for the studies of molecular-
based magnets in terms of the following two points: (1)
formation of new complexes with paramagnetic metal ions via
in situ self-assembly; (2) mixed bridging mode containing ®-
phenoxo-oxygen and EO azide can transmit ferromagnetic
interaction. Relatively strong ferromagnetic interaction may
work through the phenoxo-oxygen because of orthogonality of
magnetic orbitals among neighboring copper(II) ions. This
result opens up a route to the synthesis of a new family of
mixed EO azide bridging compounds, and the work is already
underway to establish the series.
Figure 2 shows the temperature dependence of the magnetic
susceptibility of compound 1, where the plots of »M and »MT
vs. T are displayed. The value of » T at room temperature is
M
3
¹1
0
.41 cm K mol , which is larger than the expected value for
the one spin system with S = 1/2. With lowering the temper-
ature, »MT increases gradually and reaches the maximum value
Financial support by the NSFC (No. 20761004), Scientific
Research Key Project from The Ministry of Education China
(No. 207021), and Inner Mongolia Autonomous Region
Foundation for College Scientific Research Project are kindly
acknowledged.
3
¹1
(0.64 cm K mol ) at 23 K, indicating the intra-chain ferro-
magnetic spin­spin interaction. When decreasing the temper-
ature further, » T decreases sharply, likely due to the inter-
M
chain antiferromagnetic interaction.

5
84
Bull. Chem. Soc. Jpn. Vol. 82, No. 5 (2009)
© 2009 The Chemical Society of Japan
2
mmol) were in one arm and the solution of Cu(ClO4)2¢6H2O
References
(0.74 g, 2 mmol, 10 mL) was in the other arm. And then 20 mL of
1
D. Maspoch, D. Ruiz-Molina, J. Veciana, Chem. Soc. Rev.
methanol/aqueous solvent was carefully added so that the bridge
of the tube was filled. The tube was sealed and left to stand at room
temperature. Two weeks later, the dark-green crystals were
collected and air-dried (0.124 g, 27%). IR (cm ): 3441, 3347,
2098, 1639, 1616, 1528, 1433, 1317, 1285, 1191, 770. Anal. Calcd
for C7H6CuN4O: C, 37.22; H, 2.66; N, 24.81%. Found: C, 37.37;
H, 2.95; N, 24.59%.
2
007, 36, 770, and references therein.
2
483.
3
G. F. Swiegers, T. J. Malefetse, Chem. Rev. 2000, 100,
¹1
3
A. M. Kirillov, Y. Y. Karabach, M. Haukka, M. F. C. G. da
Silva, J. Sanchiz, M. N. Kopylovich, A. J. L. Pombeiro, Inorg.
Chem. 2008, 47, 162.
4
5
S. R. Seidel, P. J. Stang, Acc. Chem. Res. 2002, 35, 972.
S. C. Manna, J. Ribas, E. Zangrando, N. Ray Chaudhuri,
14 Crystal data: C7H6CuN4O, Mr = 225.70, Orthorhombic,
Pccn, a = 14.319(3) ¡, b = 19.465(4) ¡, c = 5.7610(10) ¡, V =
3
¹3
Inorg. Chim. Acta 2007, 360, 2589.
1605.7(5) ¡ , Z = 8, Dcalcd = 1.867 g cm
;
F(000) = 904,
¹1
6
7
A. Escuer, G. Aromí, Eur. J. Inorg. Chem. 2006, 4721.
F.-C. Liu, Y.-F. Zeng, J.-P. Zhao, B.-W. Hu, X.-H. Bu, J.
®(Mo K¡) = 2.678 mm . 3358 reflections of which 1828 are
unique (Rint = 0.0197) were collected to a ª limit of 2.85­27.43°
on a Rigaku RAXIS RAPID IP instrument at 293(2) K. The
structure was solved by direct methods and refined by a least-
squares matrix method. The final cycle of full-matrix least-square
refinement was based on 1828 observed reflections [I > 2·(I)] and
118 variable parameters and converged to R = 0.0390, wR2 =
0.0625 (R indices for all data: R1 = 0.0710, wR2 = 0.0929),
GOF = 0.868, Largest diffraction peak and hole of 0.659 and
Ribas, J. Cano, Inorg. Chem. 2007, 46, 1520.
P. S. Mukherjee, T. K. Maji, A. Escuer, R. Vicente, J. Ribas,
G. Rosair, F. A. Mautner, N. R. Chaudhuri, Eur. J. Inorg. Chem.
002, 943.
S. Konar, E. Zangrando, M. G. B. Drew, T. Mallah, J.
Ribas, N. Ray Chaudhuri, Inorg. Chem. 2003, 42, 5966.
J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortés, L.
8
2
9
1
0
¹3
Lezama, T. Rojo, Coord. Chem. Rev. 1999, 193­195, 1027, and
¹0.655 e ¡ . CCDC reference number 697911.
15 G. A. Baker, Jr., G. S. Rushbrooke, H. E. Gilbert, Phys.
Rev. 1964, 135, A1272.
references therein.
1
1
L. F. Capitán-Vallvey, F. Salinas, C. Jiménez, L. Cuadros,
Can. J. Chem. 1982, 60, 1706.
D. Hakan, S. Serap, S. Yasemin, H. Tuncer, Z. Kılıç, J. Mol.
Struct. 2005, 753, 84.
Single crystals suitable for X-ray diffraction were obtained
16 S. S. Tandon, L. K. Thompson, M. E. Manuel, J. N.
Bridson, Inorg. Chem. 1994, 33, 5555.
17 E. Ruiz, J. Cano, S. Alvarez, P. Alemany, J. Am. Chem.
Soc. 1998, 120, 11122.
1
2
1
3
by slow diffusion in an H-shaped tube (total volume ca. 40 mL) of
two methanol/aqueous (1:1) solutions. A methanol/aqueous (1:1)
solution 10 mL containing L (0.44 g, 2 mmol) and NaN3 (0.13 g,
18 E.-Q. Gao, S.-Q. Bai, C.-F. Wang, Y.-F. Yue, C.-H. Yan,
Inorg. Chem. 2003, 42, 8456, and references therein.