Solvothermal syntheses and crystal structures of new Cu(II) complexes with phenylsuccinic acid

Article abstract of DOI:10.1016/j.poly.2007.04.016

Five new Cu(II) complexes [Cu(psa)(phen)] · 3H₂O (1), [Cu(psa)(2bpy)] · 0.5H₂O (2), [Cu(psa)(2bpy)(H₂O)] · 3H₂O (3), [Cu(psa)(4bpy)] · H₂O (4), and [Cu(psa)_0.5(N₃)(2bpy)] (5) (H₂psa = phenylsuccinic acid, phen = 1,10-phenanthroline, 2bpy = 2,2′-bipyridine, and 4bpy = 4,4′-bipyridine) were obtained under solvothermal conditions and characterized by single-crystal X-ray diffraction. Complexes 2 and 3 were formed by one-pot reaction. In complex 2, Cu(II) ion is four-coordinated and locates at a slightly distorted square center. In complex 3, the coordinated water molecule occupies the axial site of Cu(II) ion forming a tetragonal pyramid geometry. Complexes 1 and 3 are of 1D chain structures, and extended into 2D supramolecular network by hydrogen bonds. Complex 2 is of zipper structure, and further assembled into 2D supramolecular network by hydrogen bonds and π-π stacking interactions. Complex 4 is a 3D CdSO₄-like structure with twofold interpenetration, while complex 5 is a dinuclear compound. The different structures of complexes 1-5 can be attributed to using the auxiliary ligands, indicating an important role of the auxiliary ligands in assembly and structure of the title complexes.

Full text of DOI:10.1016/j.poly.2007.04.016

Polyhedron 26 (2007) 4025–4032
www.elsevier.com/locate/poly
Solvothermal syntheses and crystal structures of new Cu(II)
complexes with phenylsuccinic acid
a
b
a,
*
Jie Zhou , Chang-Yan Sun , Lin-Pei Jin
a
Department of Chemistry, Beijing Normal University, Beijing 100875, PR China
Department of Chemistry, School of Applied Science, University of Science and Technology Beijing, Beijing 100083, PR China
b
Received 6 March 2007; accepted 6 April 2007
Available online 27 April 2007
Abstract
Five new Cu(II) complexes [Cu(psa)(phen)] Æ 3H2O (1), [Cu(psa)(2bpy)] Æ 0.5H2O (2), [Cu(psa)(2bpy)(H2O)] Æ 3H2O (3), [Cu(psa)-
(4bpy)] Æ H2O (4), and [Cu(psa)0.5(N3)(2bpy)] (5) (H2psa = phenylsuccinic acid, phen = 1,10-phenanthroline, 2bpy = 2,20-bipyridine,
and 4bpy = 4,40-bipyridine) were obtained under solvothermal conditions and characterized by single-crystal X-ray diffraction. Com-
plexes 2 and 3 were formed by one-pot reaction. In complex 2, Cu(II) ion is four-coordinated and locates at a slightly distorted square
center. In complex 3, the coordinated water molecule occupies the axial site of Cu(II) ion forming a tetragonal pyramid geometry. Com-
plexes 1 and 3 are of 1D chain structures, and extended into 2D supramolecular network by hydrogen bonds. Complex 2 is of zipper
structure, and further assembled into 2D supramolecular network by hydrogen bonds and p–p stacking interactions. Complex 4 is a
3D CdSO4-like structure with twofold interpenetration, while complex 5 is a dinuclear compound. The different structures of complexes
1–5 can be attributed to using the auxiliary ligands, indicating an important role of the auxiliary ligands in assembly and structure of the
title complexes.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Cu(II) complexes; Phenylsuccinic acid; Solvothermal synthesis; Crystal structures
1. Introduction
In the construction of complexes, succinic acid (SA) as a
representative of symmetrical and flexible dicarboxylic
acids has been extensively used [7]. However, the research
of transition metal complexes with phenylsuccinic acid
(H2psa) has never been reported so far. One phenyl group
is introduced to SA, which makes symmetric SA ligand
asymmetric and thus induces different conformations of
the SA bridging modes due to geometrical constrains and
finally makes structures of the complexes diverse. On the
other hand, the different auxiliary ligands, such as phen,
2bpy, and 4bpy, can impact the conformations of the flex-
ible carboxylic ligand (trans- or cis-), and also play an
important role in the formation of the final complex struc-
tures [8]. The terminal ligands phen and 2bpy tend to
construct low-dimensional structure which is extended
into high-dimensional supramolecular network with the
help of the hydrogen bonds and p-p stacking interac-
tions, while 4bpy ligand can connect the metal ions into
Over the past decades, the synthesis and characteriza-
tion of metal–organic frameworks (MOFs) have been an
active area of research in coordination chemistry [1]. This
arises from their intriguing topological frameworks and
their unexpected potential applications, such as heteroge-
neous catalysis, gas storage, separation and magnetic mate-
rials [2–5]. In this area, transition metal complexes,
especially Cu(II) complexes, have been investigated widely
[6]. For Cu(II) ion, the coordination number varies from 4
to 6, the d9 configuration is Jahn–Teller active, there is one
odd d-electron occupies in one of the d-orbitals which gives
rise to structural flexibility.
*
Corresponding author.
E-mail address: lpjin@bnu.edu.cn (L.-P. Jin).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.04.016

4026
J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
higher-dimensional metal–organic frameworks easily
[7b,9]. In the present work, we chose H2psa as a bridging
ligand to link Cu(II) ions. Auxiliary ligands, phen, 2bpy,
4bpy, and N3ꢀ, were introduced to the Cu(II)/[psa]2ꢀ sys-
tem under solvothermal conditions, five new complexes
[Cu(psa)(phen)] Æ 3H2O (1), [Cu(psa)(2bpy)] Æ 0.5H2O (2),
[Cu(psa)(2bpy)(H2O)] Æ 3H2O (3), [Cu(psa)(4bpy)] Æ H2O
(4), and [Cu(psa)0.5(N3)(2bpy)] (5) were obtained. The
details of their synthesis, structure, and thermal stability
are reported.
2.2.3. Synthesis of [Cu(psa)(4bpy)] Æ H2O (4)
The synthesis of complex 4 was similar to that of com-
plex 1 expect that 4bpy (0.018 g, 0.1 mmol) was used
instead of phen. Dark blue column crystals of complex 4
were obtained. Yield: 0.030 g (69.9%). Anal. Calc. for
C20H18CuN2O5: C, 55.87; H, 4.22; N, 6.52. Found: C,
56.24; H, 4.23; N, 6.38%. IR data (KBr pellet, cmꢀ1):
3441s, 1610s, 1575s, 1487w, 1411m, 1375m, 1320w,
1215w, 1065m, 826m, 734m, 701m, 627m.
2.2.4. Synthesis of [Cu(psa)0.5(N3)(2bpy)] (5)
2. Experimental
A mixture of H2psa (0.019 g, 0.1 mmol), 2pby (0.016 g,
0.1 mmol), Cu(Ac)2 Æ H2O (0.019 g, 0.1 mmol), NaN3
(0.007 g, 0.1 mmol), 10 ml distilled water and 3 ml ethanol
was placed in a 25 ml Teflon-lined stainless steel autoclave,
and the vessel was sealed and heated to 140 °C for 72 h,
then cooled at 10 °C hꢀ1 to 100 °C, followed by slowly
cooling to room temperature. Dark green block crystals
of complex 5 were obtained. Yield: 0.029 g (80.9%). Anal.
Calc. for C15H12CuN5O2: C, 50.34; H, 3.38; N, 19.57.
Found: C, 50.12; H, 3.90, N, 19.39%. IR data (KBr pellet,
cmꢀ1): 3441br, 2048s, 1607s, 1567m, 1493m, 1472m,
1447m, 1361m, 1158w, 1029w, 772m, 732m.
2.1. Materials and characterization
All reagents were used as received without further puri-
fication. The C, H, N microanalyses were carried out with a
Vario EL elemental analyzer. Thermogravimetric analyses
were conducted on a ZRY-2P thermal analyzer using a
heating rate of 10 °C/min from room temperature to
1000 °C under nitrogen. The IR spectra were recorded with
a Nicolet Avatar 360 FT-IR spectrometer using the KBr
pellet technique.
2.2. Synthesis
2.3. X-ray structure determination
2.2.1. Synthesis of [Cu(psa)(phen)] Æ 3H2O (1)
The single-crystal X-ray data collections for the five
complexes were performed with a Bruker SMART 1000
CCD diffractometer, using graphite-monochromatized
A mixture of H2psa (0.019 g, 0.1 mmol), phen (0.020 g,
0.1 mmol), Cu(Ac)2 Æ H2O (0.019 g, 0.1 mmol), NaOH
aqueous solution (0.15 ml, 0.65 mol/L), 10 ml distilled
water and 1 ml ethanol was placed in a 25 ml Teflon-lined
stainless steel autoclave, and the vessel was sealed and
heated to 140 °C for 72 h, then cooled at 10 °C hꢀ1 to
100 °C, followed by slowly cooling to room temperature.
The resulting blue wedge shape crystals of complex 1 were
obtained. Yield: 0.032 g (64.2%). Anal. Calc. for
C22H22CuN2O7: C, 53.87; H, 4.52; N, 5.71. Found: C,
53.93; H, 4.85; N, 5.33%. IR data (KBr pellet, cmꢀ1):
3450s, 1592s, 1519w, 1494w, 1429m, 1397m, 1313w,
850m, 720m.
˚
MoKa radiation (k = 0.71073 A). Semi-empirical absorp-
tion corrections were applied using the SADABS program
[10]. The structures were solved by direct methods [11]
and refined by full-matrix least squares method on F2 using
SHELXS97 and SHELXL97 programs, respectively [11,12]. All
non-hydrogen atoms were refined anisotropically. The
hydrogen atoms were generated geometrically and treated
by a mixture of independent and constrained refinement.
The crystallographic data for complexes 1–5 are listed in
˚
Table 1, selected bond lengths (A) and angles (°) are listed
in Table 2, the details of the hydrogen bonds for complexes
1 and 3 are listed in Table 3.
2.2.2. Synthesis of [Cu(psa)(2bpy)] Æ 0.5H2O (2) and
[Cu(psa)(2bpy)(H2O)] Æ 3H2O (3)
3. Results and discussion
The synthesis of complex 2 was similar to that of com-
plex 1 expect that 2bpy (0.016 g, 0.1 mmol) was used
instead of phen. The blue square flake crystals of complex
2 were obtained. Yield: 0.004 g (9.5%). We left the mother
solution at room temperature for two days and obtained
the light green crystal of complex 3. Yield: 0.018 g
(37.2%). Anal. Calc. for C20H17CuN2O4.5 (2): C, 57.01;
H, 4.07; N, 6.65. Found: C, 57.38; H, 4.68; N, 6.82%. IR
data (KBr pellet, cmꢀ1): 3442s, 1587s, 1568s, 1495w,
1473w, 1447m, 1410s, 1395s, 1381s, 1273w, 773s, 715m.
Anal. Calc. for C20H24CuN2O8 (3): C, 49.63; H, 4.99; N,
5.79. Found: C, 49.39; H, 5.77; N, 6.07%. IR data (KBr
pellet, cmꢀ1): 3447s, 1569s, 1494w, 1468w, 1446m, 1412s,
1385s, 775m, 744w, 731w, 701w.
3.1. Structure description of [Cu(psa)(phen)] Æ 3H2O (1)
In the asymmetric unit of complex 1, there are one
Cu(II) ion, one [psa]2ꢀ ligand, one chelating phen ligand
and three lattice water molecules. As shown in Fig. 1, the
Cu(II) ion is four-coordinated by two nitrogen atoms
(N1, N2) from one phen ligand, two oxygen atoms (O1,
O4A) of the carboxylate groups from two [psa]2ꢀ ligands.
The average Cu–N bond length is slightly longer than that
of Cu–O distance. In complex 1, [psa]2ꢀ ligand displays cis-
configuration and adopts bis(monodentate) mode (see
Scheme 1a). Cu(II) ions are bridged by [psa]2ꢀ ligands into
1D chains (see Fig. 1). The phen ligands are arranged at

J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
4027
Table 1
Crystallographic data of complexes 1–5
1
2
3
4
5
Empirical formula
C22H22CuN2O7
489.96
C20H17CuN2O4.5
420.90
C20H24CuN2O8
483.95
C20H18CuN2O5
429.90
C30H24Cu2N10O4
715.67
M (g molꢀ1
)
Crystal system
Space group
monoclinic
P2(1)
monoclinic
C2/c
orthorhombic
Pca2(1)
monoclinic
Pc
monoclinic
C2/c
˚
a (A)
6.9209(19)
17.591(5)
9.088(2)
90
101.81
90
1083.0(5)
2
1.503
1.055
506
30.474
7.585
17.188
90
116.81
90
3546(3)
8
1.577
19.329(4)
6.3717(14)
16.976(4)
90
90
90
2090.7(8)
4
1.538
1.095
1004
5.710(2)
9.622(4)
17.509(7)
90
102.686(12)
90
938.5(6)
2
1.521
13.768(3)
16.752(3)
13.330(4)
90
105.192(6)
90
2967.0(12)
4
1.602
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
Dcalc (g cmꢀ1
l (mmꢀ1
F(000)
)
)
1.265
1728
1.198
442
1.489
1456
Reflections collected
5317
3104
10723
4906
8067
Reflections unique
3750
3104
4032
2620
3057
Date/restraints/parameters
Final R indices [I > 2r(I)]
3750/10/289
R1 = 0.0467,
wR2 = 0.0837
R1 = 0.0741,
wR2 = 0.0965
0.03(2)
1.068
0.472 and ꢀ0.515
3104/3/257
R1 = 0.0694,
wR2 = 0.1930
R1 = 0.1015,
wR2 = 0.2168
4032/10/280
R1 = 0.0503,
wR2 = 0.0853
R1 = 0.1279,
wR2 = 0.1112
0.06(3)
1.078
0.828 and ꢀ1.182
2620/23/254
R1 = 0.0563,
wR2 = 0.1004
R1 = 0.1275,
wR2 = 0.1238
0.0(5)
3057/39/232
R1 = 0.0550,
wR2 = 0.1189
R1 = 0.1390,
wR2 = 0.1479
R indices (all data)
Flack parameter
Goodness-of-fit on F2
Largest difference peak and hole (e A
1.097
1.321 and ꢀ1.748
1.019
0.714 and 0.449
0.999
0.519 and ꢀ0.469
ꢀ3
˚
)
one side of the chains, while the benzene rings of the [psa]2ꢀ
ligands locate at the other side of the chains, which may be
contributed to the steric effect from both the phen and
H2psa ligands. The similar coordination geometry and
structure can be observed in the complex of Cu(II) with
1,4-phenylenediacetic acid (H2pda) [13] which is an isomer
of H2psa. In this [pda]2ꢀ complex, the auxiliary ligand phen
has p–p stacking interactions, while in complex 1, the p–p
interactions could not be found.
In complex 1, three lattice water molecules form a trimer
through hydrogen bonds (O5–H5Bꢁ ꢁ ꢁO7, O6–H6Aꢁ ꢁ ꢁO5),
which acts as bridges between adjacent chains forming a
2D supramolecular network in ab plane by three kinds of
hydrogen bonds, as shown in Fig. 2. The details of hydro-
gen bonds are listed in Table 3. Undoubtedly, the hydrogen
bonds play an important role in the formation of the 2D
supramolecular network.
chain, in which aromatic p–p stacking interactions exist
between 2bpy pairs. The face-to-face distance between
˚
the paired 2bpy rings is 3.258 A, and the centroid–centroid
˚
distance is 3.466 A [14], indicating moderately strong aro-
matic p–p stacking interactions. The disordered water mol-
ecules exist between the zippers and the hydrogen bonds
˚
(O(5)–H(5A)ꢁ ꢁ ꢁO(3), Oꢁ ꢁ ꢁO distance 2.987 A) between
water molecules and the uncoordinated carboxyl oxygen
atoms connect parallel zippers to give a 2D supramolecular
structure, as shown in Fig. 4.
3.3. Structure description of [Cu(psa)(2bpy)(H2O)]
Æ 3H2O (3)
In the symmetric unit of complex 3, there are one Cu(II)
ion, one [psa]2ꢀ ligand, one 2bpy ligand, one coordinated
water molecule and three lattice water molecules. In com-
plex 3, the Cu(II) ion is five-coordinated with two nitrogen
atoms (N1, N2) from 2bpy ligand, two oxygen atoms (O1,
O3A) of two [psa]2ꢀ ligands, and one oxygen atoms(O5)
from one coordinated water molecule forming a distorted
tetragonal pyramid geometry, as shown in Fig. 5. The
3.2. Structure description of [Cu(psa)(2bpy)] Æ 0.5H2O (2)
The asymmetric unit of complex 2 contains one Cu(II)
ion, one [psa]2ꢀ ligand, one 2bpy ligand and one half of
an non-coordinated water molecule. Similar to complex
1, in complex 2, [psa]2ꢀ is also cis-configuration (see
Scheme 1a) and bis(monodentate) coordination mode, the
Cu(II) ion is four-coordinated by two N atoms from a che-
lating 2bpy ligand and two oxygen atoms of two [psa]2ꢀ
ligands, and Cu(II) ions are linked by [psa]2ꢀ ligands into
1D chains too, as shown in Fig. 3. However, in complex
2, the approximately parallel 2bpy ligands allow pairing
of two related single chains to generate double zipper-like
˚
Cu–O5(W) bond length (2.245 A) is much longer than the
˚
mean Cu–O(carboxyl) distance (1.978 A) indicating that
the O5 coordinates to the Cu(II) ion weakly.
In complex 3, the [psa]2ꢀ ligand shows cis-configuration
(see Scheme 1a) and adopts bis(monodentate) coordination
mode, the Cu(II) ions are bridged by [psa]2ꢀ into 1D
chains, and the 2bpy ligands locate at the same side of
the chains. In complex 3, the lattice water molecules consti-
tute trimers as in complex 1. And an interesting feature of

4028
J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
Table 2
Table 3
˚
˚
Selected bond distances (A) and angles (°) for complexes 1–5
Complex 1
Parameters (A, °) for hydrogen bonds of complexes 1 and 3
D–Hꢁ ꢁ ꢁA
d(D– d(Hꢁ ꢁ ꢁA) d(Dꢁ ꢁ ꢁA) \DHA Symmetry
Cu(1)–O(1)
Cu(1)–O(4)#1
1.926(3) Cu(1)–N(1)
1.976(4) Cu(1)–N(2)
2.010(4)
1.999(4)
H)
code
Complex 1
O(5)–H(5A)ꢁ ꢁ ꢁO(3)
0.86 1.99
2.787
155
ꢀ1 + x, y,
z
O(1)–Cu(1)–O(4)#1
O(1)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)
90.7(2)
93.3(2)
174.6(3)
N(1)–Cu(1)–O(4)#1
N(1)–Cu(1)–N(2)
N(2)–Cu(1)–O(4)#1
172.5(2)
81.8(2)
94.4(2)
O(5)–H(5B)ꢁ ꢁ ꢁO(7)
O(6)–H(6A)ꢁ ꢁ ꢁO(5)
O(6)–H(6B)ꢁ ꢁ ꢁO(2)
0.86 2.16
0.89 1.90
0.85 1.99
2.721
2.767
2.821
123
165
164
x, y, z
x, y, z
1 ꢀ x,
ꢀ1/2 + y,
1 ꢀ z
Symmetry transformations used to generate equivalent atoms: #1 x ꢀ 1,
y, z
Complex 2
Cu(1)–O(1)
Cu(1)–O(4)#1
O(7)–H(7A)ꢁ ꢁ ꢁO(4)
0.96 2.07
2.897
144
2 ꢀ x,
ꢀ1/2 + y,
1 ꢀ z
1.962(5) Cu(1)–N(1)
1.923(5) Cu(1)–N(2)
1.973(6)
1.988(7)
O(1)–Cu(1)–O(4)#1
O(1)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)
94.6(2)
94.3(2)
164.4(2)
N(1)–Cu(1)–O(4)#1
N(1)–Cu(1)–N(2)
N(2)–Cu(1)–O(4)#1
160.1(3)
81.0(3)
94.7(3)
Complex 3
O(5)–H(5A)ꢁ ꢁ ꢁO(6)
O(5)–H(5B)ꢁ ꢁ ꢁO(4)
O(6)–H(6A)ꢁ ꢁ ꢁO(5)
O(6)–H(6B)ꢁ ꢁ ꢁO(8)
O(7)–H(7A)ꢁ ꢁ ꢁO(8)
O(7)–H(7B)ꢁ ꢁ ꢁO(4)
O(8)–H(8A)ꢁ ꢁ ꢁO(2)
0.85 2.20
0.85 1.96
0.86 1.85
0.86 2.00
0.88 2.48
0.86 2.43
0.85 2.01
2.698
2.594
2.698
2.766
2.836
2.802
2.768
117
130
169
148
105
107
148
x, y, z
x, 1 + y, z
x, y, z
x, y, z
x, y, z
x, 1 + y, z
1/2 ꢀ x,
1 + y,
ꢀ1/2 + z
Symmetry transformations used to generate equivalent atoms: #1 x,
y + 1, z
Complex 3
Cu(1)–O(1)
Cu(1)–O(5)
Cu(1)–O(3)#1
1.969(5) Cu(1)–N(1)
2.245(5) Cu(1)–N(2)
1.939(5)
1.988(5)
1.985(6)
O(1)–Cu(1)–O(5)
O(1)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)
O(1)–Cu(1)–O(3)#1
O(5)– Cu(1)–O(3)#1
87.8 (2)
146.8(2)
93.9(2)
92.8(2)
93.7(2)
O(5)–Cu(1)–N(1)
124.5(2)
O(5)–Cu(1)–N(2)
N(1)–Cu(1)–O(3)#1
N(1)–Cu(1)–N(2)
N(2)–Cu(1)–O(3)#1
88.6(2)
92.3(2)
80.9(2)
173.0(2)
interpenetration. The asymmetric unit of 4 consists of one
Cu(II) ion, one [psa]2ꢀ ligand, one 4bpy ligand, and one
lattice molecule. Cu(II) ion is also four-coordinated by
two oxygen atoms (O1, O4A) of two [psa]2ꢀ ligands and
two nitrogen atoms (N1, N2A) from two independent
4bpy, the geometry can be described as a slightly distorted
square (see Fig. 7).
Symmetry transformations used to generate equivalent atoms: #1 x,
y + 1, z
Complex 4
Cu(1)–O(1)
Cu(1)–O(4)#1
1.930(8) Cu(1)–N(1)
1.928(9) Cu(1)–N(2)#2
2.051(8)
2.047(8)
In complex 4, the [psa]2ꢀ ligand shows trans-configura-
tion (see Scheme 1b) and also adopts bis(monodentate)
coordination mode. 4bpy ligands link the Cu(II) ions into
O(1)–Cu(1)–O(4)#1
O(1)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)#2
178.2(5)
90.3(3)
90.5(4)
O(4)#1–Cu(1)–N(2)#2
N(1)–Cu(1)–O(4)#1
N(1)–Cu(1)–N(2)#2
89.8(4)
89.3(4)
179.2(5)
Symmetry transformations used to generate equivalent atoms: #1 x,
ꢀy + 2, z + 1/2; #2 x + 1, y + 1, z
Complex 5
Cu(1)–O(1)
Cu(1)–N(1)
1.918(3) Cu(1)–N(2)
2.013(3) Cu(1)–N(3)
2.015(3)
1.987(3)
O(1)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)
171.7(1)
93.1(1)
N(1)–Cu(1)–N(2)
N(1)–Cu(1)–N(3)
80.0(1)
92.8(1)
complex 3 is that the water trimer, the coordinated water
Fig. 1. The 1D chain structure of complex 1.
molecule and the uncoordinated carboxyl oxygen atom
5
(O4) form hydrogen bonds ring in a graph set R5 (10)
[15] which link the neighbor chains by hydrogen bond
between H8A(W) and uncoordinated carboxyl oxygen
atom(O2), resulting in a 2D supramolecular structure (see
Fig. 6). The details of hydrogen bonds are listed in Table 3.
3.4. Structure description of [Cu(psa)(4bpy)] Æ H2O (4)
Scheme 1. The configurations of [psa]2ꢀ ligand in complexes 1–5. (a) cis-
form (in complexes 1–3); (b) trans-form (in complexes 4 and 5).
X-ray diffraction analysis reveals that complex 4 pos-
sesses a 3D porous metal–organic framework with twofold

J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
4029
Fig. 5. The coordination environment of Cu(II) ion in complex 3.
Fig. 2. The 2D supramolecular network of complex 1 formed by hydrogen
bonds in ab plane.
Fig. 6. The 2D network of complex 3 formed by hydrogen bonds in ab
plane.
Fig. 3. The zipper structure of complex 2.
Fig. 4. The 2D supramolecular network formed by hydrogen bonds and
p–p packing in complex 2 viewed along b-axis.
1D chains along two different directions, and the two sets
of the chains (angle 33.5°) are bridged by [psa]2ꢀ ligand
into a 3D CdSO4-like structure with large 1D channels
along the [110] direction, as shown in Fig. 8. The distances
between the Cu(II) ions at the corners of the rectangular
˚
channels are 17.509 and 11.189 A, respectively. Without
the existence of large inclusion ions or molecules in such
Fig. 7. The coordination environment of Cu(II) ion in complex 4.

4030
J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
gen atom (O1) from [psa]2ꢀ ligand (see Fig. 10). Thus
Cu(II) ion is in a slightly distorted square geometry. The
mean Cu–N bond length is longer than the Cu–O distance.
In complex 5, the [psa]2ꢀ ligand adopts bis(monoden-
tate) coordination mode and is also trans-configuration
(see Scheme 1b) bridging two Cu(II) ions. While the termi-
ꢀ
nal ligands 2bpy and monodentate N3 hinder the exten-
sion of the structure, forming a dinuclear structure. The
dinuclear structures are interlinked by hydrogen bonds
(C–Hꢁ ꢁ ꢁO) and cooperated with p–p interactions (face to
˚
face distance 3.243 A) to form 3D brick-wall supramolecu-
lar structure viewed along b-axis (Fig. 11).
Comparing complexes 1, 2, and 4, their synthetic condi-
tions are very similar, and the main difference among them
is the employment of different auxiliary ligands. However,
the differences in the auxiliary ligands have a significant
effect on the structure of the complexes. In complexes 1,
2, and 4, Cu(II) ions are all four-coordinated, while the
[psa]2ꢀ ligands are transformed from cis-configuration in
complexes 1 and 2 by the introduction of phen and 2bpy
ligands to trans-configuration in complex 4 because of
the application of the bridging 4bpy ligand. And chelating
ligands phen and 2bpy tend to forming low-dimensional
structure, while the linear ligand 4bpy is able to construct
3D metal–organic framework. Complexes 2 and 3 were
Fig. 8. The CdSO4-like structure of complex 4.
network, twofold interpenetration happens (see Fig. 9).
And thus the volume of the effective void calculated using
PLATON [16] is 5.3% of the unit-cell volume in the self-inclu-
sion structure which is occupied by the non-coordinated
water molecules. Hydrogen bonds (O5–H5Bꢁ ꢁ ꢁO2, Oꢁ ꢁ ꢁO
˚
distance 2.781 A) can be found between the non-coordi-
nated water molecules and the 3D metal–organic
framework.
3.5. Structure description of [Cu(psa)0.5(N3)(2bpy)] (5)
Complex 5 is a dinuclear compound, and in the asym-
metric of complex 5, there are one Cu(II) ion, one half of
[psa]2ꢀ ligand, one N3 ligand and one 2bpy ligand. In
ꢀ
complex 5, each Cu(II) ion is four-coordinated by two
nitrogen atoms (N1, N2) from oneꢀchelating ligand 2bpy,
one nitrogen atoms (N3) of one N3 ligand, and one oxy-
Fig. 10. The coordination environment of Cu(II) ion in complex 5.
Fig. 9. The twofold interpenetrated spacefilling diagram of complex 4, the water molecules occupied the channels are omitted (left). The simplified
representation structure of complex 4 viewed along [110] (right).

J. Zhou et al. / Polyhedron 26 (2007) 4025–4032
4031
in the temperature range 213–229 °C. The residue CuO
powder in 23.3% was obtained at 580 °C (Calc. 22.3%).
4. Conclusions
In summary, using solvothermal reaction conditions,
we obtained five new Cu(II) complexes 1–5 with [psa]2ꢀ
ligand and different auxiliary ligands phen, 2bpy, 4bpy,
and N3ꢀ. Complexes 1–3 are composed of 1D chains,
extending into 2D supramolecular structure by hydrogen
bonds (complexes 1 and 3) or hydrogen bonds and p–p
stacking interactions (complex 2), in which [psa]2ꢀ ligand
shows cis-configuration and adopts bis(monodentate)
coordination mode. Interestingly, complexes 2 and 3 were
obtained by one-pot reaction, showing that different com-
plexes can be obtained by controlling the reaction condi-
tion in the same system. Complex 4 is of a 3D CdSO4-like
metal–organic framework formed by bridging ligands
[psa]2ꢀ and 4bpy linking Cu(II) ion, and [psa]2ꢀ is in
trans-configuration. The different structures of complexes
1–5 show that the auxiliary ligands have a significant
effect on the formation and the construction of the com-
plexes 1–5.
Fig. 11. 3D supramolecular structure of complex 5 viewed along b-axis.
formed in one-pot reaction. Complex 3 was obtained by
leaving the mother solution of complex 2 at room temper-
ature. Probably with the decrease of temperature, the water
molecules attack the axial site of the square and coordi-
nated to the Cu(II) ions leading to formation of complex
3. And the coordinated water molecules result in different
stacking patterns for 1ꢀD chains and thus the final network.
With addition of N3 to system 2, the half of [psa]2ꢀ
ꢀ
ligands are replaced by the N3 ligands, complex 5 is
Acknowledgement
formed. In complex 5, two Cu(II) ions areꢀbridged by
one [psa]2ꢀ ligand. While both 2pby and N3 ligands as
terminal ligands hinder the extending of the structure,
forming a dinuclear structure. The results show the impor-
tance of the selection of auxiliary ligands in assembly of
complexes.
The authors thank the financial support of National
Nature Science Foundation of China (20331010,
20501003).
Appendix A. Supplementary material
3.6. Thermal analyses of complexes 1, 3–5
CCDC 634194, 634195, 634196, 634197, and 634198
contain the supplementary crystallographic data for 1, 2,
3, 4, and 5. The 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) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary
data associated with this article can be found, in the online
version, at doi:10.1016/j.poly.2007.04.016.
Complexes 1–5 are very stable in air at ambient temper-
ature and almost insoluble in common solvents such as
water, alcohol, acetonitrile, chloroform, methanol, and
acetone. In order to examine their thermal stability, we car-
ried out thermal gravimetric analyses (TGA) of the five
complexes expect complex 2 because of the lower yield.
The result shows that complex 1 is stable up to 75 °C. A
total weight loss of 10.5% occurred in the temperature
range 75–126 °C, corresponding to the loss of the three lat-
tice water molecules in the complex (Calc. 11.0%), the fur-
ther decomposition occurred at 205 °C, and the final
pyrolysis was completed at 670 °C, giving the powder of
CuO. For complex 3, the TG curve exhibits that complex
3 is stable up to 73 °C with the first weight loss of 13.4%
from 73 °C to 107 °C, which corresponds to the loss of four
water molecules (Calc. 13.2%), and unknown decomposi-
tion reactions took place over 200 °C. The thermal decom-
position behavior of complex 4 shows that complex 4
began complicated decomposition up to 207 °C, and the
structure collapsed with the loss of the guest water mole-
cule since no flateau in TG curve was observed during
the decomposition of complex 4. The TG curve shows that
complex 5 is stable up to 213 °C, and decomposes rapidly
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