Two new CuII coordination polymers: Studies of topological networks and water clusters

Article abstract of DOI:10.1002/ejic.200500731

Two new Cu^II coordination polymers, namely [Cu ₂(BDC)₂(L)₄-(H₂O) ₂]·14H₂O (1) and [Cu_1.5(BTC)(L) _1.5(H₂O)_0.5]·2H₂O (2), where L = 1,1′-(1,4-butanediyl)bis(imidazole), BDC = 1,4-benzenedicarboxylate, and BTC = 1,3,5-benzenetricarboxylate, have been synthesized at room temperature. Complex 1 exhibits an unusual, square-planar, four-connected 2D ₆²4 net, which has been predicated by Wells. Interestingly, three types of water clusters, namely (H₂O) ₆, (H₂O)₈, and (H₂O)₁₀, are observed in the hydrogen-bonded layers constructed by the BDC ligands and water molecules. The BTC anion in compound 2 is coordinated to the Cu ^II cation as tetradentate ligand to form a (6⁶) ₂(4²6⁴8⁴)₂(6 ⁴810) net containing three kinds of nonequivalent points. Thermogravimetric analyses (TGA) and IR spectra for 1 and 2 are also discussed in detail. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200500731

FULL PAPER
DOI: 10.1002/ejic.200500731
Two New CuII Coordination Polymers: Studies of Topological Networks and
Water Clusters
Jin Yang,[a] Jian-Fang Ma,*[a] Ying-Ying Liu,[a] Ji-Cheng Ma,[a] Heng-Qing Jia,[b] and
Ning-Hai Hu[b]
Keywords: Coordination polymers / Copper / Materials science / Topology / Water clusters
Two new CuII coordination polymers, namely [Cu2(BDC)2(L)4-
(H2O)2]·14H2O (1) and [Cu1.5(BTC)(L)1.5(H2O)0.5]·2H2O (2),
where L = 1,1Ј-(1,4-butanediyl)bis(imidazole), BDC = 1,4-
benzenedicarboxylate, and BTC = 1,3,5-benzenetricarboxyl-
ate, have been synthesized at room temperature. Complex 1
exhibits an unusual, square-planar, four-connected 2D 264
net, which has been predicated by Wells. Interestingly, three
are observed in the hydrogen-bonded layers constructed by
the BDC ligands and water molecules. The BTC anion in
compound 2 is coordinated to the CuII cation as tetradentate
ligand to form a (66)2(426484)2(64810) net containing three
kinds of nonequivalent points. Thermogravimetric analyses
(TGA) and IR spectra for 1 and 2 are also discussed in detail.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
types of water clusters, namely (H2O)6, (H2O)8, and (H2O)10
,
important to improve our study of the structures and char-
acteristics of liquid water and ice.
Introduction
During the past few years much attention has been paid to
On the other hand, understanding the structure of coor-
theoretical and experimental studies of small water clusters dination polymers is an important aspect to achieve a true
due to their unusual properties and importance in many advance in the synthesis and design of new materials for
physical, chemical, and biological processes.[1] A detailed practical applications.[5] The analysis of network topology
understanding of the numerous possible structures and sta- is a particularly useful tool for reducing multidimensional
bilities of isolated water clusters in diverse surroundings can structures to simple node-and-connection reference nets.
help us study the nature of water–water interactions in bulk Wells has listed a large number of topologies in his classic
water or ice.[2] For example, the water hexamer is the build- monographs on networks,[6] and numerous fascinating ar-
ing block of ice Ih and appears to be relevant to liquid water chetypal structures, including diamond (66), SiO2 (6482-b),
as well.[3] Several different isomers for the water hexamer, SrSi2 (103-a), α-ThSi2 (103-b), and PtS (4284) have been re-
such as book, bag, ring, cage, and prism topologies, have ported[7] that are of fundamental importance in structural
been found from theoretical calculations.[4] Thus, the search design and in the understanding of structure–property cor-
for experimental models of these small water clusters is very relations. In this work we report two new CuII coordination
Scheme 1.
polymers, namely [Cu2(BDC)2(L)4(H2O)2]·14H2O (1),
[a] Department of Chemistry, Northeast Normal University,
which contains an unusual, square-planar, four-connected
Changchun 130024, People’s Republic of China
264 net and three types of water clusters, and [Cu1.5(BTC)-
E-mail: jianfangma@yahoo.com.cn
Fax: +86-431-568-4009
[b] Changchun Institute of Applied Chemistry, Chinese Academy
of Sciences,
(L)1.5(H2O)0.5]·2H2O (2), which possesses a (66)2(426484)2-
(64810) net [L = 1,1Ј-(1,4-butanediyl)bis(imidazole),[8] BDC
= 1,4-benzenedicarboxylate, BTC = 1,3,5-benzenetricar-
boxylate; Scheme 1].
Changchun 130022, People’s Republic of China
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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Studies of Topological Networks and Water Clusters
FULL PAPER
self-assemble into extended structures, 2D (4,4) square grids
are favored.[9] This observation shows that formation of a
264 net may be attributed to the effects of the flexible L and
the BDC anion. Moreover, if two of the L molecules act as
each of two opposite edges, a single L molecule acts as each
of the other four edges, and every CuII cation can be seen
as a three-connected node, the structure of 1 can be re-
garded as a 2D (6,3) network.
Results and Discussion
Crystal Structures
The synthesis of complexes 1 and 2 is described in the
Experimental Section. Selected bond lengths and angles for
compounds 1 and 2 are listed in Table 1. Part of the struc-
ture of [Cu2(L)4(H2O)2]·(BDC)2·14H2O (1) is shown in Fig-
ure 1 (a). There are two crystallographically unique CuII
cations in the asymmetric unit. Each CuII cation adopts a
distorted square-pyramidal geometry by coordinating to
four nitrogen atoms from four L molecules and one water
molecule. Four nitrogen atoms (N1, N5, N9, and N8A for
Cu1; N4, N11, N13, and N16A for Cu2) form the base of
the pyramid and one water molecule (Ow1 for Cu1; Ow2
for Cu2) occupies the apical position, with respective Cu–
O distances of 2.380 and 2.464 Å. The BDC anion acts as
a counter-anion and structure-directing reagent, indicating
that the coordination of L to the CuII cation is stronger
than that of the BDC anion in this case.
The structure of 1 consists of an unusual, 2D, square-
planar, four-connected 264 net, which has been predicated by
Wells.[6] In this net the CuII cation acts as a four-connected
node and L acts as the edge of every circuit (Figure 1, b).
This 264 net is entirely different from the square-planar four-
connected (86) net first reported by Tong et al. and us,
which was not mentioned by Wells.[5g,8c] It is well known
that when square-planar, four-connected building blocks
In addition, a notable feature within complex 1 is the
presence of three types of water clusters, namely (H2O)6,
(H2O)8, and (H2O)10, in the hydrogen-bonded layer of BDC
anions and water molecules (Figure 2, a). The hydrogen-
bonding parameters are outlined in Table 2. Within the
(H2O)6 cluster, two water molecules (OW2 and OW2A) act
as two hydrogen-bond donors with OW4 and OW4A as hy-
drogen-bond acceptors to form a cyclic water tetramer (Fig-
ure 2, b).[10,11] Interestingly, the cyclic water tetramer is hy-
drogen-bonded to two neighboring free water molecules,
OW6 and OW6A, yielding a water hexamer. Furthermore,
the oxygen atoms O2, O2A, O5, O5A, O7, and O7A from
the BDC ligands are involved in hydrogen bonds with water
molecules OW4, OW4A, OW6, and OW6A to stabilize the
(H2O)6 cluster. Within the (H2O)10 cluster, four water mole-
cules (OW7, OW7A, OW16, and OW16A) act as both hy-
drogen-bond donors and acceptors (Figure 2, c). Four
water molecules (OW13, OW13A, OW15, and OW15A)
play the role of hydrogen-bond donors, while another two
water molecules (OW14 and OW14A) only act as hydrogen-
bond acceptors. Four water molecules (OW15, OW15A,
OW16, and OW16A) form a cyclic water tetramer through
hydrogen bonds, which is further hydrogen-bonded by
water molecules OW7, OW13, OW14, OW7A, OW13A, and
OW14A, leading to an (H2O)10 cluster. Moreover, the
(H2O)10 cluster is stabilized by oxygen atoms O1, O1A, O3,
O3A, O6A, and O6B from BDC ligands. It is of interest
that the four water molecules of the cyclic water tetramer
in the (H2O)6 or (H2O)10 clusters are completely coplanar
without regard to the connectivity of the hydrogen atoms.
The hydrogen-bond lengths are 2.818(4) [OW15–H(15C)···
OW16], 2.879(4) [OW15–H(15D)···OW16#8], 2.812(4)
[OW2–H(2D)···OW4], and 2.809(4) Å [OW2–H(2C)···
OW4#4], and are slightly longer than the average hydrogen-
bond length of liquid water tetramer (2.718 Å).[4a,12] In the
(H2O)8 cluster, the lattice water molecules (OW8A, OW8B,
OW5, and OW5A) and the coordinated water molecules
(OW1 and OW1A) of the [Cu2(L)4(H2O)2]4+ cation are as-
sociated by hydrogen bonds to form a cyclic centrosymmet-
ric water hexamer (Figure 2, d). The average OW···OW dis-
tance is about 2.80 Å, which is slightly longer than the cor-
responding value in ice Ih (2.759 Å) and the calculated value
of 2.718 Å for cyclic water hexamer.[3] However, they are
shorter than those observed in liquid water (2.854 Å).[3] The
cyclic water hexamer is hydrogen-bonded to two neighbor-
ing water molecules (OW10A and OW10B), yielding a
(H2O)8 cluster. It is worthwhile to note that two water mole-
cules of the (H2O)8 cluster bind to the CuII cations. Mean-
while, four water molecules are involved in hydrogen bonds
with the oxygen atoms from the carboxylate groups of the
Table 1. Selected bond lengths [Å] and angles [°] for compounds 1
and 2.
[Cu2(L)4(H2O)2]·(BDC)2·14H2O (1)[a]
N(1)–Cu(1)
N(5)–Cu(1)
N(9)–Cu(1)
N(13)–Cu(2)
2.030(3)
2.008(3)
2.005(3)
2.004(3)
2.380(3)
N(4)–Cu(2)
2.026(3)
1.991(3)
1.990(3)
1.985(3)
N(8)–Cu(1)#1
N(11)–Cu(2)
N(16)–Cu(2)#2
OW1–Cu(1)
N(8)#1–Cu(1)–N(9)
N(9)–Cu(1)–N(5)
N(9)–Cu(1)–N(1)
N(8)#1–Cu(1)–OW1
N(5)–Cu(1)–OW1
175.20(10) N(8)#1–Cu(1)–N(5)
91.32(11)
90.19(11)
177.40(10)
95.89(10)
91.95(11)
90.28(10)
88.05(10)
88.63(10)
90.21(11)
N(8)#1–Cu(1)–N(1)
N(5)–Cu(1)–N(1)
N(9)–Cu(1)–OW1
N(1)–Cu(1)–OW1
N(16)#2–Cu(2)–N(11) 177.28(11) N(16)#2–Cu(2)–N(13) 92.13(11)
N(11)–Cu(2)–N(13)
N(11)–Cu(2)–N(4)
89.64(11)
87.46(11)
N(16)#2–Cu(2)–N(4)
N(13)–Cu(2)–N(4)
90.95(11)
174.22(11)
[Cu1.5(BTC)(L)1.5(H2O)0.5]·2H2O (2)[b]
N(1)–Cu(2)
1.978(4)
1.952(3)
2.014(3)
2.319(7)
2.014(3)
94.02(17)
N(3)–Cu(1)
1.994(4)
2.319(3)
1.937(3)
1.966(4)
2.319(3)
86.14(16)
159.37(14)
86.81(15)
94.97(16)
91.67(13)
88.33(16)
168.7(3)
95.67(14)
O(1)–Cu(1)
O(2)–Cu(1)#1
O(5)–Cu(2)
O(3)–Cu(1)#2
OW1–Cu(2)
Cu(1)–N(6)#3
Cu(1)–O(2)#1
O(1)–Cu(1)–N(3)
Cu(1)–O(3)#4
O(1)–Cu(1)–N(6)#3
N(6)#3–Cu(1)–N(3)
173.90(18) O(1)–Cu(1)–O(3)#4
N(6)#3–Cu(1)–O(3)#4 90.98(16)
N(3)–Cu(1)–O(3)#4
O(1)–Cu(1)–O(2)#1
N(3)–Cu(1)–O(2)#1
O(5)–Cu(2)–O(5)#5
O(5)#5–Cu(2)–N(1)
O(5)–Cu(2)–OW1
107.78(14) N(6)#3–Cu(1)–O(2)#1
90.78(15)
178(2)
91.87(16)
88.900(11) N(1)–Cu(2)–OW1
O(3)#4–Cu(1)–O(2)#1
O(5)–Cu(2)–N(1)
N(1)–Cu(2)–N(1)#5
#1
#1
#4
#2
[a] Symmetry codes for 1:
–x + 1, –y, –z – 1;
–x + 1.5, –y + 1.5, –z + 1;
x, y – 1, z;
–x, –y + 1, –z.
#2
[b] Symmetry codes for 2:
x, y +
#3
#5
1, z;
x, –y + 1, z – 0.5;
–x + 1, y, –z + 1.5.
Eur. J. Inorg. Chem. 2006, 1208–1215
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J. Yang, J.-F. Ma, Y.-Y. Liu, J.-C. Ma, H.-Q. Jia, N.-H. Hu
FULL PAPER
Figure 1. (a) An ORTEP view of complex 1 showing 30% thermal probability ellipsoids. (b) The square-planar, four-connected 2D 264
network.
BDC ligands. This indicates that the (H2O)8 cluster is stabi- water–water interactions are important for the stability of
lized not only by hydrogen bonds but also by coordination the overall structure.
interactions. The water molecule, the organic BDC anion,
It should be pointed out that the angles between two
and the CuII cation play a crucial role in the formation of neighboring carboxylate groups of BDC and BTC anions
the water clusters. Furthermore, the square-planar, four- are 180° and 120°, respectively, which suggests that the BTC
connected 264 net and the hydrogen-bonded layer are further anion may be superior to the BDC anion when it comes to
connected through the coordinating water molecules to meeting the configurations of [Cu(L)n]2+ (n = 1 or 2) cat-
form 3D supramolecular structures. Figure 3 (a) displays ions, and to coordinate to the CuII cation (Scheme 1). Thus,
the packing structure of compound 1. The H-bonding lay- during the construction of 2 the multi-carboxylate ligand
ers act as a “glue” to reinforce the coordination polymeric BTC was chosen as organic anion.
264 sheet, forming an overall 3D structure. Each H-bonding
The structure of 2 contains two crystallographically
layer links two polymeric sheets, and each polymeric sheet unique CuII cations, two unique L molecules, and one
is also attached to two H-bonding layers through OW1 and unique BTC anion. As shown in Figure 4 (a), the Cu1 cat-
OW2 molecules (Figure 3, b). Here, both water–sheet and ion is five-coordinate in a distorted square-pyramidal ge-
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Studies of Topological Networks and Water Clusters
FULL PAPER
ometry by coordinating to two nitrogen atoms (N3 and
N6A) from two L molecules and three oxygen atoms (O1,
O2A, and O3A) from three BTC molecules. The Cu2 center
also has a distorted square-pyramidal coordination sphere
defined by two carboxylate oxygen atoms (O5 and O5A),
one water molecule (OW1), and two nitrogen atoms (N1
and N1A) from two L molecules. The BTC anions bridge
the CuII cations to form 2D networks, which are further
connected through the L ligands to form a 3D framework
structure, see Figure 4 (b) and Figure 4 (c). In addition,
there are some hydrogen-bonded water molecules in the
framework of 2. These water molecules are stabilized by
both hydrogen bonds and coordination interactions (OW1
coordinates to Cu2). The hydrogen-bonded water molecules
not only fill the voids in the supramolecular framework but
also contribute to the total lattice energy. The framework
host sufficiently affects the hydrogen bonds of the water
molecules and the water molecules maybe also influence the
arrangement of the framework host.
If, for reasons of classifying the net, we define the BTC
anion as a single point, then it can be considered as a four-
connected node (Scheme 1). Thus, there are three kinds of
nodes in the structure of 2: a five-connected node for Cu1,
a four-connected node for Cu2, and a four-connected node
for the BTC anion. There are some unique four-, six-, eight-,
and ten-membered circuits through the nodes in 2 (see
Figures S1–S13 in the Supporting Information). For the
four-connected BTC anion, each of six sets of links is con-
tained in six-membered circuits (see Figures S1 and S2).
Thus, the four-connected BTC anion has the Schäfli symbol
66 (Figure 5, a). For the five-connected Cu1 node, ten sets
of links are contained in four six-membered circuits (Fig-
ures S3–S5), two four-membered circuits (Figure S6), and
four eight-membered circuits (Figures S7–10), therefore this
node has the Schäfli symbol (426484) (Figure 5, b). For the
four-connected Cu2 node, four sets of links are contained
in a six-membered circuit (Figure S11), while the other two
sets of links are contained in an eight-membered circuit
(Figure S12) and a ten-membered circuit (Figure S13),
respectively, therefore the four-connected Cu2 node has the
Schäfli symbol (64810) (Figure 5, c). The molar ratio of
these three kinds of nodes is 2:2:1 (BTC/Cu1/Cu2), thus the
structure of 2 can be symbolized as a (66)2(426484)2(64810)
net with three kinds of nonequivalent points (Figure 5, d).[6]
The topological analysis of this net was performed with
OLEX.[13] The present case indicates that topological analy-
sis is a useful tool for the description and comparison of
natural and artificial networks in crystal engineering.[14]
From the above descriptions, the choice of anion is
clearly critical in determining the molecular structures of
the final compounds. In this work, both planar two-carbox-
ylate anion and three-carboxylate anion were chosen to
study the variation of the structures for 1 and 2. The topo-
logical difference between 1 and 2 should therefore result
from the structural features of the BDC and BTC anions.
The BDC anion in 1 is not coordinated to the CuII cation
but acts as a counter-anion and template reagent, whereas
the BTC anion in 2 meets the configuration of [Cu(L)n]2+
Figure 2. (a) The hydrogen-bonded layer of BDC and water mole-
cules. (b) An ORTEP view showing the (H2O)6 cluster and its coor-
dination environment. (c) An ORTEP view showing the (H2O)10
cluster and its coordination environment. (d) An ORTEP view
showing the (H2O)8 cluster and its coordination environment.
Eur. J. Inorg. Chem. 2006, 1208–1215
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FULL PAPER
Table 2. Hydrogen-bonding parameters for 1.[a]
D–H···A [Å]
d(D–H) [Å]
d(H···A) [Å]
d(D···A) [Å]
Ͻ(D···H···A) [°]
OW1–H(1D)···OW5#3
OW1–H(1C)···OW8#2
OW2–H(2D)···OW4
OW2–H(2C)···OW4#4
OW3–H(3C)···O(4)#2
OW3–H(3D)···O(8)
0.88(2)
0.80(4)
0.879(18)
0.87(2)
0.928(17)
0.868(19)
0.88(2)
1.93(3)
1.98(4)
1.97(2)
1.94(2)
1.889(19)
1.99(2)
1.89(2)
1.90(4)
2.01(3)
1.91(2)
1.91(2)
1.95(2)
2.208(16)
1.90(2)
2.03(2)
1.99(3)
1.88(4)
1.98(2)
1.78(2)
2.01(5)
2.17(5)
1.88(3)
2.134(15)
1.95(2)
2.04(2)
1.89(2)
1.82(2)
2.778(4)
2.763(4)
2.812(4)
2.809(4)
2.805(4)
2.850(4)
2.740(4)
2.719(4)
2.827(4)
2.750(4)
2.780(4)
2.816(4)
2.763(5)
2.767(4)
2.849(4)
2.702(4)
2.779(4)
2.851(4)
2.693(4)
2.812(4)
2.837(4)
2.713(4)
2.791(5)
2.818(4)
2.879(4)
2.773(4)
2.672(4)
161(5)
166(4)
159(4)
173(5)
169(3)
168(4)
163(4)
165(4)
151(3)
154(3)
172(3)
165(4)
123(2)
174(5)
151(4)
144(3)
170(3)
164(3)
176(5)
163(5)
131(5)
161(6)
122(4)
174(4)
167(3)
175(4)
163(4)
OW4–H(4D)···O(7)
OW4–H(4C)···OW6#4
OW5–H(5D)···OW10#5
OW6–H(6D)···O(2)#1
OW6–H(6C)···O(5)
0.84(4)
0.896(18)
0.901(18)
0.871(18)
0.888(18)
0.842(18)
0.875(19)
0.90(4)
0.825(18)
0.90(4)
0.896(18)
0.92(4)
0.83(5)
0.90(2)
0.866(19)
0.999(18)
0.874(19)
0.858(18)
0.89(4)
OW7–H(7C)···O(1)
OW7–H(7D)···OW14
OW8–H(8C)···O(4)
OW8–H(8D)···OW5#2
OW9–H(9C)···O(3)
OW10–H(10D)···O(2)
OW10–H(10C)···O(7)#7
OW11–H(11D)···O(5)#1
OW12–H(12C)···O(6)#1
OW12–H(12D)···OW11
OW13–H(13D)···O(6)#8
OW13–H(13C)···OW14
OW15–H(15C)···OW16
OW15–H(15D)···OW16#6
OW16–H(16D)···O(3)
OW16–H(16C)···OW7#6
0.89(4)
#1
#2
#3
#4
[a] Symmetry transformations used to generate equivalent atoms:
–x + 1, –y, –z;
–x + 1, –y, –z – 1;
–x, –y, –z – 1;
–x, –y, –z;
#5
#6
#7
#8
x – 1, y, z;
–x + 1, –y + 1, –z – 1;
x + 1, y, z;
x, y + 1, z.
IR Spectra and TGA
The solid-state IR spectra of 1 and 2 in the region 4000–
400 cm–1 exhibit characteristic bands for BDC, BTC, and L
ligands (see Figure S14 in the Supporting Information). The
IR spectrum of 1 shows a broad band centered around
3427 cm–1 attributable to the O–H stretching frequency of
the water cluster. The IR spectrum of ice shows the O–H
stretch at 3220 cm–1, while this stretching vibration in liquid
water appears at 3490 and 3280 cm–1.[15] This indicates that
the water cluster in 1 has an O–H stretching vibration sim-
ilar to that of liquid water, and the slight difference is attrib-
utable to the environment that the clusters are in.[16] The
peaks around 1600, 1560, 1400, and 1350 cm–1 for 1 and 2
can be attributed to the asymmetric and symmetric vi-
brations of the carboxylate groups.[17]
In order to characterize the compounds 1 and 2 more
fully in terms of thermal stability, we studied them by TGA.
Compounds 1 and 2 were heated from 35 to 780 °C under
N2. As expected, the TGA curves of compounds 1 and 2
exhibit three similar weight-loss stages. The first weight loss,
corresponding to the water molecules, is observed over the
Figure 3. (a) The 3D H-bonding structure of 1. (b) A schematic
representation of the 3D H-bonding structure.
(n = 1 or 2) cations and coordinates to the CuII cation as a wide temperature range 35–90 °C (observed 18.6%, calcu-
four-coordinate ligand. Although different Cu/L ratios (1:1, lated 19.1%) for 1 and 35–93 °C (observed 6.7%, calculated
1:2, 1:3, and 1:4) were used in the preparations, only 1 and 7.1%) for 2. The second weight loss is 52.4% (calculated
2 were isolated as the products. Thus, the formation of these 50.6%) for 1 in the range 238–350 °C and 46.4% (calculated
different frameworks is due to the effects of different or- 45.1%) for 2 in the range 239–344 °C, and is assigned to
ganic anions.
the release of L molecules. Drastic weight losses corre-
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Eur. J. Inorg. Chem. 2006, 1208–1215

Studies of Topological Networks and Water Clusters
FULL PAPER
Figure 5. (a) Schematic representation of the circuits through the
four-connected BTC node. (b) Schematic representation of the cir-
cuits through the five-connected Cu1 node. (c) Schematic represen-
tation of the circuits through the four-connected Cu2 node. (d) The
(66)2(426484)2(64810) net with three kinds of nonequivalent points.
(Cu2 = ᭪, BTC = ᭺, Cu1 = ᭹).
sponding to the removal of BDC and BTC were observed
from 420 to 528 °C for 1 and from 423 to 524 °C for 2,
respectively.
Conclusions
Two new CuII coordination polymers with different top-
ologies have been obtained due to the effects of different
organic anions on the final frameworks’ formation. When
the BDC anion was chosen as the dicarboxylate anion, a
coordination polymer 1 with an unusual, square-planar,
2
four-connected 4 net and three types of water clusters was
6
obtained. In 2, the BTC anion coordinates to the CuII cat-
ion as a tetradentate ligand to form a (66)2(426484)2(64810)
net with three kinds of nonequivalent points.
Experimental Section
Materials and Methods: All reagents and solvents for syntheses
were purchased from commercial sources and used as received. A
Perkin–Elmer 240 elemental analyzer was used to collect microana-
lytical data, and the FT-IR spectrum was recorded from KBr pel-
lets in the range 4000–400 cm–1 on a Mattson Alpha-Centauri spec-
trometer. TGA was performed with a Perkin–Elmer TG-7 analyzer
under nitrogen.
Synthesis of 1,1Ј-(1,4-Butanediyl)bis(imidazole) (L): A mixture of
imidazole (3.4 g, 50 mmol) and NaOH (2.0 g, 50 mmol) in DMSO
(10 mL) was stirred at 60 °C for 1 h, and then 1,4-dichlorobutane
(3.2 g, 25 mmol) was added. The mixture was cooled to room tem-
perature after stirring at 60 °C for 2 h and then poured into 200 mL
of water. A white solid formed immediately, which was isolated by
filtration in 86% yield (4.1 g) after drying in air. C10H14N4 (190.25):
calcd. C 63.16, H 7.37, N 29.47; found C 63.11, H 7.42, N 29.31.
Figure 4. (a) ORTEP view of 2 showing 30% thermal probability
ellipsoids. (b) The 2D layered structure constructed by BTC and
CuII cations. (c) The packing diagram of 2.
Eur. J. Inorg. Chem. 2006, 1208–1215
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1213

J. Yang, J.-F. Ma, Y.-Y. Liu, J.-C. Ma, H.-Q. Jia, N.-H. Hu
FULL PAPER
Synthesis of [Cu2(L)4(H2O)2]·(BDC)2·14H2O (1): A mixture of
CuCl2·2H2O (0.171 g, 1 mmol), NaOH (0.080 g, 2 mmol), and
H2BDC (0.166 g, 1 mmol) in water was stirred for 10 min at 60 °C,
then 1,1Ј-(1,4-butanediyl)bis(imidazole) (L; 0.190 g, 1 mmol) was
added to the mixture. After stirring for 30 min, the blue precipitate
was collected and dissolved in a minimum amount of ammonia
(14 ). Suitable blue single crystals of 1 were obtained by slow
evaporation of this solution at ambient temperature in 73% yield
(109.8 mg). C56H96Cu2N16O24 (1504.6): calcd. C 44.66, H 6.38, N
14.89; found C 44.89, H 6.60, N 14.49.
Acknowledgments
We thank the National Natural Science Foundation of China (no.
20471014), the Fok Ying Tung Education Foundation, and the
Natural Science Foundation of Jilin province (China) for financial
support.
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Table 3. Summary of X-ray crystallographic data for compounds 1
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Compound
1
2
Formula
Mol. mass
Space group
a [Å]
b [Å]
c [Å]
C56H96Cu2N16O24 C24H29Cu1.5N6O8.5
1504.57
P1
632.84
C2/c
¯
13.049(3)
13.334(3)
21.562(4)
91.46(3)
101.60(3)
99.41(3)
3619.2(13)
2, 1.381
0.672
25.860(6)
10.185(2)
22.790(5)
90
97.671(7)
90
5949(2)
8, 1.413
1.137
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α [°]
β [°]
γ [°]
V [Å3]
Z, dcalcd. [gcm–3]
µ (Mo-Kα [mm–1])
F(000)
1588
2612
Reflns. collected / unique 29446 / 14091
18017 / 7010
3181
0.885
0.0633, 0.1237
0.001, 0.000
0.858, –0.324
Reflns. obsd. [I Ͼ 2σ(I)] 8141
GOF on F2
0.940
0.0462, 0.1260
0.001, 0.000
R1,[a] wR2[b] (obsd.)
(∆/σ) max., mean
Max., min. peaks [eÅ–3] 0.541, –0.607
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = |Σw(|Fo|2 – |Fc|2)|/Σ|w(Fo)2|1/2
,
2
2
where w = 1/[σ2(Fo2) + (aP)2 + bP] and P = (Fo + 2Fc )/3.
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Supporting Information (see footnote on the first page of this arti-
cle): Figures of circuits around the nodes for 2 (Figures S1–S13).
The IR spectra of compounds 1 and 2 (Figure S14).
1214
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Eur. J. Inorg. Chem. 2006, 1208–1215

Studies of Topological Networks and Water Clusters
FULL PAPER
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Received: August 18, 2005
Published Online: January 27, 2006
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Eur. J. Inorg. Chem. 2006, 1208–1215
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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