Journal of the Chinese Chemical Society, 2006, 53, 305-312
305
Synthesis and Structures of Infinite Coordination Polymers from
1,3-Bis(4-pyridyl)propane Ligand and Zinc Salts
Maw-Cherng Suena* (
a
), Hui-An Tsaia (
) and Ju-Chun Wangb (
)
Department of Textile Science, Nanya Institute of Technology, Jhung-Li, Taiwan, R.O.C.
b
Department of Chemistry, Soochow University, Taipei, Taiwan, R.O.C.
The reaction of Zn(NO3)2×6H2O, NH4SCN and bpp (bpp = 1,3-bis(4-pyridyl)propane) in CH3OH afforded the complex [Zn(NCS)2(bpp)]n, 1, while the reaction of Zn(ClO4)2×6H2O and bpp in CH3OH afforded the complex [Zn(ClO4)2(bpp)2]n, 2. Both complexes have been characterized by spectroscopic
methods and their structures have been determined by X-ray crystallography. Crystal data for 1:
Orthorhombic, space group P21212, a = 12.857(6), b = 14.822(7), c = 4.820(2) Å, b = 90°, V = 918.5(8) Å3,
Z = 2 with final residuals R1 = 0.0747 and wR2 = 0.1657. Crystal data for 2: Tetragonal, space group
I4/mcm, a = 11.612(1), b = 11.612(1), c = 23.247(9) Å, b = 90°, V = 3135(1) Å3, Z = 4 with final residuals
R1 = 0.0523 and wR2 = 0.1064. The coordination polymers display a variety of structural architectures,
ranging from zigzag chains (1) and one-dimensional channel-type architectures (2). The effects of the orientation of the nitrogen atom in the pyridine rings on the resultant structures are discussed.
Keywords: Coordination polymer; 1,3-Bis(4-pyridyl)propane; Zigzag chains; Gauche-anti.
INTRODUCTION
The self-assembly of molecules in solid state architecture and crystal engineering has become an area of rapid
growth in recent years.1-3 Many researchers have proposed
strategies for the design of new crystal phase, assembled
from suitable metal centers and organic molecules of different natures and sizes. Most linking ligands are bifunctional rod-like ligands such as 4,4¢-bipyridine (4,4¢-bipy)
and related species,4 which are chosen in order to construct
linear building blocks. We are trying to utilize flexible ligands to generate coordination polymers. Bpp (bpp = 1,3bis(4-pyridyl)propane) is an interesting flexible bidentate
ligand that can adopt four discrete conformations. These
conformations are anti-anti (TT), gauche-gauche (GG),
anti-gauche (TG) and gauche-gauche¢ (GG¢) and can be
described by two dihedral angles, as shown in Fig. 1.5 Ligands accept various conformations from the occurrence of
various networks in the solid state; this is known as “supramolecular isomerism”. Nevertheless, we know very little
yet in connection with the factors deciding ligand conformation in a particular network and their influence upon
the network structure. The synthesis and structures of
[Zn(NCS)2(bpp)]n, 1 and [Zn(ClO4)2(bpp)2]n, 2 are the subject of this report. We also found that complex 1 is one-
dimensional zigzag polymeric chains, while C-H···O and/
or the O-H···O hydrogen-bonding system in 2 expands the
one-dimensional chains into the three-dimensional architectures of the supramolecular.
EXPERIMENTAL
General Procedures
All chemicals were commercially available and used
Fig. 1. Kinds of bpp ligands conformation.
306
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
as received. The IR spectra were recorded on a Jasco FT/
IR-460 plus spectrometer. Elemental analyses were obtained from a PE 2400 series II CHNS/O analyzer,
PERKIN-ELMER CHN-2400 analyzer and HERAEUS
VaruoEL analyzer.
Starting Materials
The reagent Zn(NO3)2×6H2O, Zn(ClO4)2×6H2O, NH4SCN
and bpp (bpp = 1,3-bis(4-pyridyl)propane) were purchased
from Aldrich Chemical Co. and used as receivied.
Preparation of [Zn(SCN)2(bpp)]n, 1
Zn(NO3)2×6H2O (0.19 g, 1 mmol), NH4SCN (0.15 g, 2
mmol) and bpp (0.20 g, 1 mmol) were placed in a flask containing 10 mL CH3OH. The mixture was stirred at room
temperature for 0.5 h to yield a white precipitate. The white
solid was then filtered off and washed with CH3OH. Yield
for 1: 0.379 g (78%). Anal. Calcd. for C15H14ZnN4S2: C,
47.44; H, 3.72; N, 14.75%. Found: C, 47.24; H, 3.70; N,
14.55%. IR (KBr disk): 2775 (br), 1653 (m), 1604 (s), 1567
(m), 1490 (m), 1415 (s), 1349 (s), 1310 (m), 1262 (m), 1221
(m), 1198 (m), 1100 (s), 998 (m), 874 (m), 832 (m), 644 (s),
590 (s), 535 (m), 496 (s), 421 (s).
Preparation of [Zn(ClO4)2(bpp)2]n, 2
Zn(ClO4)2×6H2O (0.37 g, 1 mmol) and bpp (0.40 g, 2
mmol) were placed in a flask containing 10 mL CH3OH.
The mixture was stirred at room temperature for 0.5 h to
yield a white precipitate. The white solid was then filtered
off and washed with CH3OH. Yield for 2: 0.462 g (70%).
Anal. Calcd. for C26H28Cl2N4O8Zn: C, 47.25; H, 4.27; N,
8.48%. Found: C, 46.98; H, 4.19; N, 8.32%. IR (KBr disk):
3543 (br), 3244 (m), 3098 (m), 3074 (m), 2934 (m), 2869
(s), 2026 (s), 1957 (s), 1864 (s), 1622 (m), 1561 (m), 1511
(m), 1437 (m), 1356 (m), 1229 (m), 1099 (m), 1035 (m),
849 (m), 814 (m), 743 (s), 624 (m), 564 (m), 522 (m).
X-RAY CRYSTALLOGRAPHY
[Zn(NCS)2(bpp)]n
Crystals suitable for X-ray diffraction were obtained
by the slow diffusion of methanol into a H2O solution of
[Zn(NCS)2(bpp)]n, 1. A colourless crystal of [Zn(NCS)2(bpp)]n was mounted on the top of a glass fiber with epoxy
cement. The diffraction data of [Zn(NCS)2(bpp)]n was col-
Suen et al.
lected on a Siemens CCD diffractometer, which was
equipped with graphite-monochromated Mo-Ka (la =
0.71073 Å) radiation. The hemisphere data collection
method was used to scan the data points at 4.20 £ 2q £
50.06. The structure factors were obtained after Lorentz
and polarization corrections.6 The positions of the heavy
atoms, including zinc atoms, were located by the direct
method. The remaining atoms were found in a series of alternating difference Fourier maps and least-square refinements.7 The final residuals of the refinement were R1 =
0.0747 [I > 2s (I)] and wR2 = 0.1743 (all data). The crystal
data are listed in Table 1, and selected bond distances and
angles are listed in Table 2.
[Zn(ClO4)2(bpp)2]n
The diffraction data of [Zn(ClO4)2(bpp)2]n, 2, was collected on a Siemens P4 diffractometer, which was equipped
with graphite-monochromated Mo-Ka (la = 0.71073 Å) radiation. Data reduction was carried out by standard methods with the use of well-established computational procedures.8 The structure was solved by direct method and was
refined by the least-squares method using SHELXTL.7 Due
to a 4-fold symmetry formed by the packing of polymeric
cation chains in the lattice, an unreasonable octahedral geometry was imposed on the ClO4 anions. Attempting to resolve this unreasonable geometry by different disordered
models was unsuccessful. The final residuals of the refinement were R1 = 0.0523 [I > 2s (I)] and wR2 = 0.1064 (all
data) for 2. The crystal data are listed in Table 1. Selected
bond distances and angles are listed in Table 3 for 2.
RESULTS AND DISCUSSIONS
Syntheses and spectroscopics studies
The reaction of Zn(NO3)2×6H2O with one equivalent
of bpp (bpp = 1,3-bis(4-pyridyl)propane) and NH4SCN in
CH3OH afforded the complex [Zn(NCS)2(bpp)]n, 1. When
Zn(ClO4)2×6H2O was reacted with two equivalents of bpp
in CH3OH, it afforded the complex [Zn(ClO4)2(bpp)2]n, 2.
The reaction pathways are shown in Scheme I. The IR
spectrum of the complex 1 clearly shows the existence of
bpp and thiocyanate molecules. The absorption bands at
2077, 874 and 496 cm-1 correspond to n(CºN), n(C-S) and
d(NºC-S), respectively. The IR spectrum of the complex 2
clearly indicated the presence of ClO4- bands at 1099 and
Zinc Coordination Polymers
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
307
Table 1. Crystal data for 1 and 2
1
formula
fw
crystal system
space group
a, Å
b, Å
c, Å
V, Å3
Z
dcalc, g/cm3
F(000)
cryst size, mm
m(Mo Ka), mm-1
data collcn instrum
radiation monochromated
in incident beam(l(Mo Ka), Å)
range(2q) for data collection, deg
temp. °C
limiting indices
reflections collected
independent reflections
refinement method
data/restraints/parameters
quality-of-fit indicatorc
final R indices [I > 2s(I)]a,b
R indices (all data)
largest diff. peak and hole, e/Å3
2
C15H14N4S2Zn
379.78
Orthorhombic
P21212
12.857(6)
14.822(7)
4.820(2)
918.5(8)
2
1.370
386
0.35 ´ 0.30 ´ 0.10
1.564
CCD
0.71073
C26H28Cl2N4O8Zn
660.79
Tetragonal
I4/mcm
11.612(1)
11.612(1)
23.247(9)
3135(1)
4
1.400
1360
0.2 ´ 0.8 ´ 0.75
1.004
P4
0.71073
4.20 £ 2q £ 50.06
25
-15 £ h £ 15,
-15 £ k £ 17,
-4 £ l £ 5
4248
1600[R(int) = 0.0411]
Full-matrix least-squares on F2
1600/0/119
1.055
R1 = 0.0747, wR2 = 0.1657
R1 = 0.0899, wR2 = 0.1734
0.754 and -0.792
3.5 £ 2q £ 49.88
25
-1 £ h £ 13,
-13 £ k £ 1,
-27 £ l £ 1
1781
763[R(int) = 0.0382]
Full-matrix least-squares on F2
763/0/80
1.052
R1 = 0.0523, wR2 = 0.1023
R1 = 0.0624, wR2 = 0.1064
0.492 and -0.610
R1 = S||Fo| – |Fc||/S|Fo|. b wR2 = [Sw(Fo2 – Fc2)2/Sw(Fo2)2]1/2.
W = 1/[s2(Fo2) + (ap)2 + (bp)], p = [max(Fo2 or 0) + 2(Fc2)]/3.
A = 0.0000, b = 4.0560 for 1; a = 0.0000, b = 16.8879 for 2.
c
quality-of-fit = [Sw(|Fo2| – |Fc2|)2/Nobserved – Nparameters ]]1/2.
a
Table 2. Selected bond distances (Å) and angles (°) for
[Zn(NCS)2(bpp)]n
Distances
Zn(1)-N(2A)
Zn(1)-N(1)
Angles
N(2A)-Zn(1)-N(2)
N(2)-Zn(1)-N(1)
N(2)-Zn(1)-N(1A)
C(11)-N(1)-Zn(1)
C(3)-N(2)-Zn(1)
1.933(8)
2.045(6)
123.0(5)
104.1(4)
106.3(4)
123.3(7)
0174.7(12)
Zn(1)-N(2)
Zn(1)-N(1)
1.933(8)
2.045(6)
N(2A)-Zn(1)-N(1)
N(2A)-Zn(1)-N(1A)
N(1)-Zn(1)-N(1A)
C(11)-N(1)-C(15)
C(15)-N(1)-Zn(1)
106.3(4)
104.1(4)
113.3(3)
118.4(7)
118.3(8)
Symmetry transformations used to generate equivalent atoms:
(A): -x + 1, -y + 1, z.
624 cm-1. The complexes 1-2 contain characteristic C-N
and C-C vibrational freqencies of the ligand bpp.
Structure
Fig. 1a shows the local coordination of the zinc center
in 1, and Fig. 1b shows an infinite one-dimensional zigzag
chain along the c axis consisting of zinc(II) ions and bpp
ligands. The distorted tetrahedral Zn(II) metal center is
achieved by means of single bridging bpp ligands and two
terminal N-bonded NCS- anions. There are two long ZnN(bpp) bonds (2.045(6) Å) and one short Zn-N (NCS) bond
(1.933(8) Å), again consistent with corresponding bond
length in, for [Zn(NCS)2(PPz)]n9 (PPz = piperazine hexahydrate), [Zn(NCS)2(bbbt)]n10 (bbbt = 1,1¢-(1,4-butanediyl)bis-1H-benzotriazole) and [Zn(NCS)2(pbbt)]n10 (pbbt
= 1,1¢-(1,3-propylene)bis-1H-benzotriazole). The N(2A)Zn(1)-N(2) and N(2A)-Zn(1)-N(1) bond angles are 123.0(5)°
and 106.3(4)°, respectively. The NCS- group is almost lin-
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J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
Suen et al.
Table 3. Selected bond distances (Å) and angles (°) for [Zn(ClO4)2(bpp)2]n
Distances
Zn(1)-N(1A)
Zn(1)-N(1)
Angles
N(1A)-Zn(1)-N(1B)
N(1B)-Zn(1)-N(1)
N(1B)-Zn(1)-N(1C)
2.004(5)
2.004(5)
Zn(1)-N(1B)
Zn(1)-N(1C)
2.004(5)
2.004(5)
112.43(14)
103.7(3)00
112.43(14)
N(1A)-Zn(1)-N(1)
N(1A)-Zn(1)-N(1C)
N(1)-Zn(1)-N(1C)
112.43(14)
103.7(3)00
112.43(14)
Symmetry transformations used to generate equivalent atoms:
(A): y - 1/2, -x + 1/2, -z + 1/2; (B): 2 - x, -y + 1, z; (C): -y + 1/2, x + 1/2, -z + 1/2
Scheme I Reaction pathways for 1-2
S
S
C
C
N
N
Zn
.
N
Zn(NO 3)2 6 H2O + NH4SCN
N
N
n
N
N
N
N
N
Zn(ClO4)2. 6H2O
N
N
Zn
N
N
N
N
ear with an N(2)-C(3)-S(1) angle of 161(1)°. The connection Zn atoms and NCS groups are bent with a C(3)-N(2)Zn(1) angle of 174(1)°.
For instance, 1-D zigzag-chain structures have been
found in [Cu(tta)(4,4¢-bipy)]n11 (tta = 2-thienoyltrifluoroacetone), [Cu(4,4¢-bipy)(MeCN)2]n,12 {[Cu(4,4¢-bipy)(dmp)]BF 4}n,13 {[Mn(4,4¢-bipy){N(SiMe3)2}thf]n,14 [Ni(4,4¢bipy)(EtXA)2]n15 (EtXA = O-ethyl dithiocarbonate),
[Cu(2,2¢-bipy)(4,4¢-bipy)(ClO4)2]n,16 [Zn{(C2H5O)2S2P}2-
n
(4,4¢-bipy)]n,17 [Zn(NO3)2(bpp)]n18 and [Zn(SPh)2(4,4¢bipy)2]n.19 The Zn×××Zn distance in the molecular chain is
12.849 Å. Fig. 2 shows the crystal packing diagram for 1.
The dihedral angle of the two pyridyl rings that coordinated
to the Zn atom is 73.6°, while the dihedral angle of the two
pyridyl rings which is in the ligand is also 73.6°. The interplanar distances between the pyridyl ring is 4.378 Å. No
p-p interactions of any kind are observed.
Fig. 3a shows the local coordination of the zinc center
Zinc Coordination Polymers
in 2, and Fig. 3b shows an infinite one-dimensional channel-type chain along the c axis consisting of zinc(II) ions
Fig. 2. (a) An ORTEP drawing of the local coordination of Zn in 1. (b) An ORTEP diagram showing
the infinite one-dimensional zigzag chain for 1,
which runs parallel to the c-axis. Hydrogen atoms are omitted for clarity.
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
309
and bpp ligands. The distorted tetrahedral Zn(II) metal center is achieved by means of four bridging bpp ligands.
Along the b axis, adjacent zinc atom are bridged by bpp ligands to form a double stranded chain base on 24-membered
macrocyclic building units. The dihedral angles of the pyridyl rings that coordinated to the Zn atom are 64.4° and
Fig. 3. Crystal packing diagram for 1. Hydrogen atoms
are omitted for clarity.
Fig. 4. (a) An ORTEP drawing of the local coordination of Zn in 2. (b) An ORTEP diagram showing the infinite onedimensional chain for 2, which runs parallel to the c-axis. Hydrogen atoms are omitted for clarity.
310
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
97.8°. The Zn×××Zn distance in the molecular chain is
11.624 Å forming the [Zn-(bpp)2-Zn-(bpp)2]n chain. Interestingly, the noncoordinated perchlorate counter-ions occupy cavities between chains. Perchlorate anions are disordered and arranged around the planes by zinc atoms perpendicular to the c axis. The complexes 2 are linked into a
three-dimensional structure through the C-H×××O-Cl (ClO4-)
(O×××H = 2.471 and 2.550 Å, ÐC-H---O = 139.5 and 146.6°)
interactions, which are formed between adjacent chains
through the oxygen atoms and the carbon hydrogen atoms
of bpp molecules (Fig. 5a). Along the c axis, adjacent Zn atoms are linked to each other through the pyridyl nitrogen
atoms of the bpp ligands to form a channel-type chain.
When looking down the c axis, each channel-type chain
forms an open channel which are occupied by the perchlorate anions. The open channels are further linked through
the perchlorate anions to form the 3-D framework structures (Fig. 5b).
Generally, the bpp ligand is well-known as a useful
bridging ligand, and various 1-D zinc zigzag-chain structures, such as [Zn(NO3)2(bpp)]n,18 [M(dca)2(bpp)]n,20 (M =
Zn, Mn, Co, Cd; dca = dicyanamido anion) [ZnCl2(bpp)]n,21(a)
[ZnMe2(bpp)]n,21(b) [Zn(FcCOO)(h 2-FcCOO)(bpp)]n,22
(FcCOO = ferrocenecarboxylate) and the 2-D framework
structure [Zn3(OH)3(bpp)3][NO3]323 have been reported.
The 1-D complex [ZnCl2(bpp)]n21 was prepared by the reaction of ZnCl2, respectively, with bpp ligands in EtOH/
H2O solution at 443 K for 60 h under hydro(solvo)thermal
condition. The novel zinc coordination polymer [Zn(FcCOO)(h2-FcCOO)(bpp)]n22 containing bpp ligands and
ferrocenecarboxylates was prepared by the reaction of
FcCOONa, bpp and Zn(OAc)2·2H2O in MeOH at room
temperature. The complex [Zn3(OH)3(bpp)3][NO3]323 possesses a trinuclear Zn3(OH)3 6-membered ring that acts as a
template for the coordination framework.
Conformation of the bpp ligand
Bpp ligand adopts an anti-anti conformation with dihedral angles of -169.7° (C13-C2-C1-C2BA) and -162.8°
(C2-C1-C2BA-C13E). The dihedral angles are normal and
are found in complexes containing anti-anti conformation,
such as [Cu(NO3)2(bpp)2]×0.25 H2O and [Cu(ClO4)2(bpp)2].24
Table 4 shows conformation and dihedral angles for some
complexes containing bpp ligand. The distances between
the pyridine nitogen atoms is 9.427 Å for the anti-anti
ligand conformation.
Suen et al.
CONCLUSION
The synthesis and structures of a new species
[Zn(NCS)2(bpp)]n and [Zn(ClO4)2(bpp)2]n have been successfully accomplished. Flexible dipyridyl ligands are interesting for the construction of novel interpenetrating coordination networks with zinc salts. In complex 1, the zigzag chains of the tetrahedral Zn(II) metal center is achieved
Fig. 5. (a) Crystal packing diagram for 2. (b) The polymeric structure of 2, viewing down the c axis.
Hydrogen atoms are omitted for clarity.
Zinc Coordination Polymers
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
311
Table 4. Conformation and dihedral angles for some complexes containing bpp ligand
Complex
1
2
Zn(NO3)2(bpp)
Cu(NO3)2(bpp)2·0.25H2O
Cu(ClO)4(bpp)2
Cu(hfac)2(bpp)
[Co(bpp)2(H2O)2]·Bpp·H2O·(ClO4)2
[Ni(bpp)2(H2O)2]·Bpp·H2O·(ClO4)2
Co(bpp)2(NO3)2·2C6H6
Cd(bpp)2(NO3)2·2C6H6
Cd(NO3)2(bpp)4(H2O)
trans-[Cd(bpp)2{Ag(CN)2}2
Fe(N3)2(bpp)2
Cd(dca)2(bpp)
Cu2(tpAc)4(bpp)2
conformation
dihedral angle
anti-anti
anti-anti
gauche-anti
gauche-gauche, anti-anti
gauche-gauche, anti-anti
gauche-anti
gauche-anti
gauche-anti
gauche-anti
gauche-anti
gauche-gauche, anti-anti
gauche-anti
gauche-anti
gauche-gauche
gauche-anti
-169.7°, -169.7°
-180°, -180°
-63.4°, -177.9°
-63.7°, -62.9°; -178.6°, -172.8°
-69.5°, -76.5°; -178.6°, -178.9°
-63°, -171°
60.9°, 168.7°
reference
this work
this work
17
19
19
24
25
25
26
26
27
28
29
30
5(b)
Hfac = hexafluoroacetylacetonate
dca = anion of dicyanamide
tpAc = 3-thiopheneacetate
by means of a single bridging bpp ligand and two terminal
N-bonded NCS- anions. In complex 2, the channel-type
chains tetrahedral Zn(II) metal center is achieved by means
of four bridging bpp ligands. The anions thus show significant influence on the supramolecular structures of Zn(II)
complexes containing bpp ligands, presumably due to the
various types of coordination abilities and geometries of
the anions.
Supplementary material
Crystallographic data (excluding structure factors)
for the structures in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publication number CCDC 234578 and 234579. Copies of
the data can be obtained, free of charge, on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax:
+44(0)-1223-336033 or e-mail: [email protected]].
ACKNOWLEDGMENT
We thank the Nanya Institute of Technology of the
Republic of China for support.
Received May 16, 2005.
REFERENCES
1. Desiraju, G. R. In Crystal Engineering: Design of Organic
Solids; Elrevier: Amsterdam, 1989.
2. Desiraju, wiley, Angew. Chem. Int. Ed. Engl. 1995, 34, 2311.
3. Robson, R.; Abrahams, B. F.; Batten, S. R.; Gable, R. W.;
Hoskins, B. F.; Lin, J. Supramolecular Architecture, ACS
publications, 1992, Ch. 19.
4. (a) Eddaoudi, M.; Batten, S. R.; Robson, R. Angew. Chem.,
Int. Ed. 1998, 37, 1460. (b) Moler, D. B.; Li, H.; Chen, B.;
Reineke, T. M.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res.
2001, 34, 319. (c) Moulton, B.; Zaworotko, M. J. J. Chem.
Res. 2001, 101, 1629. (d) Kim, K. Chem. Soc. Rev. 2002, 31,
96. (e) Evans, O. R.; Lin, W. Acc. Chem. Res. 2002, 35, 511.
5. (a) Carlucci, L.; Ciani, G.; Poserpio, D. M.; Rizzato, S.
Cryst. Eng. Commun. 2002, 4, 121. (b) Marinho, M. V.;
Yoshida, M. I.; Guedes, K. J.; Krambrock, K.; Bortoluzzi, A.
J.; Hörner, M.; Machado, F. C.; Teles, W. M. Inorg. Chem.
2004, 43, 1539.
6. SMART/SAINT ASTRO, Realease 5.06, Bruker AXS, Inc.,
Madison, WI, USA, 1998.
7. SHELXTL, Release 5.10, Bruker AXS, Inc, Karlsruhe, Germany, 1997.
8. XSCANS, Release 2.21, Siemens Energy & Automation,
Madison, WI, USA, 1995.
9. Suen, M.-C.; Keng, T.-C.; Wang, J.-C. Polyhedron 2002, 21,
2705.
10. Meng, X.; Song, Y.; Hou, H.; Fan, Y.; Li, G.; Zhu, Y. Inorg.
Chem. 2003, 42, 1306.
11. Li, M.; Xu, Z.; You, X.; Dong, Z.; Guo, G. Polyhedron 1993,
12, 921.
312
J. Chin. Chem. Soc., Vol. 53, No. 2, 2006
12. Balsnov, A. S.; Begley, M. J.; Hubberstey, P.; Stroud, J. J.
Chem. Soc. Dalton Trans. 1996, 1947.
13. Blake, A. J.; Hill, S. J.; Hubberstey, P.; Li, W.-S. J. Chem.
Soc. Dalton Trans. 1998, 909.
14. Andruh, M.; Roesky, H. W.; Noltemeyer, M.; Schmidt, Z.
H.-G. Naturfosch., Teil B 1994, 49, 31.
15. Xiong, R.-G.; Yu, Z.; Liu, C.-M.; You, X.-Z. Polyhedron
1997, 15, 2667.
16. Abraham, B. F.; Hoskin, B. F.; Winter, G. Aust. J. Chem.
1990, 43, 1759.
17. Zhu, D.-L.; Yu, Y.-P.; Guo, G.-C.; Zhuang, H.-J.; Huang,
J.-S.; Liu, O.; Xu, Z.; You, X.-Z. Acta Cryst., Sect. C 1996,
52, 1963.
18. Suen, M.-C.; Wu, Y.-Y.; Dong, G.-C.; Chen, J.-D.; Ken,
T.-C.; Wang, J.-C. J. Chin. Chem. Soc. 2002, 49, 331.
19. Sampanthar, J. T.; Vittal, J. J. J. Chem. Soc. Dalton Trans.
1999, 1993.
20. Gao, E.-Q.; Bai, S.-Q.; Wang, Z.-M.; Yan, C.-H. Dalton
Trans. 2003, 1759.
21. (a) Chen, Y.-B.; Kao, Y.; Qin, Y.-Y.; Li, Z.-J.; Cheng, J.-K.;
Suen et al.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Hu, R.-F.; Wen, Y.-H.; Yao, Y.-G. Acta Cryst., Sect. C,
2004, 60, m168. (b) Pickett, N. L.; Lightfoot, P.;
Cole-Hamilton, D. J. Adv. Mater. Opt. Electron. 1997, 7, 23.
Hou, H.; Li, L.; Li, G.; Fan, Y.; Zhu, Y. Inorg. Chem. 2004,
42, 3501.
Plater, M. J.; Foreman, M. R. St. J.; Gelbrich, M, T.;
Hursthouse, M. B. J. Chem. Soc., Dalton Trans. 2000, 1995.
Plater, M. J.; Foreman, M. R. St. J.; Slawin, A. M. Z. J.
Chem. Res. 1999, 74.
Plater, M. J.; Foreman, M. R. St. J.; Gelbrich, M, T.;
Hursthouse, M. B. Inorg. Chim. Acta 2001, 318, 171.
Bujaci, M. T.; Wang, X.; Li, S.; Zheng, C. Inorg. Chim. Acta
2002, 333, 152.
Mondal, N.; Saha, M. K.; Mitra, S.; Gramich, V. J. Chem.
Soc., Dalton Trans. 2000, 3218.
Soma, T.; Iwamoto, T. Acta Crystallogr. Sect C 1997, 1819.
Konar, S.; Zangrando, E.; Drew, M. G. B.; Mallah, T.; Ribas,
J.; Chaudhuri, N. R. Inorg. Chem. 2003, 42, 5966.
Gao, E.-Q.; Wang, Z.-M.; Liao, C.-S.; Yan, C.-H. New J.
Chem. 2001, 26, 1096.