Construction of Ag/1,2,4-triazole/polyoxometalates hybrid family varying from diverse supramolecular assemblies to 3-D rod-packing framework

Article abstract of DOI:10.1021/ic700415w

Eight members of the Ag/1,2,4-triazole/polyoxometalates (POMs) hybrid supramolecular family, namely, [Ag₄(dmtrz)₄]-[Mo ₈O₂₆] (dmtrz = 3,5-dimethyl-1,2,4-triazole, 1), [Ag ₆(3atrz)₆][PMo₁₂O₄₀] ₂·H₂O (3atrz = 3-amino-1,2,4-triazole, 2), [Ag ₂(3atrz)₂]₂[HPMo^VI ₁₀Mo^V₂O₄₀] (3), [Ag ₂(dmtrz)₂]₂[HPMo^VI ₁₀Mo^V₂O₄₀] (4), [Ag ₂(trz)₂]₂[Mo₈O₂₆] (trz = 1,2,4-triazole, 5), [Ag₂(3atrz)₂][Ag₂(3atrz) ₂(Mo₈O₂₆)] (6), [Ag₄(4atrz) ₂Cl][Ag(Mo₈O₂₆)] (4atrz = 4-amino-1,2,4- triazole, 7), and [Ag₅-(trz)₄]₂[Ag ₂(Mo₈O₂₆)]·4H₂O (8), were synthesized through hydrothermal reactions of 1,2,4-triazole or its derivatives with appropriate silver salts and molybdates. Crystal structure analysis reveals that the POM-dependent Ag-1,2,4-triazolate units in these hybrid compounds form a novel tetranuclear cluster (1), a unique double calix[3]arene-shaped hexamer (2), zigzag chains (5 and 6), helix chains (3, 4, and 8), and an interesting looped chain (7). A series of hydrogen bonding-based supramolecular assemblies varying among the 0-D + 0-D (1 and 2), 0-D + 1-D (3 and 4), 1-D + 1-D (5 and 7), and 1-D + 2-D (6) modes between the organomatic cations and POM anions were observed in these structures. Moreover, the inorganic chain [Ag(Mo ₈O₂₆)]_n^3n- in 7 constructed by the building block [Mo₈O₂₆]^4- linked only via single Ag⁺ ion is unprecedented. Compound 8 is the first high-dimensional framework constructed from the [Ag₂(Mo ₈O₂₆)]_n^2n- rod-shaped subunits. These hybrid supramolecular compounds present interesting photochemical properties. The spectroscopic experiments show that they not only are potential semiconductor materials but also have interesting photoluminescence phenomena, including O → Mo [LMCT] and intraligand [π - π*] emissions generated by internal heavy metal effect.

Full text of DOI:10.1021/ic700415w

Inorg. Chem. 2007, 46, 5046−5058
Construction of Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
Varying from Diverse Supramolecular Assemblies to 3-D Rod-Packing
Framework
Quan-Guo Zhai, Xiao-Yuan Wu, Shu-Mei Chen, Zhen-Guo Zhao, and Can-Zhong Lu*
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of
Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
Received March 4, 2007
Eight members of the Ag/1,2,4-triazole/polyoxometalates (POMs) hybrid supramolecular family, namely, [Ag4(dmtrz)4]-
[Mo8O26] (dmtrz 3,5-dimethyl-1,2,4-triazole, 1), [Ag6(3atrz)6][PMo12O40 2 H2O (3atrz 3-amino-1,2,4-triazole, 2),
[Ag2(3atrz)2]2[HPMoVI10MoV2O40] (3), [Ag2(dmtrz)2]2[HPMoVI10MoV2O40] (4), [Ag2(trz)2]2[Mo8O26] (trz
1,2,4-triazole,
5), [Ag2(3atrz)2][Ag2(3atrz)2(Mo8O26)] (6), [Ag4(4atrz)2Cl][Ag(Mo8O26)] (4atrz 4-amino-1,2,4-triazole, 7), and [Ag5-
(trz)4]2[Ag2(Mo8O26)] 4H2O (8), were synthesized through hydrothermal reactions of 1,2,4-triazole or its derivatives
with appropriate silver salts and molybdates. Crystal structure analysis reveals that the POM-dependent Ag 1,2,4-
)
]
‚
)
)
)
‚
−
triazolate units in these hybrid compounds form a novel tetranuclear cluster (1), a unique double calix[3]arene-
shaped hexamer (2), zigzag chains (5 and 6), helix chains (3, 4, and 8), and an interesting looped chain (7). A
series of hydrogen bonding-based supramolecular assemblies varying among the 0-D
(3 and 4), 1-D 1-D (5 and 7), and 1-D 2-D (6) modes between the organomatic cations and POM anions were
observed in these structures. Moreover, the inorganic chain [Ag(Mo8O26)]n
+ 0-D (1 and 2), 0-D + 1-D
+
+
3n-
in 7 constructed by the building block
linked only via single Ag+ ion is unprecedented. Compound 8 is the first high-dimensional framework
4-
[Mo8O26
constructed from the [Ag2(Mo8O26)]n
interesting photochemical properties. The spectroscopic experiments show that they not only are potential
]
2n-
rod-shaped subunits. These hybrid supramolecular compounds present
semiconductor materials but also have interesting photoluminescence phenomena, including O
f Mo [LMCT] and
intraligand [π − π*] emissions generated by internal heavy metal effect.
Introduction
coordination bonds. Usually, the hydrogen bonding (O-
H‚‚‚O, N-H‚‚‚O, O-H‚‚‚N, C-H‚‚‚O, etc.) and aryl pack-
ing (π-π and C-H···π) interactions are most frequently used
to assemble inorganic and organic molecules in solid, liquid,
or gas phase of these compounds. These intermolecular
interactions play important roles in the stabilization of
supramolecular aggregates and have led to various different
assembly modes.3 In the case of ionic supramolecular
compounds, counterions would also play an important role
in the stabilization of the structures of the compounds through
the electrostatic interaction.4 In general, -1-charged small
During the past few years, the interest in the design,
synthesis, characterization, and functions of inorganic-
organic hybrid supramolecular compounds has been growing
extensively.1 Such hybrid compounds have potential applica-
tions in separation and storage materials, molecular
recognition media, nonlinear materials, and heterogeneous
catalysts.2 Most of these compounds are composed of d-block
metal ions and organic ligands, which are connected through
* To whom correspondence should be addressed. E-mail: czlu@
ms.fjirsm.ac.cn; Fax: +86-591-83714946; Tel.: +86-591-83705794.
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1999, 38, 2638. (b) Kitagawa, S.; Kitaura, R.; Noro, S. Angew. Chem.,
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-
-
-
anions, such as, NO3 , BF4 , PF6 , etc., are used as
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5046 Inorganic Chemistry, Vol. 46, No. 12, 2007
10.1021/ic700415w CCC: $37.00
© 2007 American Chemical Society
Published on Web 05/08/2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
Scheme 1. 1,2,4-Triazole and Its Derivatives Used in the Current
Work
directing the formation of some porous entities through either
cation-anion interactions or hydrogen-bonding interactions
between an organic host and an anionic guest.6
Polyoxometalates (POMs), as one kind of significant metal
oxide cluster with nanosizes and abundant topologies, have
recently been employed as inorganic counterions for con-
structing inorganic-organic hybrid supramolecular arrays
with various organic ligands or metal-organic coordination
fragments.7 Supramolecular assembles based on polyoxo-
metalates (POMs) have been intensively investigated in many
important aspects such as catalysis, electrical conductivity,
and biological chemistry.8 Compared to simple inorganic
anions, POMs are bigger, have more diverse topologies, have
a higher charge, and are more suitable as guest units in the
metal-organic host because they lead to larger pores,
channels, and cavities. To date, several unique high-
dimensional metal-organic frameworks have been synthe-
sized using POMs as templates.7a,7c,9 A current development
is to explore novel lattice architectures resulting from the
association of organometallic units and POM anions. During
this process, we adopt the Ag/1,2,4-triazole/polyoxometalate
system as our research project for the following reasons. First,
although M′/ligands/POMs hybrid solids have been studied
extensively, less than twenty examples with M′ ) Ag have
been described to date.10 It is well-known that the 4d
transition metal silver(I) is favorable and fashionable ion for
the construction of coordination clusters or polymers because
of its coordination diversity and flexible, as well as its
positive coordination tendency with various donor atoms,
such as O, S, I, P, etc. On the other hand, the silver
coordination compounds not only are good candidates for
potential conducting materials but also show interesting
photophysical and photochemical properties.11 Second, anions
are well-known to be an important factor that affects the
structures of Ag(I)-based polynuclear compounds or poly-
mers. However, little is know about this effect of large POM
anions to date.10i Third, nearly all the organic components
studied in the POM-based hybrid family are those ligands
containing 2-, 3-, or 4-substituted pyridines, such as 2,2-
bpy, 2,2-phen, 4,4-bpy, and so on. In fact, pyridine is just
one of many readily available heterocyclic ring systems,
which differ in their electronic and structural properties;
however, most of them have been surprisingly ignored when
people look for building blocks.12 One such ligand is 1,2,4-
triazole and its derivatives, which unite the coordination of
both pyrazole and imidazole and exhibit an extensively
documented ability to bridge metal ions to afford polynuclear
clusters or polymers with unusual structural diversity.13 As
an ongoing research project dealing with the coordination
chemistry of 1,2,4-triazole ligands,14 we report a series of
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Inorganic Chemistry, Vol. 46, No. 12, 2007 5047

Zhai et al.
B. [Ag6(3atrz)6][PMo12O40]2‚H2O (2). A mixture of H3-
[PMo12O40]‚xH2O (reference molecular weight ) 1825) (0.45 g,
0.25 mmol), Ag2SO4 (0.12 g, 0.38 mmol), 3atrz (0.063 g, 0.75
mmol), and H2O (10 mL) was heated at 180 °C for 5 days under
autogenous pressure after adjustment of the pH to ∼2.1 by the
addition of dilute H2SO4 solution. Pure orange polyhedron crystals
were isolated after the reaction solution was cooled gradually
(5 °C h-1) to room temperature, washed with water, and air-dried.
Yield: 0.54 g (∼90% based on Ag). Anal. Calcd (%) for C12H26-
Ag6Mo24N24O81P2: C, 2.99; H, 0.54; N, 6.98; Mo, 47.83. Found
(%): C, 3.01; H, 0.55; N, 6.93; Mo, 47.90. IR (solid KBr pellet,
cm-1): ν 3340 (br), 1624 (s), 1579 (w), 1547 (w), 1375 (w), 1246
(w), 1060 (s), 981 (w), 969 (w), 950 (s), 869 (m), 845 (w), 791 (s),
593 (w).
Ag/1,2,4-triazole/POM hybrid solids, namely, [Ag4(dmtrz)4]-
[Mo8O26] (dmtrz ) 3,5-dimethyl-1,2,4-triazole, 1), [Ag6-
(3atrz)6][PMo12O40]2‚H2O (3atrz ) 3-amino-1,2,4-triazole, 2),
[Ag2(3atrz)2]2[HPMoVI10MoV O40] (3), [Ag2(dmtrz)2]2-
2
[HPMoVI10MoV O40] (4), [Ag2(trz)2]2[Mo8O26] (trz ) 1,2,4-
2
triazole,5),[Ag2(3atrz)2][Ag2(3atrz)2(Mo8O26)](6),[Ag4(4atrz)2-
Cl][Ag(Mo8O26)] (4atrz ) 4-amino-1,2,4-triazole, 7), and
[Ag5(trz)4]2[Ag2(Mo8O26)]‚4H2O (8). The POM-dependent
metal-organic units in these compounds are a novel tetra-
nuclear cluster (1), an unprecedented double calyx[3]arene-
shaped hexamer (2), zigzag chains (5 and 6), helix chains
(3, 4, and 8), and a looped chain (7). A series of interesting
hydrogen bonding-based supramolecular assemblies between
the organomatic units and POMs were observed in these
structures. Their structure relationship reveals that the POM-
templated synthetic approach is suitable for not only high-
dimensional metal-organic polymers (2-D or 3-D) but also
chain structures or polynuclear clusters. Here, we discuss
the supramolecular assemblies and novel photochemical
properties of this Ag/1,2,4-triazole/ polyoxometalates hybrid
family in detail.
C. [Ag2(3atrz)2]2[HPMoVI10MoV2O40] (3) and [Ag2(3atrz)2]-
[Ag2(3atrz)2(Mo8O26)] (6). A mixture of H3[PMo12O40]‚xH2O (0.45
g, 0.25 mmol), Ag(CH3CO2) (0.17 g, 1.0 mmol), 3atrz (0.084 g,
1.0 mmol), and H2O (10 mL) was heated at 180 °C for 5 days
under autogenous pressure (initial pH value was ∼2.2 without
adjustment). Black polyhedron crystals of 3 and colorless prism
crystals of 6 were isolated manually from a yellow unidentified
powder after the reaction solution was cooled gradually (5 °C h-1
)
to room temperature, washed with water, and air-dried. Compound
3. Yield: 0.22 g (∼34% based on Ag). Anal. Calcd (%) for C8H12-
Ag4Mo12N16O40P: C, 3.72; H, 0.47; N, 8.67; Mo, 44.52. Found
(%): C, 3.69; H, 0.50; N, 8.63; Mo, 44.63. IR (solid KBr pellet,
cm-1): ν 3442 (br), 3412 (m), 3347 (br), 3144 (w), 2919 (w), 2851
(w), 1639 (s), 1572 (w), 1549 (w), 1445 (w), 1300 (w), 1244 (w),
1228 (w), 1166 (w), 1077 (w), 1054 (s), 949 (s), 846 (m), 794 (s),
732 (w), 643 (w), 504 (w). Compound 6. Yield: 0.05 g (∼10%
based on Ag). Anal. Calcd (%) for C8H16Ag4Mo8N16O26: C, 4.92;
H, 0.83; N, 11.49; Mo, 39.33. Found (%): C, 5.13; H, 0.76; N,
11.68; Mo, 39.21. IR (solid KBr pellet, cm-1): ν 3420 (s), 3334
(w), 3140 (w), 2769 (w), 1643 (s), 1549 (w), 1385 (w), 1295 (w),
1225 (w), 1167 (w), 1058 (m), 997 (w), 939 (s), 895 (m), 839 (w),
747 (w), 684 (w), 630 (w), 523 (w).
D. [Ag2(dmtrz)2]2[HPMoVI10MoV2O40] (4). A mixture of H3-
[PMo12O40]‚xH2O (0.45 g, 0.25 mmol), Ag(CH3CO2) (0.17 g, 1.0
mmol), dmtrz (0.097 g, 1.0 mmol), and H2O (10 mL) was heated
at 180 °C for 5 days under autogenous pressure (initial pH value
was ∼2.1 without adjustment), followed by slow cooling (5 °C
h-1) to room temperature. Almost phase-pure black polyhedron
crystals were collected, washed with water, and air-dried. Yield:
0.56 g (∼85% based on Ag). Anal. Calcd (%) for C16H28Ag4-
Mo12N12O40P: C, 7.27; H, 1.07; N, 6.36; Mo, 43.57. Found (%):
C, 7.29; H, 1.12; N, 6.33; Mo, 43.53. IR (solid KBr pellet, cm-1):
ν 3447 (m), 3232 (m), 3108 (w), 2816 (w), 1634 (w), 1583 (w),
1561 (w), 1544 (w), 1408 (m), 1373 (m), 1289 (w), 1138 (w), 1060
(s), 962(s), 933 (w), 788 9s), 593 (w), 504 (w).
Experimental Section
Materials and Methods. The ligands dmtrz and 4atrz were
prepared according to the literature methods.15 Other reagents and
solvents employed were commercially available and were used
without further purification. C, H, N, and Mo elemental analyses
were determined on an Elementar Vario EL III elemental analyzer.
The FT-IR spectra (KBr pellets) were recorded on a PECO (U.S.A.)
SpectrumOne spectrophotometer. UV-vis absorption and diffuse
reflectance spectra were obtained with a Lamdba900 UV-vis-
NIR spectrophotometer at room temperature. Initially, the 100%
line flatness of the spectrophotometer was set using barium sulfate
(BaSO4). A powder crystal sample of the compound was mounted
on the sample holder. The thickness of the sample was ap-
proximately 2.00 nm, which was much larger than the individual
crystal particles. The fluorescence spectra were measured on powder
crystal samples at room temperature using a Cary Eclipse fluores-
cence spectrophotometer. The excitation slit and emission slit both
were 2.5 nm. The X-band ESR spectra were recorded on a Bruker
2000-D-SRC spectrometer on powder crystal materials at 298 K.
Thermal stability studies were carried out on a NETSCHZ STA-
449C thermoanalyzer under air (40-700 °C range) at a heating
rate of 10 °C min-1
.
Syntheses. A. [Ag4(dmtrz)4][Mo8O26] (1). A mixture of MoO3
(0.072 g, 0.50 mmol), Ag(CH3CO2) (0.085 g, 0.50 mmol), Na2-
MoO4‚2H2O (0.12 g, 0.50 mmol), dmtrz (0.048 g, 0.5 mmol), and
H2O (10 mL) was heated at 180 °C for 5 days under autogenous
pressure after adjustment of the pH to ∼4.3 by the addition of 20%
tetramethylammonium hydroxide (pH 2.0 after hydrothermal reac-
tion). Colorless block crystals were manually isolated from
unidentified powder after the reaction solution cooled gradually
(5 °C h-1), washed with water, and air dried. Yield: 0.16 g (∼64%
based on Ag). Anal. Calcd (%) for C16H28Ag4Mo8N12O26: C, 9.59;
H, 1.41; N, 8.39; Mo, 38.31. Found (%): C, 9.42; H, 1.50; N, 8.41;
Mo, 38.76. IR (solid KBr pellet, cm-1): ν 3458 (br), 3302 (m),
2963 (w), 2832 (w), 1631 (w), 1581 (m), 1556 (w), 1411 (w), 1393
(w), 1376 (w), 1067 (w), 939 (s), 905 (s), 836 (s), 723 (s), 687
(w), 657 (s), 548 (w), 520 (w), 472 (w), 445 (w), 407 (w).
E. [Ag2(trz)2]2[Mo8O26] (5). A mixture of (NH4)6Mo7O24‚4H2O
(0.31 g, 0.25 mmol), Ag2SO4 (0.31 g, 1.0 mmol), trz (0.069 g, 1.0
mmol), and H2O (10 mL) was heated at 180 °C for 5 days under
autogenous pressure after adjustment of the pH to ∼4.5 by the
addition of a dilute H2SO4 solution. Pure green block crystals were
isolated after the reaction solution was cooled gradually
(5 °C h-1) to room temperature, washed with water, and air dried.
Yield: 0.36 g (∼75% based on Ag). Anal. Calcd (%) for C8H12-
Ag4Mo8N12O26: C, 5.08; H, 0.64; N, 8.89; Mo, 40.58. Found (%):
C, 4.96; H, 0.72; N, 8.90; Mo, 40.12. IR (solid KBr pellet, cm-1):
ν 3435 (br), 3115 (w), 2923 (w), 1635 (s), 1496 (w), 1381 (w),
1287 (w), 1263 (w), 1171 (m), 1081 (m), 949 (s), 917 (w), 899
(m), 871 (m), 812 (s), 683 (s), 640 (m), 603 (s), 547 (w), 515 (w),
475 (w).
(15) (a) Herbst, R. M.; Garrison, J. A. J. Org. Chem. 1953, 18, 872. (b)
Baitalik, S.; Dutta, B.; Nag, K. Polyhedron 2004, 23, 913.
5048 Inorganic Chemistry, Vol. 46, No. 12, 2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
F. [Ag4(4atrz)2Cl][Ag(Mo8O26)] (7). A mixture of MoO3 (0.14
g, 1.0 mmol), Ag(CH3CO2) (0.25 g, 1.5 mmol), Na2MoO4‚2H2O
(0.24 g, 1.0 mmol), 4atrz (0.042 g, 0.50 mmol), and H2O (10 mL)
was heated at 180 °C for 5 days under autogenous pressure after
adjustment of the pH to ∼4.3 by the addition of a dilute HCl
solution (pH 1.6 after hydrothermal reaction). Gray block crystals
were manually isolated from unidentified powder after the reaction
solution cooled gradually, washed with water, and air dried.
Yield: 0.39 g (∼68% based on Ag). Anal. Calcd (%) for C4H8-
Ag5Mo8N8O26Cl: C, 2.49; H, 0.42; N, 5.82; Mo, 39.84. Found
(%): C, 2.46; H, 0.56; N, 5.79; Mo, 40.02. IR (solid KBr pellet,
cm-1): ν 3434 (br), 3222 (w), 3097 (w), 2976 (w), 1635 (m), 1593
(m), 1130 (w), 1072 (w), 944 (w), 920 (w), 903 (w), 886 (s), 830
(m), 711 (m), 667 (w), 616 (w), 575 (w).
byproduct of 3, and the search for a suitable synthesis method
was unsuccessful. The selection of a suitable Ag source is
the second key factor in our syntheses of these compounds.
Many failed experiments show that free Ag+ ions are readily
reduced to simple substance Ag or oxidized to black Ag2O
under hydrothermal conditions. Thus, the water-soluble salt
AgNO3 is not an ideal Ag source, and therefore, insoluble
salts Ag(CH3CO2) or Ag2SO4 were selected in our experi-
ments. We speculated that the slow release of Ag+ ions under
hydrothermal conditions can provide the chance for their
assembly with organic ligands and decrease the probability
of oxidation or reduction. The experimental results prove
that our selection is right. The successful isolation of these
compounds under hydrothermal conditions using Ag(CH3-
CO2) or Ag2SO4 as the silver source provides a feasible
synthetic route to Ag-based coordination polymers or hybrid
materials. Moreover, the Keggin anions in compounds 3 and
4 were reduced under hydrothermal conditions. Since these
two compounds both are synthesized in acidic media, we
G. [Ag5(trz)4]2[Ag2(Mo8O26)]‚4H2O (8). A mixture of (NH4)6-
Mo7O24‚4H2O (0.15 g, 0.12 mmol), Ag(CH3CO2) (0.25 g, 1.5
mmol), trz (0.069 g, 1.0 mmol), and H2O (10 mL) was heated at
180 °C for 5 days under autogenous pressure after adjustment of
the pH to ∼4.3 by the addition of a dilute CH3COOH solution.
Pure red block crystals were isolated after the reaction solution
was cooled gradually (5 °C h-1) to room temperature, washed with
water, and air dried. Yield: 0.34 g (∼88% based on Ag). Anal.
Calcd (%) for C16H16Ag12Mo8N24O30: C, 6.22; H, 0.52; N, 10.89;
Mo, 24.87. Found (%): C, 6.18; H, 0.64; N, 11.05; Mo, 24.64. IR
(solid KBr pellet, cm-1): ν 3435 (br), 2977 (w), 1635 (s), 1501
(w), 1384 (w), 1279 (w), 1148 (w), 1067 (w), 879 (br), 550 (w).
speculatedthereducedKegginanionscouldbe[HPMoVI10MoV O40]4-.
2
This result was in agreement with the charge neutrality,
crystal color, and ESR spectra.
Description of Crystal Structures. Compound 1 consists
of tetranuclear silver coordinated cations [Ag4(dmtrz)4]4+ and
polyoxoanions [Mo8O26]4-, and it crystallizes in the space
group C2/c with four formula units in the unit cell. Three
crystallographically independent Ag(I) are of linear coordi-
nation environments (Ag-N bonds and corresponding
N-Ag-N angles ) 2.195(4) Å and 140.7(2)° for Ag(1);
2.186(4) Å and 138.4(2)° for Ag(2); 2.130(4), 2.135(4) Å,
and 167.0(18)° for Ag(3)). Four Ag(I) atoms were linked
by dmtrz ligands through N1,N2-bridging mode to form the
coordinated [Ag4(dmtrz)4]4+ cation (Figure 1). In such a
fashion, the Ag‚‚‚Ag distances vary from 3.246(11) to 3.406-
(3) Å. A series of such structures with CuI as metal center
have been reported in our previous report,14c and tetranuclear
Ag(I) clusters based on triazole ligands are rarely presented
to date.18 It is noted that although the aromatic rings are
basically parallel, the distances between the planes of two
rings are in the range of 3.754(7)-4.328(8) Å, indicating
no significant π-π stacking interactions. The centrosym-
metric [Mo8O26]4- anion built up from eight edge-shared
{MoO6} octahedra is a typical â-octamolybdate.19 The neutral
[{Ag(dmtrz)}4Mo8O26] was further extended into three-
dimensional supramolecular arrays (Figure S1) through weak
(N-H‚‚‚O) and (C-H‚‚‚O) hydrogen bonds (Table 3). As
shown in Figure S1, the overall packing of 1 can be derived
from the NaCl structure type. The octamolybdates are
coordinated by six [Ag4(dmtrz)4]4+ clusters in the form of a
distorted octahedra with center-to-center distances of 7.394-
(13), 8.091(12), and 8.960(1) Å. The silver clusters are
connected by six octamolybdates anions octahedrally as
well. Two similar NaCl-type supramolecular intercluster
compounds had been reported to date: one is constructed
X-ray Crystallography. Suitable single crystals of 1-8 were
carefully selected under an optical microscope and glued to thin
glass fibers. Crystallographic data for all compounds were collected
with a Siemens Smart CCD Diffractometer with graphite-mono-
chromated Mo KR radiation (λ ) 0.71073 Å) at T ) 293(2) K.
Absorption corrections were made using the SADABS program.16
The structures were solved using the direct method and refined by
full-matrix least-squares methods on F2 by using the SHELX-97
program package.17 All non-hydrogen atoms were refined anis-
tropically. The positions of the hydrogen atoms attached to carbon
and nitrogen atoms were fixed at their ideal positions, and those
attached to water oxygen atoms were not located. Crystal data, as
well as details of data collection and refinement, for 1-8 are
summarized in Table 1. The structural characteristics are listed in
Table 2.
Results and Discussion
Syntheses. The compounds of this study were prepared
in good yields by exploitation of the hydrothermal reactions
of 1,2,4-triazole ligands, suitable silver salts, and molybdates
at 180 °C for 5 days. The conditions reported in the
Experimental Section have been optimized for yields of
crystalline products. Two key factors affect the formation
of the resulting products: one is the pH value, and the other
is the Ag source. It has been well-known that the formation
of different polyoxometalate clusters is mainly controlled by
the pH values. In our experiments, the pH values were kept
at 2.0-2.5 for compounds 2, 3, and 4 and at 4.3-4.5 for
compounds 1, 5, 7, and 8 or else no products could be
obtained or the yield was very low. Compound 6 is a
(16) Sheldrick, G. M. SADABS, Program for Area Detector Adsorption
Correction; Institute for Inorganic Chemistry, University of Go¨ttin-
gen: Go¨ttingen, Germany, 1996.
(17) Sheldrick, G. M. SHELXL-97, Program for Solution of Crystal
Structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(18) Wang, Y.; Yi, L.; Yang, X.; Ding, B.; Cheng, P.; Liao, D. Z.; Yan, S.
P. Inorg. Chem. 2006, 45, 5822.
(19) Klemperper, W. G.; Shum, W. J. Am. Chem. Soc. 1976, 98, 8291.
Inorganic Chemistry, Vol. 46, No. 12, 2007 5049

Zhai et al.
Table 1. Crystal Data and Structure Refinements for Compounds 1-8
1
2
3
4
empirical formula
fw
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å 3)
Z
C16H28Ag4Mo8N12O26
2003.50
C2/c
22.381(2)
11.2690(7)
19.0866(18)
90
119.119(4)
90
4205.5(6)
4
C12H26Ag6Mo24N24O81P2
4814.29
R3h
17.6706(6)
17.6706(6)
23.5201(11)
90
90
120
6360.2(4)
3
C8H13Ag4Mo12N16O40P
2587.07
P21/n
12.1848(7)
14.4015(8)
13.5158(9)
90
91.926(3)
90
2370.4(2)
2
C16H29Ag4Mo12N12O40P
2643.24
P21/n
13.755(2)
13.589(2)
14.229(2)
90
90.925(2)
90
2659.4(7)
2
F(000)
3760
3.164
4.216
6702
3.771
4.936
2398
3.625
4.823
2470
3.301
4.301
F (Mg m-3
)
abs coeff (mm-1
)
θ for data
collection (deg)
3.29-27.48
2.18-27.48
3.02-27.48
2.08-27.49
reflns
collected/unique
15 936/4810
16 630/3250
18 167/5429
20 508/6050
unique reflns (Rint
params
)
0.0289
299
1.050
0.0422, 0.0993
0.0418
225
1.106
0.0402, 0.0881
0.0438
386
1.057
0.0522, 0.1040
0.0230
403
1.055
0.0367, 0.0889
GOF on F2
R1a, wR2
[I > 2σ(I)]
R1, wR2
0.0539, 0.1075
0.0446, 0.0907
0.0651, 0.1125
0.0436, 0.0940
(all data)
5
6
7
8
empirical formula
fw
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å 3)
Z
C8H12Ag4Mo8N12O26
1891.30
P1h
C8H16Ag4Mo8N16O26
1951.37
P1h
C4H8Ag5Mo8N8O26Cl
1926.50
C2/c
14.0585(11)
14.8261(11)
14.4347(11)
90
99.582(3)
90
2966.7(4)
4
C16H16Ag12Mo8N24O30
3086.49
P1h
7.8389(6)
9.9999(7)
11.6357(9)
106.6160(10)
102.630(2)
100.051(3)
825.00(11)
1
8.2465(4)
10.8172(5)
10.9336(2)
71.101(7)
82.030(10)
87.775(10)
913.81(6)
1
9.7391(6)
11.0838(6)
13.7370(8)
72.3230(10)
84.3840(10)
73.71(3)
1356.01(14)
1
F(000)
876
5.360
3.807
908
3.546
4.848
3536
4.313
6.678
1420
3.780
6.103
F (Mg m-3
)
abs coeff (mm-1
)
θ for data
collection (deg)
2.37-27.48
3.18-27.48
3.10-27.48
1.56-25.71
reflns
collected/unique
6343/3711
6979/4098
11 292/3395
7485/5099
unique reflns (Rint
params
)
0.0193
262
1.024
0.0261, 0.0622
0.0167
283
1.024
0.0316, 0.0782
0.0307
240
1.165
0.0455, 0.1006
0.0286
391
1.061
GOF on F2
R1a, wR2
[I > 2σ(I)]
R1, wR2
0.599, 0.1328
0.0307, 0.0652
0.0382, 0.0837
0.0518, 0.1050
0.0702, 0.1418
(all data)
2
2
2
a R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) [∑w(Fo - Fc )2/∑w(Fo )2]0.5
.
from [Cu4(datrz)4]4+ and â-octamolybdate clusters,14c and
the other is based on [Au9(PPh3)8]3+ and [PW12O40]3-
clusters.20
from the cavity with a distance between two phosphrous
atoms of ∼13 Å. The guest anion is a normal R-Keggin
structure composed of 12 corner- or edge-sharing MoO6
octahedra with the central phosphorus ordered and coordi-
nated to four oxygen atoms in a tetrahedral fashion. The P-O
distances are 1.531(4) and 1.529(6) Å, respectively. The
Mo-O distances can be grouped into three sets: Mo-Ot
(terminal) ) 1.668(4)-1.685(4) Å, Mo-Oc (central) )
2.430(3)-2.435(4) Å, and Mo-Ob (bridge) ) 1.852(4)-
1.967(4) Å. The bond angles of Mo-Oc-Mo are in the range
of 88.76(12)-89.08(12)°, and those of Mo-Ob-Mo fall into
two groups: 124.9(2)-126.2(2)° in a Mo3O13 triplet and
151.5(2)-152.3(2)° between two Mo3O13 triplets. Although
thishost-guestassemblyissimilarto[Cu6(4,7-phenanthroline)8-
Compound 2 crystallizes in the space group R3h with three
formula units in the unit cell. Six two-coordinated Ag(I)
atoms are linked by six 3atrz ligands through N1,N2-bridging
mode (Figure 2a, Ag-N ) 2.132(6) and 2.123(5) Å and
N-Ag-N ) 168.0(2)°) to form a double calyx[3]arene-
shaped hexamer, where two [PMo12O40]3- are contained as
non-coordinated guest anions (Figure 2b). Two bottom-
shared bowls are open in opposite directions, and because
of the limited void, two R-Keggin ions have to protrude out
(20) Scheulz-Dobrick, M.; Jansen, M. Eur. J. Inorg. Chem. 2006, 4498.
5050 Inorganic Chemistry, Vol. 46, No. 12, 2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
Table 2. Selected Bond Lengths (Å) and Angles (deg) and Summary of Structural Characteristics of Compounds 1-8
coordination
geometry of Ag
Ag-X
(Å, X ) N/O/Cl)
X-Ag-X
(deg, X ) N/O/Cl)
assembly
mode
Ag-triazolate
POMs
[Ag4(dmtrz)4][Mo8O26] (1)
linear, {N2} (×3)
2.195(4),
2.186(4)
2.130(4),
2.135(4)
140.7(2),
tetranuclear
cluster
â-[Mo8O26]4-
0-D + 0-D
138.4(2)
167.0(18)
[Ag6(3atrz)6][PMo12O40]2·H2O (2)
linear, {N2} (×6)
linear, {N2} (×2)
2.132(6),
2.123(5)
168.0(2)
hexanuclear
cluster
R-[PMo12O40]3-
0-D + 0-D
1-D + 0-D
[Ag2(3atrz)2]2[HPMoVI10MoV2O40] (3)
2.125(7),
2.103(8)
2.129(7),
2.123(7)
172.8(3),
158.3(3)
helix chain
R-[HPMoVI10MoV2O40]4-
[Ag2(dmtrz)2]2[HPMoVI10MoV2O40] (4)
linear, {N2} (×2)
linear, {N2} (× 2)
2.135(5),
2.166(5)
2.158(5),
2.158(4)
153.33(19),
151.71(17)
helix chain
R-[HPMoVI10MoV2O40]4-
1-D + 0-D
1-D + 1-D
1-D + 2-D
[Ag2(trz)2]2[Mo8O26] (5)
175.39(14), zigzag chain
170.70(15)
2.130(4),
2.132(3)
2.184(3),
2.200(3)
[γ-Mo8O26]n4n- (1-D)
[Ag2(3atrz)2][Ag2(3atrz)2(Mo8O26)] (6)
linear, {N2} (×2)
2.205(4),
2.120(4)
2.181(4),
2.210(5)
2.411(3),
2.578(4)
180.0(2),
zigzag chain
[Ag2(3atrz)2(γ-Mo8O26)]n2n- (2-D)
180.000(1)
128.21(16),
128.40(16)
95.26(14),
85.29(14)
120.88(15),
95.44(11)
tetrahedral {N2O2} (× 2)
[Ag4(4atrz)2Cl][Ag(Mo8O26)] (7)
linear, {NCl} (× 2)
linear, {N2} (× 2)
2.163(6),
2.435(2)
2.164(6),
2.225(6)
2.355(6),
2.423(6)
2.444(6),
2.451(6)
174.06(17)
looped chain
[Ag(â-Mo8O26)]n3n-(1-D)
1-D + 1-D
171.9(2)
quadrangular plane
{O4} (×1)
163.35(8),
80.24(19)
97.30(19),
98.9(2)
78.77(19),
163.67(8)
[Ag5(trz)4]2[Ag2(Mo8O26)]·4H2O (8)
linear, {N2} (×5)
2.085(12),
2.094(1)
170.2(5),
167.9(5)
165.2(5),
174.5(5)
173.4(5)
helix chain
[Ag2(γ-Mo8O26)]n2n- (1-D)
3-D framework
2.106(11),
2.124(11)
2.107(11),
2.117(12)
2.085(12),
2.086(11)
2.100(12),
2.110(11)
2.165(11),
2.356(10)
2.367(9),
2.510(9)
tetrahedral, {NO3} (×2)
139.4(4),
130.5(4)
80.5(3),
111.4(4)
85.4(3),
96.3(3)
(MeCN)4] [PM12O40]2 (M ) Mo or W),7d reported by Keller
and co-workers, compound 2 itself is still of interest with
respect to the following aspects: (i) As far as we know, no
hexanuclear Ag(I) clusters based on triazole ligands have
been reported to date in the coordination chemistry of 1,2,4-
triazole and its derivatives. (ii) This Ag-based metallacalix-
[3]arene-shaped receptor is unique in the host-guest chem-
istry. To our knowledge, only a few metallacalic[3]arenes
of PtII and PbII have been described, and most of the
-
-
encapsulated guests are inorganic ions such as BF4 , NO3 ,
-
-
PF6 , ClO4 , etc.21 (iii) Although POM-based hybrid solids
have been extensively investigated, no supramolecular host-
guest compounds between polynuclear silver clusters and
polyoxometalate has been reported to date. As shown in
Inorganic Chemistry, Vol. 46, No. 12, 2007 5051

Zhai et al.
Figure 1. Structure of the tetranuclear cluster in compound 1.
Table 3. Hydrogen-Bonding Parameters in Compounds 1-7a
d(D-H) d(H‚‚‚A) d(D‚‚‚A)
(DHA)
(deg)
D-H‚‚‚A
(Å)
(Å)
(Å)
1
N(2)-H(2A)‚‚‚O(9)i
C(1)-H(1B)‚‚‚O(8)ii
C(3)-H(3C)‚‚‚O(13)
C(5)-H(5A)‚‚‚O(3)iii
C(6)-H(6A)‚‚‚O(2)iv
N(1)-H(1A)‚‚‚O(7)i
N(4)-H(4A)‚‚‚O(4)ii
N(4)-H(4B)‚‚‚O(7)i
N(5)-H(5A)‚‚‚O(18)
N(5)-H(5B)‚‚‚O(7)i
N(7)-H(7B)‚‚‚O(3)ii
C(4)-H(4A)‚‚‚O(13)iii
N(4)-H(4D)‚‚‚O(11)i
N(5)-H(5D)‚‚‚O(11)ii
C(1)-H(1A)‚‚‚O(19)iii
C(4)-H(4C)‚‚‚O(8)iv
N(5)-H(5A)‚‚‚O(12)i
N(6)-H(6A)‚‚‚O(9)ii
C(1)-H(1A)‚‚‚O(4)iii
C(2)-H(2A)‚‚‚O(8)iv
C(3)-H(3A)‚‚‚O(5)i
C(4)-H(4A)‚‚‚O(2)
N(2)-H(2A)‚‚‚O(3)i
N(5)-H(5A)‚‚‚O(7)ii
N(6)-H(6A)‚‚‚O(12)
N(8)-H(8A)‚‚‚O(9)iii
C(4)-H(4A)‚‚‚O(1)iv
N(3)-H(3A)‚‚‚Cl(1)i
C(1)-H(1A)‚‚‚O(6)ii
0.86
0.93
0.93
0.93
0.93
0.86
0.86
0.86
0.86
0.86
0.86
0.93
0.86
0.86
0.93
0.93
0.86
0.86
0.93
0.93
0.93
0.93
0.86
0.86
0.86
0.86
0.93
0.86
0.93
2.12
2.28
2.47
2.32
2.40
2.31
2.26
2.23
2.27
2.34
2.28
2.46
2.23
2.37
2.38
2.33
1.85
1.93
2.25
2.35
2.39
2.51
2.22
1.91
2.21
2.12
2.54
2.64
2.23
2.934(5)
3.235(8)
3.297(8)
3.243(8)
3.325(7)
2.994(7)
3.016(8)
2.979(7)
3.047(12)
3.004(11)
3.063(12)
3.171(11)
3.043(7)
3.128(10)
3.190(7)
3.222(9)
2.690(4)
2.774(4)
3.091(5)
3.212(5)
3.091(5)
3.144(5)
2.863(6)
2.757(5)
3.041(6)
2.978(6)
3.195(6)
3.395(6)
3.148(9)
158.1
172.4
144.4
160.3
162.2
136.6
146.1
146.2
151.1
133.7
151.0
133.0
156.5
147.3
141.2
154.5
165.6
167.8
149.3
154.5
131.8
126.0
131.6
169.1
161.6
173.1
128.2
146.8
167.1
2
3
4
5
Figure 2. (a) Structure of the hexanuclear cluster in compound 2. (b)
Space-filling side (left) and top (right) views of the two polyoxometalate
anions in the two bow-shaped cavities of the hexamer. (c) 1-D honeycomb
tubular channels formed by silver clusters (left) and 3-D hybrid supramo-
lecular architecture (right) viewed along the c-axis.
in Figure S2, each hexanuclear cyclic unit is linked by twelve
Keggin anions via hydrogen bonds with center-to-center
distances of about 10.28 and 13.67 Å. On the other hand,
Keggin anions are connected by six hexanuclear clusters.
Therefore, the overall 3-D packing framework of 2 can be
rationalized as a 6,12-connected net by assignment of the
[Ag6(3atrz)6]6+ rings as 12-connected nodes, the [PM12O40]3-
clusters as six-connected nodes, and the weak hydrogen
bonds as linkers.
6
7
a Symmetry coordinates for 1: (i) -x, -y, -z + 1; (ii) x, y - 1, z; (iii)
-x, y - 1, -z + 1/2; (iv) -x + 1/2, -y + 1/2, -z + 1. For 2: (i) -x +
1, -y, -z - 1; (ii) x - y - 1/3, x - 2/3, -z - 2/3). For 3: (i) x - 1/2,
-y +3/2, z - 1/2); (ii) -x, -y + 1, -z + 2; (iii) -x - 1/2, y - 1/2, -z
+ 3/2. For 4: (i) -x + 1/2, y + 1/2, -z -1/2; (ii) x +1/2, -y + 5/2, z +
1/2; (iii) -x + 1, -y + 3, -z - 1; (iv) -x + 3/2, y + 1/2, -z - 1/2). For
5: (i) -x + 1, -y + 2, -z; (ii) -x + 1, -y + 1, -z; (iii) x - 1, y, z -
1); (iv) (-x + 2, -y + 2, -z + 1). For 6: (i) -x + 2, -y + 2, -z - 1;
(ii) x, y, z + 1; (iii) -x + 3, -y + 3, -z; (iv) -x + 2, -y + 2, -z. For
7: (i) x + 1/2, y - 1/2, z; (ii) -x + 2, -y + 1, -z.
Compounds 3 and 4 crystallize isostructurally consisting
of one-dimensional Ag-1,2,4-triazolate helix chains and
Keggin anions. The metal-organic helix chains contain two
crystallographically unique silver ions linked by two organic
ligands through N1,N2- and N1,N4-bridging modes (Figure
3a). The long pitches of the helix chains in 3 and 4 along
the c-axis are 17.891(31) and 19.950(21) Å, respectively.
Both silver atoms are of linear geometry with Ag-N
distances falling in the range of 2.103(8)-2.158(5) Å. The
corresponding N-Ag-N angles are 158.3(3) and 172.8(3)°
for 3 and 153.33(19) and 151.71(17)° for 4. It should be
pointed out that because of the symmetrical structures of
1,2,4-triazole or its derivatives and the diversities of their
bridging modes, 2-D helical chain structures with triazole
ligands are rare, and to our knowledge, only one example
Figure 2c, the host metal-organic cations and guest
[PMo12O40]3- ions form three-dimensional supramolecular
network through weak N-H‚‚‚O hydrogen bonds (see Table
3). When the guest polyanions are removed, the Ag-trz
coordination fragments present 1-D honeycomb tubular
channels along the c axis, just like the exceptionally stable
coordination polymer [ZnF(3atrz)]‚solvents.22 As depicted
(21) (a) Schnebeck, R. D.; Freisinger, E.; Lippert, B. Angew. Chem., Int.
Ed. 1999, 38, 168. (b) Schnebeck, R. D.; Freisinger, E.; Glahe´, F.;
Lippert, B. J. Am. Chem. Soc. 2000, 122, 1381. (c) Yu, S. Y.; Huang,
H.; Liu, H. B.; Chen, Z. N.; Zhang, R. B.; Fujita, M. Angew. Chem.,
Int. Ed. 2003, 42, 686.
(22) Su, C. Y.; Goforth, A. M.; Smith, M. D.; Pellechia, P. J.; Loye, H. C.
J. Am. Chem. Soc. 2004, 126, 3576.
5052 Inorganic Chemistry, Vol. 46, No. 12, 2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
Figure 3. (a) Space-filling views of the helix chains in compounds 3 (left)
and 4 (right). (b) The schematic representation of the 0-D + 1-D
supramolecular assembly. The Keggin POM anions are represented as
orange spheres.
of a single-stranded 41 helix has been reported.23 Moreover,
pyrazole-like and imidazole-like bridging modes of triazole
ligands have never been observed in the same structure to
link metal centers. The polyoxoanion [HPMoVI10MoV O40]4-
2
Figure 4. (a) Zigzag Ag-triazolate chain in compound 5. (b) 1-D inorganic
4n-
[Mo8O26]n
constructed from the γ-[Mo8O26] cluster through sharing
in 3 and 4 exhibits a distorted R-Keggin structure with center
P atom surrounded by a cube of eight half-occupied oxygen
atoms. P-O bonds range from 1.481(6) to 1.592(9) Å. This
structure feature often appears in [XMo12O40]n- with the
R-Keggin structure, which has been explained by several
groups.24 Three sets of Mo-O distances are Mo-O(t) )
1.644(6)-1.668(4) Å, Mo-O(b) ) 1.810(7)-2.000(7) Å,
and Mo-O(c) ) 2.408(10)-2.522(6) Å. The helices and
Keggin anions are linked by complex hydrogen bonds (N-
H‚‚‚O or C-H‚‚‚O) to generate a three-dimensional inor-
ganic-organic hybrid supramolecular structure (Figure S3).
The distances between the N or C atoms of organic ligands
and oxygen atoms of the POM anions range from 3.004(11)
to 3.222(9) Å. The whole packing schemes of compounds 3
and 4 present layer structures (Figure 3b) following the
pattern ‚‚‚ABAB‚‚‚ (A ) POM layer and B ) Ag-trz layer)
along the a-axis. The B layers are parallel to each other along
the a-axis with a distance between the planes of two triazole
rings of about 12 Å, which is slightly longer than the
diameter of POM anions (∼10 Å).
common vertices. (c) schematic representation of the 1-D + 1-D hybrid
assembly.
octahedra connected through their edges to form the
[Mo4O13]2- unit, which are further stacked together by edge-
sharing to give rise to γ-[Mo8O26]4- octamolybdate clusters.
The γ-octamolybdate units are linked together through
sharing common vertices to form infinite chain along the
a-axis (Figure 4b). In the solid state of 5, two types of 1-D
chains are held together and extended to a 3-D framework
via strong N-H‚‚‚O and weak C-H‚‚‚O hydrogen bonding
(Figure S4). One non-coordinated nitrogen atom and two
carbon atoms of the organic ligands all participate in
hydrogen bonding with terminal oxo atoms of the POM chain
(See Table 3). As shown schematically in Figure 4c, the
overall 3-D framework of 5 also presents layer structures
following the pattern ‚‚‚ABAB‚‚‚ along the b-axis. Two types
of chains are basically vertical to each other, and they extend
along the a- and c-axes.
X-ray diffraction analysis reveals that 6 is composed of
2n-
anionic [Ag2(3atrz)2(Mo8O26)]n
two-dimensional netlike
The supramolecular structure of 5 consists of pairs of [Ag2-
2n+
2n+
4n-
frameworks penetrated by cationic [Ag2(3atrz)2]n zigzag
chains. Although numerous types of entanglements of
multiple motifs in coordination polymeric networks have
been reviewed,25 examples of threading 1-D chains into 2-D
sheets are relatively rare.26 The 1-D [Ag2(3atrz)2]n2n+ zigzag
chain is similar to the [Ag2(trz)2] n2n+ chain in compound 5.
The two unique silver atoms are both of linear geometry
(Ag-N ) 2.205(4) and 2.120(4) Å) and are connected by
the 3atrz ligands using an imidazole-like bridging mode
(trz)2]n
zigzag chains and one [Mo8O26]n
chain. Two
crystallographically unique silver ions are linked by trz
ligands through the N1,N4-bridging mode to generate a 1-D
zigzag chain (Figure 4a). Both silver atoms are of linear
geometry with Ag-N distances falling in the range of 2.130-
(4)-2.200(3) Å and N-Ag-N angles of 170.70(15) and
175.39(14)°. Each molybdenum atom of the polyoxometalate
chain attains a distorted octahedral environment by coordina-
tion of six oxygen atoms. The four asymmetric [MoO6]
2n-
(Figure 5a). The 2-D [Ag2(3atrz)2(Mo8O26)]n framework
(23) Zhang, J. P.; Lin, Y. Y.; Huang, X. C.; Chen, X. M. Chem. Commun.
2005, 1258.
(25) Carlucci, L.; Ciani, C.; Proserpio, D. M. Coord. Chem. ReV. 2003,
246, 247.
(26) (a) Sharma, C. V. K.; Rogers, R. D. Chem. Commun. 1999, 83. (b)
Tong, M. L.; Wu, Y. M.; Ru, J.; Chen, X. M.; Chang, H. C.; Kitagawa,
S. Inorg. Chem. 2002, 41, 4846. (c) Zaman, M. B.; Smith, M. D.; zur
Loye, H. C. Chem. Commun. 2001, 2256. (d) Liao, J. H.; Juang, J. S.;
Lai, Y. C. Cryst. Growth Des. 2006, 6, 354.
(24) (a) Attanasio, D.; Bonamicao, M.; Fares, V.; Imeratori, P.; Suber, L.
Dalton Trans. 1990, 3221. (b) Maguere`s, P. L.; Ouahab, L.; Golhen,
D.; Grandjean, D.; Pena, O.; Jegaden, J. C.; Gomez-Garcia, C. J.;
Delhae`s, P. Inorg. Chem. 1994, 33, 5180. (c) Neier, R.; Trojanowaki,
C.; Mattes, R. Dalton Trans. 1995, 1308. (d) Fender, N. S.; Kahwa,
I. A.; White, A. J. P.; Williams, D. J. Dalton Trans. 1998, 1729.
Inorganic Chemistry, Vol. 46, No. 12, 2007 5053

Zhai et al.
Figure 6. (a) Ball and stick (left) and space-filling (right) representations
of the looped chain in compound 7. (b) Inorganic [AgMo8O26]n3n- chain in
7. (c) Overall supramolecular assembly between two kinds of chains (left)
and the topological representation (right).
regarded three- and four-connected nodes, respectively. If
the dinuclear [Ag2(3atrz)2]2+ subunits are further simplified
as linkers, this 2-D network has a much simpler (4,4)
Figure 5. (a) 1-D zigzag metal-organic chain in 6. (b) 2-D [Ag2(3atrz)2(Mo8-
2n-
O26)]n
hybrid layer (left) and its topological representation (right). (c)
Schematic representation of the 1-D in 2-D supramolecular assembly of 6.
topology with parallelogram grids of 8.25 × 14.49 Å.
2n+
4n-
Further, the [Ag2(3atrz)2]n
infinite chains penetrate into
is constructed from 1-D [Mo8O26]n
chains and [Ag2-
the [Ag2(3atrz)2(Mo8O26)]n2n- sheets to give the 1-D in 2-D
supramolecular structure of compound 6. The spacing of the
two parallel sheets is 12.75 Å. This supramolecular assembly
is further stabilized by non-classic N‚‚‚O and C‚‚‚O hydrogen
bonding between nitrogen or carbon atoms of 3atrz ligands
in the 1-D chains and oxygen atoms of the octamolybdate
clusters in the 2-D grids (Figure S6). Moreover, there is also
N‚‚‚O hydrogen bonding between the binuclear units and
POM clusters in the 2-D grids. The overall supramolecular
architecture of rods in grids is simply shown schematically
in Figure 5c, which is intriguing in the area of chemical
topological. To the best of our knowledge, only one 1-D-
in-2-D entangled system incorporating polyoxometalates has
been reported to date.26d
Complex 7 consists of interesting cationic [Ag4(4atrz)2-
Cl]n3n+ looped chains (Figure 6a) and unprecedented anionic
[Ag(Mo8O26)]n3n- chains (Figure 6b). The two unique silver
atoms in the cationic chain are both of linear coordination
geometry. Each 4atrz ligand links two Ag+ ions through the
N1 (or N2) atom (Ag(2)-N(2) ) 2.164(6) Å) and the amino
group (Ag(2)-N(3) ) 2.225(6) Å) to give a 1-D single-
chain structure. Then, two single chains were connected by
[Ag2Cl]+ units (Ag(1)-Cl(1) ) 2.435(2) Å) through the
uncoordinated N2 (or N1) atoms of the triazole ligands (Ag-
(1)-N(1) ) 2.163(6)) to generate an interesting looped chain
structure. The [Ag2Cl]+ units locate alternately at both sides
of the chain. Notably, this is the first example in the
coordination chemistry of 4-amino-1,2,4-triazole ligands in
which an amino group participates in bonding. Moreover,
the Ag-N bond distance (2.225(6) Å) is distinctly longer
than those between Ag+ ions and the nitrogen atoms of
(3atrz)2]2+ binuclear units. Similar to compound 5, the basic
polyoxometalate building block is also the γ-isomer of
[Mo8O26]4- when the oxygen atoms donated by adjacent
octamolybdate subunits are removed. However, the two
adjacent subunits are linked not through sharing common
vertices as in 5 but through common edges (Figure S5).
Therefore, the molybdate ribbon may be regarded as being
constructed of octamolybdate units joined at two oxo-groups
or from two groups of cis-edge-sharing tetranuclear units
united through edge-sharing. Similar octamolybdate chains
have been found in K2Mo4O13,27 [(C5H7N2)2Mo4O13],28 [Cu-
(Hdipyreth)Mo4O13],29 [Cu(bpy)Mo4O13],30 and [Cu2(4-
PBIM)2Mo4O13].31 In the [Ag2(3atrz)2]2+ binuclear units, two
silver atoms are linked by two 3atrz ligands through a
pyrazole-like bridging mode, which makes the distance
between two silver atoms 3.337(24) Å. Each γ-[Mo8O26]4-
cluster in the inorganic chains uses two opposite pairs of
oxo groups of adjacent MoO6 octahedra to coordinate two
Ag+ ions, that is, to connect two binuclear units to form the
2-D network. Thus, each silver atom links two nitrogen atoms
and two terminal oxygen atoms (Ag-N ) 2.181(4) and
2.210(5) Å, Ag-O ) 2.411(3) and 2.578(4) Å) to form a
distorted tetrahedral environment. As depicted in Figure 5b,
the overall 1-D hybrid layer can be rationalized as a novel
3,4-connected net when silver atoms and octamolybdates are
(27) Gatehouse, B. M.; Leverett, P. J. Chem. Soc. A 1971, 2107.
(28) Pavani, K.; Ramanan, A. Eur. J. Inorg. Chem. 2005, 3080.
(29) Rarig, R. S., Jr.; Zubieta, J. Polyhedron 2003, 22, 177.
(30) Rarig, R. S., Jr.; Hamela, P. J.; Zubieta, J. Solid State Sci. 2002, 4,
77.
(31) Chen, L. J.; He, X.; Xia, C. K.; Zhang, Q. Z.; Chen, J. T.; Yang, W.
B.; Lu, C. Z. Cryst. Growth Des. 2006, 6, 2076.
5054 Inorganic Chemistry, Vol. 46, No. 12, 2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
triazole ring (2.164(6) and 2.163(6) Å). On the other hand,
this metal-organic chain can also be regarded as [Ag6(4atrz)4-
Cl2] hexanuclear rings linked each other to form extended
3n+
structure. Further, the cationic [Ag4(4atrz)2Cl]n units are
linked through N-H‚‚‚Cl hydrogen binding to give a three-
dimensional supramolecular porous framework (Figure S7).
The 1-D channels formed possess dimensions of about 9.28
× 9.06 Å, which are perfectly occupied by the inorganic
3n-
chains. The anionic [Ag(Mo8O26)]n
chain in 7 is con-
structed from the â-octamolybdate clusters and single-
coordinated electrophilic silver ions. The Ag+ ion is sand-
wiched between two â-octamolybdate units. Each â-Mo8O26
unit forms covalent interactions with two silver atoms
through four terminal oxygen atoms of two {Mo4O13}
subunits with the Ag-O distances range from 2.355(6) to
2.451(6) Å and the O-Ag-O angles range from 80.24(19)
to 163.67(8)°. Each four-coordinated Ag(I) ion is of a slightly
distorted quadrangular plane. The distance between two
adjacent silver atom is 9.198(16) Å. Although a large number
of hybrid materials based on octamolybdate and its analogous
compounds have been reported, such a one-dimensional
infinite chain structure constructed by [Mo8O26]4- building
blocks linked only by single Ag+ ions is the first example.
The overall 3-D suparmolecular assembly is further stabilized
by C-H‚‚‚O hydrogen bonding between the carbon atoms
of 4atrz ligands and terminal oxygen atoms of octamolybdate
clusters. The whole 1-D + 1-D supramolecular architecture
of compound 7 is simply illustrated in Figure 6c and is
completely novel to our knowledge.
Figure 7. (a) ORTEP diagram of compound 8 showing the local
coordination environment in the asymmetric unit and 30% thermal ellipsoids.
(b) 1-D helix Ag-triazolate chain. (c) 1-D inorganic [Ag2Mo8O26]n2n- chain.
(b) 3-D framework of compound 8 (left) and its topological representation
based on two kinds of rod-shaped building units (right).
coordinated Ag(I) ion is not of quadrangular plane geometry
as in the reported [Ag2(Mo8O26)]2- examples10f,10j but has a
distorted tetrahedral geometry coordinated to three oxygen
atoms and one nitrogen atoms (N(10)). The Ag-O and
Ag-N distances are 2.356(10)-2.510(9) and 2.165(11) Å,
respectively. The N-Ag-O and O-Ag-O angles are 111.4-
(4)-139.4(4) and 80.5(3)-96.3(3)°, respectively. The dis-
tance between two silver atoms is 4.911(2) Å. Moreover,
the Mo(4) atom in the {Mo4O13} subunit is coordinated to
N(12) atom with an Mo-N distance of 2.236(11) Å. Thus,
two non-coordinated nitrogen atoms (N(10) and N(12)) of
triazole ligands in the meta--organic fragments covalently
link the inorganic [Ag2Mo8O26]n2n- chains to give the unique
3-D organic-inorganic hybrid frameworks of compound 8
(Figures 7d and S8). To the best of our knowledge, only
limited discrete [Ag2Mo8O26]n2n- chains have been reported
by our and other groups to date,10f,10j and compound 8 is the
firsthighlydimensionalarchitecturewhichuses[Ag2Mo8O26]n2n-
as building blocks. The topological representation of the
overall networks is depicted in Figure 7d, which can be
described as a 3-D framework based on two kinds of 1-D
rod-shaped subunits according to the principles of rod-
packing.
2n-
Compound 8 is constructed from 1-D [Ag2(Mo8O26)]n
n-
anionic chains, integrated by pairs of [Ag5(trz)4]n chains
into a 3-D framework. As shown in Figure 7a, there are six
crystallographically independent silver(I) centers, which have
two kinds of coordination environments with the Ag(2) center
being four-coordinated and other silver centers being two-
coordinated. Linear coordinated Ag(1), Ag(4), and Ag(5) are
linked by three triazole ligands through a pyrazole-like
bridging mode to give [Ag3(trz)3] neutral trigonal units. The
Ag-N bond distances and N-Ag-N angles are 2.085(12)-
2.117(12) Å and 165.2(5)-174.5(5)°, respectively. The Ag‚
‚‚Ag distances in this trigonal unit are 3.603(2), 3.609(2),
and 3.801(2) Å. Three triazole rings all deviate slightly from
the trigonal plane formed by three silver atoms to ease the
repulsion of metal ions, and the dihedral angles are about
6.5, 15.9, and 19.4°, respectively. Although [Cu3(trz)3]
subunits have been reported to construct coordination
polymers,13e [Ag3(trz)3] in 8 is the first structurally character-
ized cyclic trinuclear example with silver centers. This unique
[Ag3(trz)3] unit is further connected by another two linear
silver ions (Ag(3) and Ag(6)) and one triazole ligands
(imidazole-like linking mode) to give a 1-D chain depicted
in Figure 7b. In the inorganic chain, the octamolybdate
cluster contains 14 µt-O, six µ2-O, four µ3-O, and two µ4-O
and is a γ-isomer like that in compounds 5 and 6. Each
γ-Mo8O26 unit forms covalent interactions with four silver
atoms (Ag(2)) through four µt-O and two µ2-O of two
{Mo4O13} subunits (Figure 7c). Thus, the Ag+ ions are
sandwiched between two octamolybdate units. Each four-
Spectroscopic Characterizations. FT-IR and ESR. In
the FT-IR spectra (Figure S9) of compounds 1-8, the peaks
between 600 and 1100 cm-1 are attributed to the octamo-
lybdate or Keggin ions, and the peaks in the range of 1000-
1700 cm-1 and 3200-3500 cm-1 are from the 1,2,4-triazole
ligands and lattice water molecules. The peak positions
corresponding the Keggin anions differed slightly from those
Inorganic Chemistry, Vol. 46, No. 12, 2007 5055

Zhai et al.
shifted λo accompanied the increase in the reduction potential
of the POM acceptors, as observed for other charge-transfer
salts. In accord with the Mulliken theory,34 the new (visible)
absorption bands were ascribed to intense charge transfer
between the host [Ag6(3atrz)6]3+ fragments and the guest
[PMo12O40]3- in complex 2. To the best of our knowledge,
hybrid supramolecular compound 2 is the first charge-transfer
salt in the M′/ligands/ POM hybrid family identified by the
UV-vis spectroscopy. This charge-transfer character is also
confirmed by the crystal color change (H3[PMo12O40]‚xH2O,
yellow f 2, orange). In the case of compounds 3 and 4, the
blue shift of λo to ∼350 nm is caused by the reduction of
R-Keggin ions under hydrothermal conditions. The black
crystal color of these two compounds is in accordance with
this result. The absorption spectra of these compounds based
on the octamolybdate cluster (1, 5, 7, and 8) are given in
Figure 8b. The absorption bonds in the UV range of the
spectra for compounds 1, 5, and 7 at 290 nm were assigned
to a charge-transfer transition from the terminal oxygen
nonbonding π-type HOMO to the molybdenum π-type
LUMO,35 which is shifted by about 45 nm in compound 8
(335 nm). This red shift maybe attributed to two aspects:
one is that 8 is not supramolecular architecture like 1, 5,
and 7 but instead is a three-dimensional frameworks, and
the other is the formation of Mo-N bonds in this com-
pound.35,36 A little absorption in the visible range is consistent
with the color of these compounds.
Study of Optical Band Gap. Several examples have
shown that POM-based inorganic-organic hybrids are
semiconductors. To explore the conductivity of compounds
1-8, the measurements of diffuse reflectivity for powdered
crystal samples were used to obtain their band gap (Eg). The
band gap, Eg, was determined as the intersection point
between the energy axis and the line extrapolated from the
linear portion of the absorption edge in a plot of Kubelka-
Munk function F against energy E.37,38 Kubelka-Munk
function, F ) (1 - R)2/2R, was converted from the recorded
diffuse reflectance data, where R is the reflectance of an
infinitely thick layer at a given wavelength. The F versus E
plots for the compounds are shown in Figure S11, and the
Eg values assessed from the steep absorption edge are 2.43
eV for H3[PMo12O40]‚xH2O, 2.52 eV for 1, 1.94 eV for 2,
2.15 eV for 3, 2.34 eV for 5, 3.58 eV for 7, and 2.27 eV for
8, which indicate that these hybrid compounds are potential
semiconductor materials. This has also been observed in
several reported POM-based inorganic-organic hybrid sol-
Figure 8. UV-vis absorption spectra of H3[PMo12O40]‚xH2O and
compounds 1-8.
of the original acids, as observed for other organic-inorganic
hybrids containing charge-compensating organics or transi-
tion metal coordination fragments and Keggin ions.7f,7g,32 The
ESR spectra for compounds 2, 3, and 4 (Figure S10) are
recorded on polycrystalline samples at room temperature.
The results show that compound 2 is ESR silent, and the
spectra of 3 and 4 are typical of Mo5+ ions, which were
consistent with the results of the X-ray analysis. The
following parameters are obtained: g ) 1.9327 for 3 and g
) 1.9374 for 4.
UV-vis Absorption Spectra. The UV-vis absorption
spectra of these hybrid supramolecular compounds, between
200 and 800 nm, are presented in Figure 8. For comparison,
the spectrum of H3[PMo12O40]‚xH2O is also investigated
under the same conditions. As shown in Figure 8a, the
absorption spectra of compounds 2-4 and phosphordode-
camolybdates all present one bond centered around 300 nm,
which is a characteristic bond of heteropolyacids attributed
to the O f Mo LMCT.33 Shoulder bonds are observed for
H3[PMo12O40]‚xH2O and compound 2 with absorption peaks
at 380 and 402 nm, respectively. The H3[PMo12O40]‚xH2O
is transparent at λ > 530 nm. In contrast, hybrid solid 2
shows new absorption up to λo ) 660 nm (λo is the value at
which the absorbance reach the baseline value). The red-
(34) (a) Mulliken, R. S. J. Am. Chem. Soc. 1952, 74, 811. (b) Mulliken, R.
S.; Person, W. B. Molecular Complexes. A Lecture and Reprint
Volume; Wiley: New York, 1969. (c) Foster, R. Organic Charge-
Transfer Complexes; Academic: New York, 1969. (d) Maguere`s, P.
L.; Hubig, S. M.; Lindeman, S. V.; Veya, P.; Kochi, J. K. J. Am.
Chem. Soc. 2000, 122, 10073.
(35) Xia, Y.; Wu, P. F.; Wei, Y. G.; Wang, Y.; Guo, H. X. Cryst. Growth
Des. 2006, 6, 253.
(36) Du, Y.; Rheingold, A. L.; Maatta, E. A. J. Am. Chem. Soc. 1992,
114, 345.
(32) Vitoria, P.; Ugalde, M.; Gutie´rrez-Zorrilla, J. M.; Roma´n, P.; Luque,
A.; Felices, L. S.; Garc´ıa-Tojal, J. New J. Chem. 2003, 27, 399.
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5056 Inorganic Chemistry, Vol. 46, No. 12, 2007

Ag/1,2,4-Triazole/Polyoxometalates Hybrid Family
ids, such as Co2(bpy)6(W6O19)2 (Eg ) 2.2 eV),39 [Cd(BPE)-
(R-Mo8O26)][Cd(BPE)(DMF)4]‚2DMF (Eg ) 3.45 eV),26d and
(n-Bu4N)2[Mo6O17-(tNAr)2] (Ar ) o-CH3OC6H4) (Eg )
2.25 eV).35 In our opinion, the discrete polyoxometalate
clusters or 1-D POM chains in the hybrid structures appear
to be responsible for their optical band gap. Moreover, the
variety of the Eg values suggests that the optical band gap
of polyoxometalates could be tuned effectively and control-
lably via chemical modification using suitable organic
ligands.
Photoluminescence Properties. Recently, inorganic-
organic hybrid solids have been investigated for fluorescence
properties and for potential applications as luminescent
materials, such as light-emitting diodes (LEDs).40 Because
of their ability to affect the emission wavelength and strength
of organic materials, the syntheses of inorganic-organic
coordination polymers or hybrids by the judicious choice of
conjugated organic spacer and transition metal centers can
be an efficient method to obtain new types of electrolumi-
nescent materials, especially for d10 or d10-d10 systems.41
In our previous work, we explored a series of Zn/Cd-1,2,4-
triazole coordination polymers or polynuclear compounds
with strong blue fluorescence.14b Here, we reported the
luminescence properties of this novel Ag/1,2,4-triazole/
polyoxometalates hybrid supramolecular family in the solid
state. As shown in Figure 9a, upon excitation of these solid
samples at λ ) 255 nm, the main emission bands of
complexes 1-8 and H3[P(Mo3O10)4] are located in similar
positions exhibiting strong fluorescence (λmax ) 421 and 488
nm) with slightly different band shapes. It is clear that the
polyoxometalate components should be responsible for the
emissions. Because the molybdenum ions in the [Mo8O26]4-
or [PMo12O40]3- clusters have d0 electron configurations,
these two emissions are the result the oxygen-to-metal (O
f Mo) ligand-to-metal transfer ([LMCT]).42 We tentatively
assign the 421 and 488 nm emissions to be mainly originated
from the Ot f Mo and µ2-O f Mo1[LMCT], respectively.
Moreover, a series of relative weak emissions in the 525-
550 nm range may be attributed to the Oc, µ3-O, or µ4-O f
Mo1[LMCT] transition. This assignment can be supported
by the basic three sets of Mo-O bonds that exist in the
polyoxometalate clusters. Searching for the AgI ion-based
[MLCT] or [LMCT] emissions for these compounds at room
temperature was further carried out. Upon excitation of these
solid samples at λ ) 325 ( 5 nm, a series of sharp emissions
in the 435-455 nm range (λmax ) 448 nm for 1, 453 nm for
2, 447 nm for 3, 436 nm for 4, 439 nm for 5, 438 nm for 7,
and 435 nm for 8) along with O f Mo emissions were
observed, except for those for H3[PMo12O40]‚xH2O (Figure
9b). The O f Mo [LMCT] emission bonds are similar to
those excited at 255 nm except that the intensity was
decreased. The sharp emission bonds in the 435-455 nm
Figure 9. Emission spectra of H3[PMo12O40]‚xH2O and compounds 1-8
upon excitation of these solid samples at λ ) 255 (top) and 325 ( 5 nm
(bottom), respectively.
range of compounds 1-5 and 7-8 are neither [MLCT] nor
[LMCT] in nature and can probably be assigned to the
intraligand fluorescent emissions for their sharpness and
similarity to the reported intraligand [π - π*] emissions
observed for the Cd/1,2,4-triazole coordination compounds.43
The 1,2,4-triazole and the alkyl-substituted ones are not
known to be strong emitters, and the [π-π*] emission peaks
of these small ligands should lie in the UV region. These
emissions may be red-shifted to the visible region; however,
they can hardly be detected because of the strong spin-
forbidden nature of the T1 f S0 processes. As described by
Chen et al. for the photoluminescence phenomena of th
e 2-D coordination polymers [Ag(trz)]n,44 the observation of
emission from the 1,2,4-triazolate from these hybrid su-
pramolecular compounds should be ascribed to the internal
heavy metal effect, in which the spin-forbidden T1 f S0
processes become allowed by shortening of the usually very
long lifetimes to milliseconds. The results demonstrated
(39) Zhang, L.; Wei, Y.; Wang, C.; Guo, H.; Wang, P. J. Solid State Chem.
2004, 177, 3433.
(40) Bunz, U. H. F. Chem. ReV. 2000, 100, 1605.
(41) (a) Seward, C.; Jia, W. L.; Wang, R. Y.; Enright, G. D.; Wang, S. N.
Angew. Chem., Int. Ed. 2004, 43, 2933. (b) Yam, V. W. W.; Lo, K.
K. W. Chem. Soc. ReV. 1999, 28, 323.
(43) Ding, B.; Yi, L.; Wang, Y.; Cheng, P.; Liao, D. Z.; Yan, S. P.; Jiang,
Z. H.; Song, H. B.; Wang, H. G. Dalton Trans. 2006, 665.
(44) Zhang, J. P.; Lin, Y. Y.; Huang, X. C.; Chen, X. M. J. Am. Chem.
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(42) Yamase, T. Chem. ReV. 1998, 98, 307.
Inorganic Chemistry, Vol. 46, No. 12, 2007 5057

Zhai et al.
again that it is a feasible strategy to enhance the phospho-
rescence of organic molecules via an internal heavy metal
effect.45
Conclusions
In this work, we have synthesized a series of Ag/1,2,4-
triazole/polyoxometalate hybrid compounds, which present
novel supramolecular assemblies between low-dimensional
Ag-1,2,4-triazolate units and POMs. The reflectance spec-
trum measurements reveal that these inorganic-organic
hybrid compounds are potential semiconductor materials.
Moreover, these compounds also exhibit interesting photo-
luminescence phenomena, including O f Mo [LMCT] and
intraligand [π-π*] emissions generated by an internal heavy
metal effect. In all, it is reasonable to believe that the present
work is important to expand the application of POM-based
materials.
Thermogravimetric Analysis (TGA). The thermal sta-
bilities of compounds 1-5 and 7-8 were investigated on
crystalline samples under an air atmosphere from 40 to
700 °C. The TG/DTA curves are provided in Figure S12.
The TG curves of these compounds are similar, and all
basically show one sharp stage of weight loss in the
temperature range of 300-450 °C. The weight loss curve
of compound 1 showed that it was stable up to ∼350 °C.
Over the range of 350-435 °C, the sharp weight loss was
caused by the decomposition of dmatrz ligands (exptl,
20.15%; calcd, 19.39%). The TG curve of 2 showed two
stages of weight loss in the temperature range of 40-403
°C. The whole weight loss (11.02%) is in good agreement
with the calculated value (10.85%) for one water molecules
and six triazole ligands. The TG curves of compound 3, 4,
5, 7, and 8 were similar to that of 1, and the sharp weight
losses all correspond to the decomposition of the organic
component. The detailed values of temperatures and weight
losses are given in Table S1. It should be pointed out that
slight weight increases are observed from the thermogravi-
metric curves of these compounds because the residual silver
atoms were finally oxidized to Ag2O under an air atmosphere.
Similar results have been formerly observed for other
compounds containing silver (I) or copper (I) atoms.46
Acknowledgment. This work was supported by the 973
key program of the MOST (2006CB932904), the National
Natural Science Foundation of China (20425313, 20521101,
20333070, and 90206040), the Chinese Academy of Sciences
(KJCX2-YW-M05), and the Natural Science Foundation of
Fujian Province (2005HZ01-1).
Supporting Information Available: X-ray crystallographic files
in CIF format and additional plots of the structures, FT-IR spectra,
ESR spectra, diffuse reflectance (DR) results, and thermogravimetric
analysis for the complexes in PDF format. This material is available
free of charge via the Internet at http://pubs.acs.org. CCDC-613927
(1), 604131 (2), 604132 (3), 604133 (4), 613928 (5), 613931 (6),
613930 (7), and 613929 (8) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Center via
www.ccdc.cam.ac.uk/data_ request/cif.
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Li, Y. Q.; Chan, M. C. W.; Che, C. M.; Cheung, K. K.; Zhu, N. Y. J.
Am. Chem. Soc. 2002, 124, 14696. (c) Omary, M. A.; Rawashdeh-
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5058 Inorganic Chemistry, Vol. 46, No. 12, 2007