Silver(I) coordination polymers based on a nano-sized bent bis(3-acetylenylphenyl-(4-cyanophenyl))oxadiazole ligand: The role of ligand isomerism and the templating effect of polyatomic anions and solvent intermediates

Article abstract of DOI:10.1021/ic052158w

One nanosized oxadiazole bridging ligand, bis(3-acetylenylphenyl-(4- cyanophenyl))oxadiazole (L11), was designed and synthesized by the reaction of bis(3-iodophenyl)oxadiazole with 4-cyanophenylacetylene via a Sonogashira-Hagihara cross-coupling reaction. Eight Ag(I)-L11 coordination polymers with one-, two-, or three-dimensional structures have been successfully prepared by the reaction of L11 with various Ag(I) salts in solution. New coordination polymers were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. All new complexes contain silver heteroatom cluster-connecting nodes, and the L11 ligand is doubling up in the frameworks. In this Ag(I)-L11 system, the conformation of L11 is versatile because of the conformational rotation around the central oxadiazole moiety and depends greatly on the counterion and solvent system used in the formation of the complexes. In addition, the luminescence property and host-guest chemistry of some complexes were investigated primarily.

Full text of DOI:10.1021/ic052158w

Inorg. Chem. 2006, 45, 3325−3343
Silver(I) Coordination Polymers Based on A Nano-Sized Bent
Bis(3-acetylenylphenyl-(4-cyanophenyl))oxadiazole Ligand: The Role of
Ligand Isomerism and the Templating Effect of Polyatomic Anions and
Solvent Intermediates
Yu-Bin Dong,* Hong-Xia Xu, Jian-Ping Ma, and Ru-Qi Huang
College of Chemistry, Chemical Engineering and Materials Science and Shandong Key Lab of
Chemical Functional Materials, Shandong Normal UniVersity, Jinan 250014, P. R. China.
Received December 19, 2005
One nanosized oxadiazole bridging ligand, bis(3-acetylenylphenyl-(4-cyanophenyl))oxadiazole (L11), was designed
and synthesized by the reaction of bis(3-iodophenyl)oxadiazole with 4-cyanophenylacetylene via a Sonogashira
Hagihara cross-coupling reaction. Eight Ag(I) L11 coordination polymers with one-, two-, or three-dimensional
−
−
structures have been successfully prepared by the reaction of L11 with various Ag(I) salts in solution. New coordination
polymers were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction.
All new complexes contain silver heteroatom cluster-connecting nodes, and the L11 ligand is “doubling up” in the
frameworks. In this Ag(I)−L11 system, the conformation of L11 is versatile because of the conformational rotation
around the central oxadiazole moiety and depends greatly on the counterion and solvent system used in the
formation of the complexes. In addition, the luminescence property and host
were investigated primarily.
−guest chemistry of some complexes
Introduction
honeycomblike,5 adamantoid-like,6 squarelike,7 brick-wall-
like,8 and parquetlike9 structures if they are allowed to
Rigid linear organic ligands, such as 4,4′-bipyridine and
4,4′-bibenzonitrile and their various derivatives, are widely
used in the construction of coordination polymers and
supramolecular complexes by chemists.1-3 During past
decades, the coordination chemistry of rigid linear organic
spacers resulted in a number of coordination polymers that
exhibit a rich variety of structural motifs with interesting
physical and chemical properties. In principle, such kinds
of ligands are dominant in generating of linear chain,4
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(j) Kong, L.-Y.; Zhang, Z.-H.; Zhu, H.-F.; Kawaguchi, H.; Okamura,
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Soc. 2003, 125, 6753. (m) Takaoka, K.; Kawano, M.; Tominaga, M.;
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* To whom correspondence should be addressed. E-mail: yubindong@
sdnu.edu.cn.
(1) Recent reviews on metal-organic polymers: (a) Yaghi, O. M.;
O’Keeffe, M.; Ockwig, N. W.; Chae, H. K.; Eddaoudi, M.; Kim. J.
Nature 2003, 423, 706. (b) Kitagawa, S.; Kitaura, R.; Noro, S.-I.;
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10.1021/ic052158w CCC: $33.50
Published on Web 03/14/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 8, 2006 3325

Dong et al.
Chart 1. Some Typical Coordination Motifs Generated from Rigid Linear Organic Ligands
Chart 2. Some Possible Coordination Motifs Generated from Bent Organic Ligands
combine with a two-, three-, or four-coordinated metal center
(Chart 1). Compared to the well-developed coordination
chemistry based on the linear organic ligands, the coordina-
tion chemistry related to the bent organic ligands still remains
a great challenge. It is obvious that the bent ligands do not
propagate the metal-coordination code directly into the
metal-organic frameworks, which makes it somewhat more
difficult to predict the coordination network topologies. We
could image that the bent organic ligands, because of their
variational conformation (cis, trans, or any intermediary
conformations between them), would offer the possibility
for construction of frameworks with novel patterns not easily
achievable by linear rigid ligands, such as the helical chain,10
rhombuslike,11 distorted-hexagon-like,12 and many other
unprecedented polymeric structures (Chart 2). In addition,
bent organic ligands are good candidates for generating
molecular polyhedral hollow coordination cages, which are
demonstrated in many previous studies.13
In the linear ligand’s case, the metal center is chosen to
be the connecting node to finish the bending in the
framework. Unfortunately, the metal coordination mode is
often contorted by some ineluctable factors, such as the
coordination nature of counterions and the templating of
solvent molecules, which affects the formation of the
expected polymeric or discrete supramolecular aggregates.
In the bent ligand’s case, the bending angle could be
(4) Typical Ag(I)-L linear chain examples were summarized in a review
by: Blake, A. J.; Champness, N. R.; Hubberstey, P.; Li, W.-S.;
Withersby, M. A.; Schro¨der, M. Coord. Chem. ReV. 1999, 183, 117.
(5) MacGillivray, L. R.; Subramamian, S.; Zaworotko, M. J. J. Chem.
Soc., Chem. Commun. 1994, 1325.
(6) For earlier examples of Ag(I) (4-fold) and Cu(I) (4-fold) diamondoid
frameworks based on linear 4, 4′-bipy, see: Carlucci, L.; Ciani, G.;
Proserpio, D. M.; Sironi, A. J. Chem. Soc., Chem. Commun. 1994,
2755. An example of an 8-fold interpenetrating diamondoid framework
based on tetrahedral Ag(I) and linear 3,3′-dicyanodiphenylacetylene
ligand was reported by: Hirsch, K. A.; Wilson, S. R.; Moore, J. S.
Inorg. Chem. 1997, 36, 2960.
(10) (a) Shin, D. M.; Lee, I. S.; Chung, Y. K. Inorg. Chem. 2003, 42, 8838.
(b) Reger, D. L.; Semeniuc, R. F.; Rassolov, V.; Smith, M. D. Inorg.
Chem. 2004, 43, 537.
(7) Fujita, M.; Kwon, Y. J.; Washizu, S.; Ogura, K. J. Am. Chem. Soc.
1994, 116, 1151.
(8) (a) Fujita, M.; Kwon, Y. J.; Sasaki, O.; Yamaguchi, K.; Ogura, K. J.
Am. Chem. Soc. 1995, 117 (7), 7287. (b) Losier, P.; Zaworotko, M. J.
Angew. Chem., Int. Ed. 1996, 35, 2779.
(9) Dong, Y.-B.; Layland, R. C.; Smith, M. D.; Pschirer, N. G.; Bunz, U.
H. F.; zur Loye, H.-C. Chem. Mater. 1999, 11, 1415.
(11) Yaghi, O. M.; Li, H.; Groy, T. L. A. Inorg. Chem. 1997, 36, 4292.
(12) Abourahma, H.; Moulton, B.; Kravtsov, V.; Zaworotko, M. J. Am.
Chem. Soc. 2002, 124, 9990.
(13) (a) Tominaga, M.; Suzuki, K.; Murase, T.; Fujita, M. J. Am. Chem.
Soc. 2005, 127, 11950. (b) Tominaga, M.; Suzuki, K.; Kawano, M.;
Kusukawa, T.; Ozeki, T.; Sakamoto, S.; Yamaguchi, K.; Fujita, M.
Angew. Chem., Int. Ed. 2004, 43, 5621.
3326 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Scheme 1. Known 1,3,4-Oxadiazole Bridging Bent Organic Ligands L1-L10
controlled relatively easier and more reliably by the ingenious
choice of geometry of the organic bridging moiety. This
alternative ligand-directed approach thereby would create
opportunities for rational design and construction of specific
and desired frameworks more accurately, especially for the
hollow molecular-cage-containing complexes.
Experimental Section
Materials and Methods. AgSO3CF3, AgClO4, AgBF4, and
AgSbF6 (Acros) were used as obtained without further purification.
Infrared (IR) samples were prepared as KBr pellets, and spectra
were obtained in the 400-4000 cm-1 range using a Perkin-Elmer
1600 FTIR spectrometer. Elemental analyses were performed on a
1
Perkin-Elmer Model 2400 analyzer. H NMR data were collected
It is reasonable to say that understanding and insight into
the self-assembly process on the basis of bent organic spacers
can be improved by carrying out a systemic study using a
series of geometrically similar bent-shaped ligands and
various inorganic metal cations. Recently, we have designed
and synthesized a series of five-membered oxadiazole and
triazole heteroatom cyclic rings that are bridging bent organic
ligands with pyridyl, cyano, aminophenyl, and acetylen-
ylphenyl groups as the terminal coordination sites (Scheme
1). As a result of the bent geometry of these five-membered
heterocyclic bridging ligands and the coordination prefer-
ences of transition metals, we have obtained various new
coordination polymers, some with open channels and inter-
esting luminescence properties.14
using an AM-300 spectrometer. Chemical shifts are reported in δ
relative to TMS. All fluorescence measurements were carried out
on a Cary Eclipse Spectrofluorimeter (Varian, Australia) equipped
with a xenon lamp and quartz carrier at room temperature.
Thermogravimetric analyses were carried out using a TA Instrument
SDT 2960 simultaneous DTA-TGA under flowing nitrogen at a
heating rate of 10 °C/min. XRD patterns were obtained on a D8
(14) (a) Dong, Y.-B.; Ma, J.-P.; Smith, M. D.; Huang, R.-Q.; Tang, B.;
Chen, D.; zur Loye, H.-C. Solid State Sci. 2002, 4, 1313. (b) Dong,
Y.-B.; Ma, J.-P.; Huang, R.-Q.; Smith, M. D.; zur Loye, H.-C. Inorg.
Chem. 2003, 42, 294. (c) Dong, Y.-B.; Ma, J.-P.; Smith, M. D.; Huang,
R.-Q.; Tang, B.; Guo, D.-S.; Wang, J.-S.; zur Loye, H.-C. Solid State
Sci. 2003, 5, 601. (d) Dong, Y.-B.; Ma, J.-P.; Smith, M. D.; Huang,
R.-Q.; Wang, J.-S.; zur Loye, H.-C. Solid State Sci. 2003, 5, 1177.
(e) Dong, Y.-B.; Cheng, J.-Y.; Wang, H.-Y.; Huang, R.-Q.; Tang, B.;
Smith, M. D.; zur Loye, H.-C. Chem. Mater. 2003, 15, 2593. (f) Dong,
Y.-B.; Ma, J.-P.; Huang, R.-Q.; Liang, F.-Z.; Smith, M. D. J. Chem.
Soc., Dalton Trans. 2003, 9, 1472. (g) Dong, Y.-B.; Cheng, J.-Y.;
Huang, R.-Q.; Tang, B.; Smith, M. D.; zur Loye, H.-C. Inorg. Chem.
2003, 42, 5699. (h) Cheng, J.-Y.; Dong, Y.-B.; Ma, J.-P.; Huang, R.-
Q.; Smith, M. D. Inorg. Chem. Commun. 2005, 8, 6. (i) Dong, Y.-B.;
Cheng, J.-Y.; Huang, R.-Q.; Smith, M. D. Inorg. Chim. Acta 2005,
358, 891. (j) Dong, Y.-B.; Cheng, J.-Y.; Ma, J.-P.; Huang, R.-Q.;
Smith, M. D. Cryst. Growth Des. 2005, 5, 585. (k) Dong, Y.-B.; Wang,
H.-Y.; Ma, J.-P.; Huang, R.-Q.; Smith, M. D. Cryst. Growth Des. 2005,
5, 789. (l) Wang, P.; Dong, Y.-B.; Ma, J.-P.; Huang, R.-Q.; Smith,
M. D. Inorg. Chem. Commun. 2005, 8, 596. (m) Dong, Y.-B.; Wang,
H.-Y.; Ma, J.-P.; Shen, D.-Z.; Huang, R.-Q. Inorg. Chem. 2005, 44,
4679. (n) Dong, Y.-B.; Zhang, Q.; Wang, L.; Ma, J.-P.; Huang, R.-
Q.; Shen, D.-Z.; Chen, D.-Z. Inorg. Chem. 2005, 44, 6591. (o) Ma,
J.-P.; Dong, Y.-B.; Huang, R.-Q.; Smith, M. D.; Su, C.-Y. Inorg. Chem.
2005, 44, 6143.
As part of our systemic and in-depth investigation of self-
assembly on the basis of bent ligands of this type, we herein
present the synthesis of a new novel nanometer-sized bent
1, 3, 4-oxadiazole bridging ligand (L11) by a Pd-catalyzed
coupling reaction and eight new silver coordination polymers,
namely, [Ag2(L11)SO3CF3]2‚C6H6 (1), [Ag2(L11)SO3CF3]2‚
C6H6 (2), [Ag(L11)]PF6 (3), [Ag(L11)SbF6]‚(C6H6)‚(THF)
(4), [Ag(L11)]ClO4‚2.5(C6H6) (5), [Ag(L11)]BF4‚2.5(C6H6)
(6), [Ag(L11)SbF6]‚unknown solvate (7), and [Ag(L11)]-
ClO4‚(C7H8) (8), generated from L11 and various silver salts,
as shown in Scheme 2.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3327

Dong et al.
Scheme 2. Synthesis of New Ligand L11 and Compounds 1-8
ADVANCE X-ray powder diffractometer (XRD) with Cu Ka
radiation (λ ) 1.5405 Å).
Caution! Two of the crystallization procedures inVolVe AgClO4,
which is a strong oxidizer.
Preparation of [Ag2(L11)SO3CF3]2‚C6H6 (1). A solution of
AgSO3CF3 (5.44 mg, 0.021 mmol) in benzene (10 mL) was layered
onto a solution of L11 (10.0 mg, 0.021 mmol) in CH2Cl2 (10 mL).
The solutions were left for about one week at room temperature,
and colorless crystals were obtained. Yield, 55%. IR (KBr, cm-1):
2225 (m), 1626 (m), 1603 (m), 1542 (m), 1502 (w), 1467 (w), 1404
(m), 1251 (vs), 1171 (s), 1104 (w), 1035 (s), 900 (w), 880 (w),
839 (m), 803 (w), 763 (w), 735 (m), 683 (m), 645 (s), 578 (w),
554 (m), 519 (m). 1H NMR (300 MHz, DMSO, 25 °C, TMS,
ppm): 8.40 (s, 2H, -C6H4), 8.27-8.25 (d, 2H, -C6H4), 7.95-
7.81 (m, 10H, -C6H4), 7.76-7.71 (t, 2H, -C6H4), 7.37 (s, C6H6).
Anal. Calcd. for C40H22Ag2F6N4O7S2: C, 45.09; H, 2.07; N, 5.26.
Found: C, 45.00; H, 2.23; N, 5.33.
Preparation of L11. 4-Cyanophenylacetylene (2.0 mmol), bis-
(3-iodophenyl)oxadiazole (1.0 mmol), (Ph3P)PdCl2 (0.044 mmol),
and CuI (0.132 mmol) were placed into a flame-dried Schlenk flask.
Next, Et3N (30 mL) and THF (10 mL) were added to the flask.
The mixture was stirred at room temperature for 24 h. After removal
of the solvent under vacuum, the residue was purified on silica gel
by a column using CH2Cl2 as the eluent to afford L11 as a colorless
crystalline solid (Yield, 90%). IR (KBr pellet, cm-1): 2224 (s),
1602 (s), 1541 (ms), 1501 (ms), 1463 (ms), 1404 (w), 1317 (w),
1257 (w), 1136 (w), 1086 (w), 973 (w), 903 (w), 880 (w), 839 (s),
805 (m), 734 (m), 683 (m), 556 (m). 1H NMR (300 MHz, CDCl3,
25 °C, TMS, ppm): 8.33 (s, 2H, -C6H4), 8.20-8.17 (d, 2H,
-C6H4), 7.75-7.56 (m, 12H, -C6H4). Anal. Calcd. for C32H16-
N4O: C, 81.36; H, 3.39; N, 11.86. Found: C, 81.15; H, 3.28; N,
11.47. Mp: 264-266 °C.
Preparation of [Ag2(L11)SO3CF3]2‚C6H6 (2). A solution of
AgSO3CF3 (5.44 mg, 0.021 mmol) in benzene (10 mL) was layered
onto a solution of L11 (10.0 mg, 0.021 mmol) in THF (10 mL).
The solutions were left for about one week at room temperature,
and colorless crystals were obtained. Yield, 50%. IR (KBr pellet,
cm-1): 2226 (m), 1602 (m), 1542 (m), 1502 (m), 1465 (m), 1404
3328 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
(w), 1258 (vs), 1174 (s), 1084 (w), 1034 (s), 880 (w), 839 (m),
804 (w), 763 (w), 736 (w), 683 (m), 645 (s), 577 (w), 555 (m),
518 (m). H NMR (300 MHz, DMSO, 25 °C, TMS, ppm): 8.39
(s, 2H, -C6H4), 8.27-8.25 (d, 2H, -C6H4), 7.95-7.87 (m, 6H,
-C6H4), 7.84-7.81 (d, 4H, -C6H4), 7.76-7.71 (t, 2H, -C6H4),
7.36 (s, C6H6). Anal. Calcd. for C40H22Ag2F6N4O7S2: C, 45.09; H,
2.07; N, 5.26. Found: C, 45.01; H, 2.00; N, 5.08.
onto a solution of L11 (10.0 mg, 0.021 mmol) in toluene (10 mL).
The solutions were left for about one week at room temperature,
and colorless crystals were obtained. Yield, 50%. IR (KBr pellet,
cm-1): 3071 (w), 2252 (m), 2224 (m), 1639 (w), 1600 (s), 1549
(m), 1502 (m), 1483 (w), 1408 (m), 1322 (w), 1256 (w), 1181 (w),
1087 (vs), 996 (m), 874 (w), 841 (m), 805 (w), 738 (m), 681 (m),
621 (m), 553 (m). 1HNMR (300 MHz, DMSO, 25 °C, TMS,
ppm): 8.40 (s, 2H, -C6H4), 8.28-8.25 (d, 2H, -C6H4), 7.96-
7.82 (m, 10H, -C6H4), 7.76-7.71 (t, 2H, -C6H4), 7.25-7.18 (m,
C6H5), 2.30 (s, -CH3). Anal. Calcd. for C39H24AgClN4O5: C, 60.63;
H, 3.11; N, 7.25. Found: C, 60.40; H, 3.02; N, 7.13.
1
Preparation of [Ag(L11)]PF6 (3). A solution of AgPF6 (5.31
mg, 0.021 mmol) in benzene (10 mL) was layered onto a solution
of L11 (10.0 mg, 0.021 mmol) in THF (10 mL). The solutions
were left for about one week at room temperature, and colorless
crystals were obtained. Yield, 49%. IR (KBr pellet cm-1): 2226
(m), 1649 (w), 1600 (m), 1543 (m), 1502 (m), 1458 (m), 1402 (s),
1318 (w), 1267 (w), 1179 (w), 1139 (w), 1089 (w), 835 (vs), 741
Single-Crystal Structure Determination. Suitable single crys-
tals of L11 and 1-8 were selected and mounted in air onto thin
glass fibers. X-ray intensity data were measured at 293 K on a
Bruker SMART APEX CCD-based diffractometer (Mo KR radia-
tion, λ ) 0.71073 Å). The raw frame data for L11 and 1-8 were
integrated into SHELX format reflection files and corrected for
Lorentz and polarization effects using SAINT.15 Corrections for
incident and diffracted beam absorption effects were applied using
SADABS.15 None of the crystals showed evidence of crystal decay
during data collection. All structures were solved by a combination
of direct methods and difference Fourier syntheses and refined
against F2 by the full-matrix least-squares technique. Crystal data,
data collection parameters, and refinement statistics for L11 and
1-8 are listed in Tables 1 and 2. Relevant interatomic bond
distances and bond angles for 1-8 are given in Tables 3-10,
respectively.
1
(m), 683 (s), 555 (s). H NMR (300 MHz, DMSO, 25 °C, TMS,
ppm): 8.40 (s, 2H, -C6H4), 8.28-8.25 (d, 2H, -C6H4), 7.96-
7.93 (d, 4H, -C6H4), 7.90-7.88 (d, 2H, -C6H4), 7.84-7.81 (d,
4H, -C6H4), 7.76-7.71 (t, 2H, -C6H4). Anal. Calcd. for C32H16-
AgF6N4OP: C, 52.94; H, 2.21; N, 7.72. Found: C, 52.89; H, 2.16;
N, 7.69.
Preparation of [Ag(L11)SbF6]‚(C6H6)‚(THF) (4) and [Ag-
(L11)SbF6]‚unknown solvate (7). A solution of AgSbF6 (7.26 mg,
0.021 mmol) in benzene (10 mL) was layered onto a solution of
L11 (10.0 mg, 0.021 mmol) in THF (10 mL). The solutions were
left for about one week at room temperature, and colorless blocklike
crystals (4 and 7) were obtained. The combined crystal yield was
8.57 mg (50%). IR (KBr pellet, cm-1): 2249 (w), 2226 (m), 1828
(w), 1635 (w), 1602 (s), 1541 (m), 1501 (m), 1466 (m), 1449 (m),
1402 (s), 1318 (w), 1260 (w), 1180 (w), 1136 (w), 1106 (w), 1088
(w), 1060 (w), 922 (w), 903 (w), 881 (w), 842 (s), 817 (w), 805
Results and Discussion
1
Ligand Synthesis. One of the important issues in deter-
mining the dimensions of porous frameworks is the scale of
the organic ligands.16 In principle, the longer the spacers used,
the larger pore dimensions would be obtained. To achieve
frameworks with larger-sized channels, we designed and
synthesized ligand L11, which has a bis(4-cyanophenyl)-
substituted bent 2,5-bis(3-ethynylphenyl)-1,3,4-oxadiazole
backbone involving two symmetric acetylene spacers. This
large-length-scale ligand L11 was synthesized by the reaction
of bis(3-iodophenyl)oxadiazole with 4-cyanophenylacetylene
via a classical Sonogashira-Hagihara cross-coupling reaction
(Scheme 2).17 When bis(3-iodophenyl)oxadiazole in a Et3N/
THF mixed-solvent system under an inert atmosphere at
room temperature was treated with 4-cyanophenylacetylene
in a 1:2 molar ratio, we obtained L11 as a white crystalline
solid in 90% yield. The results herein demonstrated that a
1, 3, 4-oxadiazole heterocyclic ring is stable under our
experimental conditions. L11 is soluble in common polar
organic solvents such as CH2Cl2, CHCl3, CH3CN, and THF,
which potentially facilitates the solution reaction between
the ligand and inorganic metal salts. To further confirm the
structure of L11, we performed single-crystal X-ray diffrac-
tion on it. As shown in Figure 1, the ligand is bent, which
(m), 735 (m), 684 (vs), 659 (vs), 556 (s). H NMR (300 MHz,
DMSO, 25 °C, TMS, ppm): 8.40 (s, 2H, -C6H4), 8.28-8.25 (d,
2H, -C6H4), 7.96-7.88 (m, 6H, -C6H4), 7.84-7.81 (d, 4H,
-C6H4), 7.76-7.71 (t, 2H, -C6H4), 7.36 (s, C6H6), 3.60 (s, C4H8O),
1.90 (s, C4H8O). Anal. Calcd. for C42H30AgF6N4O2Sb: C, 52.15;
H, 3.10; N, 5.80. Found: C, 51.09; H, 2.91; N, 5.82.
Preparation of [Ag(L11)]ClO4‚2.5(C6H6) (5). A solution of
AgClO4 (4.39 mg, 0.021 mmol) in benzene (10 mL) was layered
onto a solution of L11 (10.0 mg, 0.021 mmol) in CH2Cl2 (10 mL).
The solutions were left for about one week at room temperature,
and colorless crystals were obtained. Yield, 51%. IR (KBr pellet,
cm-1): 2224 (m), 1600 s), 1544 s), 1501 (s), 1466 (m), 1402 (vs),
1321 (w), 1256 (w), 1177 (w), 1090 (vs), 910 (w), 878 (m), 841
1
(m), 804 (w), 738 (m), 682 (m), 621 (s), 555 (m). H NMR (300
MHz, DMSO, 25 °C, TMS, ppm): 8.40 (s, 2H, -C6H4), 8.28-
8.25 (d, 2H, -C6H4), 7.96-7.81 (m, 10H, -C6H4), 7.76-7.71 (t,
2H, -C6H4), 7.37 (s, C6H6). Anal. Calcd. for C47H31AgClN4O5:
C, 64.45; H, 3.54; N, 6.40. Found: C, 64.29; H, 3.50; N, 6.27.
Preparation of [Ag(L11)]BF4‚2.5(C6H6) (6). A solution of
AgBF4 (4.11 mg, 0.021 mmol) in benzene (10 mL) was layered
onto a solution of L1 (10.0 mg, 0.021 mmol) in THF (10 mL).
The solutions were left for about one week at room temperature,
1
and colorless crystals were obtained. Yield, 51%. H NMR (300
MHz, DMSO, 25 °C, TMS, ppm): 8.38 (s, 2H, -C6H4), 8.26-
8.23 (d, 2H, -C6H4), 7.94-7.80 (m, 10H, -C6H4), 7.74-7.72 (t,
2H, -C6H4), 7.35 (s, C6H6). IR (KBr, cm-1): 3089 (w), 3035 (w),
2260 (w), 2225 (m), 1961 (w), 1824 (w), 1645 (w), 1601 (s), 1542
(s), 1501 (m), 1470 (m), 1405 (w), 1319 (w), 1271 (w), 1082 (vs),
1032 (vs), 902 (w), 881 (w), 838 (s), 805 (m), 735 (m), 678 (vs),
554 (m), 519 (w), 465 (w). Anal. Calcd. for C47H31AgBF4N4O: C,
65.40; H, 3.59; N, 6.49. Found: C, 65.29; H, 3.51; N, 6.42.
Preparation of [Ag(L11)]ClO4‚(C7H8) (8). A solution of
AgClO4 (4.39 mg, 0.021 mmol) in benzene (10 mL) was layered
(15) SADABS and SAINT; Bruker Analytical X-ray Systems, Inc.: Madison,
WI, 1998.
(16) (a) Pschirer, N. G.; Ciurtin, D. M.; Smith, M. D.; Bunz, U. H. F.; zur
Loye, H.-C. Angew. Chem., Int. Ed. 2002, 41, 583. (b) Biradha, K.;
Fujita, M. Chem. Commun. 2001, 15. (c) Stang, P.-J.; Cao, D. H.;
Saito, S.; Arif, A. M. J. Am. Chem. Soc. 1995, 117, 6273. (d) Stang,
P. J.; Olenyuk, B. Acc. Chem. Res. 1977, 30, 502.
(17) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975,
4467.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3329

Dong et al.
Table 1. Crystallographic Data for L11 and 1-3
C32H16N4O L11
C40H22Ag2F6N4O7S2 1
C40H22Ag2F6N4O7S2 2
C32H16AgF6N4OP 3
C42H30AgF6N4O2Sb 4
fw
cryst syst
a (Å)
b (Å)
c (Å)
472.49
monoclinic
18.088(4)
5.9662(14)
23.981(5)
90
110.751(3)
90
2420.2(10)
C2/c
1064.48
triclinic
10.181(2)
12.826(3)
17.657(4)
94.202(3)
97.789(3)
110.376(3)
2123.2(8)
P1h
1064.48
triclinic
10.8840(16)
13.0047(19)
16.524(3)
104.084(2)
94.263(2)
104.432(2)
2174.2(6)
P1h
725.33
966.32
triclinic
triclinic
10.7276(14)
12.2969(16)
16.825(2)
111.228(2)
105.754(2)
16.825(2)
1957.6(4)
P1h
10.7908(7)
12.5144(8)
16.8103(11)
111.4810(10)
105.9500(10)
93.8490(10)
1995.0(2)
P1
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z
4
2
2
2
2
F
calcd (g/cm3)
1.297
0.081
293(2)
1.665
1.100
293(2)
1.626
1.074
293(2)
1.231
0.610
293(2)
1.609
1.236
293(2)
µ (Mo KR; mm-1
T (K)
)
no. of observations (I > 3σ)
4244
0.0458; 0.1089
8092
0.0570; 0.1332
7908
0.0511; 0.1330
6702
0.0817; 0.2159
8494
0.0429; 0.0998
final R indicesa
[I > 2σ(I)] (R; Rw)
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
Table 2. Crystallographic Data for 5-8
C47H31AgClN4O5 5
C47H31AgBF4N4O 6
C32H16AgF6N4OSb 7
C39H24AgClN4O5 8
fw
cryst syst
a (Å)
b (Å)
c (Å)
875.08
862.44
orthorhombic
19.008(3)
24.794(4)
34.955(6)
90
90
90
16474(5)
Fddd
2
1.391
0.548
293(2)
3830
0.0593; 0.1355
816.11
orthorhombic
23.124(2)
37.368(5)
19.180(2)
90
90
90
16574(4)
Fdd2
16
1.308
1.176
293(2)
7238
0.0634; 0.1442
771.94
monoclinic
19.328(4)
23.253(5)
19.734(4)
90
118.073(4)
90
4244.0(9)
C2/c
triclinic
10.2064(19)
12.622(2)
17.865(3)
72.553(3)
82.615(3)
71.626(3)
2082.1(7)
P1h
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z
2
8
F
calcd (g/cm3)
1.369
0.599
293(2)
7624
1.310
0.628
293(2)
6839
0.0993; 0.2138
µ (Mo KR; mm-1
T (K)
)
no. of observations (I > 3σ)
final R indicesa [I > 2σ(I)] (R; Rw)
0.0564; 0.1163
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
Table 3. Interatomic Distances (Å) and Bond Angles (deg) for 1a
Table 4. Interatomic Distances (Å) and Bond Angles (deg) for 2a
Ag(1)-N(4)#1
Ag(1)-O(5)
Ag(2)-N(3)#2
Ag(2)-O(2)
2.130(5)
2.427(5)
2.144(5)
2.414(4)
Ag(1)-N(1)
Ag(1)-O(2)
Ag(2)-N(2)
Ag(2)-O(5)
2.263(4)
2.571(5)
2.276(4)
2.596(6)
Ag(1)-N(3)#1
Ag(1)-O(5)
Ag(2)-N(4)#2
Ag(2)-O(2)
2.136(4)
2.425(5)
2.141(4)
2.452(4)
Ag(1)-N(2)
Ag(1)-O(2)
Ag(2)-N(1)
Ag(2)-O(5)
2.299(3)
2.554(5)
2.307(3)
2.452(5)
N(4)#1-Ag(1)-N(1) 146.42(18) N(4)#1-Ag(1)-O(5) 120.6(2)
N(3)#1-Ag(1)-N(2) 139.35(17) N(3)#1-Ag(1)-O(5) 125.72(19)
N(1)-Ag(1)-O(5)
N(1)-Ag(1)-O(2)
89.58(18)
83.86(14)
N(4)#1-Ag(1)-O(2) 113.94(19)
79.54(18)
N(2)-Ag(1)-O(5)
N(2)-Ag(1)-O(2)
88.42(16)
84.60(13)
N(3)#1-Ag(1)-O(2) 121.33(17)
O(5)-Ag(1)-O(2) 76.33(16)
O(5)-Ag(1)-O(2)
N(3)#2-Ag(2)-O(2) 123.0(2)
N(3)#2-Ag(2)-O(5) 112.5(2)
N(3)#2-Ag(2)-N(2) 148.2(2)
N(4)#2-Ag(2)-N(1) 137.47(16) N(4)#2-Ag(2)-O(2) 128.59(16)
N(2)-Ag(2)-O(2)
N(2)-Ag(2)-O(5)
86.47(14)
82.41(17)
N(1)-Ag(2)-O(2)
N(1)-Ag(2)-O(5)
85.96(12)
87.55(16)
N(4)#2-Ag(2)-O(5) 120.10(18)
O(2)-Ag(2)-O(5) 77.77(17)
O(2)-Ag(2)-O(5)
79.28(18)
a Symmetry transformations used to generate equivalent atoms: #1 -x,
-y + 1, -z; #2 -x + 2, -y, -z + 1.
a Symmetry transformations used to generate equivalent atoms: #1 -x
+ 1, -y + 2, -z; #2 -x + 3, -y + 1, -z + 1.
Table 5. Interatomic Distances (Å) and Bond Angles (deg) for 3a
is similar to the shape of known organic spacers L1-L10.
The separation between two terminal N-donors is ∼24 Å,
which is remarkably longer than those corresponding dis-
tances found in L1-L10. It is noteworthy that two ethynyl-
benzonitrilephenyl moieties are connected via two exo-
oxadiazole carbon-carbon single bonds at the 2,5-positions
to create the bent spacer, in which two long arms can rotate
freely around the single carbon-carbon bonds. Thus, L11
is flexible and very useful in construction of elaborate metal-
organic complexes. Scheme 3 presents three possible typical
conformations of L11. The ab initio Mulliken population
analysis of L11 shows that the energies of three possible
Ag(1)-N(2)#1
Ag(1)-N(3)#2
2.282(5)
2.364(7)
Ag(1)-N(1)
2.285(5)
2.418(8)
Ag(1)-N(4)#3
N(2)#1-Ag(1)-N(1) 118.64(17) N(2)#1-Ag(1)-N(3)#2 109.5(2)
N(1)-Ag(1)-N(3)#2 115.2(2)
N(1)-Ag(1)-N(4)#3 109.4(3)
a Symmetry transformations used to generate equivalent atoms: #1 -x
+ 2, -y + 1, -z + 1; #2 -x + 2, -y + 1,-z; #3 x, y - 1, z - 1; #4 x,
y + 1, z + 1.
N(2)#1-Ag(1)-N(4)#3 113.0(2)
N(3)#2-Ag(1)-N(4)#3 86.7(3)
typical conformations of L11 in either gas or benzene
solution are almost identical;18 thus, these three conforma-
tions (I, II, and III) could be concomitant in gas or benzene
solution. Therefore, the conformation of L11 adopted in the
3330 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Table 6. Interatomic Distances (Å) and Bond Angles (deg) for 4a
size and/or polarity of the anion, the pH value of the reaction
solution, and some other subtle factors beyond the research-
er’s control.
Ag(1)-N(4)#1
2.257(9) Ag(1)-N(6)
2.278(6)
2.499(10)
2.282(9)
2.473(9)
112.2(3)
Ag(1)-N(2)
2.327(7) Ag(1)-N(8)#2
2.282(7) Ag(2)-N(3)#3
2.328(7) Ag(2)-N(7)#4
119.6(3) N(4)#1-Ag(1)-N(2)
Ag(2)-N(5)
Ag(2)-N(1)
N(4)#1-Ag(1)-N(6)
N(6)-Ag(1)-N(2)
N(6)-Ag(1)-N(8)#2
N(5)-Ag(2)-N(3)#3
N(3)#3-Ag(2)-N(1)
Figure 2 exhibits various conformations of L11 found in
complexes 1-8. As indicated in the figure, there are
conformations of I, II, and versatile intermediate conforma-
tions between three fundamental conformations (I, II, and
III), which suggests L11 will generate various polymeric
patterns of the resulting complexes if the solvent systems
and counterions are changed. In other words, we could
control the compounds’ topology by means of changing
reaction conditions. A typical trans conformation of III,
however, was not found in this series of Ag(I)-L11
polymeric complexes.
119.0(2) N(4)#1-Ag(1)-N(8)#2 86.6(3)
108.3(3) N(2)-Ag(1)-N(8)#2
121.0(3) N(5)-Ag(2)-N(1)
110.7(3) N(5)-Ag(2)-N(7)#4
106.0(3)
117.4(2)
105.4(3)
108.6(3)
N(3)#3-Ag(2)-N(7)#4 88.9(3) N(1)-Ag(2)-N(7)#4
a Symmetry transformations used to generate equivalent atoms: #1 x, y,
z - 1; #2 x, y - 1, z - 1; #3 x, y + 1, z + 1; #4 x, y, z + 1.
Table 7. Interatomic Distances (Å) and Bond Angles (deg) for 5a
Ag(1)-N(1)
Ag(1)-N(4)#2
2.272(3)
2.329(4)
Ag(1)-N(2)#1
Ag(1)-N(3)#3
2.297(3)
2.381(4)
Synthesis of the Complexes. The slow diffusion of an
organic solution (THF or CH2Cl2) of L11 into a benzene
N(1)-Ag(1)-N(2)#1
N(2)#1-Ag(1)-N(4)#2 103.24(14) N(1)-Ag(1)-N(3)#3
119.44(11) N(1)-Ag(1)-N(4)#2
120.36(14)
100.73(13)
-
-
-
-
N(2)#1-Ag(1)-N(3)#3 113.61(14) N(4)#2-Ag(1)-N(3)#3 97.57(17)
solution of AgX (X ) SO3CF3 , PF6 , ClO4 , and SbF6 )
-
afforded the 1:2 Ag(I)-L11 adduct for SO3CF3 and a 1:1
a Symmetry transformations used to generate equivalent atoms: #1 -x
+ 1, -y, -z + 1; #2 x - 1, y - 1, z; #3 -x + 1, -y + 1, -z; #4 x + 1,
y + 1, z; #5 -x, -y + 1, -z + 2.
-
-
-
adduct for PF6 , ClO4 , and SbF6 , presumably due to the
different coordinating nature and templating effect of the
counterions and solvent molecules.19 All these slow-diffusion
reactions are not affected by the metal-to-ligand mole ratio.
Their assembled structures, however, could be determined
by influencing the conformation of L11 through the change
of either the solvent intermediate or the anions. For instance,
the reaction of AgSO3CF3 with L11 in a THF/benzene or
CH2Cl2/benzene system produced a one-dimensional zigzag
chain structure, whereas the treatment of AgPF6 (THF/
benzene), AgClO4 (CH2Cl2/benzene), or AgSbF6 (THF/
benzene) with L11 gave a two-dimensional network; the
reaction of AgClO4 (THF/benzene), AgBF4 (THF/benzene),
or AgSbF6 (THF/benzene) with L11 afforded a three-
dimensional network. As depicted in Figure 2, in one-
dimensional compounds 1 and 2, L11 adopts conformation
II, in which the central oxadiazole group and its two adjacent
phenyl rings are basically coplanar. The dihedral angles
between the central oxadiazole and two neighboring phenyl
rings lie in the ranges of 3.76-4.39° and 3.87-5.69°,
respectively. In two-dimensional compounds 3-5, L11 takes
either conformation I or II, with dihedral angles between
the central oxadiazole and two neighboring phenyl rings of
23.51-34.29° and 23.94-33.64°, respectively. In three-
dimensional compounds 6-8, L11 chooses an intermediate
conformation between I and III, with the two long cyanophen-
ylacetylene arms lying in the different planes. The dihedral
angles between the two long arms attached to the central
oxadiazole are 59.80° (6), 49.16° (7), and 57.94° (8). All
the crystalline solids are not soluble in water or common
Table 8. Interatomic Distances (Å) and Bond Angles (deg) for 6a
Ag(1)-N(1)
Ag(1)-N(2)#2
2.287(3)
2.374(5)
Ag(1)-N(1)#1
Ag(1)-N(2)#3
2.287(3)
2.374(5)
N(1)-Ag(1)-N(1)#1
N(1)#1-Ag(1)-N(2)#2 98.99(17)
122.24(17) N(1)-Ag(1)-N(2)#2
N(1)-Ag(1)-N(2)#3
119.85(17)
98.99(17)
N(1)#1-Ag(1)-N(2)#3 119.85(17) N(2)#2-Ag(1)-N(2)#3 94.8(3)
a Symmetry transformations used to generate equivalent atoms: #1 -x
5
5
3
1
1
3
+ /4, -y + /4, z; #2 x + /4, y - /4, -z + 1; #3 -x + /2, -y + /2, -z
5
5
3
7
7
+ 1; #4 x, -y + /4, -z + /4; #5 -x + /4, -y + /4, z; #6 x, -y + /4,
-z + /4; #7 -x + /4, y, -z + /4.
3
5
5
Table 9. Interatomic Distances (Å) and Bond Angles (deg) for 7a
Ag(1)-N(1)
Ag(1)-N(3)#1
2.271(6)
2.319(9)
Ag(1)-N(2)
Ag(1)-N(4)#2
2.310(7)
2.442(9)
N(1)-Ag(1)-N(2)
117.06(18) N(1)-Ag(1)-N(3)#1
129.8(3)
97.6(3)
N(2)-Ag(1)-N(3)#1 100.7(3)
N(2)-Ag(1)-N(4)#2 118.8(3)
N(1)-Ag(1)-N(4)#2
N(3)#1-Ag(1)-N(4)#2 91.1(3)
a Symmetry transformations used to generate equivalent atoms: #1 x -
1/4, -y + 5/4, z + 3/4; #2 x + 1/4, -y + 5/4, z - 3/4; #3 -x + 1/2, -y + 3/2,
z.
Table 10. Interatomic Distances (Å) and Bond Angles (deg) for 8a
Ag(1)-N(1)
2.298(7) Ag(1)-N(2)#1
2.408(10) Ag(1)-N(4)#3
123.9(3) N(1)-Ag(1)-N(3)#2
2.303(8)
2.434(10)
121.4(3)
96.4(3)
Ag(1)-N(3)#2
N(1)-Ag(1)-N(2)#1
N(2)#1-Ag(1)-N(3)#2 104.0(3) N(1)-Ag(1)-N(4)#3
N(2)#1-Ag(1)-N(4)#3 117.8(3) N(3)#2-Ag(1)-N(4)#3 88.0(3)
a Symmetry transformations used to generate equivalent atoms: #1 -x
1
1
1
1
+ 1, y, -z + /2; #2 x + 1, -y, z + /2; #3 -x + /2, -y + /2, -z + 1;
1
3
#4 x - 1, -y, z - /2; #5 -x + 1, y, -z + /2.
(19) (a) Raehm, L.; Mimassi, L.; Guyard-Duhayon, C.; Amouri, H. Inorg.
Chem. 2003, 42, 5654. (b) Pike, R. D.; Borne, B. D.; Maeyer, J. T.;
Rheingold, A. L. Inorg. Chem. 2002, 41, 631. (c) Prior, T. J.;
Rosseinsky, M. J. Inorg. Chem. 2003, 42, 1564. (d) Jung, O.-K.; Kim,
Y. J.; Lee, Y.-A.; Park, K.-M.; Lee, S. S. Inorg. Chem. 2003, 42,
844. (e) Platas-Lglesias, C.; Esteban, D.; Ojea, V.; Avecilla, F.; de
Blas, A.; Rodringuez-Blas, T. Inorg. Chem. 2003, 42, 4299. (f) Wu,
B.; Yuan, D.; Lou, B.; Han, L.; Liu, C.; Zhang, C.; Hong, M. Inorg.
Chem. 2005, 44, 9175. (g) Fletcher, A. J.; Cussen, E. J.; Prior, T. J.;
Rosseinsky, M. J.; Kepert, C. J.; Thomas, K. M. J. Am. Chem. Soc.
2001, 123, 10001.
individual reaction would be determined by some parameters,
for example, the templating effect of solvent molecule, the
(18) To gain a deeper insight into the coordination behavior of this type of
ligands, we performed ab initio Mulliken population analysis on ligand
L11. The calculation results of L11 show that the energies of three
possible conformations of L11 in either gas or benzene solution are
almost identical. Thus, these three conformations, I, II, and III, could
be concomitant in gas or benzene solution.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3331

Dong et al.
Figure 1. Molecular structure of L11: ORTEP (right) and space-filling (left) figures.
Figure 2. Various conformations of L11 found in 1-8.
As shown in Figure 3, two different Ag(I) atoms are bound
together by two Noxadiazole donors on the central oxadiazole
ring of L11 and two Otriflate donors into a {Ag2O2N2} cluster
core in which the Ag(1)‚‚‚Ag(2) distance is ∼3.5 Å, which
is comparable to the sum of the van der Waals radii of two
silver atoms, 3.44 Å. In the solid state, ligand L11 adopts
conformation II and acts as a tetradentate spacer to link Ag-
(I) atoms into a one-dimensional zigzag double-chain
structure with the bending angle ca. 132° extended along
the crystallographic [01h1] direction (Figure 4). In the double
chain, two ethynylbenzonitrilephenyl arms are doubling-up
and parallel to each other, leading to the interchain π-π
interactions (centroid-to-centroid distance of ca. 3.9 Å).20
These zigzag double chains stack offset, generating channels
(Figure 5) in which two columns of benzene solvent
molecules are located as the guest. When viewed down the
crystallographic a and b axes, almost-regular rectangular and
parallelogram-like channels (effective cross section of ca.
10 × 13 Å2 and 10 × 12 Å2, respectively) were found. Inside
Figure 3. Coordination environment of Ag(I) in 1.
organic solvents because of their polymeric nature but are
dissolved by CH3CN and DMSO.
Structural Analysis. One-Dimensional Complexes of
[Ag2(L11)(SO3CF3)2]‚(C6H6) (1) and Ag2(L11)(SO3CF3)2]‚
(C6H6) (2). Crystallization of L11 with AgSO3CF3 in a CH2-
Cl2/C6H6 mixed-solvent system at room temperature afforded
compound 1 as an infinite one-dimensional chain structure
in 55% yield. Single-crystal analysis revealed that there are
two crystallographic independently Ag(I) centers in 1. Both
kinds of Ag(I) atoms adopt a {AgN2O2} coordination sphere.
-
the channels, benzene molecules and SO3CF3 counterions
are located (Figure 6).
Scheme 3. Three Typical Possible Conformations of L11
3332 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Figure 4. One-dimensional zigzag double chain of 1.
Figure 5. Representation of how the channel forms. Two sets of one-dimensional chains are given in different colors for clarity.
Figure 6. Spacing-filling representation of 1 showing channels along the crystallographic a (left) and b (right) axes. The SO3CF3- anion and benzene guest
molecule are shown in the stick-ball mode.
Figure 7. One-dimensional zigzag double chain of 2.
-
Complex [Ag2(L11)SO3CF3]2‚C6H6 (2) was obtained from
a THF/benzene mixed-solvent system. 2 is composed of the
similar one-dimensional double-zigzag Ag-L11 chain with
the same intrachain π-π interaction as 1 (Figure 7). It is
likely the different solvent intermediates gave rise to the
slight change in the ligand’s conformation, which lies in the
fact that the dihedral angles between the two phenyl rings
on the same ethynylbenzonitrilephenyl arm changed from
33.46 and 43.59° in 1 to 69.35 and 69.59° in 2, respectively.
Such changes could be what leads to the larger bending angle
of the zigzag chain in 2 (145°) and successively affects the
crystal-stacking fashion in the solid state. As indicated in
Figure 8, when viewed down the crystallographic a axis, the
coordination SO3CF3 anions occupied the parallelogram
channels and the benzene solvent molecules are covered by
the framework; when viewed down the crystallographic b
axis, both SO3CF3- anions and benzene molecules are visible
in the parallelogram-like channels but with a different
orientation compared to that of 1.
In the structures of both 1 and 2, the SO3CF3- anion acts
as a µ-η1 bridging ligand 21 rather than the µ-η2 bridging,
terminal, or chelating coordination mode commonly observed
(21) (a) Eisler, D. J.; Puddephatt, R. J. Cryst. Growth Des. 2005, 5, 57. (b)
Awaleh, M. O.; Badia, A.; Brisse, F.; Cryst. Growth Des. 2005, 5,
1897. (c) Schultheiss, N.; Powell, D. R.; Bosch, E. Inorg. Chem. 2003,
42, 8886. (d) Eisler, D. J. Puddephatt, R. J. Inorg. Chem. 2005, 44,
4666. (e) Custer, P. D.; Garrison, J. C.; Tessier, C. A.; Yongs, W. J.
Am. Chem. Soc. 2005, 127, 5738. (f) Brandys, M.-C.; Puddephatt, R.
J. J. Am. Chem. Soc. 2002, 124, 3946.
(20) Chen, C.-L.; Su, C.-Y.; Cai, Y.-P.; Zhang, H.-X.; Xu, A.-W.; Kang,
B.-S.; zur Loye, H.-C. Inorg. Chem. 2003, 42, 3788.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3333

Dong et al.
Figure 8. Crystal packing of 2 down the crystallographic a (left) and b (right) axes.
Figure 9. Coordination sphere of Ag(I) in 3.
in many other Ag-triflate complexes.14,21 Such a µ-η1
coordinated triflate anion, however, has been structurally
characterized for the first time in our bent ligand-silver
triflate system.14 The µ-η1 coordinating mode would result
in the relatively small O-Ag-O bond angles (76.33(16)-
79.54 (18)° in 1 and 2), which leans to the formation of the
sterically hindered cluster core being unfavorable in the self-
assembly process.
Figure 10. Molecular cage found in 3. The two uncoordinated PF6- anions
are omitted for clarity.
Two-Dimensional Complexes. [Ag(L11)]PF6 (3). Com-
pound 3 was prepared by reacting L11 with a stoichiometric
amount of AgPF6 in the same mixed-solvent system as that
in 2. It is different from compounds 1 and 2 in that 3 presents
a noninterpenetrating two-dimensional network in the solid
state. As shown in Figure 9, there is only one type of Ag(I)
center in 3. Compared to those of 1 and 2, the coordination
sphere of the Ag(I) atom changed from {AgO2N2} to
{AgN4}, which is clearly caused by changing the coordinated
-
-
SO3CF3 to an uncoordinated PF6 anion. The {AgN4}
sphere is composed of two Noxadiazole (Ag(1)-N ) 2.282(5)
Å) and two Nnitrile donors (Ag(1)-N(3) ) 2.364(7) and Ag-
(1)-N(4) ) 2.418(8) Å). Two central oxadiazole groups bind
two Ag(I) atoms through four oxadiazole N donors to
generate a {Ag2N2} bimetallic ring, in which the Ag‚‚‚Ag
distance is 3.7 Å. Such a bimetallic silver ring was observed
in our previous studies on L1-L10.14 Four {Ag2N4} moieties
are doubly connected to each other by the ethynylbenzoni-
trilephenyl arms of the tetradentate L11 ligands, generating
a rhombuslike molecular cage, in which the two pairs of
opposite Ag‚‚‚Ag distances are ca. 12 and 27 Å, respectively.
As shown in Figure 10, each terminal benzonitrile ring of
the ethynylbenzonitrilephenyl linkage is parallel to that of
an adjacent ethynylbenzonitrilephenyl segment, resulting in
interligand π-π interactions (centroid-to-centroid distance
between two benzene groups of ca. 3.9 Å). As depicted in
-
Figure 11. Space-filling view of the two-dimensional net containing PF6
anions in 3.
Figure 11, the two-dimensional net is extended in the
crystallographic bc plane. All of the two-dimensional nets
stack along the crystallographic a axis, generating rhombic
channels in which two columns of PF6- anions are arranged
into an approximately linear array that fits tightly into the
phenyl rings surrounding the central cavity. In addition, each
-
PF6 counterion is hydrogen bonded to the two adjacent
layers through F‚‚‚H-C hydrogen bonds and is linked
together along the crystallographic a axis, giving rise to a
three-dimensional hydrogen-bonded network (Figure 12).
The F‚‚‚H-C hydrogen bond lengths fall within the range
of 2.2-2.5 Å.22
3334 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
-
Figure 12. PF6 anion links two-dimensional nets into an H-bonded three-dimensional framework. Three layers are shown in different colors for clarity.
F‚‚‚H-C hydrogen bonds are shown as green dotted lines (left). H-bonded networks with rhombic channels along the crystallographic a axis (right).
Figure 14. Molecular Ag(I)-L11 cage in 4. The benzene and THF solvent
molecules are shown in the space-filling mode.
Figure 13. Coordination sphere of Ag(I) in 4.
like molecular cage based on {Ag2N4} connecting nodes with
the same dimensions has been found. Compared to the
A series of two-dimensional Ag(I)X-L8 polymeric co-
molecular cage in 3, the π-π interactions between the two
adjacent frame rungs is stronger, which is manifested in a
shorter centroid-to-centroid distance (3.7 Å) (Figure 14). It
is different from 3; the molecular cage herein is full of
-
-
-
ordination complexes (X ) BF4 , SbF6 , and SO3CF3 )
containing a similar molecular-cage-like building unit has
been reported by us recently. Therein, the dimensions of the
rhombic molecular cage are only ca. 8 × 16 Å2.14 As shown
above, the Ag(I)-L11 molecular cage is successfully
enlarged by the use of a longer organic spacer without
interpenetration or self-inclusion.23
[Ag(L11)]SbF6‚(C6H6)‚(THF) (4). To explore the tem-
plating effect19 of the counterion on the long-range order of
the Ag(I)-L11 coordination polymer, we used the larger-
sized SbF6- anion instead of the PF6- anion. Crystallization
of L11 with AgSbF6 in the same THF/benzene solvent
system at room temperature produced an infinite noninter-
penetrating two-dimensional polymeric compound 4 as
blocklike colorless crystals. In 4, L11 adopts the same
conformation as that of 3. Both crystallographically inde-
pendent Ag(I) centers lie in the same {AgN4} distorted
tetrahedral coordination sphere (Figure 13), which is similar
to that of compound 3. The Ag-N bond lengths lie in the
range of 2.278-2.499 Å. Two of the Ag-Nnitrile bond
distances (Ag-N(7) and Ag-N(8)) are slightly longer that
those corresponding bond lengths in 3. The same rhombus-
-
benzene and THF guest molecules besides SbF6 anions,
which could be the reason that crystals of 4 turn opaque
within minutes under an ambient atmosphere. The existence
of benzene and THF molecules were further confirmed by
1
the NMR spectrum. In the H NMR (in DMSO) spectrum
of 4, proton resonances were observed at 7.37 (singlet) ppm
and 3.53 and 1.73 (triplets) ppm, which were attributed to
benzene and the THF guest molecule, respectively.
4 features a stacking fashion similar to that of 3, which
generates the rhombic channels along the crystallographic a
axis. Two columns of benzene and two columns of THF
molecules are located in the channels (Figure 15). The
accessible void volume of the channels in one unit cell is
872.1 Å3, which is estimated to be 43.7% of the total volume
(1995.0 Å3). It is worth pointing out that compound 4
crystallizes in the chiral triclinic space group P1, an
enantiomorphous space group confirmed on the basis of an
absolute structure (Flack) parameter of 0.00 from the X-ray
data. At this stage, we could not explain the chirality-forming
-
-
mechanism of 4 by simply changing PF6 in 3 to SbF6 in
4. Nevertheless, compound 4 herein affords an additional
example of a chiral polymeric complex obtained by the
spontaneous resolution on crystallization with achiral aux-
iliary.24 The existence of this chiral and porous system
(22) (a) Braga, D.; Grepioni, F.; Desiraju, G. R. Chem. ReV. 1998, 98,
1375. (b) Shimoni, L.; Carrell, H. L.; Glusker, J. P.; Coombs, M. M.
J. Am. Chem. Soc. 1994, 116, 8162.
(23) The longer ligands would favor the formation of interpenetrating over
noninterpenetrating structures: Batten, S. R.; Robson, R. Angew.
Chem., Int. Ed. 1998, 37, 1460.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3335

Dong et al.
-
Figure 15. Crystal packing (left) and solvent and PF6 arrangement (right) found in 4.
Figure 16. Coordination environment of Ag(I) (left) and metalla-macrocycle (right) in 5.
suggests opportunities for the chiral selectivity of host
molecules and potentially even chiral selectivity for reactions
that might benefit from taking place inside spatially confined
channels and its local chemical microenvironment.
to the cage plane in 3 and 4. The different orientation of the
{Ag2N4} plane is clearly caused by the different conforma-
tions adopted by L11 in these complexes. As shown in Figure
17, the macrocyclic structure of 5 propagates along two
dimensions, resulting in the generation of a two-dimensional
layer. These two-dimensional layers are arranged in the
crystal in an AB-AB fashion resembling that of rhombic
close packing, such that the macrocyclic cavity does not
exhibit extended channels. Although such a stacking ar-
rangement effectively reduces the void volume present in
the structure, an inspection of Figure 18 reveals that the
overall array contains a three-dimensional intersecting chan-
nel system and nanoscale open windows, with an ap-
proximate effective cross section of ca. 14 × 9 Å2 (down
a), 15 × 10 Å2 (down b), and 12 × 16 Å2 (down c), which
is reflected in a large solvent-accessible volume of 898.0
Å3 (47.5% of a total unit-cell volume of 2082.1 Å3). Solvent
molecules are found in the different channel space with
different orientations. There are no significant interactions
between the solvent molecules and the host framework.
[Ag(L11)ClO4]‚2.5(C6H6) (5). Combining AgClO4 and
L11 in a CH2Cl2/benzene mixed-solvent system generated
compound 5 as a colorless blocklike crystal (Yield, 51%).
In 5, L11 adopts conformation I instead of conformation II,
as seen in complexes 3-4. In contrast to conformation II,
two long ethynylbenzonitrilephenyl arms rotate ca. 180°
around exo-oxadiazole carbon-carbon single bonds and point
in the same direction, leading to a Π-shaped spacer. As
shown in Figure 16, the Ag(I) atom again adopts a distorted
tetrahedral coordination sphere and the {Ag2N4} cluster
nodes are doubly connected to form an approximately
rhombus-shaped metalla-macrocycle through two sets of
parallel ethynylbenzonitrilephenyl linkages. The distances
between the two opposite pairs of silver ions on the
macrocycle are ∼18 and ∼22 Å. Again, each of the
macrocyclic sides is reinforced by the interligand π-π
interaction. Six benzene solvent molecules are located in the
macrocyclic cavity. In 5, the {Ag2N4} plane is nearly parallel
to the macrocyclic ring, whereas it projects perpendicularly
The common feature of two-dimensional complexes 3-5
is the coplanarity of the two long ethynylbenzonitrilephenyl
arms attached to a central oxadiazole ring, no matter which
conformation (I or II) L11 adopts. Second, the L11 spacer
doubles up and the {Ag2N2} cluster core is the connecting
node in the framework, which gives rise to the formation of
the double-decked layer. More importantly, such connectivity
(24) (a) Katsuki, I.; Motoda, Y.; Sunatsuki, Y.; Matsumoto, N.; Nakashima,
T.; Kojima, M. J. Am. Chem. Soc. 2002, 124, 629. (b) Gao, E.-B.;
Bai, S.-Q.; Wang, Z.-M.; Yan, C.-H. J. Am. Chem. Soc. 2003, 125,
4984. (c) Sasa, M.; Tanaka, K.; Bu, X.-H.; Shiro, M.; Shionoya, M.
J. Am. Chem. Soc. 2001, 123, 10750.
3336 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Figure 17. Top view of the two-dimensional net with rhombic cavity (left) and side view of the AB-AB stacking fashion (right) found in 5. Two sets of
sheets are represented by the red and blue colors in the figure.
Figure 18. Ball-stick representation of 5 showing channels opening along the crystallographic a, b, and c axes (from left to right). The benzene solvent
molecules are shown in the spacing-filling mode.
Figure 19. Four-connected {Ag2N4} cluster core being doubly linked by L11 into a tetrahedral building block.
effectively prevents the molecule’s solid-state packing from
interpenetration or self-inclusion and enables the formation
of large rhombic grids with infinite channels.
benzonitrilephenyl arms being ca. 60°) and binds two Ag(I)
ions in a back-to-back fashion through the Ag(I)-Noxadiazole
interaction. This gives rise to a {Ag2N4} cluster core upon
which four ethynylbenzonitrilephenyl arms stretch outward
in four different directions, leading to the formation of a
tetrahedral building block. The intracore Ag‚‚‚Ag distance
is 3.5 Å, which is comparable to that of 1 and indicative of
little direct metal-metal interaction. As indicated in Figure
20a, the assembly of a tetrahedral building block results in
a three-dimensional adamantoid arrangement that leaves a
huge cavity inside the framework. The three pairs of
intracage diagonal Ag‚‚‚Ag distances across the individual
adamantoid are 57, 44, and 38 Å. Two terminal benzonitrile
rings of each ethynylbenzonitrilephenyl linkage are basically
Three-Dimensional Complexes. [Ag(L11)]BF4‚2.5(C6H6)
(6) and [Ag(L11)]SbF6‚unknown solvate (7). Combining
L11 with AgBF4 in a THF/benzene mixed-solvent system
at room temperature generated compound 6 as a colorless
crystal in 51% yield. X-ray single-crystal analysis revealed
that compound 6 crystallizes in the orthorhombic space group
Fddd. The silver atom lies in a distorted coordination sphere
consisting of four N donors from two terminal benzonitrile
groups and two central oxadiazole rings. As shown in Figures
3 and 19, L11 adopts the intermediate conformation between
I and III (with the dihedral angle between the two ethynyl-
Inorganic Chemistry, Vol. 45, No. 8, 2006 3337

Dong et al.
Figure 20. (a) Ball and stick representation of single adamantoid cage formed in an individual framework. Benzene and anion guests are shown in the
space-filling mode. (b) Space-filling illustration of how three frameworks in 6 interpenetrate. The three independent frameworks are colored red, green, and
blue.
coplanar and are parallel to those of adjacent ethynylben-
zonitrilephenyl segments, again resulting in interligand π-π
interactions (a centroid-to-centroid distance between two
benzene groups of ca. 3.6 Å). Such an arrangement, beyond
all doubt, reinforces the host cage. The remarkable feature
of 6 is that the adamantoid cage is capped by the {Ag2N4}
cluster core instead of simple silver ions being connecting
nodes, which is rarely observed otherwise;25,26 Second, the
adamantoid framework is doubly pinned up by the ligand.
To the best of our knowledge, such adamantoid construction
of 1 is unprecedented (Chart 3). When viewed down the
crystallographic a, b, [101], and [01h1] directions, huge
honeycomb- (31 × 27 Å2), ellipse- (23 × 14 Å2), square-
(18 × 24 Å2), and rhombuslike (36 × 13 Å2) channels have
been found (Figure 21), respectively. Unfortunately, these
channels of an individual diamondoid framework are partially
filled by two other interpenetrated symmetry-equivalent
frameworks, leading to a 3-fold interpenetrated structure
(Figure 20b). In the case of 6, the 3-fold interpenetration of
Chart 3. Common (left) and New (right) Adamantoid Frameworksa
a The common framework consists of a simple metal ion node and a
single-linked spacer. The new adamantoid framework is composed of a
cluster core node, shown as MnEm and a double-linked space.
the framework generates reduced, yet still very large, infinite
regular honeycomb and semicircular channels along the
crystallographic a and [110] directions with dimensions of
ca. 16 × 15 and 10 × 8 Å2, respectively (Figure 22), in
-
which the BF4 anions and benzene molecules are located
as guests. The solvent-accessible volume calculated with the
PLATON program is 6556.7 Å3, which accounts for ca. 40%
of the crystal volume (16474.0 Å3).
(25) For earlier examples of diamondoid frameworks, see: (a) MacGillivray,
L. R.; Subramamian, S.; Zaworotko, M. J. J. Chem. Soc., Chem.
Commun. 1994, 1325. (b) Proserpio, D. M.; Hoffmann, R.; Preuss, P.
J. Am. Chem. Soc. 1994, 116, 9634. (c) Batten, S. R.; Robson, R.
Angew. Chem., Int. Ed. 1998, 37, 1461. (d) Zaworotko, M. J. Chem.
Soc. ReV. 1994, 283. (e) Lopez, S.; Kahraman, M.; Harmata, M.;
Keller, S. W. Inorg. Chem. 1997, 36, 6138. (f) Blake, A. J.;
Champness, N. R.; Chung, S. S. M.; Li, W.-S.; Schro¨der, M. Chem.
Commun. 1997, 1005. (g) Michaelides, A.; Kiritsis, V.; Skoulika, S.;
Aubry, A. Angew. Chem., Int. Ed. 1993, 32, 1495. (h) Hirsch, K. A.;
Venkataraman, D.; Wilson, S. R.; Moore, J. S.; Lee, S. Chem.
Commun. 1995, 2199. (i) Hirsch, K. A.; Wilson, S. R.; Moore, J. S.
Chem.sEur. J. 1997, 3, 765. (k) Hirsch, K. A.; Wilson, S. R.; Moore,
J. S. Inorg. Chem. 1997, 36, 2960. (l) Munakata, M.; Wu, L. P.;
Yamamoto, M.; Kuroda-Sowa, T.; Maekawa, M. J. Am. Chem. Soc.
1996, 118, 3117. (m) Sinzger, K.; Hu¨nig, S.; Jopp, M.; Bauer, D.;
Bietsch, W.; von Schu¨tz, J. U.; Wolf, H. C.; Kremer, R. K.;
Metzenthin, T.; Bau, R.; Khan, S. I.; Lindbaum, A.; Langauer, C. L.;
Tillmanns, E. J. Am. Chem. Soc. 1993, 115, 7696.
(26) Several diamondoid frameworks based on cluster connecting nodes
have been reported very recently: (a) Liang, K.; Zheng, H.; Song,
Y.; Lappert, M. F.; Li, Y.; Xin, X.; Huang, Z.; Chen, J.; Lu, S. Angew.
Chem., Int. Ed. 2004, 43, 5776. (b) Cheng, J.-K.; Chen, Y.-B.; Wu,
L.; Zhang, J.; Wen, Y.-H.; Li, Z.-J.; Yao, Y.-G. Inorg. Chem. 2005,
44, 3386. (c) Liang, J.-P.; Xu, Q.-F.; Yuan, R.-X.; Abrahams, B. F.
Angew. Chem., Int. Ed. 2004, 43, 4741. (d) Hoffart, D. J.; Cote, A.
P.; Shimizu, G. K. H. Inorg. Chem. 2003, 42, 8603. (e) Wang, X.-S.;
Zhao, H.; Qu, Z.-R.; Ye, Q.; Zhang, J.; Xiong, R.-G.; You, X.-Z.;
Fun, H.-K. Inorg. Chem. 2003, 42, 5786.
Compound 7 was obtained from the same reaction as that
used for the preparation of 4 as colorless crystals. It seems
to us that both 4 and 7 were constructed simultaneously
during the reaction. The shape and color of the crystals of 7
are same as those of 4; thus, we could not separate them
manually. X-ray single-crystal analysis revealed that the
given silver atom adopts the same coordination environment
as 6 (Figure 23) and that 7 exhibits a 3-fold interpenetrating
diamondoid coordination framework similar to that of 6
(Figure 24). A diamondoid cage of 7 (overall dimensions
are almost identical to those of 6; the intracage opposite Ag‚
‚‚Ag diagonal distances across the individual adamantoid are
-
5.7 × 4.5 × 4.1 nm3) is capable of encapsulating SbF6
anion, benzene, and THF guest molecules.27 Calculation
(27) Nnumerous electron-density peaks were observed in the large voids
between the 3-fold interpenetrating [Ag(L11)]+ frameworks. The single
1
peak at 7.36 and triple peaks at 3.32 and 1.76 ppm in the H NMR
spectrum of 2 indicate that the crystallographically unknown solvent
molecules are benzene and THF.
3338 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Figure 21. Space-filling diagrams of 6 viewed down the a, b, [101], and [01h1] crystallographic directions.
Figure 22. Three-fold interpenetration showing the hexagonal (viewed down the a axis, top) and semicircular (viewed down the [110] direction, bottom)
channels. Frameworks are shown as space-filling models, and three sets of diamondoid frameworks are shown as different colors.
Figure 23. Doubly linked four-connected {Ag2N4} cluster core building block in 7.
using the PLATON program suggests that the effective
volume for inclusion is 5948.6 Å3, comprising 35.4% of the
crystal volume (16 574.0 Å3). It is noteworthy that the angle
(49.16°) between two adjacent arms attached to the {Ag2N4}
cluster is smaller than that of 6; The Ag‚‚‚Ag separation in
the {Ag2N4} cluster core is 3.7 Å, which is longer than that
of 6 by 0.2 Å. These tiny differences, however, play a central
role in causing the changes of the crystal packing of 7 in
the solid state. When viewed down the crystallographic c
axis, in contrast to the regular honeycomb structure of 6,
the shape of the channels is twisted to a certain extent. When
viewed down the crystallographic [101h] direction, the
coordination pattern is comparable to the [110] view of 6,
but with enclosed cylinderlike channels (Figure 25). There
is no doubt that such a change results from the anion-
However, the relationship between a given anion and the
selective self-assembly of a certain type of polymeric motifs
is not yet well-understood.
[Ag(L11)]ClO4‚(C7H8) (8). Complex 8 was prepared by
reaction of AgClO4 with the L11 ligand in the required ratio
in a THF/toluene mixed-solvent system. 8 crystallizes in the
monoclinic space group C2/c, which is different from that
of 6 and 7, but it exhibits a 3-fold three-dimensional network
in the solid state similar to that in 6 and 7. As shown in
Figure 26, the connecting node in 8 is a {Ag2N4O2} cluster
core instead of the {Ag2N4} moiety observed in 6 and 7.
-
The ClO4 anion acts as a µ-η2 ligand to bridge two
crystallographically independent silver atoms on the Ag2N4
ring into a {Ag2N2O2} cluster core. The Ag‚‚‚Ag separation
within the disilver unit is ca. 3.5 Å, equivalent that of 6.
The angle (57.94°) between the two ethynylbenzonitrile-
phenyl arms is smaller than that of 6 but larger than that of
-
templating effect (from BF4- to SbF6 ). Counterion-depend-
ent polymeric architectures have been observed quite often.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3339

Dong et al.
Figure 24. Space-filling diagram of the adamantoid cage formed in an individual framework (left), and an illustration of how the frameworks in 7 interpenetrate.
The three independent frameworks are colored red, green, and blue (right).
Figure 25. Three-fold interpenetration showing the twisted hexagonal (viewed down the c axis, left) and cylinder (viewed down [101h] direction, right)
channels. Frameworks are shown as space-filling models.
Figure 26. Doubly linked four-connected {Ag2N4} cluster core building block in 8.
7. Again, the interligand π-π interactions present in 8 are
due to the parallel arrangement of the ethynylbenzonitrile-
phenyl linkages. By contrast with that of 6, the 3-fold three-
dimensional framework of 8 contains honeycomblike and
elliptical channels with almost identical dimensions extending
anions and toluene molecules are located in the cavities as
guests (Figure 27). The solvent-accessible volume of 3470.6
Å3 comprises 44.3% of the crystal volume (7826.0 Å3). The
AgClO4-L11 self-assembled structures (5 and 8) are not
affected by the change in molar ratios (the 1:1 adduct was
always isolated under different metal-to-ligand ratios);
-
along the crystallographic a and [110] directions. ClO4
3340 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
Figure 27. Three-fold interpenetration showing the regular hexagonal (viewed down the a axis, left) and elliptical channels. (viewed down the [110]
direction, right).
1
Figure 28. 1H NMR spectra of 6 in DMSO-d6 (left): (a) H NMR spectrum of the original sample of 6 recorded at room temperature; (b) solid sample
of 6 was heated to 110 °C and then dissolved in DMSO-d6, the spectrum was recorded at ambient temperature; (c) solid sample of 6 was heated to 200 °C
and then dissolved in DMSO-d6, the spectrum was recorded at ambient temperature; (d) 6 immersed in benzene for 24 h and dried at room temperature for
1 day. X-ray powder diffraction patterns of 6 (right): (a) the original crystals of 6; (b) 6 heated to 200 °C; (c) sample obtained by immersing (b) in benzene
for 24 h at room temperature and dried at room temperature for 1 day.
however, they are strongly dependent upon the solvent
templating. In other words, the solvent template readily gives
rise to the change in conformations taken by L11 during
self-assembly. As mentioned above, compound 5 was
isolated as a two-dimensional net from a CH2Cl2/benzene
solvent system on the basis of conformation I, whereas 8
was separated as a three-dimensional framework from a THF/
toluene solvent system generated from an intermediate
conformation between conformation I and III. Thus, com-
pounds 5 and 8 are solvent-responsive compounds because
of the rotational freedom nature of L11.
As mentioned above, in all three three-dimensional
structures 6-8, the two long substituting arms attached to
the central oxadiazole moiety are not coplanar and make the
secondary building blocks three-dimensional, which causes
the overall number of dimensions to go from two in 3-5 to
three in 6-8. The dihedral angles between the two ethynyl-
benzonitrilephenyl arms of L11 in 6-8 are slightly different,
which is reflected in the tiny different channel shapes
observed in these three complexes.
nanoporous materials.28 As a porous material, the important
feature of 6 is that it can reversibly desorb and reabsorb
benzene molecules (Figure 28).29 TGA traces together with
1H NMR spectra indicated that all benzene guest molecules
could be removed at ∼200 °C. The framework of compound
6 is stable up to 220 °C. The X-ray powder diffraction pattern
of thermally desolvated sample of 6 is compared with that
of as-synthesized, solvent-containing 6. The XRD pattern
after heating shows that the shapes and intensities of some
reflections are slightly changed relative to that of the original
sample. This means that guest loss does not result in
symmetry change or cavity volume collapse. When the
desolvated solids are immersed in benzene for 24 h at room
temperature, an XRD pattern nearly identical to that obtained
for the original crystals is regenerated, indicating the benzene
molecules were re-incorporated into the framework under
these mild conditions. After the sample was taken out of
(28) (a) Bradshaw, D.; Claridge, J. B.; Cussen, E. J.; Prior, T. J.; Rosseinsky,
M. J. 2005, 38, 273. (b) Ferey, G.; Mellot-Draznieks, C.; Serre, C.;
Millange, F. Acc. Chem. Res. 2005, 38, 217.
Host-Guest Chemistry of Compound 6. Crystal engi-
neering of organic-inorganic coordination network archi-
tectures on the basis of transition metals and organic spacers
has attracted intensive attention. One of the most important
motivations lies in that programmable crystal engineering
may provide a new approach to the synthesis of functional
(29) (a) Kondo, M.; Yoshiitomi, T.; Seki, K.; Matsuzaka, H.; Kitagawa,
S. Angew. Chem., Int. Ed. 1997, 36, 1725. (b) Li, H.; Eddaoudi, M.;
Groy, T. L.; Yaghi, O. M. J. Am. Chem. Soc. 1998, 120, 8571. (c) Li,
H.; Eddaoudi, M.; O’Keeffe, M.; Yaghi, O. M. Nature 1999, 402,
276. (d) Choi, H. J.; Lee, T. S.; Suh, M. P. Angew. Chem., Int. Ed.
1999, 38, 1405. (e) Dybtsev, D. N.; Chun, H.; Yoon, S. H.; Kim, D.;
Kim, K. J. Am. Chem. Soc. 2004, 126, 32. (f) Liao, Y.-C.; Liao, F.-
L.; Chang, W.-K.; Wang, S.-L. J. Am. Chem. Soc. 2004, 126, 1320.
Inorganic Chemistry, Vol. 45, No. 8, 2006 3341

Dong et al.
Figure 29. Photoinduced excitation (blue, 310 nm) and emission (red, 333 nm) spectra of L11 in CHCl3.
Table 11. Luminescence Properties of L11 and Complexes 1-3, 5-6,
and 8 in the Solid State
benzene, it was dried at room temperature for 24 h before
the 1H NMR spectrum was recorded. The 1H NMR spectrum
confirmed the re-uptake of benzene to the extent of 73%.
Because 6 is insoluble in benzene, the possibility of a
dissolution-recrystallization mechanism for explaining the
solvent reabsorption is unlikely.
compd
solid state (λex/λem
)
compd
solid state (λex/λem)
L11
1
2
358/380
376/413
386/422
365/423
5
6
8
360/414
355/423
369/421
3
Luminescence Properties of L11 and Its Ag(I) Com-
plexes. Inorganic-organic hybrid coordination polymers
have been investigated for fluorescence properties and for
potential applications as luminescence materials, such as
light-emitting diodes (LEDs).30 Because of the higher thermal
stability of inorganic-organic coordination polymers and the
ability to affect the emission wavelength of organic materials,
syntheses of inorganic-organic coordination polymers by
the judicious choice of conjugated organic spacers and
transition-metal centers can be an efficient method for
obtaining new types of electroluminescence materials, es-
pecially for d10 or d10-d10 systems31 and oxadiazole-
containing complexes.32 We have been exploring the lumi-
nescence properties of L1-L10 and organic-inorganic
coordination polymers and supramolecular complexes based
on these complexes in the solid state. The results indicate
that emission colors of organic spacers L1-L10 were
affected by their incorporation into metal-containing coor-
dination compounds.14 The luminescence properties of L11
and polymeric compounds 1-3, 5, 6, and 8 were investigated
in the solid state. The fluorescence spectra of L11 and its
complexes are summarized in Table 11. As indicated in
Figure 29, in CHCl3, L11 presents one maximum at 333 nm,
with a second, less-intense band present at 345 nm. In the
solid state, L11 exhibits one emission maximum at 380 nm.
As shown in Table 11, in the solid state, the emission color
of the free ligand was significantly affected by its incorpora-
tion into the Ag-containing polymeric complexes, as evi-
denced by the large red shift (33-43 nm) in the emission.
Reasonably, the presence of the intervening silver atoms,
which exert an electron-withdrawing effect as a consequence
of their +1 charge, have a significant influence on the
luminescence properties of the ligand. In CH3CN, the
emission colors between L11 and its silver complexes are
almost identical, which implies that the polymeric complexes
disaggregate into starting materials in acetonitrile.
Conclusions
In conclusion, one nanosized oxadiazole bridging ligand,
L11, was designed and synthesized by the reaction of bis-
(3-iodophenyl)oxadiazole with 4-cyanophenylacetylene via
a classical Sonogashira-Hagihara cross-coupling reaction.
Eight Ag(I)-L11 coordination polymers with one-, two- and
three-dimensional structures have been successfully prepared
by the reaction of L11 with various Ag(I) salts in solution.
All new complexes are capped by a silver cluster core
({Ag2O2N2} in 1 and 2, {Ag2N4} in 3-7, and {Ag2N2O2}
in 8) instead of a simple metal ion, and the L11 doubles up
in the frameworks. A cluster node and double rungs
participated in the π-π interaction, making the secondary
building block bulk up, which appears to inhibit high
interpenetration; this effectively facilitates the formation of
large channels or cavities in aggregates. In this Ag(I)-L11
(30) (a) Ciurtin, D. M.; Pschirer, N. G.; Smith, M. D.; Bunz, U. H. F.; zur
Loye, H.-C. Chem. Mater. 2001, 13, 2743. (b) Cariati, E.; Bu, X.;
Ford, P. C.; Chem. Mater. 2000, 12, 3385. (c) Wu¨rthner, F.; Sautter,
A. Chem. Commun. 2000, 445.
(31) (a) Harvey, P. D.; Gray, H. B. J. Am. Chem. Soc. 1988, 110, 2145.
(b) Catalano, V. J.; Kar, H. M.; Bennett, B. L. Inorg. Chem. 2000,
39, 121. (c) Tong, M.-L.; Chen, X.-M.; Ye, B.-H.; Ji, L.-N. Angew.
Chem., Int. Ed. 1999, 38, 2237. (d) Burini, A.; Bravi, R.; Fackler, J.
P., Jr.; Galassi, R.; Grant, T. A.; Omary, M. A.; Pietroni, B. R.; Staples,
R. J. Inorg. Chem. 2000, 39, 3158. (e) Seward, C.; Jia, W.-L.; Wang,
R.-Y.; Enright, G. D.; Wang, S.-N. Angew. Chem., Int. Ed. 2004, 43,
2933. (f) Yam, V. W.-W.; Lo, K. K.-W. Chem. Soc. ReV. 1999, 28,
323. (g) Wu, C.-D.; Ngo, H. L.; Lin, W. Chem. Commun. 2004, 1588.
(32) (a) Hu, N.-X.; Esteghamatian, M.; Xie, S.; Popovic, Z.; Hor, A.-M.;
Ong, B.; Wang, S.-N. AdV. Mater. 1999, 11, 1460. (b) de Silva, A.
S.; de Silva, M. A. A.; Carvalho, C. E. M.; Antunes, O. A. C.; Herrera,
J. O. M.; Brinn, I. M.; Mangrich, A. S. Inorg. Chim. Acta 1999, 292,
1. (c) Wang, J.; Wang, R.; Yang, J.; Zheng, Z.; Carducci, M. D.;
Cayou, T.; Peyghambarian, N.; Jabbour, G. E. J. Am. Chem. Soc. 2001,
123, 6179.
3342 Inorganic Chemistry, Vol. 45, No. 8, 2006

SilWer(I) Coordination Polymers
system, the conformation of L11 is versatile and depends
greatly on the counterion and solvent system used in the
formation of the complexes: (a) in one-dimensional struc-
tures 1 and 2, the ligand displays conformation II with the
central oxadiazole and its two adjacent phenyl rings being
coplanar; (b) in two-dimensional compounds 3-5, L11 takes
either conformation I or II but with the central oxadiazole
and two neighbor phenyl rings being nonplanar; and (c) in
three-dimensional compounds 6-8, L11 chooses an inter-
mediate conformation between I and III, with the two long
cyanophenylacetylene arms lying in different planes. Clearly,
we still have a lot to learn about how exactly to control the
conformation of L11 taken during the self-assembly process.
Nevertheless, the self-assembly of the bent organic ligands
with long rigid sidearms connected by a central coordinated
heterocyclic ring and metal ions is a new approach for
accessing metal-organic frameworks consisting of double
rungs and metal cluster nodes. We are currently extending
this result by preparing new symmetric and unsymmetric
five-membered heterocyclic ring bridging ligands of this type
that contain different coordination functional groups and have
different orientations of the terminal coordination sites. The
new metal-organic polymers and supramolecular complexes
based on the new bent spacers of this type with novel
polymeric patterns and properties will be reported soon.
Acknowledgment. We are grateful for financial support
from the National Natural Science Foundation of China (No.
20371030), and Shangdong Natural Science Foundation (No.
Z2004B01).
Supporting Information Available: Crystallographic data in
cif format. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC052158W
Inorganic Chemistry, Vol. 45, No. 8, 2006 3343