Toward the self-assembly of metal-organic nanotubes using metal-metal and π-stacking interactions: Bis (pyridylethynyl) silver(I) metallo-macrocycles and coordination polymers

Article abstract of DOI:10.1021/ic1020059

Shape-persistent macrocycles and planar organometallic complexes are beginning to show considerable promise as building blocks for the self-assembly of a variety of supramolecular materials including nanofibers, nanowires, and liquid crystals. Here we report the synthesis and characterization of a family of planar di-and tri-silver(I) containing metallo-macrocycles designed to self-assemble into novel metal-organic nanotubes through a combination of n-stacking and metal-metal interactions. The silver(I) complexes have been fully characterized by elemental analysis, high resolution electrospray ionization mass spectrometry (HR-ESI-MS), IR, 1H and 1C NMR spectroscopy, and the solution data are consistent with the formation of the metallo-macrocycles. Four of the complexes have been structurally characterized using X-ray crystallography. However, only the di-silver(I) complex formed with 1,3-bis(pyridin-3-ylethynyl) benzene is found to maintain its macrocyclic structure in the solid state. The di-silver(I) shape-persistent macrocycle assembles into a nanoporous chicken-wire like structure, and ClO₄- anions and disordered H ₂O molecules fill the pores. The silver(I) complexes of 2,6-bis(pyridin-3-ylethynyl)pyridine and 1,4-di(3-pyridyl)buta-1,3-diyne ring-open and crystallize as non-porous coordination polymers.

Full text of DOI:10.1021/ic1020059

Inorg. Chem. 2011, 50, 1123–1134 1123
DOI: 10.1021/ic1020059
Toward the Self-Assembly of Metal-Organic Nanotubes Using Metal-Metal
and π-Stacking Interactions: Bis(pyridylethynyl) Silver(I) Metallo-macrocycles
and Coordination Polymers
Kelly J. Kilpin,† Martin L. Gower,† Shane G. Telfer,‡,§ Geoffrey B. Jameson,‡ and James D. Crowley*,†
†Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand, ‡Institute of Fundamental
§
Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand, and MacDiarmid Institute
for Advanced Materials and Nanotechnology, Wellington, New Zealand
Received September 30, 2010
Shape-persistent macrocycles and planar organometallic complexes are beginning to show considerable promise as
building blocks for the self-assembly of a variety of supramolecular materials including nanofibers, nanowires, and
liquid crystals. Here we report the synthesis and characterization of a family of planar di- and tri-silver(I) containing
metallo-macrocycles designed to self-assemble into novel metal-organic nanotubes through a combination of
π-stacking and metal-metal interactions. The silver(I) complexes have been fully characterized by elemental
analysis, high resolution electrospray ionization mass spectrometry (HR-ESI-MS), IR, 1H and 13C NMR spectroscopy,
and the solution data are consistent with the formation of the metallo-macrocycles. Four of the complexes have been
structurally characterized using X-ray crystallography. However, only the di-silver(I) complex formed with
1,3-bis(pyridin-3-ylethynyl)benzene is found to maintain its macrocyclic structure in the solid state. The di-silver(I) shape-
persistent macrocycle assembles into a nanoporous chicken-wire like structure, and ClO4- anions and disordered H2O
molecules fill the pores. The silver(I) complexes of 2,6-bis(pyridin-3-ylethynyl)pyridine and 1,4-di(3-pyridyl)buta-1,3-
diyne ring-open and crystallize as non-porous coordination polymers.
Introduction
assemblies including host-guest complexes,3 discotic liquid
crystals,2 sensors,4 nanotubes5 and nanofibers,4,6 and organic
porous solids.7 These supramolecular systems usually exploit
either π-π interactions or hydrogen-bonding interactions in
the assembly process.2,6,8
Recently, planar organometallic complexes have also be-
gun to show promise as building blocks for the construction
of self-assembled nanoscale materials.9 In particular, the syn-
thesis of planar platinum(II) or gold(I) complexes containing
Nature exploits noncovalent forces such as hydrogen
bonding, hydrophobic, dipole-dipole, and van der Waals inter-
actions to self-assemble a vast range of functional molecular
architectures from a small set of relatively “simple” building
blocks. Inspired by this, the use of self-assembly as an
approach for the generation of ordered nanoscale structures
and (supra)molecule-based devices has engendered consider-
able attention in the materials sciences.1 Shape-persistent
macrocycles (SPMs)2 are one class of molecules that have
been extensively examined in this regard. The rigid macro-
cyclic framework of SPMs has been exploited as a building
block for the generation of a variety of supramolecular
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*To whom correspondence should be addressed. E-mail: jcrowley@
chemistry.otago.ac.nz. Fax: þ64 3 479 7906. Phone: þ64 3 479 7731.
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r
2011 American Chemical Society
Published on Web 01/05/2011
pubs.acs.org/IC

1124 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
π-conjugated ligands has received considerable attention
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of metal-metal10 (Pt-Pt11 or Au-Au12) and π-π interac-
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In light of the above work and given the excellent methods
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toward the exploitation of metal-containing shape-persistent
macrocycles (MSPMs) for the generation of novel self-
assembled materials. Inspired by the seminal work of Moore
et al. on the self-assembly of planar m-phenylene ethynylene
macrocycles7,19 and coupling with our own interests in metal
directed self-assemby20 and metal-metal interactions,21 we
have examined the use of carefully designed planar MSPMs
to assemble novel metal organic nanotubes through a com-
bination of π-stacking and metal-metal interactions.
Metallo-macrocycle Design. The metallo-macrocycles, 1
and 2, havebeencarefullydesignedto formplanarMSPMs
(Scheme 1). Combining the linear two-coordinate prefer-
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Article
Inorganic Chemistry, Vol. 50, No. 3, 2011 1125
Scheme 1. Synthesis of Silver(I)- or Gold(I)-Containing Planar MSPMs, 1 and 2
ligands24 is expected to lead to the formation of the
metallo-macrocycles, 1 and 2, in high yield under thermo-
dynamic control (Scheme 1). The use of ethynyl spacer
units within the framework removes any steric interac-
tions between the aromatic moieties of the ligands and
allows for the formation of essentially perfectly planar
macrocycles (Supporting Information, Figures S1-S2).
Furthermore, the presence of the d10 metal ions within the
macrocyclic framework is expected to be crucial for the
generation of the well-defined metal-organic nanotube
supra-structures. Because of the electrostatic nature of
π-π interactions,25 planar aromatic molecules tend to
form T-shaped or slipped stacked structures in the solid
state and are therefore unsuitable, in isolation, for linear
nanotube construction. On the other hand, it is well-
established that many sterically unencumbered or planar
supramolecular forces should lead to the formation of
well-defined linear extended porous stacks (Supporting
Information, Figures S1-S2). These planar MSPMs could
potentially be useful building blocks for the synthesis of
novel nanoscale materials.
Results and Discussion
Ligand Synthesis and Characterization. The bis(pyri-
dylethynyl) ligands L2, L3, L4, and L5 were synthesized in
good yields by a standard Pd/Cu catalyzed Sonogashira
coupling reaction26 between the appropriate dialkyne and
3-iodopyridine27 (Scheme 2). Under these conditions, the
28
29
yields of the ligands L2 and L3 are greatly increased
from those that had been previously reported in the litera-
ture. As described previously, L1 was synthesized via a
Glaser homocoupling of 3-ethynylpyridine.30 To the best
of our knowledge this is the first report on the synthesis of
both L4 and L5 and as such both ligands have been fully
characterized by IR and NMR spectroscopy (Supporting
Information, Figures S3-S7), ESI-MS, and elemental
analysis.
d
10 metal complexes stack in the crystalline state forming
“weak” metal-metal interactions, which have strengths
comparable to hydrogen bonds. Guided by the presence
of the metal-metal interactions, this combination of
Silver(I) and Gold(I) Complexes. The silver(I) com-
plexes of the ligands L1-L5 were prepared by the addition
(24) Bis(pyridylethynyl) ligands have previously been shown to form
coordination polymers and metallo-macrocycles with a variety of metal
ions, see: Liao, P.; Langloss, B. W.; Johnson, A. M.; Knudsen, E. R.; Tham,
F. S.; Julian, R. R.; Hooley, R. J. Chem. Commun. 2010, 46, 4932–4934. Zhao,
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-
of a molar equivalent of silver salt (AgX, X = BF4
,
SbF6-, SO3CF3-, or ClO4-) to an acetone solution of the
ligand. The complexes precipitated immediately from the
solution in good to excellent yields (49-97%) as analy-
tically pure white solids, which appear moderately stable
both in the solid state and in solution when stored in the
(26) Sonogashira, K. J. Organomet. Chem. 2002, 653, 46–49. Sonogashira,
K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975, 4467–4470. Chinchilla, R.;
Najera, C. Chem. Rev. 2007, 107, 874–922.
(27) Krasnokutskaya, E. A.; Semenischeva, N. I.; Filimonov, V. D.;
Knochel, P. Synthesis 2007, 81–84.
(28) Grummt, U. W.; Birckner, E.; Klemm, E.; Egbe, D. A. M.; Heise, B.
J. Phys. Org. Chem. 2000, 13, 112–126.
(29) Schultheiss, N.; Ellsworth, J. M.; Bosch, E.; Barnes, C. L. Eur. J.
Inorg. Chem. 2005, 45–46.
(25) Hunter, C. A.; Lawson, K. R.; Perkins, J.; Urch, C. J. J. Chem. Soc.,
Perkin Trans. 2 2001, 651–669. Meyer, E. A.; Castellano, R. K.; Diederich, F.
Angew. Chem., Int. Ed. 2003, 42, 1210–1250.
(30) Rodriguez, J. G.; Martin-Villamil, R.; Cano, F. H.; Fonseca, I.
J. Chem. Soc., Perkin Trans. 1 1997, 709–714.

1126 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
Scheme 2. Synthesis of Bis(pyridylethynyl) Ligands Used in This Studya
a Isolated yields, L1 (88%), L2 (65%), L3 (90%), L4 (76%), L5 (81%).
absence of light. The complexes are slightly soluble in
acetone, but demonstrate much better solubility in more
coordinating solvents such as acetonitrile and dimethyl-
sulfoxide.
resolution electrospray ionization mass spectrometry
(HR-ESI-MS) indicated that the gold(I) macrocycles
are formed in solution (Supporting Information, Figures
S8-S9). However, the cationic gold(I) macrocyclic com-
plexes were only soluble in coordinating solvents, and
disappointingly, over a 2 h period, solutions of the Au(I)
macrocycles changed from colorless to purple indicating
that the complexes had decomposed into gold nanopar-
ticles (AuNP).31 Because of the instability of these Au(I)
complexes, they were not pursued further.
Spectrometric and Spectroscopic Characterization of
Silver Complexes. Microelemental analyses of the Ag(I)
complexes were consistent with a 1:1:1 ligand/silver/an-
ion ratio. FT-IR data of the isolated Ag(I) complexes
revealed the alkyne stretching wave number to range from
2232 to 2220 cm-1; the values are slightly increased from
those observed in the free ligands (2221-2206 cm-1) and
are indicative of transfer of electron density from the
alkyne moiety of the ligand to the Ag(I) cations.
Following on from the successful synthesis and isola-
tion of the Ag(I) complexes we attempted to extend this
chemistry to Au(I). Following a recently published syn-
thetic route to cationic bispyridyl Au(I) complexes,23
ligands L1 or L3 were reacted with a molar equivalent of
AuCl(SMe)2 and NH4PF6 in dichloromethane/ethanol.
During the course of the reaction a noticeable amount of
purple solid formed, which we suspect to be Au(0) nano-
particles, and no pure product could be isolated. Alter-
natively, transmetallation from the Ag(I) complexes with
AuCl(SMe2) in acetonitrile was also attempted. However,
after filtration to remove AgCl the solution slowly be-
came purple. Nevertheless, a white solid was obtained
from the reaction mixture, and although microanalysis of
several different preparations was nonreproducible, high
A comparison between 1H and 13C NMR spectra of the
ligands and the Ag(I) complexes in d3-acetonitrile (in
which all complexes are moderately soluble) shows only
minute changes in proton environments (Supporting In-
formation, Figures S10-S12), presumably because the
coordinating solvent establishes an equilibrium between
the free ligand and the Ag(I) salt. Fortunately, the com-
(31) Similar decomposition of Au(I)-Py complexes, in coordinating
solvents, has been observed see: Chiou, J. Y. Z.; Luo, S. C.; You, W. C.;
Bhattacharyya, A.; Vasam, C. S.; Huang, C. H.; Lin, I. J. B. Eur. J. Inorg.
Chem. 2009, 1950–1959. While it is unclear what the reducing agent is,
presumably the coordinating solvents cause dissociation of the pyridine ligands
from the gold(I) ions which allows the Au atoms to aggregate into AuNP. It is well
established that pyridine ligands can stabilize AuNP, see;. Ghosh, S. K. Colloids
Surf., A 2010, 371, 98–103. Gandubert, V. J.; Lennox, R. B. Langmuir 2005, 21,
6532–6539. Rucareanu, S.; Gandubert, V. J.; Lennox, R. B. Chem. Mater. 2006,
18, 4674–4680.
-
plexes containing SbF6 anions were slightly soluble in
d6-acetone, and 1H NMR spectra were able to be acquired.

Article
Inorganic Chemistry, Vol. 50, No. 3, 2011 1127
1
Figure 1. Stacked H NMR spectra (298 K, 2 mM) of (a) L1 and (b)
{[L1Ag](SbF6)}n in d6-acetone.
1
A comparison of the H NMR data of L1 and {[L1Ag]-
(SbF6)}n is shown in Figure 1. Considerable downfield
shifts for all proton signals were observed indicating the
Ag(I) ions are strongly coordinated to L1. Comparable
shifts are also observed for the SbF6- containing complexes
of L2-L5.
The nature of the species present in solution was probed
further by examining CH3CN solutions of the silver
complexes by positive ion HR-ESI-MS. The identity of
every ion was verified by comparison of the isotopic
patterns of the observed peak with the theoretical simula-
tion (for examples see Supporting Information, Figures
S13-S18). The ESI-MS spectra of the silver(I) complexes
1 (L3, L4, L5) were dominated by peaks corresponding to
[Ag2(L)2](X)þ along with the monomeric [Ag(L)2]þ or
[AgL]þ fragment ions indicating that the dimeric metal-
locyclic structures are present in solution. Additionally, in
the case of 1 (L3, L4, X = ClO4-, BF4-) overlapping but
isotopically resolved peaks due to [Ag2(L)2]2þ and [AgL]þ,
provided further supportforthepostulate thatthe metallo-
macrocycles are formed in solution and the gas phase
(Supporting Information, Figures S13-S18). Similarly,
the silver(I) complexes 2 (L1, L2) show ions due to the tri-
meric [Ag3(L)3](2X)þ species in addition to the smaller
dimeric [Ag2(L)2](X)þ and [Ag2(L)2]2þ species and the
monomeric [Ag(L)2]þ or [AgL]þ fragment ions. Although
in combination the 1H NMR and ESI-MS data are consi-
stent with the presence of metallo-macrocycles in solu-
tion, they do not rule out the possibility that the observed
silver complexes are oligomers.32 However, it is well
established that discrete metallo-macrocycles are enthal-
pically more stable than the corresponding oligomers,
supporting the idea that the observed species are in fact
the desired discrete metallo-macrocycles.17 The presence
of ions due to [Ag3(L)3](2X)þ and [Ag2(L)2](X)þ in the
Figure 2. Labeled ORTEP diagrams of MSPM 1 (L3, X = ClO4-); (a) a
top view, (b) a side view. The thermal ellipsoids are shown at the 50%
probability level. The ClO4- anions and disordered water molecules have
been omitted for clarity. Selected bond lengths (A) and angles (deg);
Ag1-N1 2.145(4), Ag1-N2 2.146(4), N1-Ag1-N2 171.3(1). Symmetry
code; 2 - x, 1 - y, 1 - z.
˚
ESI-MS spectra of 2 (L1, L2), suggests that both 2:2 and
3:3 metallo-macrocycles (Supporting Information, Fig-
ure S19) are formed in solution, and this is presumably
due to the subtle thermodynamic balance between en-
thalpic and entropic factors as has been observed pre-
viously in related systems.33 To conclusively prove the
formation of metallo-macrocycles and examine if they
would self-assemble into metal-organic nanotubes, we
undertook an X-ray crystallographic study of the com-
plexes. Fortunately we were able to obtain X-ray quality
crystals of the complexes 1 (L3 and L5, X = ClO4-) along
with the AgSbF6 and AgClO4 complexes of L1.
X-ray Crystallographic Characterization. X-ray quality
crystals of 1 (L3, X = ClO4-) were obtained by vapor
diffusion of diethyl ether into an acetonitrile solution of
the complex. The molecule crystallizes in the triclinic
space group P1 as the expected 2:2 metallo-macrocycle,
[(L3)2Ag2](ClO4)2, with two molecules in the unit cell
(Figure 2a). The N1-Ag1 and N2-Ag1 bond distances
˚
˚
are 2.145(4) A and 2.146(4) A, respectively, and these are
typical lengths of a pyridyl-Ag(I) bond. The N1-Ag1-N2
(32) For related silver(I) metallo-macrocycles that have been character-
ized in solution using 1H NMR and ESI-MS see: Wei, W.; Wu, M.; Huang,
Y.; Gao, Q.; Zhang, Q.; Jiang, F.; Hong, M. CrystEngComm 2009, 11, 576–
579. Chen, C.-L.; Yu, Z.-Q.; Zhang, Q.; Pan, M.; Zhang, J.-Y.; Zhao, C.-Y.; Su, C.-
Y. Cryst. Growth Des. 2008, 8, 897–905. Yue, N. L. S.; Jennings, M. C.;
Puddephatt, R. J. Eur. J. Inorg. Chem. 2007, 1690–1697. Aly, A. A. M.;
Vatsadze, S. Z.; Chernikov, A. V.; Walfort, B.; Rueffer, T.; Lang, H. Polyhedron
2007, 26, 3925–3929. Chen, C.-L.; Tan, H.-Y.; Yao, J.-H.; Wan, Y.-Q.; Su, C.-Y.
Inorg. Chem. 2005, 44, 8510–8520. Caradoc-Davies, P. L.; Hanton, L. R. Dalton
Trans. 2003, 1754–1758.
(33) Ghosh, S.; Mukherjee, P. S. Inorg. Chem. 2009, 48, 2605–2613.
Weilandt, T.; Troff, R. W.; Saxell, H.; Rissanen, K.; Schalley, C. A. Inorg. Chem.
2008, 47, 7588–7598. Ferrer, M.; Gutierrez, A.; Mounir, M.; Rossell, O.; Ruiz, E.;
Rang, A.; Engeser, M. Inorg. Chem. 2007, 46, 3395–3406. Cotton, F. A.; Murillo,
C. A.; Yu, R. Dalton Trans. 2006, 3900–3905. Ferrer, M.; Mounir, M.; Rossell,
O.; Ruiz, E.; Maestro, M. A. Inorg. Chem. 2003, 42, 5890–5899. Sautter, A.;
Schmid, D. G.; Jung, G.; Wuerthner, F. J. Am. Chem. Soc. 2001, 123, 5424–
5430. Fujita, M.; Sasaki, O.; Mitsuhashi, T.; Fujita, T.; Yazaki, J.; Yamaguchi, K.;
Ogura, K. Chem. Commun. 1996, 1535–1536.

1128 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
Figure 3. Ball-and-stick and space-filling representations of the MSPM 1 (L3, X = ClO4-). (a) A top view (ball-and-stick representation) of the step
polymer structure, (b) a side view (ball-and-stick representation) of the step polymer structure, (c) a space filling representation showing the pores within the
structure. The ClO4- anions and disordered water molecules that fill the pores have been omitted for clarity. The Ag(I)---Ag(I) distance in the step polymer
˚
chains is 3.146(1) A. Color scheme: Gray = carbon, blue = nitrogen, pink = silver.
angle is 171.3(1)°, and this is consistent with the prefer-
ence of Ag(I) to adopt a linear two-coordinate coordina-
tion geometry with pyridyl donor ligands. The small
deviation of this angle from 180° is due to close contact
of the ClO4- counterion to the Ag(I) cations (Supporting
Information, Figures S20-S22, Ag-O bond distances
for Ag1-O1 and Ag1 -O2 are 2.861(5) A and 2.795(4) A).
Although the central phenyl ring and the N1-containing
pyridyl group are essentially coplanar, the N2-containing
pyridyl unit is twisted by 23° out of the plane making the
macrocyclic framework slightly non-planar (Figure 2b).
Disappointingly, despite the planarity of the MSPM, 1
(L3, X = ClO4-), the desired linear metal-organic
nanotubes were not formed in the extended crystal struc-
ture. Instead, a step-polymer of macrocycles, stabilized
by a combination of π-stacking (centroid-centroid dis-
˚
tance 3.902 A) and metal-metal interactions (Ag---Ag
0
˚
˚
˚
distance 3.146(1) A) was obtained (Figures 3a and b).
˚
π-Stacking interactions (centroid-centroid distance 3.829 A)
between the neighboring step-polymer strands result in
the formation of a nanoporous chicken-wire structure
(Figure 3c). The nanoporous channels within the structure

Article
Inorganic Chemistry, Vol. 50, No. 3, 2011 1129
Figure 4. (a) Labeled ORTEP diagram of the asymmetric unit of
{[L5Ag](ClO4) 0.5Et2O}n. The thermal ellipsoids are shown at the 50%
Figure 5. Labeled ORTEP diagrams of asymmetric units for
{[L1Ag(CH3CN)](ClO4)}n (a) and {[L1Ag(CH3CN)](SbF6) CH3CN}n
(b) coordination polymers. The thermal ellipsoids are shown at the
50% probability level. Non-coordinated solvates have been omitted for
clarity.
3
probability level. The disordereddiethylethersolvatehasbeenomittedfor
clarity. (b) A ball-and-stick and tube representation of the ladder polymer
structure formed by {[L5Ag](ClO4) 0.5Et2O}n. The ClO4 anions and
3
-
3
˚
solvent molecules have been omitted for clarity. Selected bond lengths (A)
and angles (deg); Ag1-N1 2.261(8), Ag1-N2 2.23(1), Ag1-N3 2.32(1),
N1-Ag1-N2 138.7(4), N1-Ag1-N3 102.2(4), N2-Ag1-N3 119.0(4).
Symmetry code; x, 1 þ y, z. Color scheme: Gray = carbon, blue =
nitrogen, cream = hydrogen, and pink = silver.
(Ag-N bond-angle range: 102.2 to 138.7°). Because of
steric congestion, the Ag-N bond distances (2.23(1),
2.261(8), and 2.32(1) A) are somewhat longer than those
˚
observed in the other structures. The perchlorate anion
sits in a pocket bridging two Ag(I) cations of the polymer
-
are filled with ClO4 and disordered H2O molecules
(Supporting Information, Figures S20-S22).34
In an effort to alter the packing arrangement and
0
˚
chain (Ag1-O2 2.824(9) and Ag1 -O4 3.446(8) A; see
Supporting Information, Figure S23). Individual poly-
mer strands are closely packed together, and this interac-
tion is stabilized by a face-to-face π-stacking interaction
generate the desired linear metal-organic nanotubes we
-
examined the crystallization of 1 (L4 and L5; X = BF4
,
SbF6-, SO3CF3-, or ClO4-). Repeated attempts to crys-
tallize 1 (L4; X = BF4-, SbF6-, SO3CF3-, or ClO4-) only
resulted in the rapid precipitation and isolation of amor-
phous colorless solids, presumably because of the modest
solubility of these complexes in all solvents.
˚
(centroid-centroid distance 3.645 A) between the ligands
central pyridyl ring on adjacent polymers.
Similar ring-opening behavior is observed for the tri-
-
silver(I) macrocycles, 2 (L1 X = ClO4 and SbF6-).
-
X-ray quality crystals of the L1AgX (X = ClO4 and
SbF6-) complexes were obtained by the slow diffusion of
diethyl ether into acetonitrile solutions of the silver com-
plexes at room temperature. The perchlorate complex of
L1 crystallizes in the Pbca space group with the asym-
metric unit consisting of one ligand, one silver cation, a
perchlorate anion, and an acetonitrile molecule. In the
solid state, the structure of L1AgX is not the desired
macrocycle, 2 (L1, X = ClO4-) but an infinite coordina-
tion polymer, a portion of which is shown in Figures 5
and 6. Each silver cation has pseudo square-planar geometry;
in addition to being coordinated to two ligands (the
Vapor diffusion of diethyl ether into an acetonitrile
solution of 1 (L5 X = ClO4-) provided X-ray quality
crystals of the complex. However, despite the solution
data being consistent with the formation of the 2:2
metallo-macrocycle, in the solid state the macrocycle ring
opens and crystallizes as a coordination polymer. The
perchlorate complex of L5 crystallizes in the monoclinic
space group P21/n with the asymmetric unit consisting of
one ligand, one silver cation, a perchlorate anion, and half
a molecule of disordered diethyl ether. The central pyridyl
nitrogen, which was incorporated into L5 in an attempt to
enhance the face-to-face π-stacking interactions between
the macrocycles, is found to coordinate to the Ag(I) ions
generating a twisted ladder polymer (Figure 4). The Ag(I)
ion adopts an approximately trigonal-planar geometry
˚
Ag-N bond distances, 2.199(2) and 2.202(1) A), there are
˚
also weak silver-oxygen (Ag-O bond distance 2.675(1) A)
˚
and silver-nitrogen (Ag-N bond distance 2.648(2) A)
interactions to perchlorate and acetonitrile molecules,
respectively. The SbF6- complex of L1 has a similar struc-
ture with an infinite polymeric network running through
the crystal (Figures 5 and 6). The change from a coordinating
(ClO4-) to a non-coordinating (SbF6-) anion causes a
change in the geometry around the silver center, which
now adopts a three-coordinate T-shaped arrangement.
(34) We were also able to generate very small crystals from an acetonitrile
solution of the [(L3)2Ag2](SbF6)2 macrocycle. In this case the macrocycle had
ring-opened and crystallized as a complicated disordered coordination
polymer, indicating that the counteranion plays an important role in the
formation of the solid-state structure, see Supporting Information, Figures
S24-S26.

1130 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
Figure 6. Ball-and-stick representations of the solid-state structures for
the {[L1Ag(CH3CN)](ClO4)}n (a) and {[L1Ag(CH3CN)](SbF6) CH3CN}n
3
˚
(b) coordination polymers. Selected bond lengths (A) and angles (deg)
for {[L1Ag](ClO4)}n; Ag1-N1 2.202(1), Ag1-N2 2.199(2), Ag1-N100
2.648(2), Ag1-O1 2.675(1), N1-Ag1-N2 179.41(1), N100-Ag1-O1
˚
163.93(5). Symmetry code; -1 þ x, y, z. Selected bond lengths (A) and
angles (deg) for {[L1Ag(CH3CN)](SbF6) CH3CN}n; Ag1-N1 2.159(7),
3
Ag1-N2 2.167(8), Ag1-N200 2.59(1), N1-Ag1-N2 169.7(3), N200-
Ag1-N1 95.6(3), N200-Ag1-N2 94.4(3). Symmetry code; -1 þ x, 1 þ
y, z. Color scheme: Gray = carbon, blue = nitrogen, red = oxygen,
green = chlorine, yellow = fluorine, orange = antimony, and pink = silver.
Figure 7. Ball-and-stick representations of the repeating packing inter-
actions present between the infinite polymeric chains of (a) {[L1Ag](ClO4)
The Ag(I) center is surrounded by two N-coordinated
pyridyl donor ligands (Ag-N bond distances 2.159(7)
and 2.167(8) A) and an N-coordinated acetonitrile mole-
cule (Ag-N bond distance 2.59(1) A) and in addition a
non-coordinating acetonitrile is also present.
3
CH3CN}n and (b) {[L1Ag(CH3CN)](SbF6) CH3CN}n. The SbF6- anions
3
˚
have been omitted for clarity. Color scheme: Gray = carbon, blue = nitrogen,
red = oxygen, green = chlorine, and pink = silver.
˚
formation of the slip-stacked structure.35 Although the
desired linear metal-organic nanotubes are not gener-
ated the structure still contains nanopores which are filled
with disordered water molecules. X-ray crystallography
of the silver(I) complexes of L1 and L5 show that the
metallo-macrocycles have ring-opened and crystallize as
non-porous coordination polymers.36 The lability of the
silver(I) ions enables the metallo-macrocycles to rear-
range into the linear polymers during the crystallization
process. We postulate that the rearrangement process is
driven by crystal packing forces, the coordination poly-
mers are able to form close-packed non-porous structures,
whereas the silver(I) macrocycles would presumably form
less efficiently packed porous materials. Although 1 and 2
were designed to form MSPMs, the resulting structures
are not all shape-persistent presumably because of the
lability of the silver(I)-pyridine interactions. These observ-
ations suggest that less labile metal ions such as Au(I)37
and Pt(II),18 which would not rearrange during attempted
crystallizations, should be incorporated in the framework
of the planar metallo-macrocycles to enable them to be
used as building blocks for the self-assembly of linear
metal-organic nanotubes.
In both L1 containing silver(I) complexes, the infinite
polymeric chains stack upon each other (Figure 7). In the
perchlorate example, π-stacking interactions are present
between the pyridyl rings of the chain. In addition, O1 of a
perchlorate anion acts as a weak bridge between the two
chains. Conversely, the chains of the SbF6- example are
stacked on top of each other exploiting Ag-π interactions.
The silver in one chain interacts with the π-alkyne system
of a chain above and the π-system of a pyridyl ring in the
chain below. Somewhat surprisingly, no Ag---Ag inter-
actions are present in either structure.
Although the 1H NMR and ESI-MS data indicate that
the desired planar metallo-macrocycles are present in
solution only one, 1 (L3 X = ClO4-), persists in the solid
state, and despite forming the desired planar MSPM it
does not self-assemble into a linear cofacially stacked
metal-organic nanotube. While the crystal structure of
the planar macrocycle exhibits both π-stacking and me-
tal-metal interactions a slip-stacked step-polymer is
formed instead of the desired linearly stacked metal-or-
ganic nanotube. The natural tendency of aromatic π
systems coupled with electrostatic repulsion between the
cationic MSPM building blocks presumably leads to the
(35) While it may seem obvious that electrostatic repulsion between the
cationic macrocycles would prevent the desired stacking interactions, there
are examples in the literature where cationic planar SPM are found to adopt
a face-to-face stacked arrangement, see: Maekawa, M.; Kitagawa, S.;
Kuroda-Sowa, T.; Munakata, M. Chem. Commun. 2006, 2161–2163.
Klyatskaya, S.; Dingenouts, N.; Rosenauer, C.; Mueller, B.; Hoeger, S. J. Am.
Chem. Soc. 2006, 128, 3150–3151.
(36) For a recent experimental study on the ring opening of silver(I)
metallo-macrocycles see: Yue, N. L. S.; Jennings, M. C.; Puddephatt, R. J.
Dalton Trans. 2010, 39, 1273–1281.
(37) Kilpin, K. J.; Horvath, R.; Jameson, G. B.; Telfer, S. G.; Gordon,
K. C.; Crowley, J. D. Organometallics 2010, 29, 6186–6195. Kilpin, K. J.; Paul,
U. S. D.; Lee, A.-L.; Crowley, J. D. Chem. Commun. 2011, DOI: 10.1039/
C1030CC02185G

Article
Inorganic Chemistry, Vol. 50, No. 3, 2011 1131
Experimental Section
(C-12), 132.9 (C-10), 130.3 (C-11), 124.4 (C-5), 124.1 (C-9),
120.7 (C-1) 91.9 (C-8), 87.7 (C-7) ppm; HR-ESI MS (DCM/
MeOH): m/z 331.122 ([L4þH]þ, calcd for C24H15N2 331.123),
353.103 ([L4þNa]þ, calcd for C24H14N2Na 353.105); Anal.
General Experimental Section. NMR experiments were car-
ried out on either a Varian 400-MR or a Varian 500 MHz
VNMRS spectrometer operating at 298 K with chemical shifts
Calcd for C20H12N2 0.25(H2O) C 84.34, H 4.42, N 9.84. Found:
referenced to residual solvent peaks (CDCl3: 1H δ 7.26 ppm, 13
C
3
C 84.61, H 4.55, N 9.49%
δ 77.16 ppm; CD3CN: 1H 1.94, 13C 1.32, 118.26 ppm; d6-acetone
1H δ 2.05 ppm, 13C δ 206.68 and 29.92 ppm). Chemical shifts are
reported in parts per million (ppm) and coupling constants (J) in
hertz (Hz). Standard abbreviations indicating multiplicity were
used as follows: m = multiplet, t = triplet, d = doublet, s =
singlet, b = broad. High resolution ESI-MS analysis was carried
out using acetonitrile solutions on a Bruker MicrOTOF-Q
spectrometer. IR spectroscopy was carried out using a Bruker
ALPHA FT-IR spectrometer with an ALPHA P ATR measure-
ment module. Melting points were determined on a Sanyo
Gallenkamp apparatus and are uncorrected. Microelemental
analysis was carried out at the Campbell Microanalytical Labo-
ratory at the University of Otago. 3-Ethynylpyridine, 1,4-di-
ethynylbenzene, 1,3-diethynylbenzene, AgClO4, AgSbF6, AgBF4,
and AgSO3CF3 were purchased from commercial sources and
used as received. 3-Iodopyridine,27 L130 2,7-diethynylnaphthalene,38
and 2,6-diethynylpyridine39 were synthesized using literature
procedures.
General Sonagashira Coupling Procedure26 for the Prepara-
tion of L2, L3, L4, and L5. Under an argon atmosphere CuI (0.2
equiv) and Pd(PPh3)2Cl2 (0.1 equiv), followed by the dialkyne
(l equiv), were added to a previously degassed solution of
3-iodopyridine (2 equiv) in THF and triethylamine (1:1). The
resulting yellow solution was stirred at room temperature (RT)
for 18 h then diluted with ethylacetate (50 mL) and vigorously
stirred with aqueous EDTA/NH4OH (100 mL, 1M) for 1 h. The
resulting organic phase was washed with saturated aqueous
NH4Cl (50 mL), water (50 mL), and brine (50 mL) and dried
with anhydrous MgSO4. The solvent was removed under vacuum
to give a yellow solid which was further purified by column chro-
matography (SiO2, CH2Cl2/acetone gradient 100:0 to 50:50) to
give the ligand as a pale yellow solid.
2,7-Bis(pyridin-3-ylethynyl)naphthalene, L4. CuI (0.011 g,
0.06 mmol), Pd(PPh3)2Cl2 (0.020 g, 0.03 mmol), 2,7-diethynyl-
naphthalene (0.050 g, 0.28 mmol), and 3-iodopyridine (0.116 g,
0.57 mmol) in THF (10 mL) and triethylamine (10 mL) to yield
L4 as a pale yellow solid (0.071 g, 76%). Mp: 183-184 °C; IR
(ATR): v 1557, 1503, 1472, 1437, 1405, 1188, 1119, 1020, 955,
h
916, 840, 808, 754, 720, 699, 624, 596, 540, 502, 478, 403 cm-1
;
1H NMR (500 MHz, CDCl3): δ 8.83 (s, 2H, H-2), 8.58 (d, J =
4.9 Hz, 2H, H-4), 8.05 (s, 2H, H-14), 7.86 (d, J = 7.9 Hz, 2H,
H-6), 7.83 (d, J = 8.6 Hz, 2H, H-11), 7.62 (d, J = 8.6 Hz, 2H,
H-10), 7.32 (dd, J = 7.9, 4.9 Hz, 2H, H-5); 13C (125 MHz): δ
152.5 (C-2), 148.9 (C-4), 138.7 (C-6), 132.7 (C-12 and C-13),
131.7 (C-14), 129.5 (C-10), 128.3 (C-11), 123.3 (C-5), 121.0 (C-
9), 120.5 (C-1), 92.8 (C-8), 87.0 (C-7) ppm; HR-ESI MS (DCM/
MeOH): m/z 331.122 ([L4þH]þ, calcd for C24H15N2 331.123),
353.103 ([L4þNa]þ, calcd for C24H14N2Na 353.105); Anal.
Calcd for C24H14N2: C 87.25, H 4.27, N 8.48. Found: C 87.12,
H 4.39, N 8.30%
2,6-Bis(pyridin-3-ylethynyl)pyridine, L5. CuI (0.060 g, 0.32
mmol), Pd(PPh3)2Cl2 (0.110 g, 0.16 mmol), 2,6-diethynylpyr-
idine (0.200 g, 1.57 mmol) and 3-iodopyridine (0.645 g, 3.15
mmol) in THF (15 mL) and triethylamine (15 mL) to yield L5 as
a pale yellow solid (0.357 g, 81%). Mp: 124 °C; IR (ATR): v
h
3035, 2221, 1555, 1476, 1439, 1406, 1290, 1239, 1188, 1165, 1122,
1021, 982, 797, 732, 698, 629, 527, 438, 402 cm-1; 1H NMR (500
MHz, CDCl3): δ 8.84 (dd, J = 2.0, 0.8 Hz, 2H, H-2), 8.61 (dd,
J = 4.9, 2.0 Hz, 2H, H-4), 7.89 (dt, J = 7.9, 2.0 Hz, 2H, H-6),
7.74 (dd, J = 7.8, 8.0 Hz, 1H, H-11), 7.54 (d, J = 7.8 Hz, 2H,
H-10), 7.32 (ddd, J = 7.9, 4.9, 0.8 Hz, 2H, H-5); 13C (125
MHz): δ 152.82 (C-2), 149.59 (C-4), 143.49 (C-9), 139.12 (C-6),
136.88 (C-11), 126.91 (C-10), 123.26 (C-5), 119.42 (C-1), 91.24
(C-8), 86.42 (C-7) ppm; HR-ESI MS (DCM/MeOH): m/z
282.109 ([L5þH]þ, calcd for C19H12N3 282.103), 304.084
([L5þNa]þ, calcd for C19H11N3Na 304.085). Anal. Calcd for
C19H11N3 C 81.12, H 3.94, N 14.94. Found: C 80.85, H 3.95, N
14.66%
1,4-Bis(pyridin-3-ylethynyl)benzene, L2. CuI (0.09 g, 0.49
mmol), Pd(PPh3)2Cl2 (0.17 g, 0.24 mmol), 1,4-diethynylbenzene
(0.31 g, 2.44 mmol), and 3-iodopyridine (1.00 g, 4.88 mmol) in
THF (20 mL) and triethylamine (20 mL) to yield L2 as a pale
yellow solid (0.49 g, 65%). Mp: 182-183 °C; IR (ATR): v 2206,
h
General Procedure for the Preparation of Silver Complexes of
L1, L2, L3, L4, and L5. To a solution of the ligand in acetone, a
molar equivalent of the silver salt in acetone was added drop-
wise. The solution was stirred in the dark for 30 min during
which time a white precipitate formed. This solid was isolated by
filtration and was washed with diethyl ether to yield the silver
complex.
Caution! Although no problems were encountered with this
work, perchlorate salts of metal complexes containing organic
ligands are potentially explosive and should be handled with care
and in small quantities.
1556, 1505, 1473, 1406, 1188, 1120, 1020, 847, 835, 815, 799, 699,
654, 623, 546, 520, 447 cm-1; 1H NMR (500 MHz, CD3CN): δ
8.76 (d, J = 1.5 Hz, 2H, H-2), 8.57 (dd, J = 4.8, 1.5 Hz, 2H,
H-4), 7.90 (dt, J = 7.9, 1.9 Hz, 2H, H-6), 7.61 (s, 4H, H-10), 7.39
(ddd, J = 4.8, 7.9, 0.6 Hz, 2H, H-5); 13C (125 MHz): δ 153.1 (C-
2), 150.2 (C-4), 139.5 (C-6), 132.9 (C-10), 124.5 (C-5), 124.0 (C-
9), 120.9 (C-1), 92.5 (C-8), 89.1 (C-7) ppm; HR-ESI MS (DCM/
MeOH): m/z 281.107 ([L2þH]þ, calcd for C20H13N2 281.107),
303.089 ([L2þNa]þ, calcd for C20H12N2Na 303.089); Anal.
Calcd for C20H12N2: C 85.69, H 4.31, N 9.99. Found: C 85.61,
H 4.21, N 9.69%
{[L1Ag](SbF6)}n. L1 (25 mg, 0.12 mmol) and AgSbF6 (42 mg,
0.12 mmol) in acetone (10 mL) to give 61 mg (91%) of
1,3-Bis(pyridin-3-ylethynyl)benzene, L3. CuI (0.120 g, 0.63
mmol), Pd(PPh3)2Cl2 (0.105 g, 0.15 mmol), 1,3-diethynylben-
zene (0.398 g, 3.15 mmol), and 3-iodopyridine (1.29 g, 6.30
mmol) in THF (20 mL) and triethylamine (20 mL) to yield L3 as
{[L1Ag](SbF6)}n. Mp: > 190 °C (decomp.); IR (ATR): v 1700,
h
1595, 1479, 1417, 1196, 820, 806, 691, 654, 636, 617 (br) cm-1; 1H
NMR (400 MHz, d6-acetone): δ 8.99 (dd, J = 2.1, 0.8 Hz, 2H,
H-2), 8.80 (dd, J = 5.2, 1.6 Hz, 2H, H-4), 8.25 (dt, J = 8.0, 3.7
Hz, 2H, H-6), 7.71 (ddd, J = 8.0, 5.2, 0.8 Hz, 2H, H-5), 13C (75
MHz,): δ 153.8 (C-2), 150.8 (C-4), 140.3 (C-6), 124.3 (C-5),
119.18 (C-1), 80.1 (C-7), 76.6 (C-8) ppm; HR-ESI MS (MeCN):
m/z 310.970 ([L1Ag]þ, calcd for C14H8N2Ag 310.973), 515.036
([(L1)2Ag]þ, calcd for C28H16N4Ag 515.042), 858.839 ([(L1)2-
Ag2SbF6]þ, calcd for C28H16N4Ag2SbF6 858.841), 1406.701
([(L1)3Ag3(SbF6)2]þ, calcd for C42H24N6Ag3Sb2F12 1406.710),
1954.574 ([(L1)4Ag4(SbF6)3]þ, calcd for C56H32N8Ag4Sb3F18
a pale yellow solid (0.807 g, 90%). Mp: 61-63 °C; IR (ATR): v
h
2211, 1594, 1574, 1557, 1480, 1409, 1186, 1096, 1020, 908, 808,
794, 701, 682, 539, 526, 469, 433 cm-1; H NMR (500 MHz,
1
CD3CN): δ 8.76 (d, J = 1.6 Hz, 2H, H-2), 8.57 (dd, J = 4.8, 1.6
Hz, 2H, H-4), 7.90 (dt, J = 7.9, 1.9 Hz, 2H, H-6), 7.76 (br t, J =
1.4 Hz, 1H, H-12), 7.61 (dd, J = 7.7, 1.7 Hz, 2H, H-10), 7.48 (t,
J = 7.7 Hz, 1H, H-11), 7.39 (ddd, J = 7.9, 4.8, 0.7 Hz, 2H, H-5);
13C (125 MHz): δ 153.0 (C-2), 150.1 (C-4), 139.4 (C-6), 135.2
(38) Neenan, T. X.; Whitesides, G. M. J. Org. Chem. 1988, 53, 2489–2496.
(39) Dana, B. H.; Robinson, B. H.; Simpson, J. J. Organomet. Chem.
2002, 648, 251–269.
1954.578); Anal. Calcd for C14H8N2F6AgSb 0.25(C3H6O): C
3
31.50, H 1.70, N 4.98. Found: C 31.69, H 1.65, N 4.92%. X-ray

1132 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
quality crystals with the formula {[L1Ag(CH3CN)](SbF6)
CH3CN}n were obtained by vapor diffusion of diethyl ether
into an acetonitrile solution of {[L1Ag](SbF6)}n.
2225, 1596, 1572, 1511, 1419, 1276, 1237, 1197, 1159, 1024, 832,
806, 694, 634, 547 cm-1; HR-ESI MS (MeCN): m/z; 386.995
([L2Ag]þ, calcd for C20H12N2Ag 387.005), 405.005 ([L2Agþ
H2O]þ, calcd for C20H14N2OAg 405.015), 669.081 ([(L2)2Ag]þ,
calcd for C40H24N4Ag 669.105), 924.931 ([(L2)2Ag2O3SCF3]þ,
calcd for C40H24N4O3SF3Ag 924.962); Anal. Calcd for
C21H12F3N2O3SAg C 46.95, H 2.25, N 5.21. Found: C 47.17,
H 2.19, N 4.83%.
3
{[L1Ag](ClO4)}n. L1 (25 mg, 0.12 mmol) in acetone (2 mL)
and AgClO4 (25 mg, 0.12 mmol) in acetone (2 mL) to give 42 mg
(83%) of {[L1Ag](ClO4)}n. HR-ESI MS (MeCN): m/z; 310.967
([L1Ag]þ, calcd for C14H8N2Ag 310.973), 328.985 ([L1Agþ
H2O]þ, calcd for C14H10N2OAg 328.984), 515.033 ([(L1)2Ag]þ,
calcd for C28H16N4Ag 515.042), 722.887 ([(L1)2Ag2ClO4]þ, calcd
for C28H16N4Ag2ClO4 722.895); Anal. Calcd for C14H8N2O4-
[(L3)2Ag2](SbF6)2. L3 (56 mg, 0.20 mmol) in acetone (8 mL) and
AgSbF6 (69 mg, 0.20 mmol) in acetone (2 mL) to give 114 mg
ClAg 0.25(C3H6O): C 41.58, H 2.25, N 6.57. Found: C 41.35, H
(91%) of [(L3)2Ag2](SbF6)2. Mp: >205 °C (decomp.); IR (ATR) v
h
3
1.95, N 6.87%. X-ray quality crystals with the formula {[L1Ag-
(CH3CN)](ClO4)}n were obtained by vapor diffusion of diethyl
ether into an acetonitrile solution of {[L1Ag](ClO4)}n.
2218, 1600, 1571, 1486, 1418, 1198, 1126, 1098, 1055, 1031, 797,
694, 684, 653 cm-1;1H NMR (500 MHz, d6-acetone): δ8.95 (s, 2H,
H-2), 8.73 (d, J = 5.0 Hz, 2H, H-4), 8.17 (dt, J = 8.0, 1.7 Hz, 2H,
H-6), 7.78 (s, 1H, H-12), 7.70 (d, J = 7.6 Hz, 2H, H-10), 7.67 (dd,
J = 7.0, 5.0 Hz, 2H, H-5), 7.58 (t, J = 7.6 Hz, 1H, H-11); 13C (125
MHz): δ 154.0 (C-2), 151.1 (C-4), 141.0 (C-6), 135.2 (C-12), 133.2
(C-10), 130.4 (C-11), 125.5 (C-5), 123.8 (C-9), 121.7 (C-1), 92.7 (C-
8), 86.8 (C-7) ppm; HR-ESI MS (MeCN): m/z 387.006 ([L3Ag]þ,
calcd for C20H12N2Ag 387.005), 1010.904 ([(L3)2Ag2SbF6]þ, calcd
for C40H24N4F6SbAg2 1010.904), 1634.802 ([(L3)3Ag3(SbF6)2]þ,
calcd for C60H36N6F12Sb2Ag3 1634.804), 2258.711 ([(L3)4Ag4-
(SbF6)3]þ, calcd for C80H48N8F18Sb3Ag4 2258.704); Anal. Calcd
for C40H24Ag2N4Sb2F12: C 38.50, H 1.94, N 4.49. Found: C
38.61, H 2.13, N 4.43%.
{[L1Ag](BF4)}n. L1 (35 mg, 0.17 mmol) in acetone (2 mL) and
AgBF4 (33 mg, 0.17 mmol) in acetone (2 mL) to give {[L1Ag]-
(BF4)}n as a white solid (66 mg, 97%). Mp: >210 °C; IR (ATR):
v 1595, 1480, 1420, 1198, 1049 (br), 1025 (br), 807, 765, 693, 656,
h
518, 405 cm-1; HR-ESI MS (MeCN): m/z 310.962 ([L1Ag]þ,
calcd for C14H8N2Ag 310.973), 642.918 ([(L1)2Ag2F]þ, calcd for
C28H16N4Ag2F 642.945), 710.923 ([(L1)2Ag2BF4]þ, calcd for
C28H16N4Ag2BF4 710.950); Anal. Calcd for C14H8N2F4BAg
0.5(H2O): C 41.22, H 2.22, N 6.87. Found: C 41.54, H 1.98, N
6.61%.
3
{[L1Ag](SO3CF3)}n. L1 (50 mg, 0.25 mmol) in acetone (2 mL)
and AgSO3CF3 (63 mg, 0.25 mmol) in acetone (2 mL) to give 96
[(L3)2Ag2](ClO4)2. L3 (56 mg, 0.20 mmol) in acetone (8 mL)
and AgClO4 (41 mg, 0.20 mmol) in acetone (2 mL) to give 144
mg (73%) of [(L3)2Ag2](ClO4)2. HR ESI MS (MeCN): m/z
387.008 ([L3Ag]þ, calcd for C20H12N2Ag 387.005), 387.008
([(L3)2Ag2]2þ, calcd for C40H24N4Ag2 387.005), 669.102 ([(L3)2-
Ag]þ, calcdfor C40H24N4Ag669.105), 874.953([(L3)2Ag2ClO4]þ,
calcd for C40H24N4O4ClAg2 874.958); Anal. Calcd for C40H24-
mg (85%) of {[L1Ag](SO3CF3)}n. Mp: >230 °C; IR (ATR): v
h
1593, 1472, 1419, 1271, 1236, 1221, 1196, 1170, 1051, 1022, 811,
696, 633, 573, 515, 408 cm-1; HR-ESI MS (MeCN): m/z 310.968
([L1Ag]þ, calcd for C14H8N2Ag 310.973), 515.029 ([(L1)2Ag]þ,
calcd for C28H16N4Ag 515.042), 772.882 ([(L1)2Ag2SO3CF3]þ,
calcd for C29H16N4Ag2SO3F3 772.889); Anal. Calcd for
AgClN4O8 0.5(C3H6O): C 49.98, H 2.93, N 5.42. Found: C
50.13, H 2.92, N 5.08%. X-ray quality crystals with the formula
[(L3)2Ag2](ClO4)2 3H2O were obtained by vapor diffusion of
diethyl ether into an acetonitrile solution of [(L3)2Ag2](ClO4)2.
[(L3)2Ag2](BF4)2. L3 (50 mg, 0.18 mmol) in acetone (8 mL)
and AgBF4 (35 mg, 0.18 mmol) in acetone (2 mL) to give 56 mg
C15H8N2O3F3SAg 0.25(H2O): C 38.69, H 1.84, N 6.02. Found:
3
3
C 38.52, H 1.75, N 5.90%.
{[L2Ag](SbF6)}n. L2 (50 mg, 0.18 mmol) in acetone (2 mL) and
AgSbF6 (61 mg, 0.18 mmol) in acetone (2 mL) to give 55 mg
3
(49%) of {[L2Ag](SbF6)}n. Mp: >230 °C; IR (ATR): v 2226,
h
1598, 1572, 1510, 1419, 1196, 1158, 1125, 1102, 838, 807, 695,
654, 548, 409 cm-1; 1H NMR (500 MHz, d6-acetone): δ 8.86 (d,
J = 1.7 Hz, 2H, H-2), 8.69 (dd, J = 4.9, 1.4 Hz, 2H, H-4), 8.09
(dt, J = 7.9, 1.7 Hz, 2H, H-6), 7.67 (s, 4H, H-10), 7.59 (dd, J =
7.9, 4.9 Hz, 2H, H-5) ppm; HR-ESI MS(MeCN) m/z; 386.997
([L2Ag]þ, calcd for C20H12N2Ag 387.005), 405.008 ([L2Agþ
H2O]þ, calcd for C20H14N2OAg 405.015), 669.085 ([(L2)2Ag]þ,
calcd for C40H24N4Ag 669.105); Anal. Calcd for C20H12N2-
F6AgSb: C 38.50, H 1.94, N 4.49. Found: C 38.84, H 1.92, N
4.37%.
(66%) of [(L3)2Ag2](BF4)2. Mp: >210 °C; IR (ATR) v 2220,
h
1632, 1598, 1417, 1023 (br), 795, 694, 683, 654, 520, 436 cm-1
;
HR-ESI MS (MeCN): m/z 387.008 ([L3Ag]þ, calcd for C20H12-
N2Ag 387.005), 387.008 ([(L3)2Ag2]2þ, calcd for C40H24N4Ag2
387.005), 669.104 ([(L3)2Ag]þ, calcd for C40H24N4Ag 669.105);
Anal. Calcd for C20H12N2AgBF4 0.5(H2O): C 49.63, H 2.71, N
3
5.79. Found: C 49.71, H 2.63, N 5.55%.
[(L3)2Ag2](SO3CF3)2. L3 (56 mg, 0.20 mmol) inacetone (8 mL)
and AgSO3CF3 (51 mg, 0.20 mmol) in acetone (2 mL) to give 81
{[L2Ag](ClO4)}n. L2 (50 mg, 0.18 mmol) in acetone (2 mL)
and AgClO4 (37 mg, 0.25 mmol) in acetone (2 mL) to give 83 mg
(95%) of {[L2Ag](ClO4)}n. HR-ESI MS (MeCN): m/z 387.002
mg (75%) of [(L3)2Ag2](SO3CF3)2. Mp: 205 °C; IR (ATR) v
h
2216, 1597 1569, 1483, 1414, 1250, 1163, 1026, 803, 697, 683,
636, 573, 517 cm-1; HR-ESI MS (MeCN): m/z 387.008 ([L3Ag]þ,
calcd for C20H12N2Ag 387.005), 644.865 (L3Ag2SO3CF3]þ,
calcd for C21H12N2Ag2F3SO3 644.862), 924.963 ([(L3)2Ag2
SO3CF3]þ, calcd for C41H24N4Ag2F3SO3 924.962); Anal. Calcd
for C21H12AgN2SO3F3: C 46.95, H 2.25, N 5.21. Found: C
47.20, H 2.32, N 5.06%.
([L2Ag]þ, calcd for C20H12N2Ag 387.005), 388.005 ([(L2)2Ag2]2þ
,
calcd for C40H24N4Ag2 388.005), 405.012 ([L2AgþH2O]þ, calcd
for C20H14N2OAg 405.015), 669.097 ([(L2)2Ag]þ, calcd for
C40H24N4Ag 669.105); Anal. Calcd for C20H12N2O4ClAg
3
0.5(H2O): C 48.37, H 2.64, N 5.64. Found: C 48.35, H 2.67, N
5.34%.
[(L4)2Ag2](SbF6)2. L4 (20 mg, 0.06 mmol) in acetone (3 mL)
and AgSbF6 (21 mg, 0.06 mmol) in acetone (3 mL) to give 32 mg
{[L2Ag](BF4)]}n. L2 (50 mg, 0.18 mmol) in acetone (5 mL) and
AgBF4 (35 mg, 0.18 mmol) in acetone (5 mL) to give 71 mg
(79%) of [(L4)2Ag2](SbF6)2. Mp: >210 °C; IR (ATR) v 2216,
h
(84%) {[L2Ag](BF4)]}n. Mp: >210 °C; IR (ATR): v 2226, 1597,
1592, 1571, 1505, 1482, 1418, 1367, 1226, 1196, 1055, 909, 847,
805, 693, 649, 487 cm-1; HR-ESI MS (MeCN): m/z 769.140
([(L4)2Ag]þ, calcd for C48H28N4Ag 769.136), 1110.941 ([(L4)2-
h
1572, 1509, 1479, 1419, 1198, 1049 (br), 836, 807, 695, 654, 548,
533, 518, 495, 419 cm-1; HR-ESI MS (MeCN): m/z; 386.994
([L2Ag]þ, calcd for C20H12N2Ag 387.005), 405.004 ([L2Agþ
H2O]þ, calcd for C20H14N2OAg 405.015), 669.079 ([(L2)2Ag]þ,
calcd for C40H24N4Ag 669.105); Anal. Calcd for C20H12N2-
1
Ag2SbF6]þ, calcd for C48H28N4Ag2SbF6 1110.936); H NMR
(400 MHz, d6-acetone): δ 8.95 (br s, 2H, H-2), 8.70 (br s, 2H,
H-4), 8.23 (s, 2H, H-14), 8.13 (m, 2H, H-6), 8.04 (d, J = 8.4 Hz,
2H, H-11), 7.73 (dd, J = 8.4, 1.2 Hz, 2H, H-10), 7.62 (m, 2H,
AgBF4 H2O: C 48.72, H 2.86, N 5.68. Found: C 48.89, H 2.54,
3
N 5.30%.
{[L2Ag](SO3CF3)}n. L2 (50 mg, 0.18 mmol) in acetone (10 mL)
and AgSO3CF3 (46 mg, 0.18 mmol) in acetone (2 mL) to give
H-5) ppm; Anal. Calcd for C48H28Ag2N4Sb2F12 (C3H6O): C
3
43.56, H 2.44, N 3.98. Found: C 43.39, H 2.20, N 3.86%.
[(L4)2Ag2](ClO4)2. L4 (20 mg, 0.06 mmol) in acetone (3 mL)
and AgClO4 (13 mg, 0.06 mmol) in acetone (3 mL) to give 28 mg
55 mg (57%) of {[L2Ag](SO3CF3)}n. Mp: >210 °C; IR (ATR): v
h

Article
Inorganic Chemistry, Vol. 50, No. 3, 2011 1133
Table 1. Crystallographic Data for the Silver(I) Complexes
{[L1Ag(CH3CN)](ClO4)}n {[L1Ag(CH3CN)](SbF6) CH3CN}n [(L3)2Ag2](ClO4)2 3H2O {[L5Ag](ClO4) 0.5Et2O}n
3
3
3
CCDC depository
formula
formula weight
T (K)
795010
16H11N3O4ClAg
452.60
90
orthorhombic
Pbca
14.4471(10)
13.9583(11)
16.5272(13)
90
90
90
795008
795011
795009
C
C18H14N4F6AgSb
629.95
89
triclinic
P1
7.623(5)
11.505(6)
12.375(9)
92.43(2)
99.992(11)
92.46(3)
C20H15N2O5.5ClAg
514.66
90
triclinic
P1
9.9203(25)
10.8747(29)
11.6781(33)
112.223(10)
102.814(12)
106.508(11)
1038.4(4)
2
C42H32N6O9Cl2Ag2
1051.38
93
monoclinic
P21/n
9.5050(10)
13.797(2)
16.3534(17)
90
97.151(5)
90
crystal system
space group
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
crystal size
3332.8(4)
8
1069.7(12)
2
2128.0(5)
2
0.40 ꢀ 0.21 ꢀ 0.12
0.21 ꢀ 0.15 ꢀ 0.06
0.84 ꢀ 0.26 ꢀ 0.12
0.53 ꢀ 0.15 ꢀ 0.10
F /g cm3
1.804
1.396
104979
1.956
2.241
13514
1.646
1.135
21794
1.641
1.108
11963
μ/mm-1
reflections collected
independent reflections (Rint
data/restraints/parameters
goodness of fit on F2
final indexes [I > 2σ(I)]
)
6084 (0.0465)
6084/0/227
1.047
R1 = 0.0254
wR2 = 0.0580
R1 = 0.0380
wR2 = 0.0622
0.569 and -0.625
3669 (0.0722)
3669/0/273
1.019
R1 = 0.0649
wR2 = 0.1645
R1 = 0.0940
wR2 = 0.1856
2.455 and -1.084
3745 (0.0345)
3745/0/253
1.089
R1 = 0.0350
wR2 = 0.1025
R1 = 0.0370
wR2 = 0.1051
0.958 and -0.698
3572 (0.0480)
3572/21/299
1.077
R1 = 0.0778
wR2 = 0.2091
R1 = 0.0876
wR2 = 0.2144
3.670 and -1.039
final indexes (all data)
-3
˚
largest difference (e A
)
(87%) of [(L4)2Ag2](ClO4)2. HR-ESI MS (MeCN): m/z 437.023
([L4Ag]þ, calcd for C24H14N2Ag 437.020), 437.023 ([(L4)2-
Ag2]2þ, calcd for C48H28N4Ag2 437.020), 769.132 ([(L4)2Ag]þ,
calcd for C48H28N4Ag 769.136), 974.991 ([(L4)2Ag2ClO4]þ, calcd
for C48H28N4Ag2ClO4 974.989), 1512.965 ([(L4)3Ag3(ClO4)2]þ,
calcd for C72H42N6Ag3Cl2O8 1512.959); Anal. Calcd for
were carried out using SHELXL-9741 with all non-hydrogen
atoms being refined anisotropically. The hydrogen atoms were
included in calculated positions and were refined as riding atoms
with individual (or group, if appropriate) isotropic displacement
parameters.
In the structure [(L3)2Ag2](ClO4)2 3H2O, the channels
3
C48H28Ag2Cl2N4O8 (C3H6O): C 54.04, H 3.02, N 4.92. Found:
C 54.07, H 3.19, N 4.52%.
formed by the slip-stacked Ag-pyridylalkyne rings are filled
with disordered water molecules. Four discrete sites with partial
occupancy accounted for most of the electron density in these
channels, so that the largest residual peaks of electron density
were concentrated near the silver center. However, the model
that led to the lowest values for R1 and wR2 (0.037 and 0.107,
3
[(L5)2Ag2](SbF6)2. L5 (50 mg, 0.18 mmol) in acetone (3 mL)
and AgSbF6 (61 mg, 0.18 mmol) in acetone (3 mL) to give 101
mg (91%) of [(L5)2Ag2](SbF6)2. Mp: >210 °C; IR (ATR): v
h
2232, 1582, 1557, 1482, 1450, 1415, 809, 697, 653 (br), 557 cm-1
;
1H NMR (400 MHz, d6-acetone): δ 8.97 (s, 2H, H-2), 8.76 (d,
J = 5.3 Hz, 2H, H-4), 8.13 (m, 3H, H-6 and H-11), 7.87 (d, J =
8.0 Hz, 2H, H-10), 7.62 (dd, J = 7.9 and 5.3 Hz, 2H, H-5) ppm;
HR-ESI MS (MeCN): m/z 387.998 ([L5Ag]þ, calcd for C19H11-
N3Ag 387.999), 671.091 ([(L5)2Ag]þ, calcd for C38H22N6Ag
671.095), 1012.887 ([(L5)2Ag2SbF6]þ, calcd for C38H22Ag2N6-
SbF6 1012.895), 1637.775 ([(L5)3Ag3(SbF6)2]þ, calcd for C57-
H33Ag3N9Sb2F12 1637.790); Anal. Calcd for C38H22Ag2N6-
Sb2F12: C 36.52, H 1.77, N 6.72. Found: C 36.44, H 1.76, N
6.65%.
˚
respectively) lacked chemical sense (3 sites within 2 A, each
having 0.5 occupancy) and atoms had highly eccentric ellipsoids
for the atomic displacement parameters. The SQUEEZE42
routine of PLATON revealed 24 electrons or approximately 3
water molecules per unit cell. Crystal data and collection para-
meters are given in Table 1. CCDC 795008-795011 contain the
supplementary crystallographic data for this paper. These data
can be obtained free of charge from the Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif
Conclusions
[(L5)2Ag2](ClO4)2. L5 (50 mg, 0.18 mmol) in acetone (3 mL)
and AgClO4 (37 mg, 0.18 mmol) in acetone (3 mL) to give 76 mg
(87%) of [(L5)2Ag2](ClO4)2. HR-ESI MS (MeCN): m/z 671.108
([(L5)2Ag]þ, calcd for C38H22N6Ag 671.095); Anal. Calcd for
C38H22N6O8Cl2Ag2: C 46.70, H 2.28, N 8.60. Found: C 46.86, H
2.28, N 8.55%. X-ray quality crystals with the formula {[(L5)2-
We have synthesized and characterized a family of planar
di- and tri-silver(I) metallo-macrocycles. The silver(I) com-
plexes have been fully characterized by elemental analysis,
HR-ESI-MS, IR, H and 13C NMR spectroscopy, and the
1
solution data are consistent with the formation of the
metallo-macrocycles. However, X-ray crystallography shows
that only one of the silver(I) complexes maintains its macro-
cyclic structure in the solid state. This di-silver(I) macrocycle
assembles into a nanoporous chicken-wire like structure in
Ag2](ClO4)2 Et2O}n were obtained by vapor diffusion of diethyl
3
ether into an acetonitrile solution of [(L5)2Ag2](ClO4)2.
X-ray Data Collection and Refinement. X-ray data for
[(L3)2Ag2](ClO4)2 3H2O, {[(L5)Ag](ClO4) 0.5Et2O}n, {[(L1)Ag-
3
3
(CH3CN)](ClO4)}n, {[(L1)Ag(CH3CN)](SbF6) CH3CN}n were
recorded with a Bruker APEX II CCD diffractometer at 90(2) or
3
-
which the pores are filled with ClO4 and disordered H2O
ꢀ
˚
89(2) K using Mo-KR radiation (λ = 0.71073 A). The struc-
tures were solved by direct methods using SIR9740 with the
resulting Fourier maps revealing the location of all non-hydro-
gen atoms. Weighted full-matrix least-squares refinements on F2
molecules. The lability of the silver(I) ions enables the other
macrocyclic complexes to ring-open and crystallize as non-
porous coordination polymers. In combination these results
(41) Sheldrick, G. M.; Schneider, T. R. Methods Enzymol. 1997, 277, 319–
343. Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr. 2008,
A64, 112–122.
(40) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Gia-
covazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R.
J. Appl. Crystallogr. 1999, 32, 115–119.
(42) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7–13.

1134 Inorganic Chemistry, Vol. 50, No. 3, 2011
Kilpin et al.
suggest that the cationic planar silver(I) metallo-macrocycles
are not suitable building blocks for the self-assembly of linear
metal-organic nanotubes. In light of this we are now investi-
gating second-generation neutral planar metallo-macro-
cycles of less labile metal ions such as Au(I) and Pt(II).
technology is thanked for providing funding for the purchase
of X-ray optics and a detector and the Allan Wilson Centre
for Molecular Ecology and Evolution for the purchase of
the microfocus rotating-anode X-ray generator.
Supporting Information Available: X-ray crystallographic
data for {[L1Ag(CH3CN)](ClO4)}n, {[L1Ag(CH3CN)](SbF6)
CH3CN}n, [(L3)2Ag2](ClO4)2 3H2O, and {[L5Ag](ClO4)
0.5Et2O}n in CIF format. NMR and ESI-MS data, molecular
modelling and crystal-packing diagrams are also available. This
material is available free of charge via the Internet at http://
pubs.acs.org.
Acknowledgment. WethankDr. MervynThomas for his
assistance collecting NMR data and Dr. David McMorran
for useful discussions. A University of Otago Research
Grant and the Department of Chemistry, University of
Otago provided financial support for this work. The
MacDiarmid Institute for Advanced Materials and Nano-
3
3
3