Construction of interlocking and threaded rings using two different transition metals as a templating and connecting centers: Catenanes and rotaxanes incorporating Ru(terpy)2-units in their framework

Article abstract of DOI:10.1021/ja963955j

This work describes a new method for the preparation of metal-containing catenanes and rotaxanes, using pure coordination chemistry, by stepwise reaction of organic fragments with two different transition metals. The key organic compound contains two terpyridine (terpy) ligands and one diphenylphenanthroline (dpp) moiety and was prepared in high yield by alkylation of 2,9-bis(hydroxyphenyl)-1,10-phenanthroline with 5-(3-methanosulfonyl-1-propyl)-5''-methyl-2,2':6',2''-terpyridine. Reaction of this polyfunctional ligand with 1 equiv of a dpp-containing 30-membered macrocycle and Cu(I) as a template led to a threaded Cu(dpp)₂⁺-type precursor complex (P). Due to the high affinity of Cu(I) for the dpp ligands, the reaction is selective, and no competition of the terpy units for the metal takes place. Thus, this threaded complex contains two free terpy moieties suitable for a further coordination reaction. Ru(II) was used to build the stoppers or to clip the free ligands due to the high stability of Ru(terpy)₂²⁺ complexes. Compound P reacts with Ru(DMSO)₄Cl₂ in 1,2-dichloroethane-EtOH at 70 °C under high dilution conditions to give the desired catenate in 43% yield. A Cu coordinated rotaxane was obtained by stoppering the free ends of precursor P with 2 equiv of Ru(terpy)(acetone)₃(BF₄)₂. In both cases the intertwined geometry of the dpp units is maintained after Ru(II) coordination. The complexes were characterized by spectroscopic methods, FAB-MS, and cyclic voltammetry. The high stability of the Ru complexes allows for the selective removal of Cu(I). Thus, reaction of the Cu-complexed rotaxane or the catenate with KCN in MeCN-H₂O led to the corresponding rotaxane or catenane, respectively, in which the intertwined topography has been destroyed upon liberation of the dpp ligands. This approach opens a new way for the preparation of multicomponent species with promising photochemical properties.

Full text of DOI:10.1021/ja963955j

2656
J. Am. Chem. Soc. 1997, 119, 2656-2664
Construction of Interlocking and Threaded Rings Using Two
Different Transition Metals as Templating and Connecting
Centers: Catenanes and Rotaxanes Incorporating
Ru(terpy)2-Units in Their Framework
Diego J. Ca´rdenas, Pablo Gavin˜a, and Jean-Pierre Sauvage*
Contribution from the Laboratoire de Chimie Organo-Mine´rale UA 422 au CNRS, Institut de
Chimie, UniVersite´ Louis Pasteur, 4 rue Blaise Pascal, F-67070 Strasbourg, France
ReceiVed NoVember 14, 1996X
Abstract: This work describes a new method for the preparation of metal-containing catenanes and rotaxanes, using
pure coordination chemistry, by stepwise reaction of organic fragments with two different transition metals. The
key organic compound contains two terpyridine (terpy) ligands and one diphenylphenanthroline (dpp) moiety and
was prepared in high yield by alkylation of 2,9-bis(hydroxyphenyl)-1,10-phenanthroline with 5-(3-methanosulfonyl-
1-propyl)-5′′-methyl-2,2′:6′,2′′-terpyridine. Reaction of this polyfunctional ligand with 1 equiv of a dpp-containing
30-membered macrocycle and Cu(I) as a template led to a threaded Cu(dpp)2+-type precursor complex (P). Due to
the high affinity of Cu(I) for the dpp ligands, the reaction is selective, and no competition of the terpy units for the
metal takes place. Thus, this threaded complex contains two free terpy moieties suitable for a further coordination
2+
reaction. Ru(II) was used to build the stoppers or to clip the free ligands due to the high stability of Ru(terpy)2
complexes. Compound P reacts with Ru(DMSO)4Cl2 in 1,2-dichloroethane-EtOH at 70 °C under high dilution
conditions to give the desired catenate in 43% yield. A Cu coordinated rotaxane was obtained by stoppering the
free ends of precursor P with 2 equiv of Ru(terpy)(acetone)3(BF4)2. In both cases the intertwined geometry of the
dpp units is maintained after Ru(II) coordination. The complexes were characterized by spectroscopic methods,
FAB-MS, and cyclic voltammetry. The high stability of the Ru complexes allows for the selective removal of
Cu(I). Thus, reaction of the Cu-complexed rotaxane or the catenate with KCN in MeCN-H2O led to the corresponding
rotaxane or catenane, respectively, in which the intertwined topography has been destroyed upon liberation of the
dpp ligands. This approach opens a new way for the preparation of multicomponent species with promising
photochemical properties.
Introduction
In the course of the last 15 years, the field has undergone
some kind of renaissance due to the introduction of template
strategies, making the preparation of threaded and interlocking
systems much more accesible. These developments as well as
the early works above mentionned have been surveyed and
discussed in several reviews.4-10
Catenanes and rotaxanes have attracted considerable attention
in the 1960s and the 1970s, representing a real synthetic
challenge. They also appeared as promising chemical objects,
with novel physical properties, and as precursors to new
molecular materials. Particularly significants are the pioneering
contributions by Schill,1 Wassserman,2 and their co-workers,
in the field of chemical topology and interlocking rings.
Somewhat surprisingly, although their structure looks simpler
than that of interlocking rings and their topology is clearly less
noble, rotaxanes were not reported in a fully convincing way
before catenanes.1-3 Schill and co-workers have described an
elegant directed route to rotaxanes, based on the stepwise
construction of the molecule.1 An alternative attractive approach
is based on the threading reaction of an acyclic fragment bearing
two bulky groups at both extremities and forcing it to thread
inside a presynthesized ring by heating.3 After cooling down
to room temperature, the system is frozen, the bulky groups
playing the role of stoppers and thus preventing the acyclic string
from dethreading from the ring, provided the latter is small
enough to block the unthreading process.3
In modern approaches, more and more functionality is
introduced into the catenanes and rotaxanes made, so that the
compounds are able to fulfill more and more complex chemical
and physical functions, and they display interesting and
sophisticated properties, such as photoinduced intramolecular
electron transfer,11 electrochemically triggered molecular mo-
tions,12,13 photochemical dethreading processes,14 etc. Some of
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X Abstract published in AdVance ACS Abstracts, February 15, 1997.
(1) Schill, G. Catenanes, Rotaxanes and Knots Academic Press: New
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S0002-7863(96)03955-8 CCC: $14.00 © 1997 American Chemical Society

Preparation of Metal-Containing Catenanes and Rotaxanes
J. Am. Chem. Soc., Vol. 119, No. 11, 1997 2657
the multicomponent molecular systems, able to perform some
kind of chemical action, have been named “molecular ma-
chines”.15
We would now like to describe our strategy for making
rotaxanes and catenanes, using two different types of transition
metals, both acting as assembling and templating species but
utilizing different coordinating fragments of the organic back-
bone precursors:29 (i) the first metal center will gather and orient
two ligands, leading to the “intertwined” situation which has
been used extensively in the past for building interlocking
rings.4-6,30 (ii) The second metal will effect a clipping reaction
on the intertwined precursor and thus freeze the interweaving
or the interlocking situation. This step will afford a rotaxane
or a catenate. Subsequently, removal of the first templating
metal will be allowed without destruction of the complete
structure. Obviously, this last step requires demetalation
selectivity since the complexes formed in the blocking or closing
reaction with the second metal (leading to rotaxanes or catenates,
respectively) will have to resist the decomplexation conditions
necessary to remove the first metal.
Due to their potential electro- and photochemical properties,
transition metal complexes are appealing units to incorporate
into the target structures. In fact, the use of the transition metal-
to-ligand bond as a structural element is not very common, also
for the reason that this type of bonding is less considered as a
“normal” covalent bond by the organic chemists who have tried
to make catenanes and rotaxanes in the past. A remarkable
achievement was reported in 1981 by Ogino, whose strategy
was based on both a template effect (cyclodextrin threaded by
a hydrocarbon fragment) and the use of transition metals to
stopper the threaded unit.16 The strategy was in part related to
previous unsuccessful attempts published long ago by German
chemists in a historical paper17 and aimed at making a catenane
after threading of a cyclodextrin by a doubly end-functionalized
polymethylene chain. Since then, several metal incorporating
rotaxanes and catenanes have been described,18-20 including a
structurally characterized catenane constructed via the templating
effect of two different transition metal centers.21 A wide family
of fascinating catenanes containing Pd(II) centers has also been
recently described by Fujita et al.22 Noteworthy, macrocycles
containing transition metal atoms as constitutive elements are
numerous and known for many years,23-27 including essential
natural products such as vitamin B12.28
Results and Discussion
Strategy. The strategy leading to rotaxanes or catenanes
using a complexation reaction with a transition metal as stopper-
forming or cyclization reaction from a threaded precursor is
represented in a schematic way in Figure 1.
Clearly, the two metal centers to be used along the strategy
of Figure 1 must have very different properties. In fact Cu(I)
and Ru(II) are ideally suited to the synthetic approach since (i)
Cu(I) is preferentially low-coordinate, with a strong tendency
to form tetrahedral complexes (bis-bidentate complexes of the
type Cu(dpp)2+; dpp ) 2,9-diphenyl-1,10-phenanthroline) and
(ii) Ru(II) is invariably six-coordinate when complexed to
aromatic imine-based ligands. Furthermore, whereas Cu(I)
complexes are substitutionally labile, Ru(II) forms very stable
and kinetically inert complexes, as required for the selective
demetalation step of copper, leading to rotaxanes or catenanes
with a free coordination site (reaction (iii) of Figure 1).
(12) Livoreil, A.; Dietrich-Buchecker, C. O.; Sauvage, J.-P. J. Am. Chem.
Soc. 1994, 116, 9399. Collin, J.-P.; Gavin˜a, P.; Sauvage, J.-P. J. Chem.
Soc., Chem. Commun. 1996, 2005. Ca´rdenas, D. J.; Livoreil, A.; Sauvage,
J.-P. J. Am. Chem. Soc. 1996, 118, in press.
(13) Bissell, R. A.; Co´rdova, E.; Kaifer, A. E.; Stoddart, J. F. Nature
1994, 369, 133. Benniston, A. C.; Harriman, A. Angew. Chem., Int. Ed.
Engl. 1993, 32, 1459. Benniston, A. C.; Harriman, A.; Lynch, V. M.
Tetrahedron Lett. 1994, 35, 1473.
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Philp, D.; Ricketts, H. G.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl.
1993, 32, 1301.
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Angew. Chem., Int. Ed. Engl. 1996, 35, 976. Ashton, P. R.; Iqbal, S.;
Stoddart, J. F.; Tinker, N. D. J. Chem. Soc., Chem. Commun. 1996, 479.
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Ed. Engl. 1996, 35, 978.
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M. P.; Yau, J.; Menzer, S.; Williams, D. J. Angew. Chem., Int. Ed. Engl.
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Ligands. The organic compounds used in the present study
are indicated in Figure 2. The starting 5,5′′-dimethyl-2,2′:6′,2′′-
terpyridine (1) was prepared by the Stille cross-coupling reaction
as previously reported.31 Alkylation of 1 was performed in THF
by deprotonation with LDA (1 equiv) followed by reaction with
Br(CH2)2OTHP to give the desired monosubstituted derivative
2 in 44% yield after chromatographic purification. Hydrolysis
of the acetal in refluxing EtOH in the presence of a catalytic
amount of HCl afforded the free alcohol 3 (85%, isolated yield),
which was transformed into the mesylate 4 by reaction with
MsCl in the usual conditions (CH2Cl2, NEt3; 95%). On the
other hand, the phenanthroline containing building block (2,9-
di(4-hydroxyphenyl)-1,10-phenanthroline, 5) was prepared as
(21) Piguet, C.; Bernardinelli, G.; Williams, A. F.; Bocquet, B. Angew.
Chem., Int. Ed. Engl. 1995, 34, 582.
(22) Fujita, M.; Ibukuro, F.; Hagihara, H.; Ogura, K Nature 1994, 367,
720. Fujita, M.; Ibukuro, F.; Seki, H.; Kamo, O.; Imanari, M.; Ogura, K. J.
Am. Chem. Soc. 1996, 118, 899. Fujita, M.; Ibukuro, F.; Yamaguchi, Y.;
Ogura, K. J. Am. Chem. Soc. 1995, 117, 4175. Fujita, M.; Yazaki, J.; Ogura,
K. Chem. Lett. 1991, 1031.
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Ed.; Pergamon Press: Oxford, 1996; Vol. 9, p 253 and references cited
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Lehn, J.-M.; Kneisel, B. O.; Baum, G.; Fenske, D. Angew. Chem., Int. Ed.
Engl. 1996, 35, 1838. Irwin, M. J.; Rendina, L. M.; Vittal, J. J.; Puddephatt,
R. J. J. Chem. Soc., Chem. Commun. 1996, 1281. Benelli, C.; Parsons, S.;
Solan, G. A.; Winpenny, R. E. P. Angew. Chem., Int. Ed. Engl. 1996, 35,
1825 and references cited.
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Soc. 1993, 115, 1574. See also ref 22.
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1973, 947. March, F. C.; Mason, R.; Thomas, K. M.; Shaw, B. L. J. Chem.
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Commun. 1975, 893. Errington, R. J.; McDonald, W. S.; Shaw, B. L. J.
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Schwabacher, A. W., Lee, J.; Lei, H. J. Am. Chem. Soc. 1992, 114, 7597.
Lee, J.; Schwabacher, A. W. J. Am. Chem. Soc. 1994, 116, 8382. Fujita,
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(29) A preliminary account on this work has been published: Ca´rdenas,
D. J.; Gavin˜a, P.; Sauvage, J.-P. J. Chem. Soc., Chem. Commun. 1996,
1915.
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2658 J. Am. Chem. Soc., Vol. 119, No. 11, 1997
Ca´rdenas et al.
Synthesis of a Catenane and a Rotaxane. The reaction
between 7 and Cu(MeCN)4BF4 in MeCN at 23 °C for some
minutes gave a yellow solution of complex Cu(7)(MeCN)2(BF4).
Treatment of this complex with a CH2Cl2 solution of 6
proceeded regioselectively on the ambidentate ligand to give
the desired threaded bis(dpp) complex 8 in 75% yield after
column chromatography (Figure 3). 1H-NMR spectrum of 8
shows the usual high field shifted signals corresponding to the
H of phenyl rings of both ligands, due to the phenanthroline
(phen) ring current effect in the intertwined structure (6.05 and
5.97 ppm, for the H meta to the phen moiety; and 7.49 and
7.29 ppm for the ortho H). The absorption at 440 nm in the
visible spectrum and the redox potential (+0.60 V vs SCE in
MeCN) are typical of these bis(dpp) complexes.34 Reactions
leading to Cu(dpp)2+ species usually proceed with quantitative
yields. The presence of small amounts of Cu(II) in the starting
Cu complex, which may interact with the terpy moieties, leads
to lower yields in this case. As expected, once the complex
had been formed, no competition of the terpy ligands versus
dpp for Cu(I) was observed. This is in agreement with the
results previously obtained in the electrochemically triggered
ring gliding motion in catenates containing the same coordinat-
ing units,12 and it is a consequence of the preferred tetrahedral
coordination for Cu(I).
Figure 1. Principle of the two-metal approach leading to rotaxanes or
catenanes from organic fragments, using coordination reactions.
Noteworthy, the strategy does not involve organic reactions once the
two building blocks have been made (the ring R and the string S). The
two chelates used are a 2,9-diphenyl-1,10-phenanthroline unit (dpp,
bidentate ligand symbolized by a U) and a 2,2′:6′,2′′-terpyridine motif
(terpy, terdentate ligand represented by a stylized W). The metal center
with a preferred tetrahedral geometry is indicated by a dotted disk,
whereas the six coordinate (octahedral) metal is represented by a white
circle. (i) The gathering and threading step: The tetrahedral metal
(Cu(I) in the present case) is first reacted with the ring. It will first
coordinate to the dpp fragment. After the string S has been added, due
to the great stability of four-coordinate complexes, it will thread inside
the ring in order to also bind to the metal already coordinated to the
dpp unit of the macrocyclic ring, R. By analogy with similar Cu(I)-
governed threading reactions,4-6,29 formation of the precursor P is
expected to be quantitative. (ii) The stopper-forming reaction: By
adding a second metal (Ru(II) in the present work) already complexed
to a terpy chelate, with its three remaining coordination sites being
occupied by labile ligands. These ancillary ligands are substituted by
the appended terpys of the precursor P to give a trimetallic complex.
Selective removal of the first assembling metal in the Cu-complexed
rotaxane (Cu(I), black dot) will afford a rotaxane containing a free
coordination site and whose blocking groups are two Ru(terpy)2-
derivatives. (iii) The cyclization reaction: Upon addition of an
octahedral metal, the two dangling terpy chelates will gather and
complex to this second metal (white circle). In this case, a starting
complex with a fully exchangeable coordination sphere is used.
Similarly as for (ii), selective demetalation of the tetrahedral center of
the catenate will lead to a “free” catenane (a catenand).
As shown in Figure 1, threaded complex (P of Figure 1 or 8
of Figure 3) is the common intermediate in the preparation of
rotaxanes and catenates. A rotaxane could be prepared by
stoppering the ends with a suitable metal complex already
containing a terpy ligand, whereas a catenate should be
synthesized by clipping both free terpy ligands with a metal in
a macrocyclization coordination reaction. As it has been
indicated before, Ru(II) was chosen as the most suitable metal,
since it forms highly kinetically stable bis(terpy) complexes.
In addition, it permits the stepwise introduction of two terpy
ligands, a necessary condition for the preparation of rotaxanes
following the strategy shown above.
The complex Ru(terpy)(acetone)3(BF4)2 was used to build the
stoppers. This species was prepared as previously reported from
Ru(terpy)Cl3, by removal of the chloro ligands with AgBF4 in
acetone,35 which affords a more reactive species toward a second
terpy ligand. Reaction between this Ru complex and the
threaded species 8 in EtOH-1,2-dichloroethane at 70 °C for 5
h gave the trimetallic Cu-coordinated rotaxane 9 (Figure 4, top).
After two column chromatographies and recrystallization, the
product was isolated in 33% yield as a deep red solid. This
complex was characterized by spectroscopic methods, FAB-
MS (calc. for [9-(PF6)]+: 2817.9, found: 2818.4) and cyclic
previously reported.32 Alkylation of diphenol 5 with mesylate
4 in DMF at 80 °C in the presence of K2CO3 gave the target
bifunctional ligand (6). The compound can be easily recrystal-
lized from CHCl3-EtOH to give a high yield (88%) of
analytically pure white product. Compound 6 contains both
terpy and dpp-derived binding sites suitable for Ru(II) and Cu(I)
coordination, respectively. The spacers joining the coordinating
units are long enough to permit ring closure after templated
threading of a macrocycle (see Figure 1). On the other hand,
30-membered macrocycle 7 (Figure 2), which has been exten-
sively used in previous syntheses of catenates and catenands,32,33
was chosen as the ring partner for Cu(I) coordination. It
contains the dpp unit necessary to furnish a stable Cu(I)
complex, and it has the suitable ring size to thread ligand 6
through it.
1
voltammetry (CV). Its H-NMR spectrum presents the same
features as in 8 for the phenyl hydrogens, indicating that the
intertwined structure remains after Ru complexation. The UV-
vis spectrum shows an absorption at 475 nm (ꢀ ) 24 200
L‚mol-1‚cm-1) typical of Ru(terpy)22+ moieties,35b the ꢀ value
corresponding to two Ru complexes. Its cyclic voltammogram
(Figure 6a) exhibits three reversible waves: one for the central
Cu complex (Cu(II)/Cu(I):E° ) +0.59 V vs. SCE in CH3CN)
and two waves for the Ru(terpy)2 subunits (Ru(III)/Ru(II):E°
) 1.23 V and Ru(II)/Ru(I):E° ) -1.30 V) having both double
the intensity of the Cu couple signal, as expected for the
observed stoichiometry.
(32) Dietrich-Buchecker, C.; Sauvage, J.-P. Tetrahedron 1990, 46, 503.
Chambron, J.-C.; Chardon-Noblat, S.; Dietrich-Buchecker, C. O.; Heitz,
V.; Sauvage, J.-P. Macrocycle Synthesis. A Practical Approach; Parker,
D., Ed.; Oxford University Press: Oxford, 1996; p. 207.
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Am. Chem. Soc. 1994, 116, 7692.

Preparation of Metal-Containing Catenanes and Rotaxanes
J. Am. Chem. Soc., Vol. 119, No. 11, 1997 2659
Figure 2. Synthesis of polyfunctional ligand 6. (a) LDA, THF, -78 °C; then Br(CH2)2OTHP; 44%. (b) EtOH, HCl (catalyst); reflux; 85%. (c)
MsCl, NEt3, CH2Cl2, -5 °C; 95%.
Figure 3. The regioselective threading step.
The related catenate 10 (Figure 4, bottom) was prepared by
reaction of 8 with Ru(DMSO)4Cl2.36 This starting Ru complex
presents the advantage of requiring less drastic conditions than
RuCl3 for the formation of a Ru(terpy)2 complex. Since
preparation of 10 requires the formation of a 29-membered ring
(i.e., a macrocycle), the Ru atom being a part of the cyclic
structure, relatively high dilution of the reactants is expected
to be favorable.37 The reaction was thus performed by slow
addition of a solution of Ru(DMSO)4Cl2 in EtOH (4 × 10-4
M) to a solution of precatenate 8 in EtOH-1,2-dichloroethane
(1:1; 1.2 × 10-4 M) at 70 °C. The desired catenate 10 was
1
isolated in 43% yield after column chromatography. Its H-
NMR spectrum (Figure 7a) shows the expected high field signals
for the H atoms of the phenyl rings (6.05 and 5.98 ppm, for the
H meta to the phen moiety; and 7.43 and 7.38 ppm for the ortho
H). Besides, there is another signal (singlet) appearing at high
field (6.27, 2H), corresponding to the H atoms of the phenan-
throline central ring of macrocycle 7 (H5′,6′; Figure 7a), as shown
by 1H COSY and ROESY experiments. This chemical shift is
a consequence of the effect of the Ru(terpy)2 unit, since it has
(36) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans.
1973, 204.
(37) Mu¨rner, H.; Belser, P.; von Zelewsky, A. J. Am. Chem. Soc. 1996,
118, 7989.

2660 J. Am. Chem. Soc., Vol. 119, No. 11, 1997
Ca´rdenas et al.
Figure 4. Clipping and stoppering coordination reactions leading to a Cu-complexed rotaxane (9) and to a catenate (10), respectively.
not been previously found for these hydrogens in non-Ru-
containing catenates.32 The ꢀ value for the absorption at 474
nm (ꢀ ) 14 900) is the result of the addition of the absorptivities
of both metal complexes. The CV shows three reversible waves
(Ru(III)/Ru(II):E° ) 1.24 V; Ru(II)/Ru(I):E° ) -1.32 V and
Cu(II)/Cu(I):E° ) 0.58 V), as observed for complex 9, but, in
the case of the catenate, the intensity for the Cu couple wave is
the same as for the Ru ones, in accordance with the stoichi-
ometry.
Demetalation Reactions. As it has been previously reported,
Cu catenates and Cu-coordinated rotaxanes can be easily
demetalated by reaction with cyanide.4,32,33 Our aim was to
selectively remove the templating metal (Cu) from compounds
9 and 10 without affecting the Ru complexes, so that the
stoppers or the clipping units remained unaltered. This would,
of course, preserve the topological properties of the compounds
and lead to a rotaxane and a catenane, respectively.
fragment, as usually observed for interlocked or threaded
systems. A dramatic downfield shift of the H-NMR phenyl
1
signals takes place upon demetalation, as it has been observed
for other catenands. This indicates that these hydrogens are
no longer undergoing ring current effects from the other
phenanthroline nucleus and, thus, that the entwined topography
of the dpp units has been destroyed. Similar features are
observed in the 1H-NMR spectrum of catenane 12 (Figure 7b),
analogously obtained by reaction of 10 with KCN in 86% yield
after column chromatography (Figure 5, bottom). In this case,
the downfield shift of the meta hydrogens corresponding to
macrocycle 7 is not so large (Hm′; Figure 7), indicating that
they are under the influence of the metal-containing ring. The
previously mentioned singlet signal (H5′,6′; Figure 7) exhibits
the highest downfield shift (ca. 1.6 ppm). Demetalation also
affects some of the terpy hydrogens (H3t, H9t, and H11t), which
appear at higher field. The structure of this catenane was also
confirmed by the absence of peaks between the ones for the
molecular ions and those correponding to the macrocycles in
the FAB-MS spectrum. CV and UV-vis data are also in
accordance with this structure.
The reaction between the trimetallic complex 9 and KCN in
MeCN-H2O at room temperature led to the rotaxane 11 (Figure
5, top) in 59% yield after column chromatography. The UV-
vis spectrum and the CV clearly indicate the absence of Cu.
Figure 6 shows the CV of complexes 9 and 11. Ru(II) oxidation
and reduction potentials for both 9 and 11 are the same and
within the range usually observed for Ru(terpy)2 complexes.
The rotaxane structure was confirmed by FAB-MS spectrometry.
No peaks are observed in the region lying between the signals
2+
Thus, the high stability of Ru(terpy)2 moieties allows for
the selective demetalation of Cu(I), giving rise to multicompo-
nent species with interlocked and threaded structures containing
Ru complexes within the skeleton and free coordination sites,
ready to be remetalated at will to afford new multimetallic
complexes.
-
of the molecular ions resulting from the loss of PF6 anions
and the peaks corresponding to the loss of the macrocyclic

Preparation of Metal-Containing Catenanes and Rotaxanes
J. Am. Chem. Soc., Vol. 119, No. 11, 1997 2661
Figure 5. Selective demetalation gives Ru-containing rotaxane 11 and catenane 12.
coordination chemistry are illustrated. A bifunctional ligand
and two different metals participate in the construction of
multicomponent complexes using pure coordination chemistry,
by taking advantage of the different stereoelectronic require-
ments of both metals. The ambidentate ligand 6 containing one
diphenylphenanthroline (dpp) and two terpyridine (terpy) units
reacts with a preformed Cu(dpp) macrocyclic complex to give
regioselectiVely a Cu(dpp)2+ species. This fact is in accordance
with the preferred tetrahedral coordination for Cu(I) complexes,
especially in the case of dpp ligands, since a highly stable
intertwined structure is obtained. This threaded Cu complex
presenting two free terpy moieties has been used for the
preparation of a catenate and a Cu complexed rotaxane. Thus,
a macrocyclization coordination reaction with a suitable Ru(II)
source afforded a catenate containing a Cu atom as a template
and a Ru(terpy)2 complex as a lock. Ru(II) is also suitable for
the preparation of a rotaxane, since it permits the formation of
appropiate stoppers from mono(terpy) complexes containing
ancillary labile ligands which can be replaced by the free terpy
units of the precatenate. Both the catenate and the Cu-
complexed rotaxane can be selectively demetalated to give a
catenane and a rotaxane containing Ru complexes in their
structure. The high stability of these fragments makes them
compatible with our templated synthesis and with the Cu(I)
decomplexation procedure. It will also allow to incorporate back
into the free coordination site, formed by the two dpp motifs,
a large variety of tetrahedrally coordinated metal centers or
Figure 6. Cyclic voltammograms of (a) trimetallic complex 9, showing
the waves of both Ru and Cu complexes, and (b) rotaxane 11, containing
free dpp moieties (vs. SCE; MeCN, Bu4NBF4, 0.1 M; 200 mV s-1).
Conclusion
A new way for the preparation of metal-containing rotaxanes
and catenanes is presented in this work. Several concepts on

2662 J. Am. Chem. Soc., Vol. 119, No. 11, 1997
Ca´rdenas et al.
Applied Research Model 273A connected to a computer was used
(software: Programme Research Electrochemistry Software) as well
as a potentiostat Bruker E130M, connected to a printing table.
5,5′′-Dimethyl-2,2′:6′,2′′-terpyridine (1). This compound was
prepared by Stille cross coupling reaction as previously reported:31 white
needles (EtOH), mp 303-304 °C. 1H NMR (CDCl3, 200 MHz): δ
8.52 (br s, 2H), 8.50 (d, J ) 8.1 Hz, 2H), 8.38 (d, J ) 7.8 Hz, 2H),
7.92 (t, J ) 7.5 Hz, 1H), 7.65 (ddd, J ) 8.1, 2.4, 0.7 Hz, 2H), 2.41 (s,
6H); 13C{1H}NMR (CDCl3, 50 MHz, DEPT) δ 155.45 (C), 153.87 (C),
149.58 (CH), 137.76 (CH), 137.36 (C), 133.38 (CH), 120.71 (CH),
120.38 (CH), 18.42 (CH3); EIMS m/z (rel intensity, %): 261 (M+, 100),
233 (11), 219 (12), 169 (11), 149 (15). Anal. Calcd for C17H15N3: C,
78.13; H, 5.79; N, 16.08. Found: C, 78.20; H, 5.79; N, 16.18.
5′′-Methyl-5-{3-[(tetrahydro-2H-pyran-2-yl)oxy]-1-propyl}-2,2′:
6′,2′′-terpyridine (2). A titrated commercial solution of LDA in THF
(ca. 1.5 M, 20.2 mL, 30.3 mmol) was slowly added dropwise to a
degassed solution of 5,5′′-dimethyl-2,2′,6′,2′′-terpyridine 1 (7.15 g, 27.4
mmol) in anhydrous THF (275 mL) at -78 °C. The resulting deep
purple solution was stirred under Ar at -78 °C for 2 h and then at 0
°C for 0.5 h. After cooling back to -78 °C, a degassed solution of
2-(2-bromoethoxy)tetrahydro-2H-pyran (5.72 g, 27.4 mmol) in anhy-
drous THF (270 mL) at 0 °C was added by means of a double-ended
needle. The resulting mixture was left at 0 °C and slowly allowed to
reach room temperature with stirring for 16 h. Then, it was hydrolyzed
at 0 °C with 100 mL of H2O. THF was evaporated, and the residue
was taken in CH2Cl2, washed with H2O, dried over MgSO4, and filtered.
Solvent was evaporated, and the residue was subjected to column
chromatography on alumina (eluent: hexane-Et2O) yielding 2 (4.66
g, 44%) as a white solid: mp 67-69 °C. 1H NMR (CDCl3, 200
MHz): δ 8.55-8.49 (m, 4H), 8.39 (d, J ) 7.8 Hz, 2H), 7.93 (t, J )
7.9 Hz, 1H), 7.72-7.64 (m, 2H), 4.60 (t, J ) 3.0 Hz, 1H), 3.95-3.77
(m, 2H), 3.58-3.39 (m, 2H), 2.82 (t, J ) 7.3 Hz, 2H), 2.42 (s, 3H),
1.99 (qt, J ) 7.4 Hz, 2H), 1.91-1.50 (m, 6H); 13C{1H}NMR (CDCl3,
50 MHz, DEPT): δ 155.48 (2C), 154.29 (C), 153.89 (C), 149.60 (CH),
149.36 (CH), 137.79 (CH), 137.52 (C), 137.38 (CH), 136.79 (CH),
133.40 (C), 120.86 (CH), 120.72 (CH), 120.44 (2CH), 99.10 (CH),
66.51 (CH2), 62.54 (CH2), 31.09 (CH2), 30.83 (CH2), 29.58 (CH2), 25.53
(CH2), 19.77 (CH2), 18.43 (CH3); EIMS m/z (rel intensity, %): 389
(M+, 10), 360 (11), 334 (8), 287 (69), 274 (73), 261 (100).
Figure 7. 1H-NMR spectra of (a) catenate 10 and (b) catenand 12
(acetone-d6, 400 MHz).
protons. This approach opens a new way for the preparation
of multicomponent species with promising photochemical
properties.38
5-(3-Hydroxy-1-propyl)-5′′-methyl-2,2′:6′,2′′-terpyridine (3). A
solution of 2 (5.11 g, 13.1 mmol) in EtOH (300 mL) was heated to
reflux. Concentrated HCl (0.5 mL) was added, and the mixture was
refluxed for 3 h. After cooling to 23 °C, the solution was neutralized
with concentrated NaOH (ca. 30%). EtOH was evaporated, and the
residue was treated with CH2Cl2 and washed with brine. The organic
phase was dried over Na2SO4 and filtered. Evaporation of the solvent
led to a yellow solid (3.78 g) which was purified by column
chromatography on alumina (eluent: CH2Cl2 containing 0-1% MeOH)
to give pure alcohol 3 (3.40 g, 85%) as a white powder: mp 111-112
°C. 1H NMR (CDCl3, 200 MHz): δ 8.53-8.47 (m, 4H), 8.37 (d, J )
7.8 Hz, 2H), 7.92 (t, J ) 7.8 Hz, 1H), 7.70-7.62 (m, 2H), 3.70 (t, J
) 6.3 Hz, 2H), 2.79 (t, J ) 7.7 Hz, 2H), 2.40 (s, 3H), 2.10 (br s, 1H),
1.99-1.85 (m, 2H); 13C{1H}NMR (CDCl3, 50 MHz, DEPT): δ 155.40
(C), 155.31 (C), 154.15 (C), 153.74 (C), 149.48 (CH), 149.18 (CH),
137.82 (CH), 137.57 (C), 137.50 (CH), 136.89 (CH), 133.50 (C), 121.02
(CH), 120.86 (CH), 120.48 (2 CH), 61.46 (CH2), 33.80 (CH2), 29.12
(CH2), 18.39 (CH3); EIMS m/z (rel intensity, %): 305 (100, M+), 287
(18), 286 (38), 275 (35), 274 (45), 260 (65), 143 (20). Anal. Calcd
for C19H19N3O: C, 74.73; H, 6.27; N, 13.76. Found: C, 74.63; H,
6.19; N, 13.61%.
5-(3-Methanosulfonyl-1-propyl)-5′′-methyl-2,2′:6′,2′′-ter-
pyridine (4). A solution of 3 (3.38 g, 11.1 mmol) and freshly distilled
NEt3 (9.3 mL, 66.6 mmol) in anhydrous CH2Cl2 (300 mL) was cooled
to -3 °C. Mesyl chloride (3.5 mL, 44.4 mmol) in anhydrous CH2Cl2
(85 mL) was added dropwise (-5 °C < T < -2 °C) and the resulting
mixture was stirred under Ar for 4 h at -3 °C. The reaction mixture
was washed with cold H2O and dried over Na2SO4. The organic phase
was filtered and concentrated to furnish a white solid which was purified
through a short alumina column (CH2Cl2) to give 4 as a white powder
(4.05 g, 95%): mp 92-94 °C. 1H NMR (CDCl3, 200 MHz): δ 8.58-
8.48 (m, 4H), 8.40 (d, J ) 7.8 Hz, 2H), 7.93 (t, J ) 7.8 Hz, 1H),
7.72-7.64 (m, 2H), 4.29 (t, J ) 6.2 Hz, 2H), 3.03 (s, 3H), 2.86 (t, J
Experimental Section
Materials and General Procedures. The following chemicals were
prepared according to literature procedures: Cu(MeCN)4BF4,39
Ru(DMSO)4Cl2,36 and 2,9-bis(4-hydroxyphenyl)-1,10-phenanthroline
5.32 All other chemicals were of the best commercially available grade
and were used without further purification. Dry solvents were distilled
from suitable dessicants (DMF from CaH2 under reduced pressure,
CH2Cl2 from P2O5 or CaH2, and THF from Na and benzophenone).
1,2-Dichloroethane (SDS, synthesis grade) and EtOH (Normapur,
analytical reagent) were used as received. UV-vis spectra were
recorded on a Kontron Instruments UVIKON 860 spectrophotometer.
1H NMR spectra were recorded on either Brucker WP 200SY (200
MHz) or WP 400SY (400 MHz) spectrometers (using the deuterated
solvent as the lock and residual solvent as the internal reference). Fast
atom bombardment mass spectra (FABMS) were recorded in the
positive ion mode with either a krypton primary atom beam in
conjunction with a 3-nitrobenzyl alcohol matrix and a Kratos MS80RF
mass spectrometer coupled to a DS90 system or a xenon primary atom
beam with the same matrix and a ZAB-HF mass spectrometer. Melting
points were mesured with a Bu¨chi SMP20 apparatus. Electrochemical
measurements were performed with a three-electrode system consisting
of a platinum working electrode, a platinum-wire counter-electrode,
and a standard reference calomel electrode (SCE), versus which all
potentials are reported. All measurements were carried out under Ar,
in degassed spectroscopic grade solvents, using 0.1 M n-Bu4NBF4
solutions as supporting electrolyte. A potentiostat EG&G Princeton
(38) Sauvage, J.-P.; Collin, J.-P.; Chambron, J.-C.; Guillerez, S.; Coudret,
C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Chem. ReV. 1994,
94, 993.
(39) Meerwein, H.; Hederick, V.; Wunsderlich, K. ArkiV. Pharm. 1958,
291, 541.

Preparation of Metal-Containing Catenanes and Rotaxanes
J. Am. Chem. Soc., Vol. 119, No. 11, 1997 2663
)7.6 Hz, 2H), 2.42 (s, 3H), 2.22-2.08 (m, 2H); 13C{1H}NMR (CDCl3,
50 MHz, DEPT): δ 155.41 (C), 155.15 (C), 154.72 (C), 153.66 (C),
149.54 (CH), 149.19 (CH), 137.91 (CH), 137.58 (CH), 136.95 (CH),
135.94 (C), 133.61 (C), 121.11 (CH), 120.79 (CH), 120.66 (CH), 120.57
(CH), 68.72 (CH2), 37.50 (CH3), 30.47 (CH2), 28.73 (CH2), 18.46 (CH3);
EIMS m/z (rel intensity, %): 383 (45, M+), 287 (49), 286 (52), 274
(100), 260 (38).
7.91 (d, J ) 8.5 Hz, 2H), 7.86 (br d, J ) 8.5 Hz, 2H), 7.67 (br d, J )
4.7 Hz, 4H), 7.56 (d, J ) 8.7 Hz, 4H), 7.52 (d, J ) 1.5 Hz, 2H), 7.49
(br s, 2H), 7.38 (d, J ) 8.7 Hz, 4H), 7.28 (m, 4H), 6.08 (d, J ) 8.7
Hz, 4H), 5.98 (d, J ) 8.7 Hz, 4H), 3.84 (s, 4H), 3.71 (m, 4H), 3.65
(m, 4H), 3.61 (m, 4H), 3.49 (m, 4H), 3.40 (t, J ) 6.2 Hz, 4H), 2.50
(m, 4H), 2.01 (s, 6H), 1.68 (m, 4H); FABMS: m/z 2818.4 ([M - PF6]+,
calcd 2817.9), 2672.0 ([M-2PF6]+, calcd 2672.9), 2527.5 ([M - 3PF6]+,
calcd 2527.9); UV-vis. (MeCN) λ (nm) (ꢀ, mol-1 L cm-1): 475
(24 200), 311 (127 800), 274 (96 000), 248 (83 400); electrochemical
data: ERu(III)/Ru(II) ) +1.23 V (∆E ) 65 mV); ECu(II)/Cu(I) ) 0.59 V (∆E
) 70 mV); ERu(II)/Ru(I) ) -1.30 V (∆E ) 65 mV) (ligand-centered
reduction).
Ligand 6. A mixture of mesylate 4 (1.58 g, 4.12 mmol), 2,9-bis-
(4-hydroxyphenyl)-1,10-phenanthroline32 (5) (792 mg, 2.16 mmol) ,and
K2CO3 (854 mg, 6,18 mmol) in DMF (90 mL) was heated at 80 °C for
16 h. After cooling to 23 °C, the suspension was diluted with CHCl3
(600 mL) and washed with H2O. The organic phase was evaporated
to dryness, the residue was dissolved in boiling CHCl3 (80 mL), and
the resulting solution was concentrated to 40 mL by heating at
atmospheric pressure. EtOH (240 mL) was added to precipitate the
desired product as a white solid which was filtered and washed with
EtOH and Et2O (1.70 g, 88%): mp 209-211 °C. 1H NMR (CDCl3,
200 MHz): δ 8.59 (m, 2H), 8.51 (m, 8H), 8.40 (m, 6H), 8.28 (d, J )
8.5 Hz, 2H), 8.10 (d, J ) 8.5 Hz, 2H), 7.93 (t, J ) 7.8 Hz, 2H), 7.76
(br s, 2H), 7.73 (dd, J ) 8.2, 5.9 Hz, 2H), 7.63 (br d, J ) 8.2 Hz, 2H),
7.13 (d, 8.9 Hz, 4H), 4.12 (t, J ) 6.1 Hz, 4H), 2.96 (t, J ) 7.5 Hz,
4H), 2.40 (s, 6H), 2.22 (m, 4H); 13C{1H}NMR (CDCl3, 100 MHz,
DEPT): δ 160.21 (C), 156.39 (C), 155.47 (C), 155.33 (C), 154.45 (C),
153.79 (C), 149.53 (CH), 149.34 (CH), 146.07 (C), 137.79 (CH), 137.38
(CH), 136.95 (CH), 136.77 (CH), 133.37 (C), 132.32 (C), 129.06 (CH),
127.55 (C), 125.63 (CH), 120.94 (CH), 120.70 (CH), 120.44 (CH),
119.36 (CH), 114.79 (CH), 66.56 (CH2), 30.59 (CH2), 29.25 (CH2),
18.38 (CH3); there is one C signal left; a CH signal either overlaps or
does not appear; FABMS: m/z 939 (M+), 652, 518, 470, 261. Anal.
Calcd for C62H50N8O2: C, 79.29; H, 5.37; N, 11.93. Found: C, 79.22;
H, 5.55; N, 12.07.
Threaded Complex 8. A solution of Cu(MeCN)4BF4 (25.8 mg,
0.082 mmol) in degassed MeCN (5 mL) was transferred via a cannula
to a stirred solution of macrocycle 7 (47 mg, 0.084 mmol) in CH2Cl2
(15 mL) under Ar. The resulting orange solution was stirred at 23 °C
for 30 min. Then, a degassed solution of ligand 6 (82 mg, 0.087 mmol)
in CH2Cl2 (50 mL) was transferred via a cannula into it, resulting in
the immediate formation of a brown-red solution which was stirred
under Ar at 23 °C for 3 h. After evaporation of the solvent, the residue
was chromatographed (alumina column; CH2Cl2-MeOH, 99.5:0.5) to
give the desired complex 8 as a brown solid (102 mg, 75%): 1H NMR
(CD2Cl2, 200 MHz): δ 8.63 (br d, J ) 8.1 Hz, 2H), 8.61 (d, J ) 8.4
Hz, 2H), 8.52 (d, J ) 7.8 Hz, 4H), 8.50 (m, 2H), 8.48-8.39 (m, 4H),
8.37 (d, J ) 8.4 Hz, 2H), 8.23 (s, 2H), 7.94 (t, J ) 7.8 Hz, 2H), 7.87
(d, J ) 8.4 Hz, 2H), 7.86 (s, 2H), 7.81 (d, J ) 8.4 Hz, 2H), 7.75 (dd,
J ) 8.2, 2.2 Hz, 2H), 7.67 (br d, J ) 8.1 Hz, 2H), 7.49 (d, J ) 8.7 Hz,
4H), 7.29 (d, J ) 8.7 Hz, 4H), 6.05 (d, J ) 8.7 Hz, 4H), 5.97 (d, J )
8.7 Hz, 4H), 3.83 (br s, 4H), 3.72 (m, 4H), 3.65-3.45 (m, 16H), 2.84
(t, J ) 7.3 Hz, 4H), 2.40 (s, 6H), 2.04 (m, 4H); FABMS: m/z 1569
([M-BF4]+), 1001, 939, 785 ([M-BF4]2+), 629; UV-vis (MeCN-
CH2Cl2, 1:1) λ (nm) (ꢀ, mol-1 L cm-1): 440 (2200), 283 (103 000),
246 (100 000), 224 (111 500); electrochemical data: ECu(II)/Cu(I) ) +
0.60 V (∆E ) 90 mV).
Complex 9. Ru(terpy)(Me2CO)3(BF4)2 was prepared without isola-
tion inmediately before use from Ru(terpy)Cl3 and AgBF4 in refluxing
acetone.35 A degassed solution of the threaded precursor 8 (80 mg,
0.046 mmol) in 1,2-dichloroethane (8 mL) was added to a degassed
solution of freshly prepared Ru(terpy)(Me2CO)3(BF4)2 (2.15 equiv) in
refluxing EtOH (40 mL), and the mixture was stirred under Ar at 70
°C for 5 h. Solvent was evaporated, and the residue was purified by
two successive column chromatographies (SiO2; eluent: MeCN-H2O
9:1, containing 0.5-1% saturated aqueous KNO3). The product was
isolated as the PF6- salt by anion exchange with KPF6. A solution of
the eluted nitrate in the minimum amount of MeCN was treated with
excess of a KPF6 saturated solution in MeCN. The complex was
precipitated as a brown-red solid by addition of H2O, filtered, washed
with H2O, and dried under vacuum. It was recrystallized from MeCN-
Et2O (45 mg, 33%): 1H NMR (acetone-d6, 400 MHz): δ 8.98 (d, J )
8.2 Hz, 2H), 8.96 (d, J ) 8.9 Hz, 2H), 8.94 (d, J ) 8.2 Hz, 4H), 8.80
(d, J ) 8.5 Hz, 2H), 8.72 (d, J ) 8.5 Hz, 2H), 8.67 (m, 6H), 8.59 (d,
J ) 8.5 Hz, 2H), 8.52 (t, J ) 8.1 Hz, 2H), 8.49 (t, J ) 8.1 Hz, 2H),
8.36 (s, 2H), 8.06 (d, J ) 8.2 Hz, 2H), 8.05 (s, 2H), 7.99 (m, 6H),
Rotaxane 11. A red-brown solution of 9 (33 mg, 0.011 mmol) in
MeCN (8 mL) was reacted with an aqueous KCN solution (36 mg,
0.55 mmol, in 1 mL). The mixture turned bright red. After having
been stirred at 23 °C for 1.5 h, the solution was evaporated to 4 mL
and treated successively with an excess of solid KPF6 and H2O (50
mL). The resulting red precipitate was filtered and washed with H2O.
It was purified by column chromatography (SiO2; MeCN-H2O, 9:1,
-
containing 0.1-1.5% saturated aqueous KNO3) and isolated as the PF6
salt (18 mg, 59%): 1H NMR (acetone-d6, 400 MHz): δ 8.88 (d, J )
8.0 Hz, 2H), 8.76 (d, J ) 8.2 Hz, 2H), 8.57 (d, J ) 8.2 Hz, 4H), 8.53
(m, 6H), 8.49 (d, J ) 8.5 Hz, 2H), 8.42 (d, J ) 8.0 Hz, 4H), 8.34 (m,
6H), 8.23 (d, J ) 8.5 Hz, 2H), 8.10 (d, J ) 8.5 Hz, 2H), 8.07 (t, J )
8.1 Hz, 2H), 8.02 (s, 2H), 7.98 (m, 6H), 7.94 (s, 2H), 7.82 (d, J ) 8.7
Hz, 4H), 7.74 (br d, J ) 8.2 Hz, 2H), 7.63 (s, 2H), 7.55 (d, J ) 5.6
Hz, 2H), 7.24 (m, 6H), 7.21 (br s, 2H), 6.77 (d, J ) 8.7 Hz, 4H), 6.42
(d, J ) 8.7 Hz, 4H), 3.73 (t, J ) 5.6 Hz, 4H), 3.67 (t, J ) 5.8 Hz, 4H),
3.63 (s, 4H), 3.49 (m, 4H), 3.37 (m, 8H), 2.62 (m, 4H), 1.86 (s, 6H),
1.83 (m, 4H); FABMS: m/z 2610.2 ([M-PF6]+, calcd 2609.3), 2464.5
([M-2PF6]+, calcd 2464.3), 2318.9 ([M-3PF6]+, calcd 2319.3), 2043.1
([M-7 - PF6]+), 1897.6 ([M-7 - 2PF6]+), 1752.6 ([M-7 - 3PF6]+);
UV-vis (MeCN) λ (nm) (ꢀ, mol-1 L cm-1): 476 (22 100), 311
(123 300), 276 (111 200), 233 (77 000); electrochemical data: ERu(III)/Ru(II)
) +1.26 V (∆E ) 60 mV); ERu(II)/Ru(I) ) -1.29 V (∆E ) 50 mV)
(ligand-centered reduction).
36
Catenate 10. A degassed solution of Ru(DMSO)4Cl2 (33.5 mg,
0.069 mmol) in EtOH (250 mL) was added dropwise during 24 h, under
efficient stirring, to an argon-flushed solution of the threaded complex
8 (115 mg, 0.069 mmol) in 1,2-dichloroethane-EtOH (1:1, 500 mL)
kept at 70 °C. Once the addition was complete, the solution was stirred
under Ar at 70 °C for 12 more hours. Solvent was evaporated, and
the brown-red crude mixture was purified by column chromatography
on silica gel (eluent: MeCN-H2O, 9:1, containing 0.1-0.5% saturated
-
aqueous KNO3). Catenate 10 was isolated as the PF6 salt after
treatment of the solid with a large excess of KPF6 in the minimum
amount of MeCN, addition of excess of H2O, filtration and washing
with H2O (brown solid, 63 mg, 43%): 1H NMR (acetone-d6, 400
MHz): δ 9.12 (d, J ) 8.1 Hz, 2H), 9.06 (d, J ) 8.4 Hz, 2H), 9.01 (d,
J ) 8.3 Hz, 2H), 8.77 (d, J ) 8.3 Hz, 2H), 8.70 (d, J ) 8.3 Hz, 2H),
8.60 (t, J ) 8.2 Hz, 2H), 8.38 (s, 2H), 8.10 (dd, J ) 8.3 and 1.6 Hz,
2H), 7.94-7.90 (m, 6H), 7.86 (d, J ) 8.4 Hz, 2H), 7.80 (d, J ) 8.4
Hz, 2H), 7.56 (s, 2H), 7.43 (d, J ) 8.5 Hz, 4H), 7.38 (d, J ) 8.5 Hz,
4H), 6.27 (s, 2H), 6.05 (d, J ) 8.5 Hz, 4H), 5.98 (d, J ) 8.5 Hz, 4H),
3.82 (s, 4H), 3.70-3.40 (m, 20H), 2.42-2.22 (m, 4H), 2.07 (s, 6H),
1.40-1.29 (m, 4H); FABMS: m/z 1959.3 ([M-PF6]+, calcd 1959.4),
1815.4 ([MH - 2PF6]+, calcd 1815.4), 1669.4 ([M-3PF6]+, calcd
1669.5); UV-vis (MeCN): λ max (nm) 474 (ꢀ ) 14 900); electrochemi-
cal data: ERu(III)/Ru(II) ) +1.24 V (∆E ) 60 mV); ECu(II)/Cu(I) ) +0.58
V (∆E ) 70 mV); ERu(II)/Ru(I) ) -1.32 V (∆E ) 60 mV) (ligand-
centered reduction).
Catenand 12. A solution of KCN (50 mg, 0.77 mmol) in H2O (1
mL) was added to a stirred solution of catenate 10 (27 mg, 0.0128
mmol) in MeCN (5 mL), and the mixture was stirred at 23°C for 1.5
h. An excess of KPF6 was added to the resulting bright red solution.
Addition of H2O triggered the precipitation of a red solid which was
purified by column chromatography (SiO2; MeCN-H2O, 9:1, containing
-
0-0.1% saturated aqueous KNO3) and isolated as the PF6 salt as
described above (21 mg, 86%). 1H NMR (acetone-d6, 400 MHz): δ
8.61 (d, J ) 8.1 Hz, 2H), 8.54 (d, J ) 8.4 Hz, 2H), 8.51 (d, J ) 8.3
Hz, 4H), 8.47 (d, J ) 7.4 Hz, 2H), 8.45 (d, J ) 8.5 Hz, 2H), 8.35 (d,
J ) 8.7 Hz, 4H), 8.19 (d, J ) 8.5 Hz, 2H), 8.12 (s, 2H), 8.10 (d, J )

2664 J. Am. Chem. Soc., Vol. 119, No. 11, 1997
Ca´rdenas et al.
8.3 Hz, 2H), 7.97 (s, 2H), 7.91 (s, 2H), 7.91-7.87 (m, 2H), 7.83 (d, J
) 8.4 Hz, 2H), 7.79 (d, J ) 7.4 Hz, 2H), 7.65 (d, J ) 8.8 Hz, 4H),
7.33 (s, 2H), 6.72 (d, J ) 8.7 Hz, 4H), 6.34 (d, J ) 8.8 Hz, 4H),
3.87-3.80 (m, 4H), 3.69-3.63 (m, 4H), 3.66 (s, 4H), 3.54-3.49 (m,
2H), 3.44-3.28 (m, 10H), 2.63-2.54 (m, 2H), 2.46-2.38 (m, 2H),
1.99 (s, 6H), 1.95-1.87 (m, 2H), 1.80-1.72 (m, 2H); FABMS: m/z
1751.6 ([M-PF6]+, calcd 1751.5), 1606.6 ([M-2PF6]+, calcd 1606.6),
1185.3 ([M-7 - PF6]+), 1039.4 ([M-7 - 2PF6]+); UV-vis (MeCN):
λ (nm) (ꢀ, mol-1 L cm-1) 474 (12 300), 314 (94 500), 278 (95 500);
electrochemical data: ERu(III)/Ru(II) ) +1.24 V (∆E ) 60 mV); ERu(II)/Ru(I)
) -1.34 V (∆E ) 60 mV).
Acknowledgment. We thank the Ministerio de Educacio´n
y Ciencia (Spain) and the European Communities for their
financial support.
JA963955J