Formation of a [2]rotaxane and [2]catenane based on PdBr2L 2 as a template

Article abstract of DOI:10.1139/V08-126

Previous studies have determined that neutral palladium(II) dibromide complexes template the formation of [2]pseudorotaxanes, albeit with weaker affinities than the analogous palladium(II) dichloride species. Here, the self-assembly of both [2]rotaxane (2

Full text of DOI:10.1139/V08-126

205
Formation of a [2]rotaxane and [2]catenane based
on PdBr2L2 as a template1
Barry A. Blight, James A. Wisner, and Michael C. Jennings
Abstract: Previous studies have determined that neutral palladium(II) dibromide complexes template the formation of
[2]pseudorotaxanes, albeit with weaker affinities than the analogous palladium(II) dichloride species. Here, the self-
assembly of both [2]rotaxane (2) and [2]catenane (5) were attempted using a PdBr2L2 centre as the template, resulting
in the desired interlocked structures. The structures were confirmed by NMR spectroscopy, CSI-MS, and single crystal
X-ray diffraction analyses. [2]Rotaxane 2 was isolated in 53% and [2]catenane 5 in 41% yields. The lower yields ob-
served in comparison to the chloride analogues can be attributed to the reduced template effect of the palladium(II)
dibromide subunits, caused by both the poor steric fit of the bromides in the isophthalamide cleft and bromide’s re-
duced capacity as a hydrogen bond acceptor.
Key words: rotaxane, catenane, hydrogen bonding, interlocked, supramolecular chemistry.
Résumé : Des études antérieures ont permis de déterminer que les complexes de dibromure de palladium(II) neutre
peuvent être utilisés comme gabarit pour la formation de [2]pseudorotoxanes, même si leur affinité est plus faible que
celle des espèces analogues à base de dichlorure de palladium(II). Dans ce travail, on a tenté de réaliser l’autoassemblage
du [2]rotoxane (2) et du [2]caténane (5) en utilisant un gabarit à base de PdBr2I2 et on a obtenu les structures compor-
tant les interrelations désirées. Les structures ont été confirmées par spectroscopie RMN, par spectrométrie de masse
avec ionisation par nébulisation à froid (SM-INF) et par des analyse de diffraction des rayons X par un cristal unique.
On a isolé le [2]rotoxane (2) avec un rendement de 53% et le [2]caténane (5) avec un rendement de 41%. Ces rende-
ments plus faibles que ceux obtenus avec les analogues chlorés peuvent être attribués à l’effet de gabarit réduit des
unités de dibromure de palladium(II) qui est provoqué par le mauvais ajustement stérique des bromures dans les espa-
ces disponibles de l’isophtalamide ainsi que par la capacité réduite du bromure comme accepteur d’une liaison hydrogène.
Mots-clés : rotaxane, caténane, liaison hydrogène, interrelié, chimie supramoléculaire.
[Traduit par la Rédaction] Blight et al. 211
Introduction
We have previously reported a study (6) that examined the
complexation of trans-bis-pyridine palladium(II) dihalide
axles by the well-known isophthalamide-based macrocycle 1
(7). Their combination resulted in [2]pseudorotaxane forma-
tion, employing second-sphere coordination of the halide
ligands (hydrogen-bond acceptors) by the isophthalamide
clefts (hydrogen-bond donors) of 1 as the template. It was
concluded that the size of the PdCl2 subunit of a trans-
PdCl2Py2 axle was a complimentary fit to the size of the
hydrogen-bond donating macrocyclic cavity (Ka = 5000 (mol/L)–1
in CDCl3 at 298 K). Nitrogen-based ligand exchange
allowed us to then apply this template strategy in the facile
self-assembly of palladium(II) dichloride templated
[2]rotaxane (8) and [2]catenane superstructures (9).
The study of interlocked molecules (e.g., rotaxanes and
catenanes) (1), conceptual precursors to molecular machines
(2), has largely been possible because of the potentially high
yields of products that self-assemble by applying modern
template-based synthetic methods (1, 2). In this context, the
use of transition metals in these assemblies generally falls
into one of two categories. The metal may be used as a re-
versible connection point in the backbone of one or more of
the components (3). Alternatively, the metal can participate
in the template process to organize accompanying ligands in
a desired spatial arrangement (4). The simultaneous use of
the metal in both roles is rare but offers a possible route to
further simplify syntheses of these interlocked products (5).
Anion recognition studies by Crabtree and co-workers
(10), Smith and co-workers (11), Beer and co-workers (12),
and Gale and co-workers (13) have demonstrated that neutral
isophthalamide-based acyclic receptors associate with a vari-
ety of anions through hydrogen bonding in solution. Studies
specifically examining isophthalamide–halide complexation
in solution revealed an inferior affinity for bromide com-
pared with chloride, which can be rationalized by a reduced
hydrogen-bond acceptor ability and a poorer steric fit of bro-
mide anions for such receptors. [2]Pseudorotaxanes formed
between 1 and a trans-PdBr2Py2 axle exhibit a similarly re-
duced affinity (Ka = 750 (mol/L)–1 in CDCl3 at 298 K) in
Received 31 March 2008. Accepted 11 April 2008. Published
on the NRC Research Press Web site at canjchem.nrc.ca on
16 September 2008.
B.A. Blight, J.A. Wisner,2 and M.C. Jennings. Department
of Chemistry, The University of Western Ontario, London,
ON N6A 5B7, Canada.
1This article is part of a Special Issue dedicated to Professor
R. Puddephatt.
2Corresponding author (e-mail: jwisner@uwo.ca).
Can. J. Chem. 87: 205–211 (2009)
doi:10.1139/V08-126
© 2008 NRC Canada

206
Can. J. Chem. Vol. 87, 2009
Scheme 1. Syntheses of [2]rotaxane 2 and [2]catenane 5. Aromatic protons are labeled identically to the previously reported PdCl2-
1
based structures (8, 9) to aid in discussion of their respective H NMR spectra.
1
Fig. 1. The aromatic region of the H NMR spectra (600 MHz,
CDCl3, 298 K) of free macrocycle 1 (top), [2]rotaxane 2 (mid-
dle), and free dumbbell 4 (bottom). Illustrated are the observed
perturbations in chemical shift between free and interlocked
components (dashed lines). COSY, and ROESY NMR experi-
comparison with the chloride analogue, which can be ex-
plained using similar arguments (6). To date, however, there
are no literature examples of bromide anions or ligands act-
ing as, or in, the organizational template to form a finite in-
terlocked structure. We sought to examine this potential
phenomenon by observing whether bromide can indeed be
used to template interlocked products, and, if so, how they
compare structurally to other bromide-bound isophthalamide-
based receptors. Herein, we describe the syntheses and
characterization of a [2]rotaxane (2) and [2]catenane (5)
templated by second-sphere coordination of palladium(II)
dibromide complexes via hydrogen bonding (Scheme 1) and
rendered interlocked through first-sphere ligation.
1
ments were performed to determine individual H NMR spectro-
scopic assignments.
Results and discussion
[2]Rotaxane (2)
Ligand substitution of benzonitrile from trans-bis-
benzonitrile palladium(II) dibromide (14) by sterically
demanding pyridine co-ligands (4-(3,5-di-tert-butylbenzyl)-
oxypyridine) 3 (8) in the presence of 1 (2 equiv.) results in
the synthesis of interlocked 2 in modest yields (Scheme 1).
Its preparation proceeds via dissolution of the above three
components in chloroform and allowing them to stir for 4 h
at room temperature. After selective crystallization of
macrocycle 1 and precipitation of the remaining liquor’s
contents into hexanes, flash column chromatography was re-
quired to separate the product from the reaction mixture, af-
fording [2]rotaxane 2 in 53% yield.
superstructure with ions of [M – Br]+ at 1797.9 amu and
[M – 2Br]2+ at 858.5.3 amu, signals that do not appear in so-
lutions of 1 and (or) 4 subjected to the same conditions.
Determination of the solid-state structure by single crystal
X-ray diffraction analysis confirmed the solution evidence
for the interlocked geometry (Fig. 2). Colorless plate-like
single crystals were grown by slow diffusion of
diisopropylether into a concentrated chloroform solution of
2. The anticipated interlocked architecture crystallized in
space group P(-1) and contained structural similarities to
isophthalamide–bromide complexes in the existing literature
(10–13). In these cases, hydrogen-bond contacts are slightly
longer (3.42 to 3.63 Å) than the sums of the Van der Waals
radii (3.40 Å), with the exception of one isophthalamide–
bromide conjugate reported by Smith and co-workers (3.28
and 3.39 Å) and are in agreement with those measured in 2.
The larger size of bromide anions (or ligands) also causes
each amide nitrogen from these examples, including 2, to
deviate from coplanarity from the central isophthalamide
ring in the direction of bromide (by >20°) resembling a
perching-type geometry. This also results in a 2.11 Å dis-
1
Comparison of the H NMR spectra of the free compo-
nents macrocycle 1 and dumbbell 4 with the pale yellow
powder isolated from chromatography supported the ex-
pected interlocked geometry in solution (Fig. 1). Hydrogen-
bonding interactions with the bromide ligands result in the
deshielding of the macrocyclic amide protons (Ha Dd = 0.94
ppm). As a consequence of the interpenetrated nature of the
structure, both pyridyl-protons (He Dd = –1.44 ppm, Hf Dd =
–0.55 ppm) are shifted upfield from the frequency of their
free components due to C-HLp interactions with the
diphenylcyclohexyl sidewalls of the macrocycle, which also
results in deshielding of the diphenylcyclohexyl arene pro-
tons (Hd Dd = 0.23 ppm). Cold spray ionization mass spec-
trometry (CSI-MS) confirmed the presence of the solvated
© 2008 NRC Canada

Blight et al.
207
1
Fig. 2. Stick representation of [2]rotaxane 2 in the solid state.
All methyl, cyclohexyl, and t-butyl groups of the macrocycle and
all C-H hydrogen atoms have been removed for clarity. Hydro-
gen bonds and weak contacts have been represented by yellow
dashed lines. Color code: C gray, H white, N blue, O red, Br or-
ange, Pd teal.
Fig. 3. The aromatic region of the H NMR spectra (600 MHz,
298 K) of Pd2Cl4-[2]catenane (top), and [2]catenane 5 (bottom).
Individual proton assignments are compared between the two su-
perstructures (dashed lines). NOESY, and ROESY NMR experi-
1
ments were performed to determine individual H NMR
assignments.
placement of the palladium centre from the least-squares
plane of the macrocyclic ring (plane defined by the four car-
bonyl carbons), caused by the poor steric fit of the bromide
ligands in the isophthalamide clefts of 1. The dissymmetric
geometry of 2, in the solid state, prompted us to investigate
its potential shuttling activity in solution (15). However, low
dence could not explain these two proton assignments, a rea-
sonable explanation presented itself upon receipt of the
solid-state structure. CSI-MS also confirmed the presence of
[2]catenane 5 in solution with ions of [M + H]+ at
2300.8 amu and [M + 2H]2+ at 1150.3 amu. Compound 5
was then dissolved in 1 mol/L of DMSO-d6 and monitored
1
temperature H NMR showed no sign of exchange broaden-
ing down to –50 °C (248 K). Contact distances and angles of
interest include: N(25)LBr(1) = 3.46 Å (N-HLBr = 156°),
N(40)LBr(1) = 3.45 Å (N-HLBr = 153°), N(63)LBr(2) =
3.57 Å (N-HLBr = 164°), N(78)LBr(2) = 3.67 Å (N-HLBr =
150°).
1
by H NMR spectroscopy in an attempt to disassemble it
into its degenerate macrocyclic components. Unfortunately,
the system completely degrades under these conditions, giv-
ing rise to a mixture of unidentifiable polymeric materials.
Orange platelike single crystals were grown from a con-
centrated chloroform solution of 5 by slow diffusion of
diisopropyl ether crystallizing in space group P2(1)/c and
subjected to single crystal X-ray diffraction analysis. Struc-
tural elucidation of 5 established the desired interlocked ge-
ometry in the solid state (Fig. 4), which unexpectedly
contained two exotopically arranged amide functionalities
(with respect to the NH groups) in the structure of macro-
cycle B (all eight amide NHs of the Pd2Cl4-[2]catenane are
endotopic). We posit that competition for hydrogen-bond ac-
ceptors (PdBr2 subunits and the carbonyl-oxygen atoms in
the backbone of each macrocyclic component) by the hydro-
gen-bond donating clefts results in an overall geometry con-
taining a blend of structural elements from Crabtree’s
isophthalamide–bromide complex (10) and the amide-based
[2]catenanes of Hunter (16), Vögtle and co-workers (17),
and Leigh and co-workers (18) in the solid state.
The isophthalamide subunit of macrocycle A participates
in the mutual recognition of Br(2B) (N(17A)LBr(2B) = 3.37 Å
(N-H-Br = 165°), N(32A)LBr(2B) = 3.36 Å (N-H-Br = 166°)),
resembling those of the isophthalamide–bromide conjugates
previously discussed (10–13), as well as 2. The second
isophthalamide subunit of macrocycle A bifurcates O(69B)
of macrocycle B with its NH groups (N(55A)LO(69B) =
3.75 Å (N-H-O = 158°), N(70A)LO(69B) = 2.95 Å (N-H-O =
171°), while the exotopically arranged NHs of macrocycle B
are independently engaged in hydrogen bonding with adjacent
macrocycle A units through the crystal lattice (N(32B)LO(57A) =
[2]Catenane (5)
[2]Catenane 5 is designed to employ a trans-bidentate
ligand 6 (9) that incorporates the structural components of
both macrocycle 1 and the required pyridine co-ligands
(Scheme 1). A chloroform–acetonitrile solution of 6 and
trans-bis-benzonitrile palladium(II) dibromide (14) were
refluxed for 18 h. The reaction mixture was concentrated,
precipitated into hexanes to remove residual benzonitrile,
and the resulting orange solid subjected to column chroma-
tography to afford [2]catenane 5 (a yellow powder) in 41%
yield.
1H NMR spectral comparison of the reaction product to
the previously synthesized Pd2Cl4-based [2]catenane (9)
confirmed in solution that the desired interlocked geometry
was likely obtained using palladium(II) dibromide to tem-
plate [2]catenane formation (Fig. 3). Similar chemical shifts
of protons Ha, Hb, He, Hf, Hg, Hh, Hj, and Hk between 5 and
its Pd2Cl4-counterpart lead us to this conclusion. In this
case, however, Hh is more shielded (Dd = –0.32 ppm) and Hj
is less shielded (Dd = 0.13 ppm) than observed in the
Pd2Cl4-based [2]catenane, which may be attributed to stronger
and (or) more frequent C-HLp interactions of Hh (resulting
in weaker interactions with Hj) with the diphenylcyclohexyl
cavity of the opposing macrocycle. Unexpectedly, amide
proton Hd is extremely shielded (Dd = –0.87 ppm) and Hc
deshielded (Dd = 1.07 ppm) in comparison with the Pd2Cl4-
1
[2]catenane, and although examination of the H NMR evi-
© 2008 NRC Canada

208
Can. J. Chem. Vol. 87, 2009
Fig. 4. Stick representation of [2]catenane 5 in the solid state.
All C-H hydrogen atoms, methyl, cyclohexyl, and t-butyl groups
have been removed for clarity. Hydrogen bonds and weak con-
tacts have been represented by yellow dashed lines. Color code:
C gray, H white, N blue, O red, Br orange, Pd teal.
ability of the macrocycle to hydrogen bond to the bromide
ligands of the metal complex gives rise to distortions of the
resulting interlocked molecules from the planned template
geometry, yielding recognizable structural elements from
other known isophthalamide-containing supramolecules in
the solid state. The [2]catenane generated using the PdBr2
template was unstable to attempts to dissociate the two
catenated rings, using DMSO as a competitive solvent for
both hydrogen bonding and ligand exchange.
Experimental
General
All reactions were performed in dry solvents and under an
inert N2(g) atmosphere. All organic reagents, including palla-
dium(II) dibromide, were purchased from Sigma-Aldrich
Chemical Company and all were used without further purifi-
cation. 1D NMR spectral analyses of 4 for characterization
purposes were performed on a Varian Mercury 400MHz in-
strument. 1D NMR and 2D NMR spectral analyses of 2 and
5 or individual assignments were performed on a Varian
Inova 600MHz instrument. Cold-spray ionization mass de-
terminations were performed with Micromass LCT instru-
mentation with carrier gases cooled to 200 K.
2.91 Å (N-H-O = 158°), N(70B)LO(31A) = 2.98 Å (N-H-O =
141°)) and are both features of the mentioned amide-based
[2]catenanes in the solid state. Each isophthalamide subunit
of macrocycle B is singularly engaged in weak hydrogen-
bond contacts with the opposing bromide ligands of
macrocycle A (N(17B)LBr(2A) = 3.67 Å (N-H-Br = 151°),
N(55B)LBr(2A) = 3.99 Å (N-H-Br = 155°). As in 2, the Br-
Pd-Br subunits in 5 are also too large for the macrocyclic
cavity, which forces the displacement of each PdBr2 from
the centre of its respective host macrocycle (macrocyclic-
plane-ALPd(B) = 1.48 Å, macrocyclic-plane-BLPd(A) =
2.40 Å). This results in perched geometries of both PdBr2
subunits in the mouths of their respective macrocyclic com-
ponents, with all amides engaged in bromide–ligand contacts
deviating from coplanarity with their respective
isophthalamide phenyl ring (>20°) but one. Finally, from the
solid-state structure we can postulate that the unusual up-
field 1H NMR shift of Hd (N(32A), N(55A), N(32B),
N(55B)) is likely due to this hydrogen-bond competition re-
sulting in increased exposure to the bulk solvent, while the
downfield shift of Hc (C(21A), C(59A), C(21B), C(59B))
may be the result of positioning in the deshielding cone of a
neighboring endotopically arranged carbonyl-oxygen atom.
X-ray crystallographic analyses
Single crystal X-ray diffraction data, for both 2 and 5
(grown from a concentrated chloroform solution of 2 or 5 by
slow vapor diffusion of diisopropyl ether), was obtained
from a programmed hemisphere scan routine on a Nonius
Kappa-CCD diffractometer. The unit cell parameters were
calculated and refined from the full data set. Crystal cell re-
finement and data reduction were carried out using DENZO
(Nonius B.V., 1998). The data were scaled using
SCALEPACK (Nonius B.V., 1998). The solution for 2 was
solved by Patterson methods, and the solution for 5 by direct
methods, followed by difference Fourier syntheses to find
the remaining atoms in each subsequent structure. Refine-
ment was with full-matrix least-squares methods using
SHELXTL-NT 6.1 (G.M. Sheldrick, Madison, Wisconsin,
USA, 2000). The organic material and the metal center(s)
were very well resolved in both structures. All of the non-
hydrogen atoms were refined with anisotropic thermal pa-
rameters. The hydrogen atom positions were calculated geo-
metrically and were included as riding on their respective
carbon atoms. A summary of the data collection, solution,
and refinement parameters are listed in Table 1.3
Procedures
Conclusion
In summary, palladium(II) dibromide metal centres have
been used successfully to self-assemble both a [2]rotaxane
and [2]catenane despite the reduced magnitude of the tem-
plate interactions present in comparison with previously re-
ported palladium(II) dichloride analogues. The reduced
[2]Rotaxane (2)
Macrocycle 1 (50 mg, 0.049 mmol) and trans-bis-
benzonitrile palladium(II) dibromide (14) (12 mg, 0.025
mmol) were dissolved in chloroform (10 mL) in a 25 mL
round-bottomed flask and stirred for 10 min. 4-(3,5-Di-tert-
3 Supplementary data for this article are available on the journal Web site (canjchem.nrc.ca) or may be purchased from the Depository of Un-
published Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 3817. For more in-
formation on obtaining material refer to cisti-icist.nrc-cnrc.gc.ca/cms/unpub_e.shtml. CCDC 672440 (2) and 672439 (5) contain the
crystallographic data for this manuscript. These data can be obtained, free of charge, via www.ccdc.cam.ac.uk/conts/retrieving.html (Or
from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax +44 1223 336033; or de-
posit@ccdc.cam.ac.uk).
© 2008 NRC Canada

Blight et al.
209
Table 1. Crystal data, solution, and refinement parameters for [2]rotaxane 2 and [2]catenane 5.
Compound
2
5
CCDC number
Empirical formula
672440
C122H164Br2Cl6N6O8Pd
672439
C122H146Br4Cl3N12O9.5Pd2
(2·2 CHCl3·2 isopropyl ether)
2321.51
(5·1 CHCl3·1.5 isopropyl ether)
2571.3
Formula mass
Crystal description
Crystal size (mm)
Crystal system
Space group
Colorless plates
0.50 × 0.06 × 0.04
Triclinic
Orange plates
0.33 × 0.10 × 0.05
Monoclinic
P2(1)/c
P (-1)
a (Å)
b (Å)
c (Å)
a (°)
b (°)
g (°)
17.415(2)
20.501(3)
15.2868(5)
32.6803(12)
24.8098(8)
90
95.628(2)
90
21.0011(17)
107.372(6)
100.449(6)
113.911(5)
2
6 136.3(12)
1.256
0.988
Z
4
V (Å3)
12 334.7(7)
1.385
1.712
Dcalcd (gcm–3)
m (mm–1)
Independent reflections (Rint)
20 709 (0.0780)
21 137 (0.187)
Data, restraints, parameters
Goodness-of-fit on F2
Final R1 [F2 > 2sF2]
Final wR2 [F2 > 2sF2]
20 709, 0, 1340
1.056
0.0985
21 137, 22, 1370
0.921
0.091
0.1836
0.2089
Final R1 (all data)
0.219
0.3346
Final wR2 (all data)
Residuals peak, hole (e, Å3)
0.2404
0.2959
0.994, –0.794
1.248, –0.784
butylbenzyl)-oxypyridine 3 (15 mg, 0.049 mmol) was dis-
solved in chloroform (2 mL) and added dropwise via pipette.
The solution was stirred for 4 h, followed by cooling in the
freezer to selectively crystallize unreacted macrocycle. The
precipitate was isolated via vacuum filtration, and volume of
the filtrate reduced under reduced pressure to approximately
2 mL of solvent. This concentrated solution was then added
dropwise to a beaker of hexanes to precipitate the product
away from the high-boiling benzonitrile. The precipitate was
collected via vacuum filtration. The crude product was then
chromatographed (5% EtOAc in DCM, leading band) to af-
ford 24 mg (0.013 mmol, 53% yield) of pure [2]rotaxane 2.
1H NMR (CDCl3, 600 MHz) d: 8.13 (d, 4H, 6 Hz), 8.07 (s,
4H), 7.77 (t, 4H, 6 Hz), 7.45, (t, 2H, 5 Hz), 7.20 (s, 8H),
7.19 (d, 4H, 5 Hz), 7.04 (d, 4H, 12 Hz), 6.46 (d, 4H, 12 Hz),
5.07 (s, 4H), 2.48 (bs, 8H), 2.10 (s, 24H), 1.70 (bs, 8H),
1.57 (bs, 4H), 1.37 (s, 18H), 1.30 (s, 36H). 13C NMR
(CDCl3, 600 MHz) d: 166.13, 166.00, 153.49,152.91,
151.91, 135.11, 134.53, 133.11, 131.56, 129.00, 123.38,
123.11, 121.70, 112.20, 71.82, 35.26, 34.90, 34.73, 31.40,
31.36, 31.20, 22.79, 19.30, 19.19. LR CSI-MS (MeOH ma-
trix in CHCl3) [M – 2Br]2+ m/z: 858.5.3, [M – Br]+ m/z:
1797.9.
(1 mL) and added dropwise to the bulk solution. The
reaction was stirred for 30 min to allow ample time for pre-
cipitation of the desired product. The product was isolated
1
via vacuum filtration (65.1 mg, 0.076mmol, 88% Yield). H
NMR (CDCl3, 400 MHz) d: 8.48 (d, 4H, 8 Hz), 7.46 (t, 2H,
4 Hz), 7.24 (d, 4H, 4 Hz), 7.02 (d, 4H, 8 Hz), 5.10 (s, 4H),
1.34 (s, 36H). 13C NMR (CDCl3, 400 MHz) d: 166.28,
154.90, 151.51, 133.42, 123.09, 122.31, 111.89, 71.69,
34.88, 31.39. LR-ESI MS (MeOH matrix in CHCl3) [M –
Br]+ m/z: 781.2, [M – 2Br + H]+ m/z: 699.3.
[2]Catenane (5)
Dipyridyl ligand 6 (50 mg, 0.057 mmol) was dissolved in
a 3:1 chloroform/acetonitrile solvent mixture (10 ml). A
chloroform solution (2 ml) of trans-bis-benzonitrile palla-
dium(II) dibromide (14) (27 mg, 0.057 mmol) was added
dropwise to the reaction mixture, and the reaction refluxed
for 18 h. The crude reaction mixture was filtered through
celite to remove any precipitate, and solvent removed under
reduced pressure. The resulting solid was dissolved in
a minimum amount of dichloromethane and precipitated into
hexanes to remove residual benzonitrile. The precipitate was
collected via vacuum filtration and the crude product was
then chromatographed (5% EtOAc in DCM, leading band) to
afford 27 mg (0.012 mmol, 42% yield) of pure [2]catenane
Dumbbell (4)
1
In a 10 mL round-bottomed flask, trans-bis-benzonitrile
palladium(II) dibromide (14) (40.0 mg, 0.085 mmol) was
dissolved in dry acetonitrile (3 mL) and allowed to stir for
5 minutes. 4-(3,5-Di-tert-butylbenzyl)-oxypyridine 3 (14)
(50.5 mg, 0.17 mmol) was dissolved in dry acetonitrile
5. H NMR (CDCl3, 600 MHz) d: 9.16 (d, 4H, 1.8 Hz), 9.12
(s, 4H), 9.01 (d, 4H, 8.4 Hz), 8.26 (dd, 4H, 1.8 and 1.8 Hz),
8.18 (dd, 4H, 1.8 Hz and 1.8 Hz), 8.09 (s, 4H), 8.02 (s, 4H),
7.40 (s, 8H), 7.14 (d, 4H, 5.4 Hz), 6.88 (dd, 4H, 8.4 Hz and
5.4 Hz) 2.61 (bs, 8H), 2.22 (s, 24H), 1.77 (bs 8H), 1.61 (bs,
© 2008 NRC Canada

210
Can. J. Chem. Vol. 87, 2009
4H), 1.34 (s, 36H). 13C NMR (CDCl3, 600 MHz) d: 165.48,
164.78, 153.68, 148.22, 146.41, 143.20, 138.25, 135.45,
134.35, 133.50, 131.52, 130.49, 129.75, 129.17, 126.27,
125.93, 120.67, 44.98, 35.19, 34.63, 31.03, 26.34, 22.79,
19.34. LR CSI-MS (MeOH matrix in CHCl3) [M + 2H]2+
m/z: 1150.3, [M + H]+ m/z: 2300.8.
Chem. Soc. 103, 1303 (1981); (i) M. Chas, E. Pia, R. Toba, C.
Peinador, and J.M. Quintela. Inorg. Chem. 45, 6117 (2006);
( j ) M. Chas, V. Blanco, C. Peinador, and J.M. Quintela. Org.
Lett. 9, 675 (2007); (k) V. Blanco, M. Chas, D. Abella, C.
Peinador, and J.M. Quintela. J. Am. Chem. Soc. 129, 13878
(2007); (l) M.J. Gunter, N. Bampos, K.D. Johnstone, and
J.K.M. Sanders. New J. Chem. 25, 166 (2001); (m) G.J.E.
Davidson, S.J. Loeb, N.A. Parekh, and J.A. Wisner. J. Chem.
Soc. Dalton Trans. 3135 (2001); (n) K. Kim. Chem. Soc. Rev.
31, 96 (2002); (o) S.Y. Chang and K.-S. Jeong. J. Org. Chem.
68, 4014 (2003); (p) C.O. Dietrich-Buchecker, B. Colasson,
M. Fujita, A. Hori, N. Geum, S. Sakamoto, K. Yamaguchi,
and J.-P. Sauvage. J. Am. Chem. Soc. 125, 5717 (2003).
Acknowledgements
We are grateful for the financial support provided by the
Natural Sciences and Engineering Research Council of Can-
ada and the University of Western Ontario.
4. (a) C.O. Dietrich-Buchecker and J.-P. Sauvage. Tetrahedron.
Lett. 24, 5095 (1985); (b) C.O. Dietrich-Buchecker and J.-P.
Sauvage. J. Am. Chem. Soc. 106, 3043 (1984); (c) B. Mohr,
M. Weck, J.-P. Sauvage, and R.H. Grubbs. Angew. Chem Int.
Ed. Engl. 36, 1308 (1997); (d) J.-C. Chambron, V. Heitz, and
J.-P. Sauvage. J. Chem. Soc. Chem. Commun. 1131 (1992);
(e) J.-C. Chambron, V. Heitz, and J.-P. Sauvage. J. Am. Chem.
Soc. 115, 12378 (1993); ( f ) P. Gavina and J.-P. Sauvage. Tet-
rahedron Lett. 38, 3521 (1997); (h) L. Hogg, D.A. Leigh, P.J.
Lusby, A. Morelli, S. Parsons, and J.K.Y. Wong., Angew.
Chem. Int. Ed. 43, 1218 (2004); (i) A.-M. Fuller, D.A. Leigh,
P.J. Lusby, I.D.H. Oswald, S. Parsons, and D.B. Walker. Angew.
Chem. Int. Ed. 43, 3914 (2004); ( j ) A.-M. Fuller, D.A. Leigh,
P.J. Lusby, A.M.Z. Slawin, and D.B. Walker. J. Am. Chem.
Soc. 127, 12612 (2005); (k) D.A. Leigh, P.J. Lusby, A.M.Z.
Slawin, and D.B. Walker. Chem. Commun. 4919 (2005); (l)
A.-M. Fuller, D.A. Leigh, P.J. Lusby, A.M.Z. Slawin, and D.B.
Walker. J. Am. Chem. Soc. 127, 12619 (2005); (m) J.C. Loren,
P. Gantzel, A. Linden, and J.S. Siegel. Org. Biomol. Chem. 3,
3105 (2005); (n) M. Hutin, C.A. Schalley, G. Bernardinelli,
and J.R. Nitschke. Chem. Eur. J. 12, 4069 (2006); (o) M.
Ammann, A. Rang, C.A. Schalley, and P. Bäuerle. Eur. J. Org.
Chem. 1940 (2006); (p) K.S. Chichak, S.J. Cantrill, A.R. Pease,
S.-H. Chiu, G.W.V. Cave, J.L. Atwood, and J.F. Stoddart. Sci-
ence, 304, 1308 (2004).
5. (a) C.P. McArdle, M.J. Irwin, M.C. Jennings, and R.J.
Puddephatt. Angew. Chem. Int. Ed. 38, 3376 (1999); (b) C.P.
McArdle, J.J. Vittal, and R.J. Puddephatt. Angew. Chem. Int.
Ed. 39, 3819 (2000); (c) C.P. McArdle, M.C. Jennings, J.J.
Vittal, and R.J. Puddephatt. Chem. Eur. J. 7, 3572 (2001);
(d) N.C. Habermehl, F. Mohr, D.J. Eisler, M.C. Jennings, and
R.J. Puddephatt. Can. J. Chem. 84, 111 (2006); (e) M.E.
Padilla-Tosta, O.D. Fox, M.G.B. Drew, and P.D. Beer. Angew.
Chem. Int. Ed. 40, 4235 (2001); (f ) W.W.H. Wong, J. Cookson,
E.A.L. Evans, E.J.K. McInnes, J. Wolowska, J.P. Maher, P.
Bishop, and P.D. Beer. Chem. Commun. 2214 (2005); (g) J.
Cookson and P.D. Beer. Dalton Trans. 1459 (2007).
References
1. (a) G. Schill. Catenanes, rotaxanes and knots. Academic Press,
New York, USA. 1971; Molecular catenanes, rotaxanes, and
knots. Edited by J.P. Sauvage and C.O. Dietrich-Buchecker
Wiley-VCH, Weinheim, Germany. 1999; (b) F. Arico, T.
Chang, S.J. Cantrill, S.I. Khan, and F.J. Stoddart. Chem. Eur.
J. 11, 4655 (2005); (c) C.A. Schalley. J. Phys. Org. Chem. 17,
967 (2004); (d) S.J. Loeb and J.A. Wisner. Angew. Chem. Int.
Ed. 37, 2838 (1998); (e) C.A. Hunter. J. Am. Chem. Soc. 114,
5303 (1992); ( f ) C. Reuter, R. Schmieder, and F. Vögtle. Pure
Appl. Chem. 72, 2233 (2000); (g) H. Adams, F.J. Carver, and
C.A. Hunter. Chem. Commun. 809 (1995); (h) B. Therrien, A.
Hori, M. Tominaga, and M. Fujita. Acc. Chem. Res. 38, 369
(2005); (i) X.-Y. Li, J. Illigen, M. Nieger, S. Michel, and C.A.
Schalley. Chem. Eur. J. 9, 1332 (2003); ( j ) A.-M. Fuller, D.A.
Leigh, P.J. Lusby, A.M.Z. Slawin, and D.B. Walker. J. Am.
Chem. Soc. 127, 12612 (2005); (k) M.R. Sambrook, P.D. Beer,
J.A. Wisner, R.L. Paul, and A.R. Cowley. J. Am. Chem. Soc.
126, 15364 (2004); (l) A.L. Hubbard, G.J.E. Davidson, R.H.
Patel, J.A. Wisner, and S.J. Loeb. Chem. Commun. 138
(2004).
2. (a) E.R. Kay, D.A. Leigh, and F. Zerbetto. Angew. Chem. Int.
Ed. 46, 72 (2007) and refs. cited therein; (b) A. Mateo-Alonso,
C. Ehli, G.M. Aminur Rahman, D.M. Guldi, G. Fioravanti, M.
Marcaccio, F. Paolucci, and M. Prato. Angew. Chem. Int. Ed.
46, 3521 (2007); (c) F. Durola and J.-P. Sauvage. Angew.
Chem. Int. Ed. 46, 3537 (2007); (d) W. Abraham, K. Buck, M.
Orda-Zgadzaj, S. Schmidt-Schaeffer, and U.-W. Grummet.
Chem. Commun. 3094 (2007); (e) V. Aucagne, J. Berna, J.D.
Crowley, S.M. Goldup, K.D. Haenni, D.A. Leigh, P.J. Lusby,
V.E. Ronaldson, A.M.Z. Slawin, A. Viterisi, and D.B. Walker.
J. Am. Chem. Soc. 129, 11950 (2007); ( f ) S. Saha, A.H.
Flood, J.F. Stoddart, S. Impellizzeri, S. Silvi, M. Venturi, and
A. Credi. J. Am. Chem. Soc. 129, 12159, (2007); (g) J.D.
Crowley, D.A. Leigh, P.J. Lusby, R.T. McBurney, L.-E. Perret-
Aebi, C. Petzold, A.M.Z. Slawin, and M.D. Symes. J. Am.
Chem. Soc. 129, 15085 (2007); (h) S.J. Vella, J. Tiburcio, and
S.J. Loeb. Chem. Commun. 4752 (2007).
6. B.A. Blight, K.A. Van Noortwyk, J.A. Wisner, and M.C.
Jennings. Angew. Chem. Int. Ed. 44, 1499 (2005).
7. C. Fischer, M. Nieger, O. Mogck, V. Böhmer, R. Ungaro, and
F. Vögtle. Eur. J. Org. Chem. 1, 155 (1998).
3. (a) M. Fujita, F. Ibukuro, H. Hagihara, and K. Ogura. Nature,
367, 720, (1994); (b) M. Fujita, F. Ibukuro, K. Yamaguchi, and
K. Ogura. J. Am. Chem. Soc. 117, 4175 (1995); (c) K.-I.
Yamashita, M. Kawano, and M. Fujita. J. Am. Chem. Soc.
129, 1850 (2007); (d) I. Yoon, M. Narita, T. Shimizu, and M.
Asakawa. J. Am. Chem. Soc. 126, 16740, (2004); (e) C.O.
Dietrich-Buchecker, N. Geum, A. Hori, M. Fujita, S.
Sakamoto, K. Yamaguchi, and J.-P. Sauvage. Chem. Comun.
1182 (2001); ( f ) R.S. Wylie and D.H. Macartney. Supramol.
Chem. 3, 29 (1993); (g) K.-Y. Chang, H.-Y. Jang, and K.-S.
Jeong. Chem. Eur. J. 9, 1535 (2003); (h) H. Ogino. J. Am.
8. B.A. Blight, J.A. Wisner, and M.C. Jennings. Chem. Commun.
4593 (2006).
9. B.A. Blight, J.A. Wisner, and M.C. Jennings. Angew. Chem.
Int. Ed. 46, 2835 (2007).
10. (a) K. Kavallieratos, S.R. de Gala, D.J. Austin, and R.H. Crab-
tree. J. Am. Chem. Soc. 119, 2325 (1997); (b) K.
Kavallieratos, C.M. Bertao, D.J. Austin, and R.H. Crabtree. J.
Org. Chem. 64, 1675 (1999).
11. (a) J.M. Mahoney, A.M. Beatty, and B.D. Smith. J. Am.
Chem. Soc. 123, 5847 (2001); (b) A.V. Koulov, J.M. Mahoney,
© 2008 NRC Canada

Blight et al.
A.M. Beatty, and B.D. Smith. Org. Biomol. Chem. 1, 27
211
Sanchez, P. Prados, and R. Quesada. J. Am. Chem. Soc. 129,
1886 (2007).
14. (a) C. Tessier and F.D. Rochon. Inorg. Chim. Acta, 295, 25
(1995); (b) G.B. Kauffman. Inorg. Synth. 7, 249 (1970);
(c) M.M. Olmstead, P.-P. Wei, A.S. Ginwalla, and A.L. Balch.
Inorg. Chem. 39, 4555 (2000).
15. B.A. Blight, J.A. Wisner, and M.C. Jennings. Inorg. Chem. 46,
8445 (2007).
16. (a) C.A. Hunter. J. Am. Chem. Soc. 114, 5303 (1992); (b) H.
Adams, F.J. Carver, and C.A. Hunter. J. Chem. Soc. Chem.
Commun. 809 (1995).
17. (a) S. Ottens-Hildebrandt, M. Nieger, K. Rissanen, J.
Rouvinen, S. Meier, G. Hardera, and F. Vögtle. J. Chem. Soc.
Chem. Commun. 777 (1995); (b) Q.-Y Li,. E. Vogel, A.H.
Parham, M. Nieger, M. Bolte, R. Fröhlich, P. Saarenketo, K.
Rissanen, and F. Vögtle. Eur. J. Org. Chem. 4041 (2001).
18. A.G. Johnston, D.A. Leigh, R.J. Pritchard, and M.D. Deegan.
Angew. Chem. Int. Ed. Engl. 34, 1209 (1995).
(2003); (c) J.M. Mahoney, R.A. Marshall, A.M. Beatty, B.D.
Smith, S. Camiolo, and P.A. Gale. J. Supramol. Chem. 1, 289
(2001); (d) J.M. Mahoney, J.P. Davis, and B.D. Smith. J. Org.
Chem. 68, 9819 (2004); (e) J.M. Mahoney, G.U. Nawaratna,
A.M. Beatty, P.J. Duggan, and B.D. Smith. Inorg. Chem. 43,
5902 (2004).
12. (a) J.A. Wisner, P.D. Beer, and M.G.B. Drew. Angew. Chem.
Int. Ed. 40, 3606 (2001); (b) J.A. Wisner, P.D. Beer, N.G.
Berry, and B. Tomapatanaget. Proc. Nat. Acad. Sci. 99, 4983
(2002); (c) M.R. Sambrook, P.D. Beer, J.A. Wisner, R.L. Paul,
A.R. Crowley, F. Szemes, and M.G.B. Drew. J. Am. Chem.
Soc. 127, 2292 (2005); (d) J.A. Wisner, P.D. Beer, M.G.B.
Drew, and M.R. Sambrook. J. Am. Chem. Soc. 124, 12469
(2002); (e) M.R. Sambrook, P.D. Beer, M.D. Lankshear, R.F.
Ludlow, and J.A. Wisner. Org. Biomol. Chem. 4, 1529 (2006);
( f ) K.-Y. Ng, A.R. Cowley, and P.D. Beer. Chem. Commun.
3676 (2006).
13. (a) P.A. Gale. Acc. Chem. Res. 39, 465 (2006); (b) P.V.
Santacroce, J.T. Davis, M.E. Light, P.A. Gale, J.C. Iglesias-
© 2008 NRC Canada