Transition metal(II)-salen and -salophen macrocyclic complexes for rotaxane formation: Syntheses and crystal structures

Article abstract of DOI:10.1002/ejic.200700208

We used a threading-followed-by-shrinking approach to prepare [2]rotaxanes possessing nickel(II)-salen and -salophen moieties. Reactions of macrocycles incorporating salen and salophen moieties with secondary dialkylammonium salts, followed by the addition of aqueous sodium sulfate, afforded the corresponding pseudorotaxanes; subsequent addition of nickel acetate shrank the effective size of the macrocycles to give the respective [2]rotaxanes. We obtained a [2]rotaxane possessing a salen unit in remarkably high yields - even in a polar solvent - indicating that the threading- followed-by-shrinking and salen-ring-opening-and-closing approaches occurred together. In addition, we expanded the threading- followed-by-shrinking approach to prepare a [2]rotaxane and a bis[2]rotaxane comprising two palladium(II)-salophen moieties linked in a bis-macrocycle and one and two secondary dialkylammonium salts, respectively. Furthermore, we prepared a tetraphenylporphyrin rhodium(III) chloride [Rh(TPP)Cl]-stoppered [2]rotaxane comprising a palladium(II)-salophen macrocycle and a pyridyl-terminated thread-like ion coordinated to the rhodium(III) center, which has potential as a next-generation molecular machine exhibiting catalytic function. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200700208

FULL PAPER
DOI: 10.1002/ejic.200700208
Transition Metal(II)–Salen and –Salophen Macrocyclic Complexes for
Rotaxane Formation: Syntheses and Crystal Structures
Mamiko Narita,[a][‡] Il Yoon,[a][‡‡] Masaru Aoyagi,[a] Midori Goto,[a] Toshimi Shimizu,[a] and
Masumi Asakawa*[a]
Dedicated to Professor J. Fraser Stoddart on the occasion of his 65th birthday
Keywords: Rotaxanes / Ring opening / Ring closing / Transition metals / Porphyrinoids
We used
a
“threading-followed-by-shrinking” approach
we expanded the “threading-followed-by-shrinking” ap-
proach to prepare a [2]rotaxane and a bis[2]rotaxane com-
prising two palladium(II)–salophen moieties linked in a bis-
to prepare [2]rotaxanes possessing nickel(II)–salen and
–salophen moieties. Reactions of macrocycles incorporating
salen and salophen moieties with secondary dialkylammo- macrocycle and one and two secondary dialkylammonium
nium salts, followed by the addition of aqueous sodium sul-
fate, afforded the corresponding pseudorotaxanes; subse-
quent addition of nickel acetate shrank the effective size of
the macrocycles to give the respective [2]rotaxanes. We ob-
tained a [2]rotaxane possessing a salen unit in remarkably
high yields Ϫ even in a polar solvent Ϫ indicating that the
salts, respectively. Furthermore, we prepared a tetraphen-
ylporphyrin rhodium(III) chloride [Rh(TPP)Cl]-stoppered
[2]rotaxane comprising a palladium(II)–salophen macrocycle
and a pyridyl-terminated thread-like ion coordinated to the
rhodium(III) center, which has potential as a next-generation
molecular machine exhibiting catalytic function.
“threading-followed-by-shrinking” and “salen-ring-open- (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
ing-and-closing” approaches occurred together. In addition,
Germany, 2007)
into ordered monolayer arrays on solid substrates.[6]
Furthermore, we synthesized porphyrin-stoppered rotax-
anes, explicitly pseudorotaxanes bound to the metal centers
of metalloporphyrins through axial coordination, which
suggest that such organic molecules can be immobilized
onto two-dimensional arrays of metalloporphyrins on a so-
lid substrate.[6a,6b,6d] Transition metals are often incorpo-
rated as templating or assembling centers for the formation
of rotaxanes.[7] Previously, we demonstrated the synthesis
of a [2]rotaxane incorporating a palladium(II)–salophen
[N,NЈ-o-phenylenebis(salicylideneiminato) dianion] moiety
by using a “threading-followed-by-shrinking” approach
(Figure 1a) that involves threading a rod-like unit through
a macrocycle and then shrinking the free space within the
macrocycle through coordination of its salophen moiety to
palladium metal; the rotaxane formation in this system oc-
curs in a nonpolar solvent (dichloromethane) when a sodi-
um(I)-complexed macrocycle possessing a salophen unit is
used.[8] Furthermore, we reported the synthesis of mono-
meric and dimeric macrocycles incorporating salen [N,NЈ-
ethylenebis(salicylideneiminato) dianion] moieties and a [2]-
rotaxane formed by using a “ring-opening-and-closing” ap-
proach (Figure 1b) through the cleavage and formation of
imino bonds of a salen moiety; the self-assembly of this
macrocycle in the presence of a dumbbell-shaped rod-like
component, followed by the addition of nickel acetate, af-
Introduction
Interest in functionalized rotaxanes and their future po-
tential as molecular machines in nanotechnology has in-
creased in recent years.[1] Many template-directed methods
for the preparation of rotaxanes have appeared in the litera-
ture; they generally involve clipping,[2] threading followed
by stoppering,[3] and slipping[4] approaches. Functionalized
rotaxanes can be immobilized onto solid surfaces through
the use of self-assembled monolayers or Langmuir–Blodg-
ett techniques.[5] We demonstrated Ϫ through molecularly
resolved scanning tunneling microscopy (STM) images –
that porphyrin and phthalocyanine derivatives self-assemble
[a] Nanoarchitectonics Research Center, National Institute of Ad-
vanced Industrial Science and Technology (AIST),
Tsukuba Central 5, 1-1-1 Higashi, Tsukuba Ibaraki 305-8565,
Japan
Fax: +81-29-861-4679
E-mail: masumi-asakawa@aist.go.jp
[‡] Current address: Toyota Central R&D Labs., Inc., 41-1, Aza
Yokomichi, Oaza Nagakute, Nagakute-cho,
Aichi-gun, Aichi-Ken 480-1192, Japan
[‡‡] Current address: California NanoSystems Institute and De-
partment of Chemistry and Biochemistry, University of Cali-
fornia, Los Angeles,
405 Hilgard Avenue, Los Angeles, California 90095, USA
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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FULL PAPER
Figure 1. (a) “Threading-followed-by-shrinking” and (b) “ring-
opening-and-closing” approaches toward [2]rotaxanes.
Scheme 1. Syntheses of [2]rotaxanes 3a-H·PF6 and 3b-H·PF6.
Scheme 2. Syntheses of macrocycles 4-Ba, 4-K, 4-Na, and rotaxanes 5-H·ClO4 and 6-2H·2ClO4.
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Transition Metal(II)–Salen and –Salophen Macrocyclic Complexes
forded, after counterion exchange, a [2]rotaxane that was Scheme 3) by combining sequential “threading-followed-
stabilized through coordination of the Ni ion to the macro- by-shrinking” and end-capping approaches, the latter
cyclic salen moiety.[9]
through axial coordination of a pyridyl unit in the thread-
In this paper, we describe a different synthetic system in like component and the rhodium(III) metal center. Such ro-
which we combined both “threading-followed-by-shrink- taxanes may allow the construction of catalytically active
ing”[8] and “ring-opening-and-closing”[9] approaches Ϫ and molecular machines on solid surfaces. We characterized rot-
note the remarkably higher yield for the synthesis of a axanes 3a/b-H·PF6, 5-H·ClO4, 6-2H·2ClO4, and 8-H·
salen-based rotaxane relative to that of our previous ap- Rh(TPP)Cl·ClO4 by using NMR and IR spectroscopy,
proach[8] Ϫ for the formation of [2]rotaxanes 3a/b-H·PF6 mass spectrometry, elemental analysis, and X-ray crystal-
(Scheme 1) from a precursor macrocycle [a barium(II)-com- lography (see the Supporting Information).
plexed macrocycle possessing either a salen or salophen
unit], a transition metal [nickel(II)], and a polar solvent (a
mixture of water, methanol, and acetonitrile). Furthermore,
we expanded the “threading-followed-by-shrinking” ap-
Results and Discussion
proach (Figure 2) to afford [2]rotaxane 5-H·ClO4 and bis-
As thread-like moieties, we used two types of the second-
[2]rotaxane 6-2H·2ClO4, which features two palladium(II)– ary dialkylammonium salt: 2-H·PF6,[4c] which contains two
salophen moieties linked in a bismacrocycle (Scheme 2). terminal tBu groups, and 7-H·O2CCF3,[13] which contains
The transition metal(II)–salen or –salophen moiety, which one tBu group and one pyridyl unit as its termini. For the
behaves as the shrinking center, might also be of use for shrinking centers, we incorporated a salen moiety into
applications in areas related to, for example, metallocata- macrocycle 1a[9] and salophen moieties into macrocycle
lysis,[10] nonlinear optical response,[11] and electron trans- 1b[12d] and bismacrocycle 4 (with each of these macrocycles
fer[12] when incorporated into rotaxane structures. In ad- prepared as a Ba complex). For end-capping, we used the
dition, we synthesized Rh(TPP)Cl-stoppered rotaxane rhodium(III) metal center of Rh(TPP)Cl. The reaction of
8-H·Rh(TPP)Cl·ClO4 (TPP
=
tetraphenylporphyrin; 1a/b-Ba and 2-H·PF6, followed by the addition of aqueous
sodium sulfate, afforded the corresponding intermediate
pseudorotaxanes, which could form free of macrocyclic and
dumbbell components; the subsequent addition of nickel-
(II) acetate afforded [2]rotaxanes 3a/b-H·PF6 in yields of
55 and 20%, respectively (Scheme 1). The yield of rotaxane
3a-H·PF6, which incorporates the salen moiety, was re-
markably high when considering that the use of polar sol-
vents, which disrupt hydrogen bonding, was necessary be-
Figure 2. Graphical representation of the [2]rotaxane and bis[2]rot-
axane when using the bismacrocycle and the “threading-followed-
by-shrinking” approach.
cause of the poor solubility of nickel(II) acetate in nonpolar
solvents. Previously, we reported evidence for the “ring-
opening-and-closing” approach occurring during the syn-
thesis of a [2]rotaxane incorporating a salen moiety.[9] We
believe that the unexpectedly high yield of 3a-H·PF6 relative
to that of 3b-H·PF6 may be attributed to the different envi-
ronments experienced by the salen and salophen moieties
during their respective “ring-opening-and-closing” pro-
cesses, which occurred through reactions at their imine
bonds. The relatively low yield in the synthesis of 3b-H·PF6
may have arisen from the fact that ring opening and closing
are very slow in the macrocycle incorporating the salophen
moiety. In the case of salen rotaxane 3a-H·PF6, both “thre-
ading-followed-by-shrinking” and “ring-opening-and-clos-
ing” processes occurred together, whereas salophen rotax-
ane 3b-H·PF6 formed only through the “threading-fol-
lowed-by-shrinking” process.
For the synthesis of an extended system, we used the
“threading-followed-by-shrinking” approach[8] with bis-
macrocycle 4 possessing two macrocycle units linked
through two salophen moieties (Figure 2). The reaction of
two dialdehyde derivatives and 3,3Ј-diaminobenzidine af-
forded the barium(II)-complexed bismacrocycle possessing
linked salophen moieties 4-Ba (Scheme 2). The addition of
aqueous potassium sulfate or aqueous sodium sulfate re-
moved the coordinated barium(II) ions as precipitated
Scheme 3. Synthesis of tetraphenylporphyrin-stoppered [2]rotaxane
8-H·Rh(TPP)Cl·ClO4.
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M. Narita, I. Yoon, M. Aoyagi, M. Goto, T. Shimizu, M. Asakawa
FULL PAPER
BaSO4 to afford 4-K or 4-Na, respectively. The self-as- units in the thread in bent conformations of the compo-
sembly of 4-K or 4-Na with 2-H·PF6, followed by the ad- nents (Figure 6). In addition, the signals of the protons of
dition of palladium(II) acetate and counterion exchange, af- the aromatic groups in the salen moiety (g; Figure 3c) as
forded a mixture of [2]rotaxane 5-H·ClO4 (i.e. possessing well as in the thread (B and C; Figure 3c) have shifted up-
one thread-like moiety; 3% yield) and bis[2]rotaxane 6- field relative to their locations in the corresponding free
2H·2ClO4 (i.e. possessing two thread-like moieties; 20% components probably as a result of π–π stacking interac-
1
yield).
tions.[15] As indicated in Figure 4, the H NMR spectrum
Toward our goal of immobilizing catalytically active rot- of [2]rotaxane 3b-H·PF6 (Figure 4c) displays signals that are
axanes as molecular machines on solid substrates, we syn- very similar to those observed for 3a-H·PF6, which provides
thesized the Rh(TPP)Cl-stoppered [2]rotaxane 8- good evidence of the successful formation of this rotaxane.
H·Rh(TPP)Cl·ClO4. The reaction of 1b-PdII·Na and 7- Moreover, the ROESY NMR spectra (see Supporting In-
H·O2CCF3, followed by the addition of Rh(TPP)Cl and formation) of both rotaxanes 3a/b-H·PF6 feature cross
counterion exchange, afforded the Rh(TPP)Cl-stoppered peaks between the signals of the protons of the ether units
[2]rotaxane 8-H·Rh(TPP)Cl·ClO4 in 40% yield (Scheme 3). (e and f) in their respective macrocycles and the CH2N+
The yield of this [2]rotaxane is lower than the one we units (A) in their thread-like moieties.
achieved previously (75%)[6b] when using dibenzo[24]-
crown-8 as the macrocycle, possibly because of an increased
steric clash between the larger salophen-containing macro-
cycle and the Rh(TPP)Cl unit or because of relatively
weaker interactions between the components of this pseu-
dorotaxane.
1
Figure 3 displays representative H NMR spectra of [2]-
rotaxane 3a-H·PF6, the salen-incorporating macrocycle
bound with nickel(II) [1a-NiII·Na],[9] and thread-like salt 2-
1
H·PF6. The H NMR spectrum of 3a-H·PF6 (Figure 3c),
together with its 2D ROESY and COSY NMR spectra (see
Supporting Information) provides evidence for the success-
ful formation of the [2]rotaxane. The signal of the CH2N+
protons (A) in the rotaxane has shifted downfield signifi-
cantly relative to that in the free thread (Figure 3a) as a
result of the formation of [C–H···O] hydrogen bonds[14]
(Figure 6). In addition, these protons (A) resonate as a trip-
1
let in the rotaxane (Figure 3c), whereas they appear as a
Figure 4. H NMR spectra (600 MHz, CD3CN, 25 °C) of (a) 2-H·
singlet in the free thread (Figure 3a), which might be a re- PF6, (b) 1b-NiII·Na(I), and (c) 3b-H·PF6.
sult of the reduced exchange rates of the ammonium pro-
tons in the rotaxane structure owing to the hydrogen bonds.
Figure 5 displays representative 1H NMR spectra of
bis[2]rotaxane 6-2H·2ClO4, the salophen-incorporating bis-
macrocycle bound with palladium(II) [4-PdII·Na; for its
synthesis, see the Supporting Information], and thread-like
salt 2-H·PF6. Most of signals for the protons of bis[2]rotax-
ane 6-2H·2ClO4 (Figure 5c–e) are very similar to those ob-
served for [2]rotaxanes 3a/b-H·PF6, which provides good
evidence for the successful formation of this rotaxane and
confirms its structure. At 25 °C (Figure 5c), the protons of
the salophen and ether units in the bismacrocycle suggest
1
that slow conformational changes occur on the H NMR
spectroscopic timescale, which results in broadening and
splitting (e, h, and j) of the signals for a few protons of the
bismacrocycle. The spectrum became much simpler when
the signals for these protons coalesced at higher tempera-
tures (Figure 5d, e). In addition, the ROESY NMR spec-
trum (see Supporting Information) of this bis[2]rotaxane
features cross peaks between the signals of the protons of
1
Figure 3. H NMR spectra (600 MHz, CD3CN, 25 °C) of (a) 2-H·
PF6, (b) 1a-NiII·Na(I), and (c) 3a-H·PF6.
In contrast, two of the signals for the ether CH2O pro- the ether unit (c and d) in the bismacrocycle component and
tons (e and f; Figure 3c) in the NiII-bound macrocycle of aromatic protons (B and C) in its two thread-like moieties.
the rotaxane have shifted upfield relative to their location
The 1H NMR spectrum of the Rh(TPP)Cl-stoppered [2]-
in the unthreaded NiII-complexed macrocycle (Figure 3b); rotaxane 8-H·Rh(TPP)Cl·ClO4 (see Supporting Infor-
we attribute this phenomenon to shielding by the aromatic mation) displays signals that are very similar to those that
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Transition Metal(II)–Salen and –Salophen Macrocyclic Complexes
(Figures 6 and 7, respectively) confirm the proposed [2]rot-
axane structures incorporating the nickel(II)–salen and
–salophen moieties, respectively. Stabilization of these [2]-
rotaxanes is achieved through a combination of (1) [N+–
H···O][17] and [C–H···O][17a,17c] hydrogen bonds involving
+
NH2 centers, their adjacent CH2 groups, and the oxygen
atoms in the macrocycles and (2) π–π stacking interac-
tions[17] between aromatic rings (see Supporting Infor-
mation). The packing arrays of both 3a/b-H·PF6 are stabi-
lized by intra- and intermolecular [C–H···π] interac-
tions.[17b,17d] The [N+– H···O][17] and [C–H···O][17a,17c] hy-
drogen bonding distances (2.737–3.498 Å) are comparable
to those found in a related [2]rotaxane incorporating a pal-
ladium(II)–salophen,[8] a nickel(II)–salen[9] moiety, and
other[17] similar compounds. The nickel atom exists in a dis-
torted square-planar array (see Supporting Information)
that is very similar to the geometries we have observed pre-
viously for palladium atoms in related structures.[8,12d]
Figure 5. 1H NMR spectra (400 MHz, [D6]DMSO) of (a) 2-H·PF6,
(b) 4-PdII·Na(I), and 6-2H·2ClO4 recorded at temperatures of (c)
298 K, (d) 323 K, and (e) 353 K.
we observed previously.[6a,6b,6d] In particular, the signal of
the aromatic protons (A; Scheme 3) in the terminal pyridyl
unit of the thread-like moiety is shifted upfield drastically
relative to that in the free salt as a result of the shielding
effect of the diamagnetic current of the porphyrin ring.[16]
We obtained dark-brown-colored single crystals of 3a-
H·PF6 that were suitable for X-ray crystallographic analysis
upon slow evaporation of a CH2Cl2/EtOAc solution of the
[2]rotaxane; 3b-H·PF6 provided yellowish-brown-colored
single crystals, also suitable for X-ray crystallographic
analysis, upon vapor diffusion of diisopropyl ether into a
CH2Cl2 solution of the [2]rotaxane. The crystal structures
Figure 7. Molecular structure of 3b-H·PF6 that indicates the inter-
component [N+–H···O] and [C–H···O] hydrogen bonds. The nonhy-
drogen-bonding hydrogen atoms, disordered carbon atoms, and the
counter anion have been omitted for clarity. Hydrogen bonding
geometries: [X···O], [H···O] distances [Å] and [X–H···O] angles [°]
are (a) 2.906, 2.148, 141.5; (b) 2.829, 2.074, 140.7; (c) 2.858, 2.127,
137.8; (d) 3.498, 2.572, 162.1; (e) 2.920, 2.141, 144.4; (f) 3.408,
2.545, 149.7; (g) 3.259, 2.329, 162.8; (h) 3.323, 2.575, 134.9.
Figure 8. Molecular structure of 4–Ba. Perchlorate anions, solvent
molecules, and hydrogen atoms have been omitted for clarity. Se-
lected bond lengths [Å] and angles [°]: Ba1–O1 2.745(5), Ba1–O2
3.001(5), Ba1–O3 2.975(5), Ba1–O4 2.934(5), Ba1–O5 3.010(5),
Ba1–O6 2.965(5), Ba1–O7 2.903(5), Ba1–O8 2.786(5), Ba2–O9
2.828(5), Ba2–O10 3.046(6), Ba2–O11 2.945(6), Ba2–O12 2.932(6),
Ba2–O13 2.956(5), Ba2–O14 2.984(6), Ba2–O15 2.995(6), Ba2–O16
2.816(5); O1–Ba1–O6 156.66(15), O8–Ba1–O3 116.71(14), O7–
Figure 6. One molecular structure of 3a-H·PF6 that indicates the
intercomponent [N+–H···O] and [C–H···O] hydrogen bonds. The
other rotaxane molecule, the nonhydrogen-bonding hydrogen
atoms, disordered carbon atoms, and the counter anion have been
omitted for clarity. Hydrogen bonding geometries: [X···O], [H···O]
distances [Å] and [X–H···O] angles [°] are (a) 3.067, 2.348, 136.8;
(b) 2.840, 2.032, 148.6; (c) 2.737, 2.207, 117.1; (d) 2.892, 2.008,
166.8; (e) 3.264, 2.523, 134.0; (f) 3.429, 2.580, 147.6; (g) 3.185,
2.318, 149.9.
Ba1–O3
171.01(15),
O4–Ba1–O2 98.17(14),
O6–Ba1–O2
147.28(14), O2–Ba1–O5 149.92(14), O16–Ba2–O11 122.12(17),
O9–Ba2–O14 154.50(16), O12–Ba2–O15 119.58(17), O11–Ba2–O15
175.73(17), O13–Ba2–O10 152.92(16), O14–Ba2–O10 150.05(16).
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troscopy experiments were recorded by using 1 K data points and
256 time increments in phase-sensitive mode and were processed in
a 1 Kϫ1 K matrix. The ROESY NMR spectroscopic experiment
was performed with the use of a spin–lock mixing time of 200 ms
and was processed using a forward linear prediction in the F1 di-
mension. Matrix-assisted laser-desorption/ionization time-off-light
mass spectrometry (MALDI-TOF MS) was performed with a Shi-
mazu Kratos Kompact-MALDI III with a 2,5-dihydroxybenzoic
acid as the matrix. FAB mass spectra were recorded with an
MS600H spectrometer. Infrared (IR) spectra were recorded by
using a Jasco FTIR 620 spectrophotometer. Elemental analyses
were performed with a CE Instruments EA1110. Gel permeation
chromatography (GPC) separation was performed with an LC-918
(Japan Analytical Industry Co. Ltd.) equipped with JAIGL-1H and
–2H columns; chloroform was used as the eluent.
We obtained orange-colored single crystals of 4-Ba suit-
able for X-ray crystallographic analysis upon the slow evap-
oration of a CH2Cl2/THF/MeOH solution of the BaII-coor-
dinated bismacrocycle. The crystal structure (Figure 8) con-
firms that this bismacrocycle possesses two barium(II) ions;
the two salophen macrocyclic units, which are attached
through aromatic rings, are twisted at a dihedral angle of
14.8°. Each oligoether unit is folded completely to allow
coordination of all of its oxygen atoms to the barium(II)
ion.
Conclusions
We synthesized [2]rotaxanes 3a/3b-H·PF6 that feature
nickel(II)–salophen and –salen moieties, respectively. Both
“ring-opening-and-closing” and “threading-followed-by-
shrinking” processes occurred during the synthesis of the
salen-based [2]rotaxane 3a-H·PF6, resulting in its remarka-
bly higher yield than that of the salophen-based [2]rotaxane
3b-H·PF6, for which only a “threading-followed-by-shrink-
ing” process occurs. During the formation of these [2]rotax-
anes, the binding of nickel(II) ions to the salophen and
salen moieties constitutes the shrinking event. Furthermore,
we extended the synthetic system by using a “threading-
followed-by-shrinking” approach to afforded [2]rotaxane 5-
H·ClO4 and bis[2]rotaxane 6-2H·2ClO4, which both feature
two palladium(II)–salophen moieties linked in a bismacro-
cycle. In addition, we synthesized the Rh(TPP)Cl-stoppered
[2]rotaxane 8-H·Rh(TPP)Cl·ClO4 from salophen-based
macrocycle 1b-PdII·Na by using a combination of “thread-
ing-followed-by-shrinking” and end-capping through axial
coordination between the pyridyl unit of the thread-like cat-
ionic component and the rhodium(III) center. We believe
that these approaches will be useful for the construction
of multifunctional rotaxanes and for the development of
molecular devices as new tools. Such rotaxanes possessing
salen and salophen moieties have the potential to behave as
catalytically active molecular machines on solid surfaces.
Macrocycle Coordinated to Both Nickel(II) and Sodium(I), 1b-
NiII·Na: A solution of sodium sulfate (2.00 g, 14.0 mmol) in water
(20 mL) was added to a solution of 1b-Ba (935 mg, 1.0 mmol) in
MeCN (40 mL), and then the mixture was stirred at r.t. for 3 h.
The reaction mixture was filtered to remove the precipitated bar-
ium sulfate. The filtrate was dried (anhydrous Na2SO4), the solvent
was evaporated, and the residue was dried under high vacuum to
yield 1b-Na as an orange solid (801 mg, 95%). A solution of nicke-
l(II) acetate tetrahydrate (274 mg, 1.1 mmol) in MeOH (12 mL)
was added to a solution of 1b-Na (616 mg, 0.73 mmol) in CH2Cl2
(40 mL), and then the mixture was stirred at r.t. for 2 h. The solvent
was evaporated under reduced pressure. The residue was dissolved
in a small amount of MeCN and purified by column chromatog-
raphy (SiO2; CH2Cl2/MeOH, 98:2). Fractions containing the prod-
uct [Rf = 0.42 for 1b-NiII·Na; CH2Cl2/MeOH, 9:1] were combined,
and the solvent was evaporated under reduced pressure to afford
1
1b-NiII·Na (454 mg, 80%) as a brown solid. M.p. 141–142 °C. H
NMR (400 MHz, CD3CN, 25 °C): δ = 8.00 (s, 2 H, j), 7.44 (br., 2
H, k), 6.89–6.86 (m, 2 H, a), 6.79–6.74 (m, 6 H, b, i, l), 6.61 (d, J
= 7.8 Hz, 2 H, g), 6.40 (t, J = 7.8 Hz, 2 H, h), 4.13 (br., 4 H, f),
4.07 (br., 4 H, c), 3.86–3.85 (br., 8 H, d/e) ppm. 13C NMR
(100 MHz, CD3CN, 25 °C): δ = 155.3, 154.1, 148.4, 147.3, 141.9,
127.4, 125.5, 121.7, 119.7, 115.4, 115.1, 114.7, 68.9, 68.2, 67.8,
67.0 ppm. IR (KBr): ν = 3504, 2920, 2874, 1707, 1610, 1543, 1503,
˜
1450, 1254, 1202, 1100 (ClO4 ), 936, 739 cm–1. MS (MALDI-TOF):
–
m/z = 678 (100) [M + 1 – ClO4]+. C34H32ClN2NaNiO12 (777.77):
calcd. C 52.51, H 4.15, N 3.60; found C 52.58, H 4.28, N 3.51.
3a/b-H·PF6: A solution of Na2SO4 (101 mg, 0.71 mmol) in H2O
(2 mL) and MeCN (2 mL) was added to a solution of the relevant
macrocycle–barium perchlorate complex (0.25 mmol; 222 mg for
1a-Ba; 234 mg for 1b-Ba) and 2-H·PF6 (229 mg, 0.50 mmol) in
MeCN (20 mL), and then the mixture was stirred for 2 h. A solu-
tion of Ni(OAc)2·4H2O (63.3 mg, 0.25 mmol) in MeOH (2 mL) and
MeCN (2 mL) was added to the reaction mixture, which was stirred
for 12 h. The solution was filtered, and then the solvent was evapo-
rated under reduced pressure. The residue was dissolved in a small
amount of MeCN and purified by column chromatography (SiO2;
CH2Cl2/MeOH, 9:1). Fractions containing the product (Rf = 0.37
for 3a-H·PF6; Rf = 0.33 for 3b-H·PF6; CH2Cl2/MeOH, 9:1) were
combined, and the solvent was evaporated under reduced pressure
to afford the [2]rotaxanes as either a yellow-green (3a-H·PF6:
146 mg, 55%) or dark-brown solid (3b-H·PF6: 56 mg, 20%). Se-
lected data for 3a-H·PF6: M.p. 145–147 °C (decomp.). 1H NMR
(600 MHz, CD3CN, 25 °C): δ = 8.74 (br., 2 H, D), 7.60 (s, 2 H, j),
7.31 (d, J = 8.4 Hz, 4 H, C), 7.23 (d, J = 8.4 Hz, 4 H, B), 6.95 (m,
2 H, b), 6.90 (m, 2 H, a), 6.88 (d, J = 7.8 Hz, 2 H, i), 6.68 (d, J =
7.8 Hz, 2 H, g), 6.55 (t, J = 7.8 Hz, 2 H, h), 4.71 (t, J = 6.6 Hz, 4
H, A), 4.25 (m, 4 H, c), 3.85 (m, 4 H, d), 3.68 (m, 4 H, f), 3.63 (m,
Experimental Section
General Information: Nickel(II) acetate tetrahydrate, 3,3Ј-diami-
nobenzidine, palladium(II) acetate, and tetracarbonyl-di-µ-chloro-
rhodium(I) ([Rh(CO)2Cl]2) were purchased from Aldrich. Sodium
sulfate, potassium sulfate, and barium perchlorate were purchased
from Wako Pure Chemical Industries. 1a-Ba[9] (Scheme 1), 1b-
Ba[12d] (Scheme 1), 1a-NiII·Na,[9] 1b-PdII·Na[12d] (Scheme 3), 2-
H·PF6 (Scheme 1), 7-H·CF3COO[13] (Scheme 3), and Rh(TPP)-
[4c]
Cl[6b] (Scheme 3) were all prepared according to literature pro-
cedures. Solvents were purchased from commercial sources. Each
reaction was performed under an anhydrous nitrogen atmosphere.
Thin-layer chromatography (TLC) was performed by using alumin-
ium sheets precoated with silica gel 60F (Merck 5554). The plates
were inspected under UV light and developed in I2 vapor. Column
chromatography was conducted by using Wakogel C-400HG
(Wako Pure Chemical Industries). H and 13C NMR spectra were
1
recorded with a Bruker AVANCE 400 spectrometer (400 and
1
100 MHz for H and 13C NMR, respectively). All 2D NMR spec-
4234
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4229–4237

Transition Metal(II)–Salen and –Salophen Macrocyclic Complexes
4 H, e), 3.29 (s, 4 H, k), 1.22 (s, 18 H, E) ppm. 13C NMR PdII·Na (752 mg, 80%) as a orange solid. 1H NMR (400 MHz, [D6]-
(150 MHz, CD3CN, 25 °C): δ = 163.2, 152.7, 150.6, 147.9, 147.6,
130.2, 128.3, 124.8, 124.7, 120.5, 120.2, 114.8, 114.1, 111.9, 68.8,
DMSO, 25 °C): δ = 9.37 (s, 2 H, jЈ), 9.22 (s, 2 H, j), 8.74 (s, 2 H,
m), 8.45 (d, J = 9 Hz, 2 H, k), 8.02 (d, J = 9 Hz, 2 H, l), 7.43 (m,
4 H, i), 7.08 (br., 4 H, g), 6.98 (m, 4 H, b), 6.91 (m, 4 H, a), 6.66
(m, 4 H, h), 4.21 (br., 8 H, f), 4.14 (br., 8 H, c), 3.97 (br., 8 H, e),
68.3, 67.6, 67.1, 58.4, 50.4, 33.9, 30.3 ppm. IR (KBr): ν = 3436,
˜
3094, 2958, 1629, 1607, 1549, 1504, 1450, 1304, 1228, 1132, 1089,
839 (PF6 ), 741, 557 cm–1. MS (FAB): m/z (%) = 916 (72) [M – 3.89 (br., 8 H, d) ppm. IR (KBr): ν = 3003, 2391, 1853, 1630, 1481,
–
˜
PF6]+. C52H64F6N3NiO8P (1062.75): calcd. C 58.77, H 6.07, N
3.95; found C 59.07, H 6.27, N 3.61. Selected data for 3b-H·PF6:
M.p. 314–315 °C. 1H NMR (600 MHz, CD3CN, 25 °C): δ = 8.73
(br., 2 H, D), 8.44 (s, 2 H, j), 7.73 (m, 2 H, k), 7.28 (d, J = 8.4 Hz,
4 H, C), 7.24 (d, J = 8.4 Hz, 4 H, B), 7.21 (m, 2 H, l), 7.19 (d, J =
7.8 Hz, 2 H, i), 6.94 (m, 2 H, b), 6.89 (m, 2 H, a), 6.73 (d, J =
7.8 Hz, 2 H, g), 6.64 (t, J = 7.8 Hz, 2 H, h), 4.78 (t, J = 6.6 Hz, 4
H, A), 4.28 (m, 4 H, c), 3.88 (m, 4 H, d), 3.72 (s, 8 H, e/f), 1.09 (s,
18 H, E) ppm. 13C NMR (150 MHz, CD3CN, 25 °C): δ = 156.9,
154.2, 150.9, 147.8, 147.5, 142.0, 130.1, 128.2, 127.9, 126.6, 124.6,
120.5, 120.3, 115.6, 115.5, 115.1, 111.9, 68.8, 68.0, 67.6, 67.0, 50.6,
1346, 1163, 1053 (ClO4 ), 976 cm–1. MS (MALDI-TOF): m/z (%)
–
= 1428 (100) [M + 1 – Na – 2ClO4]+, 1548 (4) [M – 1 – ClO4]+.
5-H·ClO4 and 6-2H·2ClO4: A solution of 2-H·PF6 (592 mg,
1.3 mmol) in MeCN (20 mL) was added to a solution of the bis-
macrocycle with potassium(I) perchlorate 4-K (173 mg, 0.13 mmol)
in CH2Cl2 (20 mL) and stirred for 16 h at r.t. Then, solid Pd-
(OAc)2 (87 mg, 0.39 mmol) was added, and the reaction mixture
was stirred for 4 h. The solvent was evaporated under reduced pres-
sure, and the residue was dissolved in CH2Cl2 and filtered through
a column (SiO2; CH2Cl2/MeOH, 98:2). The crude material was
purified by GPC (CHCl3) to afford 6-2H·2ClO4 as a red-orange
33.7, 30.0 ppm. IR (KBr): ν = 3067, 2961, 1618, 1441, 1258, 1204,
˜
solid (58 mg, 20%). Selected data for 5-H·ClO : IR (KBr): ν = 1100
˜
4
–
1103, 840 (PF6 ), 743, 556 cm–1. MS (FAB): m/z (%) = 965 (90) [M
–
(ClO4 ) cm–1. MS (FAB): m/z (%) = 1715 (18) [M – ClO4]+. Selected
+ 1 – PF6]+. C56H64F6N3NiO8P (1110.79): calcd. C 60.55, H 5.81,
1
data for 6-2H·2ClO4: M.p. 184–187 °C. H NMR (400 MHz, [D6]-
N 3.78; found C 60.88, H 5.88, N 3.47.
DMSO, 25 °C): δ = 9.22 (s, 2 H, jЈ), 9.06 (m, 4 H, D), 8.68 (s, 2 H,
j), 8.33 (m, 2 H, m), 8.32 (s, 2 H, k), 8.03 (m, 2 H, l), 7.36 (m, 4
H, i), 7.25 (m, 8 H, C), 7.11 (m, 8 H, B), 6.95 (m, 4 H, b), 6.83 (m,
8 H, g, a), 6.75 (t, J = 8 Hz, 2 H, h), 6.47 (br., 2 H, hЈ), 4.79 (br.,
8 H, A), 4.22 (m, 8 H, c), 4.12 (m, 4 H, e), 4.02 (m, 4 H, eЈ), 3.91
4-Ba: A solution of the dialdehyde-functionalized crown ether
derivative (526.5 mg, 1.0 mmol) and 3,3Ј-diaminobenzidine
(107.2 mg, 0.5 mmol) in dry THF (20 mL) was added over 2 h to a
solution of barium perchlorate (336.3 mg, 1.0 mmol) heated under
reflux in dry MeOH (100 mL). The mixture was heated under re-
flux for an additional 24 h. During the reaction, an orange-colored
solid precipitated out. This solid was filtered off and washed with
CH2Cl2 to afford the barium perchlorate–bismacrocycle complex
4-Ba as an orange solid (691 mg, 74%). M.p. 221–226 °C. 1H NMR
(400 MHz, CD3CN, 25 °C): δ = 14.89–14.67 (m, 4 H, OH), 9.42
(br., 2 H, jЈ), 9.04 (br., 2 H, j), 8.02 (s, 2 H, m), 7.95–7.90 (m, 2 H,
k), 7.74–7.69 (m, 2 H, l), 7.24 (m, 4 H, i), 7.08 (m, 4 H, g), 6.93–
(br., 8 H, d), 3.81 (br., 8 H, f) ppm. IR (KBr): ν = 3181, 2060,
˜
–
1856, 1525, 1488, 1382, 1090 (ClO4 ), 989, 687 cm–1. MS (FAB):
m/z (%) = 2023 (6) [M – 1 – ClO4]+, 1012 (13) [M – 2 ClO4]2+
.
8-H·Rh(TPP)Cl·ClO4: The thread-like salt 7-H·O2CCF3 (44 mg,
0.12 mmol) was added to a CH2Cl2/MeCN (10:1, 50 mL) solution
of the salophen macrocycle with palladium(II)-sodium(I) 1b-
PdII·Na(I) (100 mg, 0.12 mmol) and stirred for 1 h at r.t. Then,
solid Rh(TPP)Cl (90 mg, 0.12 mmol) was added, and the reaction
mixture was stirred for 60 h. The solvent was evaporated under
reduced pressure. The residue was dissolved in CH2Cl2 and chro-
matographed (SiO2; CH2Cl2/MeOH, 98:2) to afford the 8-
H·Rh(TPP)Cl·ClO4 as a violet solid (86 mg, 40%). 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 8.79 (s, 10 H, j, 6), 8.35 (br., 2 H,
H), 8.24 (m, 4 H, 5), 8.04 (m, 2 H, F), 7.83 (d, J = 7 Hz, 4 H, 4),
7.70 (m, 8 H, 1, 3), 7.52 (m, 4 H, 2), 7.33 (m, 2 H, k), 7.11 (br., 2
H, E), 6.85 (m, 2 H, b), 6.70 (d, J = 8 Hz, 2 H, g), 6.65 (m, 2 H,
a), 6.53 (d, J = 8 Hz, 2 H, l), 6.33 (m, 2 H, i), 6.17 (m, 2 H, h),
5.44 (m, 2 H, B), 4.13 (m, 4 H, c), 4.01 (m, 8 H, f, e), 3.95 (m, 4
H, d), 3.84 (m, 2 H, C), 3.75 (br., 2 H, D), 1.05 (d, J = 7 Hz, 2 H,
A), 0.88 (s, 9 H, G) ppm. MS (MALDI-TOF): m/z (%) = 835 (4)
6.85 (m, 8 H, a, b), 6.61 (m, 4 H, h), 4.47 (m, 8 H, f), 3.97–3.82
–
(m, 24 H, c–e) ppm. IR (KBr): ν = 1080 (ClO ) cm–1. MS (FAB):
˜
4
m/z (%) = 1431 (10) [M – Ba – 3ClO4]+. C68H66Ba2Cl4N4O32·3H2O
(1921.80): calcd. C 42.50, H 3.78, N 2.92; found C 42.23, H 3.92,
N 2.69.
4-K and 4-Na: A solution of potassium sulfate (1 g, 5.7 mmol) or
sodium sulfate (0.81 g, 5.7 mmol) in H2O (50 mL) was added to a
solution of 4-Ba (1.06 g, 0.57 mmol) in a solution of MeOH/THF/
MeCN/Me2CO (4:4:1:1, 200 mL), and then the mixture was stirred
at r.t. for 3 h. The reaction mixture was filtered to remove the pre-
cipitated barium sulfate. The solvent was evaporated, and the resi-
due was dried under high vacuum to yield 4-K as an orange solid
(684 mg, 90%) or 4-Na as an orange solid (683 mg, 91%). Selected
[M – 1 – ClO4 – Cl]2+
.
1
data for 4-K: H NMR (400 MHz, [D6]DMSO, 25 °C): δ = 13.59–
X-ray Measurements: X-ray data were obtained with a Bruker
SMART-CCD diffractometer; structural determination and refine-
ment were performed by using SAINT[18] and SHELXTL[19] soft-
ware packages, and the empirical absorption correction was per-
formed by using the SADABS[20] program. All structures were
solved by direct methods and refined by a full-matrix least-squares
method.
13.56 (m, 4 H, OH), 9.11–9.02 (m, 4 H, j, jЈ), 8.55 (s, 2 H, m), 7.99
(m, 2 H, k), 7.67 (m, 2 H, l), 7.29–7.26 (m, 4 H, i), 7.15–7.14 (m,
4 H, g), 6.98–6.91 (m, 8 H, a, b), 6.89–6.86 (m, 4 H, h), 4.17 (m, 8
H, f), 4.11 (m, 8 H, c), 3.86 (m, 8 H, e), 3.83–3.82 (m, 8 H, d) ppm.
13C NMR (100 MHz, [D6]DMSO, 25 °C): δ = 192.3, 192.2, 150.9,
150.8, 150.3, 148.1, 147.7, 147.6, 146.8, 146.3, 146.0, 143.9, 124.2,
121.8, 121.7, 120.8, 120.6, 118.7, 118.6, 118.0, 114.3, 113.7, 98.7,
–
54.3, 52.6, 48.0, 30.0 ppm. IR (KBr): ν = 1100 (ClO ) cm–1. MS
˜
Crystallographic Data
4
(FAB): m/z (%) = 1233 (10) [M – ClO4]+.
3a-H·PF6:
[Ni(C30H32N2O8)C22H32N]2(PF6)2·CH2Cl2·C4H8O2,
4-PdII·Na: Solid palladium(II) acetate (384 mg, 1.71 mmol) was C109H138Cl2F12N6Ni2O18P2, M = 2298.51, monoclinic, space group
added to a CH2Cl2/THF/MeOH (6:2:2, 200 mL) solution of 4-Na C2/c, a = 67.469(4) Å, b = 13.7577(8) Å, c = 24.5387(14) Å, β =
(751 mg, 0.57 mmol), and then the mixture was stirred at r.t. for 96.183(2)°, V = 22645(2) Å3, Z = 8, ρcalcd. = 1.348 gcm–3, µ(Mo-
2 h. The solvent was evaporated under reduced pressure. The resi-
due was dissolved in a small amount of MeCN and purified by
column chromatography (SiO2; CH2Cl2/MeOH, 98:2) to afford 4-
Kα)
=
4.94 cm–1,
T
=
183(2) K, yellow-brown plates,
0.20ϫ0.15ϫ0.10 mm, R1 = 0.0819 [IϾ2σ(I)], wR2 = 0.2822 (all
data), GOF = 0.940.
Eur. J. Inorg. Chem. 2007, 4229–4237
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4235

M. Narita, I. Yoon, M. Aoyagi, M. Goto, T. Shimizu, M. Asakawa
FULL PAPER
ase, J. F. Stoddart, A. J. P. White, D. J. Williams, Chem. Eur. J.
2000, 6, 2274–2287.
3b-H·PF6: [Ni(C34H32N2O8)C22H32N]PF6, C56H64F6N3NiO8P, M
= 1110.78, triclinic, space group P1, a = 11.8973(12) Å, b =
¯
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15.3612(16) Å, c = 15.4538(16) Å, α = 104.457(2)°, β = 97.949(2)°,
γ = 96.015(2)°, V = 2679.8(5) Å3, Z = 2, ρcalcd. = 1.377 gcm–3,
µ(Mo-Kα)
= T = 203(2) K, dark-brown plates,
4.70 cm–1,
0.40ϫ0.30ϫ0.20 mm, R1 = 0.0538 [IϾ2σ(I)], wR2 = 0.1645 (all
data), GOF = 1.055. 4-Ba: [Ba2(C68H66N4O16)(ClO4)(MeOH)3-
(H2O)2](ClO4)3(H2O)3, C71H88Ba2Cl4N4O40, M = 2053.93, triclinic,
¯
space group P1, a = 10.4086(9) Å, b = 18.7294(16) Å, c =
23.9428(20) Å, α = 107.823(2)°, β = 99.645(2)°, γ = 91.602(2)°, V
4365.1(6) Å3, 1.563 gcm–3, µ(Mo-Kα)
Z = 2, ρcalcd. = =
[5]
[6]
=
11.12 cm–1, T = 183 K, orange plates, 0.35ϫ0.20ϫ0.10 mm, R1 =
0.0812 [IϾ2σ(I)], wR2 = 0.2670 (all data), GOF = 1.060.
CCDC-273373 (for 3a-H·PF6), -273372 (for 3b-H·PF6), and
-622229 (for 4-Ba) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Supporting Information (see also the footnote on the first page of
this article): NMR spectroscopic data of 3a/b-H·PF6 and 8-
H·Rh(TPP)ClClO4, additional crystal structures of 3a/b-H·PF6 and
4-Ba, and crystal data for 3a/b-H·PF6 and 4-Ba.
[7]
Acknowledgments
M. N. thanks the New Energy and Industrial Technology Develop-
ment Organization (NEDO), Japan, for sponsoring an Industrial
Technology Research Grant Program. I. Y. thanks the Japan Soci-
ety for the Promotion of Science (JSPS) for a postdoctoral fellow-
ship. We thank Dr. P. T. Glink (http://www.editchem.com) for valu-
able discussions.
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