Organometallic rotaxanes with a triazole group in the axle component and their behavior as ligands of PtII complexes

Article abstract of DOI:10.1002/asia.201100617

Two ferrocenylmethyl ammonium salts were used as axle components of pseudorotaxanes with dibenzo[24]crown-8. The pseudorotaxane with an alkyne terminal group in the axle component underwent a Cu-catalyzed Huisgen coupling reaction (click reaction) with an alkyl azide to afford cationic [2]rotaxanes with a triazole group in the axle molecule. The rotaxane reacted with Ac ₂O to produce neutral rotaxanes with an amide group in the axle component. Both cationic and neutral rotaxanes were treated with K[PtCl ₃(CH₂=CH₂)] to form the Pt^II- containing rotaxanes.

Full text of DOI:10.1002/asia.201100617

DOI: 10.1002/asia.201100617
Organometallic Rotaxanes with a Triazole Group in the Axle Component
and Their Behavior as Ligands of PtII Complexes
Gilbert Yu, Yuji Suzaki, Tomoko Abe, and Kohtaro Osakada*[a]
Abstract: Two ferrocenylmethyl ammo-
nium salts were used as axle compo-
nents of pseudorotaxanes with diben-
zo[24]crown-8. The pseudorotaxane
with an alkyne terminal group in the
axle component underwent a Cu-cata-
lyzed Huisgen coupling reaction (click
reaction) with an alkyl azide to afford
cationic [2]rotaxanes with a triazole
group in the axle molecule. The rotax-
ane reacted with Ac2O to produce neu-
tral rotaxanes with an amide group in
the axle component. Both cationic and
neutral rotaxanes were treated with K-
(CH2=CH2)] to form the PtII-con-
ACHUTNRGEN[NUG PtCl3ACHTUNGTRENNUGN
Keywords: click chemistry · copper ·
ferrocene · platinum · rotaxanes
taining rotaxanes.
Introduction
Rotaxanes are defined as supramolecules composed of inter-
locked macrocyclic and dumbbell-shaped axle molecules.[1–3]
They have unique structures and chemical properties, which
can be potentially applied to molecular machines,[4] molecu-
lar electronic devices,[5] and hydrogels with various func-
tions.[6–9] Most of the rotaxanes reported so far are com-
posed completely of organic molecules. Introduction of par-
tial structures that contain transition metals to the compo-
nents adds a new character to the rotaxanes. Some research
groups have reported the synthesis and properties of rotax-
anes that have transition metals.[10] Ferrocene is known as a
stable, electrochemically active center and can be intro-
duced into many organic molecules. Thus, various research
groups have synthesized rotaxanes, the component molecule
of which is equipped with ferrocenyl groups, and demon-
strated their special properties.[11] Recently, we reported ro-
taxanes and pseudorotaxanes that contain ferrocenyl groups
in the axle or as cyclic components.[12] Their electrochemical
oxidation and reduction can induce the shuttling of the
cyclic component depending on the valence of the Fe
center. Electrochemically induced formation of pseudoro-
taxane was also achieved by using a ferrocene derivative as
the axle component.[12a,b] Further introduction of a function-
al group with coordination ability to the ferrocene-contain-
ing rotaxanes would provide a new supramolecular organo-
metallic ligand as well as a heterobimetallic transition-metal
Scheme 1. Synthesis of the rotaxane ligand and its platinum complex.
complex. We chose the click reaction of an alkyne with an
organic azide because it forms a disubstituted triazole ring
selectively. Scheme 1 summarizes the synthetic route of the
rotaxane ligand that has a triazole group and its platinum
complex in this study. The click reaction provides the tria-
zole that can act as the coordinating site to the transition-
metal complexes in the axle.[11d,13] This type of rotaxane
complex is much less common than rotaxanes that contain a
transition metal at the end of the axle component.[14] In this
study, we report the synthesis of triazole-containing rotax-
anes as well as their properties as ligand of a PtII complex.
Results and Discussion
Scheme 2 summarizes the preparation procedure for the
precursors of the axle component, [1a]PF6 and [1b]PF6, and
its pseudorotaxane formation with dibenzo[24]crown-8
(DB24C8). The condensation reaction of ferrocenecarboxal-
dehyde with para-methoxybenzylamine forms [FcCH=
NCH2C6H4-4-OMe] (Fc=FeACHTNUTRGENNUG(C5H4)CAHTUNGTRNE(NUNG C5H5)). Reduction of
[a] G. Yu, Dr. Y. Suzaki, T. Abe, Prof. K. Osakada
Chemical Resources Laboratory (box R1-3)
Tokyo Institute of Technology
the product with NaBH4 followed by hydrolysis with HCl
and exchange of the counteranion with NH4PF6 yielded
[FcCH2NH2CH2C6H4-4-OMe]PF6 ([1a]PF6). Analogous re-
actions with para-hexynoxybenzylamine yield [1b]PF6,
which has a terminal alkyne group. These compounds were
4259 Nagatsuta, Midori-ku
Yokohama 226-8503 (Japan)
Fax : (+81)45-924-5224
E-mail: kosakada@res.titech.ac.jp
1
characterized by H and 13C{1H} NMR spectroscopy and IR
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201100617.
spectrometry as well as elemental analyses.
Chem. Asian J. 2012, 7, 207 – 213
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
207

FULL PAPERS
Figure 1. ORTEP drawing of [2a]PF6 (50% probability). Some of the hy-
drogen atoms were omitted.
of DB24C8. The distance between the hydrogen and the ar-
omatic plane is 3.15 ꢂ. Another aromatic ring of the cyclic
component also has a short contact with an aromatic hydro-
gen, H18, of the axle component (3.75 ꢂ).
Scheme 3 summarizes the end-capping reaction of pseu-
dorotaxane [2b]PF6 to yield the rotaxane [3]PF6 and its fur-
ther conversion into neutral rotaxane 4. Treatment of
Scheme 2. Synthesis of dialkylammonium salts, [1a]PF6 and [1b]PF6, and
their pseudorotaxanes, [2a]PF6 and [2b]PF6.
Compound [1b]PF6 forms
a
pseudorotaxane with
1
DB24C8 in CDCl3 at 208C. The H NMR spectrum of the
mixture of [1b]PF6 and DB24C8 ([[1b]PF6]0 =9.9 mm,
[DB24C8]0 =11 mm) shows signals assigned to the pseudoro-
taxane. A similar solution in CD3CN contains an equilibrat-
ed mixture of [1b]PF6, DB24C8, and their pseudorotaxane,
[2b]PF6. The ratio between [2b]PF6 and [1b]PF6 was deter-
mined to be 1:1. The association constant between DB24C8
and [1b]PF6 was calculated to be 2.4ꢁ102 mꢀ1 in CD3CN at
208C.[15,16] ESI mass spectrometry of the solution of [1b]PF6
and DB24C8 in CH3CN shows signals that are assigned
clearly to pseudorotaxane [2b]+.
Recrystallization of [1a]PF6 and DB24C8 in a CHCl3/n-
hexanes solution affords pseudorotaxane [2a]PF6 as single
crystals in 59% yield. Figure 1 depicts the molecular struc-
ture of [2a]PF6 obtained by X-ray crystallography. The am-
monium hydrogen atoms, H1 and H2, have short contacts
with oxygen atoms of DB24C8, O1 and O7 (H1···O1
ꢀ
2.372 ꢂ, H2···O7 2.092 ꢂ), through attractive N H···O hy-
drogen bonds. The IR spectroscopy of [2a]PF6 shows peaks
assigned to the stretching vibration of the NH2 group at
3195 and 3065 cmꢀ1. These positions are at lower wavenum-
bers than those of [1a]PF6 (3268 and 3235 cmꢀ1) owing to
the hydrogen bonds between the ammonium and the oxygen
atoms of DB24C8. A hydrogen atom of the cyclopentadien-
Scheme 3. Synthesis of rotaxanes [3]PF6 and 4.
[1b]PF6 with N
(CH2CH2O)2C6H3-3,5-Me2 in the presence of
(MeCN)4]PF6 at room temperature for two
DB24C8 and [CuACHTUNGTRENNUNG
ꢀ
yl ligand, H4, forms an C H···p interaction with a C6H4 ring
days causes Huisgen coupling of the alkynyl group with the
alkyl azide to yield [3]PF6 in an isolated yield of 92%.[17–19]
The ESI mass spectrum shows a peak at m/z 1085.4955 as-
1
signed to the cationic rotaxane [3]+. The H NMR spectrum
Abstract in Japanese:
of [3]PF6 in CD3CN shows a signal at d=7.59 ppm, which is
assigned to the triazole hydrogen, Ha (Figure 2a). The
1H NMR spectroscopic signals of the NCH2 and NH2 hydro-
gen atoms of [3]PF6 were observed at lower magnetic field
positions (d=4.20 (NCH2), 4.36 (NCH2), 7.12 ppm (NH2))
than the corresponding signals of [1b]PF6 (d=4.02 (NCH2),
208
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Chem. Asian J. 2012, 7, 207 – 213

Organometallic Rotaxanes
Figure 3. ORTEP drawing of 5 (50% probability). The hydrogen atoms
were omitted.
at position 3 of the triazole ring (Figure 3). Ethylene and
the triazole ligand occupy trans positions to the square-
planar PtII center.
Addition of K
N
3ACTHUGNTREN(NNUG CH2=CH2)] to a solution of [3]PF6
([[3]PF6], [K[PtCl
N
E
in
CD3CN
Figure 2. 1H NMR spectra of a) [3]PF6; b) 4; c) a mixture of [3]PF6, [PtCl2
A
2A
A
CHTUNGTRENNUNG
1
4.04 (NCH2), 6.75 ppm (NH2)). These H NMR spectroscop-
ic results indicate that intermolecular hydrogen bonds are
present between the ammonium of the axle component and
the oxygen atoms of DB24C8.
Acetylation of the ammonium group of [3]PF6 with Ac2O
in MeCN forms neutral rotaxane 4, which was isolated in
75% yield.[20] The ESI mass spectrum of 4 shows a peak at
m/z 1127.5040 assigned to the protonated rotaxane, [4+H]+.
The presence of the amide group was confirmed by an IR
peak at 1651 cmꢀ1 assigned to the C=O vibration. The
1H NMR spectroscopic signal of the triazole proton of 4,
Ha’, (d=7.83 ppm; Figure 2b) is shifted downfield compared
to that of [3]PF6 (d=7.59 ppm; Figure 2a). This observation
seemed to be supported in the literature: Takata et al. have
reported the acetylation of the rotaxane composed of bis(ar-
ylmethyl)ammonium hexafluorophosphate and DB24C8.[20]
In their work, the macrocyclic component of the synthesized
neutral rotaxane in the solid state includes an aromatic ring
Scheme 4. Synthesis of a) [(3)PtCl
AHCTUNGTREN(GUNN CH2=CH2)].
2CAHTUNGTRNEUN(NG CH2=CH2)]PF6 and b) [(4)PtCl2
1
on the axle component. The H NMR spectroscopic peaks
of the NCH2 groups are also observed at slightly higher
magnetic field positions. Neutral rotaxane 4, formed by ace-
tylation of [3]PF6 in this study, shows one of the NCH2 sig-
nals to be more upfield (d=4.83 ppm) than that of [3]PF6
(d=4.38 and 4.49 ppm).
shows the highest peak at m/z 1379.4377 owing to [(3)PtCl2
AHCTUNGTRENNUNG
(CH2=CH2)]+ (calcd 1379.4274). Distribution of the isotopo-
mer is in agreement with the calculation for the formula of
1
the Pt-containing rotaxane. The H NMR spectroscopic sig-
nals of the hydrogen of the triazole as well as those a to the
Treatment of phenyl benzyl-1,2,3-triazole with K
(CH2=CH2)] was used as a model reaction for the coordina-
tion of the supramolecular ligands to transition metals.
[PtCl3
triazole of [(3)PtCl2ACHTUNGETRNNU(G CH2=CH2)]PF6, Ha’’ and Hb’’, were ob-
E
served at d=7.79 and 2.90 ppm (Figure 2c), respectively.
These signals are further downfield than those of [3]PF6
(d=7.59 (Ha), 2.68 ppm (Hb); Figure 2a).[21] A broadened
1H NMR spectroscopic signal at d=4.73 ppm is assigned to
the hydrogen atoms of the ethylene ligand. The integrated
peak area ratio between the signals of ethylene and triazole
at ꢀ358C is consistent with the formulation in Scheme 4a.
ꢀ
ꢀ
Complex [PtCl2ACHTUNGTRENNUNG(CH2=CH2)(Ph C2HN3 CH2Ph)] (5), was
prepared (see the Experimental Section) and characterized
by 1H NMR spectroscopy and X-ray crystallography. The
crystal
structure
indicates
that
the
dichloro-
ACHTUNGTRENNUNG(ethylene)platinum(II) moiety is coordinated to the nitrogen
Chem. Asian J. 2012, 7, 207 – 213
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
209

K. Osakada et al.
FULL PAPERS
These mass and NMR spectroscopic results indicate 1:1
ꢀ52 kJmolꢀ1, and DS8=ꢀ23 Jmolꢀ1 Kꢀ1 for [(3)PtCl
2ACHTUNGTRENNUNG(CH2=
complexation of [3]PF6 with [PtCl
G
CH2)]PF6, and DG8=ꢀ4.0 kJmolꢀ1, DH8=ꢀ11 kJmolꢀ1,
and DS8=ꢀ7.1 Jmolꢀ1 Kꢀ1 for 5, respectively. These results
indicate that the triazole group of rotaxane [3]+ coordinates
1
CTHUNGTRENNUNG
CH2)]PF6 (d=4.49 (NCH2), 4.35 (NCH2), 2.22 ppm (Me))
and [3]PF6 (d=4.36, 4.20, 2.22 ppm) suggest that the struc-
ture that has the NCH2 group interacts with DB24C8
through multiple hydrogen bonds. Job plots obtained from
to [PtCl
1,2,3-triazole, which forms 5 upon coordination to [PtCl2
(CH2=CH2)].
Neutral rotaxane 4 also reacted with K
2ACHTUNGERTN(NUNG CH2=CH2)] more strongly than phenyl benzyl-
AHCTUNGTRENNUNG
A
3ACHTUNGRTNE(NUNG CH2=CH2)]
1
1
the position of the H NMR spectroscopic signal of Ha and
to produce [(4)PtCl2ACHTUNGTRENNUNG
Ha’’ showed a maximum at a mole fraction of 0.5, which
confirmed formation of the 1:1 complex [(3)PtCl2ACTHNUTRGENUN(G CH2=
CH2)]PF6 (Figure 4).
the mixture (Figure 2d) shows peaks due to triazole hydro-
gen (d=8.61 ppm) and a-hydrogen (d=2.86 ppm) atoms
with significant broadening. They can be assigned to the sig-
nals of [(4)PtCl2ACHTUNGTRNEGN(U CH2=CH2)], Ha’’ and Hb’’, respectively. The
corresponding signals of 4 (d=7.83, 2.51 ppm) were not ob-
served possibly owing to severe broadening. The ESI mass
spectrum of the mixture exhibits the highest peak at m/z
1459.3908 (calcd as [(4)PtCl2ACHTUNTRGNEUNG(CH2=CH2)]+K: 1459.3938).
Keeping the solution for two weeks caused a decrease in
broadening of the signals originally at d=8.61 ppm to d=
7.83/7.84 ppm (free) and d=8.45/8.50 ppm (complexed).
Comparison of the peak intensity showed a relative ratio of
4 to [(4)PtCl2ACHTNUGTRNEG(UN CH2=CH2)] to be 0.69:0.31 at 278C in
CD3CN. This corresponds to a formation constant of ap-
proximately 9.0ꢁ102 mꢀ1.
Figure 4. Job plots for treatment of [3]PF6 with K
afford [(3)PtCl2A
(CH2=CH2)]PF6 obtained from 1H NMR spectroscopic
peak position of Ha’’, d(Ha’’), ([[3]PF6]0+[K[PtCl3A(CH2=CH2)]]0 =10 mm,
[PtCl
E
Conclusion
CHTUNGTRENNUNG
G
N
CHTUNGTRENNUNG
In summary, we succeeded in the syntheses of rotaxanes
with a 1,4-disubstituted 1,2,3-triazole unit and their platinu-
m(II) complexes. Copper-catalyzed Huisgen coupling intro-
duced not only the bulky end group but also the triazole
group to the axle component of the rotaxane. The rotaxane
ligands in this study are revealed to coordinate more strong-
ly to platinum(II) than the organic triazole. The formation
constants of the platinum complexes of the triazole com-
in CD3CN, 208C). (X1 =molar fraction of [3]PF6; Dd [ppm]= j
d(Ha)ꢀd(Ha’’, observed in the mixture of [3]PF6 and
CH2)])j.
KACHTUNGTERNNU[G PtCl3ACHTUNGRTEN(NUNG CH2=
The formation constant of the Pt-containing rotaxane was
estimated to be Ka =1.0ꢁ102 mꢀ1 in CD3CN at ꢀ208C by
Scatchard analysis of the mixture of [3]PF6 and KACHTGNUTRENNUNG
A
U
pounds at 278C decrease in the order: [(4)PtCl
2ACHTUNGRTNE(NUNG CH2=CH2)]
A
(ca. 9ꢁ102 mꢀ1)>[(3)PtCl (CH2=CH2)]PF6 (19mꢀ1)>[PtCl2
2A
determined to be 8.6mꢀ1 (CD3CN, ꢀ208C).[23] Temperature
dependence of the association constants (Figure 5) gave
thermodynamic parameters for formation of the platinu-
m(II) complexes to be DG8=ꢀ7.4 kJmolꢀ1, DH8=
AHCTUNGTRENNUNG
(CH2=CH2)(Ph C2HN3 CH2Ph)]PF6 (4.9mꢀ1), with the
latter two obtained by interpolation of the van’t Hoff plots.
ꢀ
ꢀ
Thus, the neutral and cationic rotaxanes with a triazole
group bind to the PtII center more strongly than the Ph
ꢀ
ꢀ
C2HN3 CH2Ph in spite of severe steric hindrance of the
ꢀ
cyclic component in the rotaxane ligand. The triazole plati-
num bond of the rotaxanes may prevent shuttling of the
cyclic component, but its dissociation might enable the
motion across the entire molecule. Leigh et al. have report-
ed that bulky trialkylsilyl groups of the axle component
work as a ratchet to block molecular shuttling.[24] Further
studies on controlling the dissociation of the rotaxane ligand
from PtII or other transition-metal centers are now in prog-
ress.
Figure 5. Van’t Hoff plots of the reactions for a) formation of [(3)PtCl2
ACHTUNGTRENNUNG(CH2=CH2)]PF6 and for b) formation of 5 in CD3CN.
210
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Chem. Asian J. 2012, 7, 207 – 213

Organometallic Rotaxanes
Complex [2a]PF6
Experimental Section
A crystal of [2a]PF6 was obtained by recrystallization from a solution of
[1a]PF6 (48 mg, 0.10 mmol) and DB24C8 (45 mg, 0.10 mmol) in CHCl3
(3.0 mL) by diffusion of the vapor of n-hexane at room temperature
General
Dried solvents were purchased from Kanto Chemical Co., Inc. KACTHNUTRGNEUNG[PtCl3
ACHTUNGTRENNUNG
(CH2=CH2)] was prepared according to the literature.[25] Other chemicals
(55 mg, 5.9ꢁ10ꢀ2 mmol, 59%). IR (KBr disk, RT): n˜ =3195 (N H), 3065
ꢀ
were commercially available. NMR spectra (1H, 13C{1H},
H H COSY,
1
1
ꢀ1
ꢀ
ꢀ
ꢀ
ꢀ
(N H), 843 (P F), 558 cm (P F); elemental analysis calcd (%) for
C43H54F6FeNO9P: C 55.55, H 5.85, N 1.51; found: C 55.33, H 5.90, N 1.40.
13C{1H}-1H COSY) were recorded with Varian MERCURY300 and
Bruker Biospin Avance instruments. The chemical shifts were referenced
with respect to CHCl3 (d=7.26 ppm) and CD2HCN (d=1.93 ppm) for
1H, and CDCl3 (d=77.0 ppm) and CD3CN (d=1.30 ppm) for 13C as inter-
nal standards. IR absorption spectra were recorded with Shimadzu FTIR-
8100 spectrometers. Fast-atom bombardment mass spectra (FAB-MS)
were obtained with a JEOL JMS-700 (matrix, m-nitrobenzylalcohol).
Electrospray ionization mass spectrometry (ESI-MS) was recorded with a
Complex [2b]PF6
The
pseudorotaxane
[2b]PF6
was
formed
by
mixing
[FcCH2NH2CH2C6H4-4-OCH2CH2CH2CH2CꢁCH]PF6 (2.7 mg, 4.9ꢁ
10ꢀ3 mmol) and DB24C8 (2.5 mg, 5.6ꢁ10ꢀ3 mmol) in CD3CN (0.50 mL)
1
at 208C. H NMR (400 MHz, CD3CN, 208C): d=1.61 (m, 2H; CH2-axle),
1.65 (m, 2H; CH2-axle), 2.17 (m, 2H), 2.23 (t, 4J
ACHTUNGTRENNUNG
Bruker micrOTOF II. Elemental analyses were carried out with
Yanaco MT-5 CHN autorecorder.
a
3
AHCTUNGTRENNUNG
C6H4-axle), 6.95–6.89 (10H), 7.16 ppm (d, 3J
ACHTNUTRGNEG(UN H,H)=8 Hz, 2H; C6H4-
axle); MS (ESI): m/z calcd for C48H60FeNO9: 850.3613 [2b]+; found:
[FcCH=NCH2C6H4-4-OCH2CH2CH2CH2CꢁCH]
850.3635.
A
solution of ferrocenecarboxaldehyde (2.14 g, 10.0 mmol) and
H2NCH2C6H4-4-OCH2CH2CH2CHCCH (2.54 g, 12.5 mmol) in nBuOH/
EtOH (40 mL:10 mL) was heated to reflux for 1 day. The reaction mix-
ture was then evaporated to yield the crude product, which was purified
by recrystallization from Et2O/n-hexane to yield [FcCH=NCH2C6H4-4-
OCH2CH2CH2CHCCH] as a reddish-brown solid (3.99 g, 10 mmol, quan-
titative). 1H NMR (400 MHz, [D6]DMSO, RT): d=1.57 (m, 2H; CH2),
Complex [3]PF6
A
solution of [1b]PF6 (200 mg, 0.37 mmol), DB24C8 (194 mg,
0.43 mmol), N3CH2CH2OCH2CH2OC6H3-3,5-Me2 (142 mg, 0.60 mmol),
and [Cu(MeCN)4]PF6 (274 mg, 0.74 mmol) in CH2Cl2 (8.0 mL) was
AHCTUNGTRENNUNG
stirred for 2 days at room temperature. The resulting solution was evapo-
rated to give the crude product, which was purified by silica-gel column
chromatography (n-hexane/Et2O/acetone 10:0:0, 7:3:0, then 0:6:4) and
re-precipitated from Et2O/n-hexane to yield [3]PF6 as a yellow solid
(420 mg, 0.34 mmol, 92%). H NMR (400 MHz, CD3CN, 208C): d=1.71–
1.74 (4H; CH2-axle), 2.22 (s, 6H; Me), 2.68 (t, J
1.77 (m, 2H; CH2), 2.21 (td, 3J
CH2CCH), 2.76 (m, 1H; CCH), 3.94 (t, J
(s, 5H; C5H5), 4.38 (m, 2H; C5H4), 4.49 (s, 2H; NCH2), 4.63 (m, 2H;
C5H4), 6.88 (d, 3J 3(H,H)=8 Hz, 2H;
(H,H)=8 Hz, 2H; C6H4), 7.19 (d,
(H,H)=7 Hz, 4J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
3
AHCTUNGTRENNUNG
1
A
ACHTUNGTRENNUNG
C6H4), 8.24 ppm (s, 1H; NCH); 13C{1H} NMR (100 MHz, [D6]DMSO,
RT): d=17.4 (CH2), 24.6 (CH2), 27.8 (CH2), 63.6, 66.8, 68.2, 68.8 (C5H5),
70.0, 71.4, 80.8, 84.3, 114.3 (C6H4), 129.0 (C6H4), 131.8 (C6H4), 157.4
(C6H4), 160.8 ppm (N=C); elemental analysis calcd (%) for C24H25FeNO:
C 72.19, H 6.31, N 3.51; found: C 72.52, H 6.27, N 3.51.
3
G
3.56–3.66 (m, 8H; CH2-DB24C8), 3.70–3.88 (16H), 3.93 (s, 5H; C5H5),
3.98 (m, 2H; CH2-axle), 4.02–4.07 (4H), 4.06 (m, 2H), 4.10–4.17 (4H),
4.20 (m, 2H; CH2), 4.36 (m, 2H; NCH2), 4.46 (t, 3J
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Complex [1b]PF6
2H; NH2), 7.16 (d, 3J
ACHTUNTRGENUNG(H,H)=9 Hz, 2H; C6H4), 7.59 ppm (s, 1H;
CtriazoleH); 13C{1H} NMR (100 MHz, CD3CN, 208C): d=21.5 (Me), 26.0
(CH2), 26.8 (CH2), 29.4 (CH2), 49.4 (NCH2), 50.8 (NCH2), 52.7, 68.1,
68.4, 69.1, 69.8, 70.0, 70.2, 70.3, 71.3, 71.7 (C5H4), 77.9 (C5H4), 113.3,
[FcCH=NCH2C6H4-4-OCH2CH2CH2CH2CꢁCH] (500 mg, 1.25 mmol)
was dissolved in MeOH (5.0 mL) at 08C. NaBH4 (350 mg, 9.25 mmol)
was added to the solution and stirred for 1 day in an ice bath, which was
allowed to rise to room temperature. The resulting solution was diluted
with Et2O and mixed with HCl (6m). The resulting solution was fractio-
nated by the addition of n-hexane/EtOAc and water. The separated or-
ganic phase was evaporated to give the crude product, which was dis-
solved in CH2Cl2. The solution was washed with water, dried over
MgSO4, and evaporated to yield [1b]Cl (220 mg, 5.03 mmol, 40%).
1H NMR of [1a]Cl (400 MHz, CDCl3, RT): d=1.71 (m, 2H; CH2), 1.83
ꢀ
113.7, 115.2 (C6H4), 122.4, 123.1 (Ctriazole H), 123.5, 125.1, 131.9 (C6H4),
140.3 (C6H3), 148.3 (CtriazoleCH2), 148.8 (C6H4-DB24C8), 159.9 (C6H3),
160.4 ppm (C6H4); IR (KBr disk, RT): n˜ =3156 (NH2), 3069 (NH2), 841
(PF6), 558 cmꢀ1 (PF6); MS (ESI): m/z calcd for C60H77FeN4O11: 1085.4983
[3]+; found: 1085.4955; elemental analysis calcd (%) for
C60H77FeN4O11PF
N 4.38.
6ACHTUNGTRENUN(NG H2O): C 57.69, H 6.37, N 4.49; found: C 57.63, H 6.42,
(m, 2H; CH2), 1.97 (t, 4J
A
G
4
8 Hz, J
N
Complex 4
3.87 (t, 3J
C5H4), 4.42 (s, 2H; C5H4), 6.85 (d, J
(H,H)=8 Hz, 2H; C6H4), 9.78 ppm (s, 2H; NH2). Compound [1b]Cl was
used without further purification. suspension of [1b]Cl (312 mg,
ACHTUNGTRENNUNG
Et3N (57 mL, 0.41 mmol) and acetic anhydride (39 mL, 0.41 mmol) were
added to a solution of [3]PF6 (101 mg, 0.082 mmol) in MeCN (3.0 mL),
and the reaction mixture was stirred overnight at room temperature.
After the removal of the solvent by evaporation, the product was purified
by silica-gel column chromatography (EtOAc/n-hexane 2:1) to yield 4 as
yellow solid (82 mg, 0.073 mmol, 89%). 1H NMR (400 MHz, CD3CN,
208C): d=1.63–1.71 (4H; CH2), 1.97 (s, 3H; C(=O)Me), 2.15 (s, 6H;
3
ACHTUNGTRENNUNG
A
0.713 mmol) in CH2Cl2 (5 mL) was stirred with saturated NH4PF6 (aq
10 mL) for 0.5 h at room temperature. The resulting mixture was diluted
with CH2Cl2 and the organic layer was separated. Addition of CHCl3 to
the solution resulted in separation of [1b]PF6 as a yellow solid, which
was collected by filtration (130 mg, 0.238 mmol, 33%). 1H NMR
(400 MHz, CD3CN, RT): d=1.66 (m, 2H; CH2), 1.85 (m, 2H; CH2), 2.17
C6H3-3,5-(CH3)2), 2.51 (t, 3J
4.37 (m, 2H; NCH2), 4.83 (m, 2H; NCH2), 6.41 (s, 2H; C6H3), 6.51 (s,
2H; C6H3), 6.81–6.81 (10H), 7.02 and 7.08 (d, 3J
(H,H)=8 Hz, 2H;
ACHTUNGTERN(NUNG H,H)=4 Hz, 2H; CH2), 3.67–4.20 (43H),
AHCTUNGTRENNUNG
(t, 4J
2H; CH2), 4.01 (t, 3J
(s, 2H; NCH2), 4.20 (s, 5H; C5H5), 4.27 (m, 2H; C5H4), 4.37 (m, 2H;
C5H4), 6.75 (br, 2H; NH2), 6.69 (d, 3J
(H,H)=9 Hz, 2H; C6H4), 7.33 ppm
(d, 3J(H,H)=9 Hz, 2H, C6H4); 13C{1H} NMR (100 MHz, CD3CN, RT):
A
(H,H)=7 Hz, 4J
ACHUTGTNRENNUG ACHUTGNTREN(NUNG H,H)=3 Hz,
C6H4O), 7.83 ppm (s, 1H; CtriazoleH); 13C{1H} NMR (100 MHz, CD3CN,
208C): d=21.4, 22.1, 22.2, 26.0, 26.6, 29.4, 44.7, 47.4, 47.7, 49.5, 51.5, 67.6,
68.6, 68.6, 68.8, 68.9, 69.1, 69.2, 69.4, 69.6, 69.6, 70.0, 70.6, 71.4, 84.7, 84.9,
113.2, 115.4, 115.7, 121.6, 122.9, 123.7, 128.9, 130.0, 130.1, 130.8, 139.3,
147.3 (C6H4-DB24C8), 159.3, 139.5, 160.0, 170.8, 170.9 ppm (the
13C{1H} NMR spectrum shows splitting signals probably, due to the s-cis
and s-trans conformational structures of the amide group); IR (KBr disk,
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
d=18.6 (CH2), 25.9 (CH2), 29.1 (CH2), 48.6 (NCH2), 51.5 (NCH2), 68.6,
70.1 (C5H5), 70.6, 71.6, 76.6 (C5H4), 85.2 (CꢁC), 115.9 (C6H4), 123.4
(C6H4), 132.8 (C6H4), 161.1 ppm (C6H4); elemental analysis calcd (%) for
C24H28F6FeNOP: C 52.67, H 5.16, N 2.56; found: C 52.73, H 5.42, N 2.61.
RT): n˜ =1651 cmꢀ1 (C=O); MS (ESI): m/z calcd for C62H79FeN4O12
:
1127.5044 [2+H]+; found: 1127.5040; elemental analysis calcd (%) for
C62H78FeN4O12: C 66.07, H 6.97, N 4.97; found: C 65.82, H 6.98, N 4.81.
Chem. Asian J. 2012, 7, 207 – 213
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
211

K. Osakada et al.
FULL PAPERS
Complex [(3)PtCl
G
Crystal Structure Determination
An NMR spectroscopy tube was charged with [3]PF6 (14.8 mg, 1.2ꢁ
Crystals of [2a]PF6 and 5 suitable for X-ray diffraction studies were ob-
tained by recrystallization from CHCl3/n-hexane and acetone/acetonitrile,
respectively. CCDC 818203 ([2a]PF6) and 818204 (5) contain the supple-
mentary 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.
10ꢀ2 mmol) and (CH2=CH2)] (4.4 mg, 1.2ꢁ10ꢀ2 mmol), which
[PtCl3A
were then dissolved in CD3CN (0.50 mL). 1H and 13C{1H} NMR spectra
showed formation of [(3)PtCl2A
(CH2=CH2)]PF6. 1H NMR (400 MHz,
CD3CN, 208C): d=1.71 (m, 2H), 1.93 (m, 2H), 2.22 (s, 6H; C6H3-3,5-
(CH3)2), 3.01 (t, 3J
(H,H)=4 Hz, 2H; CH2), 3.57–4.20 (45H), 4.35 (m,
K
N
CHTUNGTRENNUNG
CTHUNGTRENNUNG
ACHTUNGTRENNUNG
2H; NCH2), 4.49 (m, 2H; NCH2), 4.57 (m, 2H), 4.73 (br, 4H; CH2=CH2)
6.51–6.58 (5H; C6H4, C6H3), 6.89 (s, 8H; CH2-DB24C8), 7.16 (d, 3J-
ACHTUNGTRENNUNG
(H,H)=8 Hz, 2H; C6H4), 7.91 ppm (s, 1H; CtriazoleH); 13C{1H} NMR
(100 MHz, CD3CN, 208C): d=21.5, 25.8, 26.2, 29.2, 49.4, 52.5, 52.6, 68.0,
68.2, 69.1, 69.3, 69.4, 69.5, 69.6, 69.7 (C5H5), 70.0 (C5H4), 70.3 (C5H4), 71.2
(CH2-DB24C8), 77.8, 113.7, 115.1, 122.3, 123.5, 125.1, 126, 131.8, 140.3,
148.7 (C6H4-DB24C8), 149.0, 149.5, 159.8, 160.3 ppm; MS (ESI): m/z
Acknowledgements
We thank our colleagues in the Center for Advanced Materials Analysis,
Technical Department, Tokyo Institute of Technology for elemental anal-
ysis and for FAB-MS measurement. This work was supported by a
Grant-in-Aid for Scientific Research for Young Scientists from the Minis-
try of Education, Culture, Sports, Science and Technology, Japan
(19750044) and by the Global COE program “Education and Research
Center for Emergence of New Molecular Chemistry”.
calcd for C62H81Cl2FeN4O11Pt: 1379.4274 [(1)PtCl2ACHTNUTRGNEUNG
(CH2=CH2)]+; found:
1379.4377.
Complex [(4)PtCl
2ACHTUNGTRENNUNG(CH2=CH2)]
An NMR spectroscopy tube was charged with
2
(13.6 mg, 1.2ꢁ
10ꢀ2 mmol) and
(CH2=CH2)] (4.4 mg, 1.2ꢁ10ꢀ2 mmol), which
KACHTUNGTRENNUNG[PtCl3ACHTUNGTRENNUNG
were then dissolved in CD3CN (0.50 mL). 1H and 13C{1H} NMR spectra
1
showed formation of [(4)PtCl
N
[1] a) Catenanes, Rotaxanes, and Knots, Vol. 22 (Ed.: G. Schill), Aca-
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208C): d=1.75–1.81 (CH2), 1.97 (s, 3H; COCH3), 2.15 (s, 6H; C6H3-3,5-
(CH3)2), 2.74 (s, 2H), 3.40–4.24 (47H), 4.38 (m, 2H; NCH2), 5.25 (m,
2H; NCH2), 6.36 (s, 2H; C6H3), 6.53 (s, 1H; C6H3), 6.80–6.89 (10H), 7.04
and 7.10 (d, 3J
ACHTUNGTRENNUNG(H,H)=8 Hz, 2H; C6H4), 8.61 ppm (s, 1H; CtriazoleH); se-
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25.8, 25.9, 29.0, 44.7, 47.4, 47.7, 51.0, 51.1, 67.5, 67.8, 68.2, 69.1, 69.2, 69.6,
69.8, 67.0, 70.7, 71.7, 113.0, 113.1, 115.4, 115.7, 121.7, 123.1, 128.2, 128.9,
130.0, 140.0 149.0, 159.8, 170.8 ppm (the 13C{1H} NMR spectrum shows
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structures of the amide group); MS (ESI): m/z calcd for
C64H82Cl2FeN4O12PtNa and C64H82Cl2FeN4O12PtK: 1443.4200 [(4)PtCl2
ACHTUNGTRENNUNG 2ACHTUNGTRENNUGN
(CH2=CH2)+Na]+ and 1459.3938 [(4)PtCl (CH2=CH2)+K]+; found:
1443.4152 and 1459.3908.
Complex 5
Crystals of 5 suitable for X-ray diffraction studies were obtained as fol-
ꢀ
ꢀ
lows. The mixing of Ph C2HN3 CH2Ph (30 mg, 0.13 mmol) with K
ACHTUNGTRENNUNG(CH2=CH2)] (70 mg, 0.19 mmol) in a solution of acetone/acetonitrile
ACHTUNGERTN[NUNG PtCl3
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´
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Estimation of the Association Constants for Platinum Complexes [3]PF6
and 5
Several NMR spectroscopic samples that contained [3]PF6 at a fixed con-
centration (25 mm) and KACHTUNGRTENNUG[PtCl3ACHTUNGTRENN(UGN CH2=CH2)] at various concentrations in
CD3CN were prepared. 1H NMR spectra of the samples were measured
at several fixed temperatures. Chemical shifts of the triazole hydrogen
atoms (dH) were obtained at each temperature. The concentrations, [K-
ACHTUNGTRENNUNG[PtCl3ACHTUNGTRENNUNG(CH2=CH2)]]=17–30 mm, were found to be optimal for the follow-
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are determined by calculation on the basis of the following equation
[Eq. (1)] (Scatchard equation[22]):
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ACHTUNGTERN(NUNG Ha’’) is the chemical shift of triazole
A
CHTUNGTRENNUNG
A
CHTUNGTRENNUNG
212
www.chemasianj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2012, 7, 207 – 213

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Received: July 13, 2011
Published online: October 27, 2011
Chem. Asian J. 2012, 7, 207 – 213
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