Amine-assisted C-Cl bond activation of aryl chlorides by a (phebox)Rh-chloro complex

Article abstract of DOI:10.1021/om8002174

Oxidative addition of chlorobenzene and p-chlorotoluene by (Phebox)RhCl₂(H₂O) (1) in the presence of diisopropylamine was examined and was shown to produce the corresponding aryl complexes (Phebox)RhCl(Ar)(H₂O) in high yields via C-Cl bond cleavage. Reaction of 1 with chloropyridine in the presence of diisopropylamine provided a pyridinium rhodate complex.

Full text of DOI:10.1021/om8002174

3312
Organometallics 2008, 27, 3312–3315
Amine-Assisted C-Cl Bond Activation of Aryl Chlorides by a
(Phebox)Rh-Chloro Complex
Jun-ichi Ito, Takeshi Miyakawa, and Hisao Nishiyama*
Department of Applied Chemistry, Graduate School of Engineering, Nagoya UniVersity, Chikusa, Nagoya
464-8603, Japan
ReceiVed March 7, 2008
of NH(iPr)2 and successive C-C bond formation between
Summary: OxidatiVe addition of chlorobenzene and p-chloro-
toluene by (Phebox)RhCl2(H2O) (1) in the presence of diiso-
propylamine was examined and was shown to produce the
corresponding aryl complexes (Phebox)RhCl(Ar)(H2O) in high
yields Via C-Cl bond cleaVage. Reaction of 1 with chloropy-
ridine in the presence of diisopropylamine proVided a pyri-
dinium rhodate complex.
CH2Cl2 and NH(iPr)2 to provide a azarhodacyclopentene
complex (eq 1).11,12 In this reaction, the presence of the amine
seems to be responsible for activation of an inactive Rh(III)
complex to a (Phebox)Rh(I) species. We therefore envisioned
that such a (Phebox)Rh(I) species may show a potential for
C-Cl bond activation of aryl halides as well as CH2Cl2. Here
we report a significant effect of amines to the reaction of 1 with
aryl chlorides to provide aryl-Rh complexes.
Introduction
Oxidative addition of aryl halides to low-valent transition
metal complexes is a common process to generate aryl
complexes having a metal-carbon bond. Such a process is one
of the most important steps in transition metal catalyzed
reactions such as the Heck reaction and cross-coupling reaction.1,2
Utilization of an aryl chloride, which has the higher dissociation
energy of a C-Cl bond compared with that of C-Br or C-I,
has also been achieved in Pd-catalyzed arylation reactions.3 In
comparison with the oxidative addition of an aryl halide to group
10 metals, examples for group 9 metal complexes such as Rh(I)
and Ir(I) are still rare.4–9 Recent studies of the oxidative addition
of Ar-Cl to Rh and Ir have been limited to RhCl3(py)3,5
(PCy3)2Rh(H)(Cl)2,6 [(diiminate)Rh(cod)],7 [(PPh3)3RhF],8 and
(PNP)MX2.9
Results and Discussion
Thermolysis of 1 in a neat solution of chlorobenzene with
an excess amount of NH(iPr)2 at 80 °C for 1 h resulted in the
clean formation of a phenyl complex, (Phebox)Rh(Ph)Cl(H2O)
(2) (eq 2). Complex 2 was isolated in 90% yield after
purification by column chromatography on silica gel. Similarly,
reaction of 1 with p-chlorotoluene provided the p-tolyl complex
(Phebox)Rh(p-CH3C6H4)Cl(H2O) (3) in 80% yield.
In this context, we have reported that (Phebox)Rh(Cl)2(H2O)
[1; Phebox ) bis(oxazolinyl)phenyl]10 exhibits high reactivity
toward double C-Cl bond activation of CH2Cl2 in the presence
* To whom correspondence should be addressed. E-mail: hnishi@
apchem.nagoya-u.ac.jp.
(1) Examples of reviews: (a) Suzuki, A. Chem. Commun. 2005, 4759.
(b) Hassan, J.; Se´vignon, M.; Gozzi, C.; Schulz, E.; Lemaire, M. Chem.
ReV. 2002, 102, 1359. (c) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37,
2046.
(2) (a) Ishiyama, T.; Hartwig, J. J. Am. Chem. Soc. 2000, 122, 12043.
(b) Bedford, R. B.; Limmert, M. E. J. Org. Chem. 2003, 68, 8669. (c) Lewis,
J. C.; Wiedemann, S. H.; Bergman, R. G.; Ellman, J. A. Org. Lett. 2004,
6, 35. (d) Ueura, K.; Satoh, T.; Miura, M. Org. Lett. 2005, 7, 2229.
(3) (a) Grushin, V. V.; Alper, H. Chem. ReV. 1994, 94, 1047. (b) Littke,
A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176. (c) Bedford, R. B.;
Cazin, C. S.J.; Holder, D. Coord. Chem. ReV. 2004, 248, 2283.
(4) (a) Semmelhack, M. F.; Ryono, L. Tetrahedron Lett. 1973, 2967.
(b) Mori, K.; Mizoroki, T.; Ozaki, A. Bull. Chem. Soc. Jpn. 1976, 49, 758.
(c) Mureinik, R. J.; Weitzberg, M.; Blum, J. Inorg. Chem. 1979, 18, 915.
(5) Love, C. J.; McQuillin, F. J. J. Chem. Soc., Perkin Trans. 1 1973,
2509.
Complexes 2 and 3 were characterized on the basis of 1H and
13C NMR and IR spectra. In the 13C NMR spectra of 2 and 3, the
signals of the ipso-phenyl carbons were observed at δ 140.3 (JRhC
) 35.4 Hz) and 134.5 (JRhC ) 35.3 Hz), respectively. The
molecular structure of 3 was confirmed by X-ray diffraction, which
revealed the pseudo-octahedral geometry on the Rh atom (Figure
1). The tolyl ligand was coordinated to the Rh at the perpendicular
position to the Phebox plane. The Rh-Ctolyl bond length of 2.028(5)
Å was comparable to that of the related Phebox acetate complex
(6) Grushin, V. V.; Alper, H. Organometallics 1991, 10, 1620.
(7) Willems, S. T. H.; Budzelaar, P. H. M.; Moonen, N. N. P.; de Gelder,
R.; Smits, J. M. M.; Gal, A. W. Chem.-Eur. J. 2002, 8, 1310.
(8) (a) Grushin, V. V.; Marshall, W. J. J. Am. Chem. Soc. 2004, 126,
3068. (b) Macgregor, S. A.; Christopher Roe, D.; Marshall, W. J.; Bloch,
K. M.; Bakhmutov, V. I.; Grushin, V. V. J. Am. Chem. Soc. 2005, 127,
15304.
(9) (a) Fan, L.; Parkin, S.; Ozerov, O. V. J. Am. Chem. Soc. 2005, 127,
16772. (b) Gatard, S.; C¸ elenligil-C¸ etin, R.; Guo, C.; Foxman, B. M.; Ozerov,
O. V. J. Am. Chem. Soc. 2006, 128, 2808. (c) Gatard, S.; Guo, C.; Foxman,
B. M.; Ozerov, O. V. Organometallics 2007, 26, 6066.
(11) Ito, J.; Miyakawa, T.; Nishiyama, H. Organometallics 2006, 25,
5216.
(10) Nishiyama, H. Chem. Soc. ReV. 2007, 36, 1133.
10.1021/om8002174 CCC: $40.75
2008 American Chemical Society
Publication on Web 06/07/2008

Notes
Organometallics, Vol. 27, No. 13, 2008 3313
to generate (Phebox)Rh(I).18 Although we could not detect those
intermediates, Ozerov and co-workers recently reported dehy-
drochlorination of (PNP)Rh(Cl)(H) with a base to provide the
(PNP)Rh(I) complex.9c
In contrast to NH(iPr)2, NEt3 is not a suitable reagent for
C-Cl bond activation. Addition of NEt3 instead of NH(iPr)2 to
a chlorobenzene solution of 1 at 80 °C for 1 h led to a decrease
in the yield of 2 (35%).
It is interesting to note that an acetate analogue,
(Phebox)Rh(OAc)2(H2O), did not undergo C-Cl bond activation
but did undergo C-H bond activation to produce the corre-
sponding chlorophenyl complex (Phebox)Rh(OAc)(C6H4Cl).13
Our results indicate that selectivity between C-Cl and C-H
bonds of chloroarene can be controlled by the choice of ligand
on the Rh center and a proper base.
Figure 1. ORTEP diagram of 3 at the 50% probability level.
Selected bond lengths (Å): Rh1-C1 1.909(4), Rh1-C21 2.028(5),
Rh1-N1 2.078(4), Rh1-N2 2.067(4), Rh1-Cl1 2.5144(14),
Rh1-O3 2.292(3).
(Phebox)Rh(Ph)(OAc) (2.005(2) Å).13 The Rh-Cl bond length of
2.5144(14) was significantly longer than those of (Phebox)-
RhCl2(H2O) (Rh-Cl ) 2.325(3), 2.331(3) Å)14 due to a trans
influence of the tolyl group.
Complex 1 also reacts with chloropyridine in the presence
of NH(iPr)2 in toluene at 70 °C to provide the rhodium complex
5 in 94% yield (eq 4). The 1H NMR spectrum of 5 showed the
low-field signal of the N-H proton at δ 15.8 (1H), which
disappeared on treatment with D2O. The IR spectrum of 5 also
exhibited the νNH band at 3447 cm-1. In the 13C NMR spectrum,
two low-field singals were observed at δ 184.3 (JRhC ) 38.3
Hz) and 185.5 (JRhC ) 25.7 Hz). In comparison with the Rh-C
coupling constants of 2 and 3, the signal at δ 184.3 is assigned
to the pyridium carbon and the signal at δ 185.5 is assigned to
the phenyl carbon in the Phebox ligand.
As we reported earlier, the Rh(III) dichloro complex
(Phebox)Rh(Cl)2(H2O) did not react with chlorobenzene even
at 120 °C for 40 h.13 Therefore, the presence of NH(iPr)2 is
essential to the C-Cl bond activation. In general, an electron-
rich Rh(I) complex is active to the oxidative addition of a C-Cl
bond.7 In the case of a Rh(III) complex, it is known that
reductive elimination provides an active Rh(I) intermediate.9a,15
To gain insight into the C-Cl bond activation by 1 with the
amine, we checked the crude products on the reaction of 1 with
1
chlorobenzene by H NMR spectroscopy. Although other Rh
complexes besides 2 were not detected, the formation of
N(dCMe2)(iPr) (4) as well as 2 was observed with the 2:4 ratio
of 1:1.1 (eq 3).16 The formation of 4 is formally derived from
dehydrogenation of NH(iPr)2, involving deprotonation of the
N-H bond and successive ꢀ-elimination.17 Such a dehydroge-
nation of an amine might afford a hydride intermediate,
(Phebox)Rh(Cl)(H), that finally undergoes dehydrochlorination
(12) Examples of C-Cl bond activation of CH2Cl2 by Rh complexes: (a)
Werner, H.; Hofmann, L.; FeserR.; Paul, W. J. Organomet. Chem. 1985,
281, 317. (b) Fennis, P. J.; Budzelaar, P. H. M.; Frijns, J. H. G.; Orpen,
A. G. J. Organomet. Chem. 1990, 393, 287. (c) Burns, E. G.; Chu, S. S. C.;
Meester, P.; Lattman, M. Organometallics 1986, 5, 2383. (d) Nishiyama,
H.; Horihata, M.; Hirai, T.; Wakamatsu, S.; Itoh, K. Organometallics 1991,
10, 2706. (e) de Pater, B, C.; Zijp, E. J.; Fruhauf, H.; Ernsting, J. M.;
Elsevier, C. J.; Vrieze, K.; Budzelaar, P. H. M.; Gal, A. W. Organometallics
2004, 23, 269. (f) Haarman, H. F.; Ernsting, J. M.; Kranenburg, M.;
Kooijman, H.; Veldman, N.; Spek, A. L.; van Leeuwen, P. W. N. M.; Vrieze,
K. Organometallics 1997, 16, 887. (g) Ball, G. E.; Cullen, W. R.; Fryzuk,
M. D.; James, B. R.; Rettig, S. J. Organometallics 1991, 10, 3767. (h) Chan,
K. T. K.; Spencer, L. P.; Masuda, J. D.; McCahill, J. S. J.; Wei, P.; Stephan,
D. W. Organometallics 2004, 23, 381.
The molecular structure of 5 was confirmed by X-ray
diffraction (Figure 2). The Phebox ligand and two chlorides are
coordinated to the Rh atom. The C5NH5 ligand of 5 as observed
in the tolyl ligand of 3 is bonded perpendicularly to the Phebox
plane. The Rh-C bond lengths of 1.998(6) and 2.015(6) Å were
comparable with those of 3. The Rh-Cl bond length was also
ca. 0.08 Å shorter than that of 3 probably due to weaker trans
influence of the C6H5N ligand. The C5NH5 moiety of 5 is
described to be a pyridinium rhodate (I).19 Alternatively such
(13) Ito, J.; Nishiyama, H. Eur. J. Inorg. Chem. 2007, 1114.
(14) Motoyama, Y.; Okano, M.; Narusawa, H.; Makihara, N.; Aoki, H.;
Nishiyama, H. Organometallics 2001, 20, 1580.
(15) (a) Jones, W. D.; Feher, F. J. Acc. Chem. Res. 1989, 22, 91. (b)
Peterson, T. H.; Golden, J. T.; Bergman, R. G. J. Am. Chem. Soc. 2001,
123, 455.
(16) (a) 4 was confirmed by comparison with the 1H NMR spectrum
reported in ref 18b. (b) Kowalski, C.; Creary, X.; Rollin, A. J.; Burke, M. C.
J. Org. Chem. 1978, 43, 2601.
(18) Grushin, V. V. Acc. Chem. Res. 1993, 26, 279.
(19) (a) Cordone, R.; Taube, H. J. Am. Chem. Soc. 1987, 109, 8101.
(b) Lavorate, D.; Terlouw, J. K.; Dargel, T. K.; Koch, W.; McGlbbon, G. A.;
Schwarz, H. J. Am. Chem. Soc. 1996, 118, 11898.
(17) Barrera, J.; Orth, S. D.; Harman, W. D. J. Am. Chem. Soc. 1992,
114, 7316.

3314 Organometallics, Vol. 27, No. 13, 2008
Notes
JRhC ) 28.5 Hz). IR (KBr, cm-1): 3311, 2965, 1624, 1563. Anal.
Calcd for C26H34ClN2O3Rh: C, 55.67; H, 6.11; N, 4.99. Found: C,
55.60; H, 5.98; N, 4.80. HRMS (FAB): calcd for C26H32ClN2O2Rh
[M - OH2]+ 542.1207, found: 542.1199.
Synthesis of 3. To a p-chlorotoluene solution (0.5 mL) of 1 (26.0
mg, 0.050 mmol) and 4 Å molecular sieves (100 mg) was added
NH(iPr)2 (140 µL, 1.0 mmol). After being stirred at 80 °C for 3 h,
the mixture was filtered. The concentrated filtrate was purified by
column chromatography on silica gel (hexane/ethyl acetate ) 1:4)
to give 3 (23.2 mg, 0.040 mmol, 80%). 1H NMR (300 MHz, CDCl3,
rt): 1.27 (s, 6H, CH3), 1.40 (s, 9H, C(CH3)3), 1.65 (s, 6H, CH3),
2.15 (s, 3H, CH3), 2.18 (s, 2H, H2O), 4.28 (d, JHH ) 8.4 Hz, 2H,
CH2), 4.45 (d, JHH ) 8.4 Hz, 2H, CH2), 6.52 (d, JHH ) 8.0 Hz, 2H,
C6H4), 6.73 (d, JHH ) 8.0 Hz, 2H, C6H4), 7.59 (s, 2H). 13C NMR
(75 MHz, CDCl3, rt): 20.4, 27.0, 28.8, 31.8, 35.2, 66.7, 82.7, 124.6,
126.6, 130.6, 131.4, 134.5 (d, JRhC ) 35.3 Hz), 136.2, 145.9, 171.3
(d, JRhC ) 5.7 Hz), 186.4 (d, JRhC ) 28.5 Hz). IR (KBr, cm-1):
3324, 2961, 1622, 1586. Anal. Calcd for C27H36ClN2O3Rh: C,
56.40; H, 6.31; N, 4.87. Found: C, 56.27; H, 6.11; N, 4.56. HRMS
(FAB): calcd for C27H34ClN2O2Rh [M - H2O]+ 556.1364, found
556.1384.
Figure 2. ORTEP diagram of 5 with 50% probability level
ellipsoids. Selected bond lengths (Å): Rh1-C1 1.928(6), Rh1-C21
1.998(6), Rh1-N1 2.064(5), Rh1-N2 2.089(5), Rh1-Cl1 2.434317,
Rh1-Cl2 2.4856(17); Rh2-C26 1.921(6), Rh2-C46 2.015(6),
Rh2-N4 2.071(6), Rh2-N5 2.086(5), Rh2-Cl3 2.4384(17),
Rh2-Cl4 2.4859(18).
Synthesis of 5. To a toluene solution (2 mL) of 1 (26.0 mg,
0.0500 mmol), 2-chloropyridine (24 µL, 0.25 mmol), and 4 Å
molecular sieves (200 mg) was added NH(iPr)2 (140 µL, 1.0
mmol). After being stirred at 70 °C for 1 h, the mixture was
filtered. The concentrated filtrate was purified by column
chromatography on silica gel (CH3Cl/MeOH ) 8:1) to give 5
a pyridiunium rhodate can be described as an N-heterocyclic
carbene complex (II) or unstable pyridine tautomers.20
In summary, we found a significant effect of amines on
C-Cl bond activation of aryl chorides by the Rh(III) complex
to provide the corresponding aryl complexes. Formation of
an equivalent amount of the imine 4 suggests that oxidation
of amine promotes reduction of the inactive Rh(III) complex
1 to Rh(I) species. We envision that this method provides
an alternative method for activation of an inactive Rh(III)
complex.
1
(27.4 mg, 0.047 mmol, 94%). H NMR (300 MHz, CDCl3, rt):
1.05 (s, 6H, CH3), 1.41 (s, 9H, C(CH3)3), 1.77 (s, 6H, CH3),
4.28 (d, JHH ) 8.1 Hz, 2H, CH2), 4.46 (d, JHH ) 8.1 Hz, 2H,
CH2), 6.39 (d, JHH ) 8.4 Hz, 1H, C5NH5), 7.04 (t, JHH ) 6.0
Hz, 1H, C5NH5), 7.29 (d, JHH ) 8.1 Hz, 1H, C5NH5), 7.66 (s,
2H), 8.16 (d, JHH ) 8.1 Hz, 1H, C5NH5), 15.8 (brs, w1/2 ) 27.1
Hz, 1H, NH). 13C NMR (75 MHz, CDCl3, rt): 27.6, 27.9, 31.8,
35.1, 66.5, 82.5, 118.5, 125.0, 129.4, 136.2, 137.8, 138.0, 146.0,
169.6 (d, JRhC ) 5.1 Hz), 184.3 (d, JRhC ) 38.3 Hz), 185.5 (d,
JRhC ) 25.7 Hz). IR (KBr, cm-1): 3447 (NH), 2964, 1623, 1571.
Anal. Calcd for C25H32Cl2N3O2Rh: C, 51.74; H, 5.56; N, 7.24.
Found: C, 51.35; H, 5.53; N, 6.83. HRMS (FAB): calcd for
C25H32ClN3O2Rh [M]+: 544.1238, found 544.1254.
X-ray Analyses. Single crystals of 3 and 5 suitable for X-ray
diffraction study were obtained from slow vaporization of a hexane/
ethyl acetate/dichloromethane solution and hexane/ethyl acetate at
room temperature, respectively. The diffraction data were collected
on a Bruker SMART APEX CCD diffractometer with graphite-
monochromated Mo KR radiation (λ ) 0.71073 Å). An empirical
absorption correction was applied by using SADABS. The structure
was solved by direct methods and refined by full-matrix least-
squares on F2 using SHELXTL. All non-hydrogen atoms were
refined with anisotropic displacement parameters. Crystallographic
data for 3: C27H36ClN2O3Rh; Mr ) 574.94; temperature 153 K;
monoclinic, P21/c; a ) 15.962(2) Å, b ) 10.6524(14) Å, c )
Experimental Section
1
General Procedures. H and 13C NMR spectra were obtained
at 25 °C on a Varian Mercury 300 spectrometer. 1H NMR chemical
shifts are reported in δ units, in ppm relative to the singlet at 7.26
ppm for CDCl3. 13C NMR spectra are reported in terms of chemical
shift (δ, ppm) relative to the triplet at δ ) 77.0 ppm for CDCl3.
Infrared spectra were recorded on a JASCO FT/IR-230 spectrom-
eter. Mass spectra were recorded on a JEOL JMS-700. Elemental
analyses were recorded on a Perkin-Elmer 2400II and a Yanoco
MT-6. Column chromatography was performed with a silica gel
column (Kanto Kagaku silica gel 60N). Complex 1 was prepared
according to the literature.11
Synthesis of 2. To a chlorobenzene solution (0.5 mL) of 1 (10.4
mg, 0.020 mmol) and 4 Å molecular sieves (100 mg) was added
NH(iPr)2 (56 µL, 0.40 mmol) under an argon atmosphere. After
being stirred at 80 °C for 1 h, the mixture was filtered. The
concentrated filtrate was purified by column chromatography on
silica gel (hexane/ethyl acetate ) 1:1) and then crystallized by slow
vaporization from a solution of ethyl acetate/dichlorometane/hexane
to give 2 (10.1 mg, 0.018 mmol, 90%). 1H NMR (300 MHz, CDCl3,
rt): 1.25 (s, 6H, CH3), 1.41 (s, 9H, C(CH3)3), 1.66 (s, 6H, CH3),
1.71 (s, 2H, H2O), 4.28 (d, JHH ) 8.4 Hz, 2H, CH2), 4.45 (d, JHH
) 8.4 Hz, 2H, CH2), 6.67-6.70 (m, 3H, C6H5), 6.86-6.92 (m,
2H, C6H5), 7.60 (s, 2H). 13C NMR (75 MHz, CDCl3, rt): 27.0,
28.7, 31.7, 35.1, 66.6, 82.6, 122.1, 124.5, 125.5, 130.4, 136.6, 140.3
(d, JRhC ) 35.4 Hz), 145.8, 171.1 (d, JRhC ) 5.1 Hz), 186.4 (d,
17.215(2) Å, ꢀ ) 114.013(2)°; V ) 2673.9(6) Å3; Z ) 4; Fcalcd
)
1.428 Mg/m3; µ ) 0.769 mm-1; reflections collected 18 678,
independent reflections 6137 [R(int) ) 0.0399]; data/restraints/
parameters 6137/0/323; goodness-of-fit on F2: 1.081; final R indices
[I > 2σ(I)] R1 ) 0.0320, wR2 ) 0.0803; R indices (all data) R1
) 0.0364, wR2 ) 0.0834; largest diff peak/hole 1.223 and -0.314
e Å-3. Crystallographic data for 5: C25H32Cl2N3O2Rh · 1.5(CH2Cl2);
j
Mr ) 706.22; temperature 153 K; triclinic, P1; a ) 13.364(4) Å,
b ) 15.834(5) Å, c ) 16.154(5) Å, R ) 105.268(7)°, ꢀ )
97.952(6)°, γ ) 90.103(7)°; V ) 3263.2(18) Å3; Z ) 4; Fcalcd
)
1.438 Mg/m3; µ ) 0.960 mm-1; reflections collected 22 966,
independent reflections 14 967 [R(int) ) 0.0478]; data/restraints/
parameters 14 967/1/682; goodness-of-fit on F2 1.022; final R
indices [I > 2σ(I)] R1 ) 0.0697, wR2 ) 0.1737; R indices (all
(20) (a) Esteruelas, M. A.; Ferna´ndez-Alvarez, F. J.; On˜ate, E. J. Am.
Chem. Soc. 2006, 128, 13044. (b) Alvarez, E.; Conejero, S.; Paneque, M.;
Petronilho, A.; Poveda, M. L.; Serrano, O.; Carmona, E. J. Am. Chem. Soc.
2006, 128, 13060.

Notes
Organometallics, Vol. 27, No. 13, 2008 3315
data) R1 ) 0.1251, wR2 ) 0.2041; largest diff peak/hole 2.471
the Promotion of Science (18350049), G-COE in chemistry
(Nagoya), and The Mitsubishi Foundation.
and -1.618 e Å-3
.
Supporting Information Available: Spectral data for 2, 3, and
5 and CIFs of 3 and 5. This material is available free of charge via
the Internet at http://pubs.acs.org.
Acknowledgment. This research was partly supported by
a Grant-in-Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science, and Technology, Japan
(460:18065011, Concerto Catalyst), the Japan Society for
OM8002174