Syntheses of novel di- and trinucleating ligands having a triethylbenzene core with N,N-bidentate tethers: Their complexation toward Pd and Rh organometallic fragments

Article abstract of DOI:10.1039/b713503c

A series of di- and trinucleating ligands with a 1,3,5-triethylbenzene core connected to N,N-bidentate tethers was synthesized. The ligands readily reacted with monuclear Rh and Pd precursors to give the corresponding di- and trinuclear complexes, which were characterized by using NMR and ESI mass spectroscopy. In the solid state, the trinuclear complexes with ligands having pyridylpyrazolyl tethers adopt the most stable ababab configuration, in which the organometallic fragments are on the same side of the benzene plane. On the other hand, in solution, the linker moieties between the benzene core and the metals are flexible enough to interconvert between other configurations, that is, they exhibit dynamic behavior, and the rotational barrier was dependent on the length of the linkers. From variable temperature (VT) ¹H NMR measurements, the rotational barrier for a trinuclear Rh-CO complex with a ligand having methylene linkers was estimated to be ～12.6 kcal mol ^-1. However, no spectral changes were observed for the ethylene derivative in the temperature range of -60 °C to 50 °C, indicating that the rotation was not frozen out on the ¹H NMR timescale, even at -60 °C. The Royal Society of Chemistry.

Full text of DOI:10.1039/b713503c

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Syntheses of novel di- and trinucleating ligands having a triethylbenzene core
with N,N-bidentate tethers: their complexation toward Pd and Rh
organometallic fragments†
Gou Higashihara, Akiko Inagaki and Munetaka Akita*
Received 4th September 2007, Accepted 21st January 2008
First published as an Advance Article on the web 26th February 2008
DOI: 10.1039/b713503c
A series of di- and trinucleating ligands with a 1,3,5-triethylbenzene core connected to N,N-bidentate
tethers was synthesized. The ligands readily reacted with monuclear Rh and Pd precursors to give the
corresponding di- and trinuclear complexes, which were characterized by using NMR and ESI mass
spectroscopy. In the solid state, the trinuclear complexes with ligands having pyridylpyrazolyl tethers
adopt the most stable ababab configuration, in which the organometallic fragments are on the same side
of the benzene plane. On the other hand, in solution, the linker moieties between the benzene core and
the metals are flexible enough to interconvert between other configurations, that is, they exhibit
dynamic behavior, and the rotational barrier was dependent on the length of the linkers. From variable
temperature (VT) 1H NMR measurements, the rotational barrier for a trinuclear Rh–CO complex with
a ligand having methylene linkers was estimated to be ∼12.6 kcal mol−1. However, no spectral changes
were observed for the ethylene derivative in the temperature range of −60 ◦C to 50 ◦C, indicating that
the rotation was not frozen out on the 1H NMR timescale, even at −60 ◦C.
supramolecular chemistry.8 The 1,3,5-triethylbenzene derivatives
Introduction
effectively force the tethers at the 2, 4 and 6 positions to be
Controlling the structure of multinuclear complexes with the
on the same side of the phenyl ring, meaning that the ligand
appropriate supporting ligands has brought about a variety of
unique reactions.1 It has been shown that the reaction site
adopts an ababab (a denotes ‘above’ and b denotes ‘below’)
configuration. The ababab configuration is thermodynamically
provided by the complexes plays a key role in the activa-
the most stable configuration, because the steric repulsion between
tion of substrates through cooperative interaction of the metal
the adjacent substituents is minimized (Fig. 1). This configuration
centers.2 Until now, much of the research on multinuclear
makes it possible to introduce metal centers at the 2, 4 and 6
organometallic complexes has involved clusters with metal–
positions, indicated by “functional group” in Fig. 1, thus forming
metal bonds, and little attention has been paid to clusters
a multinuclear reaction site in which organic substrates can be
with no metal–metal bonds.2 However, model systems of met-
activated in a concerted manner. Here, we report the syntheses of
alloenzymes with well-designed multidentate ligands have been
di- and trinucleating ligands having a 1,3,5-triethylbenzene core
extensively studied.3 To gain a better understanding of clusters
and their complexes with Pd and Rh organometallic fragments.
without metal–metal bonds, we have been studying multinuclear
Properties of the ligands having different chain lengths between the
complexes with 3,5-bis((diphenylphosphino)methyl)pyrazolato
core phenyl ring and the N,N-bidentate coordination site and their
(PNNP)4 and (3-(diphenylphosphino)methyl-5-pyridylpyrazolato
complexes are compared. Conformational flexibility and reactivity
(PNNN) ligands, which separate the metal centers beyond the
studies of the new multinuclear complexes are also described.
distance for metal–metal bonding interaction but are flexible
enough to accommodate substrates of various sizes.5 With the
aim of extending our study to multinuclear complexes without
metal–metal bonds, we started investigating complexes having
a ligand with a 1,3,5-triethylbenzene core, which can arrange
the metal centers to form a three-dimensional coordination site.
Thus far, to the best of our knowledge, there are no examples
of a multinuclear complex having a 1,3,5-triethylbenzene core and
reactive organometallic fragments. Recently, 1,3,5-triethylbenzene
derivatives with functionalized pendant arms have been widely
used as a core in molecular recognition6 and biomimetic7 and
Chemical Resources Laboratory, Tokyo Institute of Technology, R1-27, 4259,
Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
† Electronic supplementary information (ESI) available: Crystallographic
results; crystallographic data in CIF format (CCDC reference numbers
659502–659504). See DOI: 10.1039/b713503c
Fig. 1 Steric configuration of the substituents of 1,3,5-triethylbenzene
derivatives.
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(pypz) ligands, probably due to the instability of the carbanion
species.
Results and discussion
Ligand synthesis
Scheme 1 shows the synthetic routes used to prepare the
trinucleating ligands Lpypz3, Lphen3, Lphen3ꢀ and Lbpy3, which have
different alkyl chain lengths between the benzene core and the
N,N-bidentate coordination site. The corresponding dinucleating
ligands Lpypz2 and Lphen2 were also synthesized for comparison. All
of the ligands were synthesized via a nucleophilic substitution
reaction involving 1,3,5-tri(halomethyl)- or 1,3-di(halomethyl)-
2,4,6-triethylbenzene9 and the appropriate nucleophile (Scheme 1).
The 3-(2-pyridyl)pyrazolyl derivatives with methylene linkers,
Lpypz3 and Lpypz2, were prepared by reacting the appropriate
2,4,6-triethylbenzene starting material with 3-(2-pyridyl)pyrazole
under phase transfer conditions (NaOH in H2O–toluene–40%
NBu4OH). The 1,10-phenanthroline (phen) and 2,2ꢀ-bipyridyl
(bpy) derivatives with ethylene linkers were prepared by reacting
with a carbanion species generated by deprotonation of the
corresponding methyl derivatives with lithium diisopropylamide
(LDA). The yields were lower than those of the pyridylpyrazolyl
Synthesis of di- and trinuclear complexes
The obtained polynucleating ligands were converted to polynu-
clear organometallic species (1, 2, 8, and 9 with 3-(2-pyridyl)-
pyrazolylmethyl tethers; 4, 5, 6, 11, and 12 with the phenan-
3
thrylethyl tethers) by treating with labile Pd ([(cod)Pd(g -
C3H5)]BF4, (cod)PdMeCl) and Rh precursors ([Rh(cod)2]BF4,
[Rh(nbd)2]BF4 (cod = 1,5-cyclooctadiene; nbd = 2,5-norbo-
rnadiene)), and the results are summarized in Schemes 2 and
3. Rh–diene complexes 2, 6, and 9 were carbonylated under an
atmospheric pressure of CO to give the corresponding Rh–CO
complexes 3, 7, and 10, respectively. The Pd–Cl complex formed
in the reaction of Lphen3 and (cod)PdMeCl was converted to the
MeCN-coordinated cationic species 5 by abstracting Cl− with
AgOTf in MeCN. Attempts to isolate analytically pure trinuclear
complexes with Lbpy3 were unsuccessful due to the high solubility
of the product.
Scheme 1
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Scheme 2
Scheme 3
Spectroscopic characterization
symmetry, two sets of inequivalent resonances for the ethyl groups
in a 1 : 2 integral ratio were observed, whereas the resonances for
the pypz ligand and methylene (Cphenyl-CH2-) protons appeared as
a single set of resonances. The signal for H17 on the phenyl ring
presumably overlaps that for H12, based on the integral ratio of the
signals (Fig. 2). The molecular structure of Lpypz3 was determined
by using X-ray crystallography.
All ligands and metal complexes were fully characterized by using
1H and 13C NMR spectroscopy, FAB and ESI mass spectroscopy,
respectively, and X-ray structural studies (vide infra). The 1H
NMR spectrum of the trinucleating ligand Lpypz3 measured at
room temperature contained only a single set of the resonances for
the ethyl, methylene (Cphenyl-CH2-), and pypz parts, which agrees
with the pseudo-C3 symmetry of the molecule (Fig. 2). In the 1H
NMR spectrum of the dinucleating ligand Lpypz2 with pseudo-Cs
The NMR spectra of the ethylene-bridged ligands Lphen3, Lphen3ꢀ
,
and Lphen2 have spectral features similar to those of the pypz
derivatives, which is consistent with the symmetry of the ligands.
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Fig. 2 1H NMR spectra of Lpypz2 and Lpypz3
.
No spectral changes in the spectra of the ligands were observed in
the temperature range of −60 to 50 ◦C.
carbon atoms of the phenyl ring (dC (C17 for 8–10, C22 for 11,12)
∼130 (doublet)) were observed. Compared to ethylene-bridged
complexes 4–7, the methylene-bridged complexes showed broad
signals, probably due to dynamic behavior (vide infra).
Formation of polynuclear complexes 1–7 was evidenced by the
downfield shifts of the signals for the olefinic moieties of the
diene ligands and the hydrogen atoms adjacent to the coordinated
N atom of the tether moieties (e.g., H18 for Lphen3), which
is probably due to a decrease in the electron density of the
heteroaromatic ring caused by introducing the cationic metal
fragments (Fig. 3). Similar to the ligand NMR data, only one
set of signals for the ethyl, methylene or ethylene moieties and the
tethered metal fragments were observed, which agrees with the
pseudo-C3 symmetry of the trinuclear complexes. In the spectra
of the dinuclear complexes, characteristic NMR signals for the
protons (dH (H17 for 8–10, H22 for 11–12) ∼7.0 (singlet)) and the
The IR spectra of the Rh carbonyl complexes in nitromethane
solution exhibited two C–O stretching bands at 2100 and
2038 cm−1 for the pypz complexes 3 and 10, and 2096 and
2034 cm−1 for the phenanthroline complex 7. These wavenum-
bers are similar to those of the corresponding mononuclear
model complexes [(pypzMe)Rh(CO)2]BF4 (pypzMe = 1-Me-3-(2-
pyridyl)pyrazole, mCO = 2100, 2038 cm−1) and [(bpy)Rh(CO)2]BF4
(mCO = 2100, 2040 cm−1), suggesting that the metal centers have
a similar electron density, irrespective of the numbers of metal
fragments incorporated.
Fig. 3 1H NMR spectra of 6 and Lphen3
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Although we were unable to obtain single crystals of the
ethylene-bridged compounds, crystals of the methylene-bridged
ligand Lpypz3, 1, and 2 were obtained, and their structures were
determined by using single crystal X-ray crystallography.† The
crystal data and data collection parameters are given in Table 1,
and top and side views of Lpypz3 and the cations of 1 and 2 are
shown in Fig. 4. Although Lpypz3 has an ababba configuration,
complexes 1 and 2 have an ababab configuration, which is
generally seen for the structures of 2,4,6-trisubstituted 1,3,5-
triethylbenzene compounds.7a,c,e,f ,8b,e,10 In the solid state structures
of 1 and 2, the pypz–metal side arms are below the benzene
plane, and the Pd–allyl and Rh–cod fragments point toward the
outside of the complex to relieve steric repulsion. Preliminary
crystal structure determination of the dinuclear Pd–allyl complex
8 showed that both of the pypz metal side arms are also
below the benzene core and the conformation adopted by the
ligand is very similar to that of 1, although one of the ethyl
substituents adjacent to the phenyl H was directed downward.
The Pd–N bond lengths and N–Pd–N bond angles are similar
to those of the corresponding mononuclear complexes, such as
[(pypz)PdCl2]11 and [(pypzMe)Rh(cod)PPh3]OTf.12 The angles at
the methylene group connecting the pypz ligand and the benzene
core (∠C(phenyl)–C(methylene)–N(pyrazole)) are summarized in
Table 2. The averaged bond angles were 111.2◦, 110.6◦, and 111.1◦
for Lpypz3, 1, and 2, respectively, and the differences in the angles
between the ligands and di- and trinuclear complexes was less
than 1◦. This result shows that the steric hindrance caused by
introduction of the metal fragments is avoided by rotation of the
metal fragment around the CH2–N bond.
Fig. 4 ORTEP representation (top and side views) of Lpypz3, 1, and 2 with
thermal ellipsoids at 30% probability. H atoms are omitted for clarity.
Fluxional behavior
1
No H NMR spectral changes were observed for the ethylene-
methylene-bridged complexes displayed broad signals at room
temperature, which led us to further investigate their fluxional
behavior. VT 1H NMR spectra (500 MHz) of the trinuclear Rh–
carbonyl complex 3 were recorded in CD3NO2 in the temperature
bridged trinuclear complexes (4–7) in the temperature range of
−40 to 65 ◦C, suggesting fast rotation of the ethyl and ethylene–
ML groups around the C(phenyl)–CH2 bonds. In contrast, the
Table 1 Crystallographic data for Lpypz3, 1, and 2
Lpypz3
L
pypz3-Pd(allyl) (1)
L
pypz3-Rh(cod) (2)
Formula
C39H39N9
633.80
C51H63B3F12N12O6Pd3
1519.76
C65H81B3F12N11O4Rh3 +0.5(CH3NO2)
Formula weight
Crystal system
Space group
1680.09
Triclinic
Monoclinic
P21/n (#14)
11.3126(6)
26.386(2)
12.211(1)
90
109.579(4)
90
3434.1(5)
4
Triclinic
¯
¯
P1 (#2)
P1 (#2)
˚
a/A
13.074(8)
15.005(9)
17.337(9)
105.76(4)
97.23(4)
110.73(2)
2967(3)
2
14.304(3)
14.663(5)
18.456(6)
104.890(11)
90.88(2)
108.688(16)
3523.5(19)
2
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
Z
d
calc/g cm−3
1.226
1.701
1.584
Temp./◦C
Radiation
l/cm−1
−60
−60
−60
˚
˚
˚
MoKa (k = 0.71069 A)
MoKa (k = 0.71069 A)
MoKa (k = 0.71069 A)
7.60
9.96
7.83
Diffractometer
Rigaku RAXIS IV
55.0
Rigaku RAXIS IV
55.0
Rigaku RAXIS IV
55.0
Max 2h/◦
Reflections collected; independent reflections 27257; 7173 [R(int) = 0.061] 15780; 10416 [R(int) = 0.0757] 25478; 14223 [R(int) = 0.0880]
No. of parameters refined
R1 (I > 2r) (%)
591
694
7.52
22.64
0.904
895
8.92
27.26
1.060
4.57
12.2
1.031
wR2 (all) (%)
Goodness of fit
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Table 2 Selected bond angles (◦)
(such as HA, HAꢀ, HAꢀꢀ and HBꢀ, HBꢀꢀ) were observed at different
chemical shifts. Unfortunately, further investigation was hampered
by the high melting point of the deuterated nitromethane.14 The
VT NMR study shows the dynamic behavior of the metal fragment
[(pypz)Rh(CO)2]+ around the C(phenyl)–CH2 bond, similar to
those reported for the tetra- and triethyl substituted benzene
compounds, such as 1,4-dineohexyl-2,3,5,6-tetraethylbenzene and
its chromium tricarbonyl complex.15 The rotational barrier around
the C–C axis is slightly larger than the corresponding barriers
∠N1–C13–C2
∠N4–C14–C4
∠N7–C15–C6
Average
Lpypz3
1
2
112.31(10)
109.7(7)
111.3(5)
110.4(1)
111.9(7)
110.6(6)
110.9(1)
110.2(6)
111.3(5)
111.2
110.6
111.1
range of −25 to 65 ◦C (Fig. 5). The 1H NMR spectrum measured
at room temperature contained broad signals for the methyl and
methylene protons of the ethyl groups and pyrazolyl protons
(H6), whereas those of the other protons were relatively sharp.
As the temperature was raised, the broad signals changed into
a single set of sharp signals, indicating C3 symmetry on the
NMR timescale. The broad singlet for the methyl groups at
ambient temperature decoalesced at 0 ◦C, and the spectrum at
−25 ◦C displayed two inequivalent singlets (dm = 218 Hz) with
an integral ratio of 3 : 1. Using the data, the barrier for the
rotation process on the C–C axis was calculated to be 12.6 kcal
mol−1 at the coalescence temperature.13 The methylene (of the
ethyl group) and the pyrazolyl-H (H6) signals also split into
two inequivalent signals at this temperature, whereas the other
signals did not show any significant changes in the temperature
range. The inequivalent signals suggest the presence of at least
two conformational isomers, such as those shown in Fig. 6.
Interconversion among the isomers was frozen below −25 ◦C,
and thus, signals for protons in different magnetic environments
6
for the various 1,4-disubstituted g -2,3,5,6-tetraethylbenzene Cr
carbonyl complexes.15
The lack of changes in the VT NMR spectra observed for
the ethylene-bridged complexes indicates much lower energy
barriers for the C–C bond rotation, because of the reduced steric
congestion among the tether parts, due to the longer linkers. In
addition, the VT NMR study shows that the bulky metal centers
of the methylene- and ethylene-bridged tethers can interact with
substrates due to C(phenyl)–CH2 bond rotation.
Summary
New di- and trinucleating ligands having N,N-chelating tethers
with different chain lengths incorporated at the 2, 4 and 6 positions
of the 1,3,5-triethylbenzene backbone, which readily reacted
with various Pd and Rh precursors to form di- and trinuclear
complexes, were synthesized. X-Ray structural studies showed
that the trinuclear complexes with methylene-bridged pypz ligands
adopt an ababab configuration, in which the metal fragments
are beneath the benzene plane. VT 1H NMR studies showed
that the methylene-bridged tethers rotate around the C(phenyl)–
CH2 bonds, causing inequivalent sets of ethyl and pyrazolyl
proton signals at low temperature. These results indicate that the
structures are flexible, which may allow multiple metal centers
to interact with substrates in a concerted manner under ambient
reaction conditions. From a comparison of the complexes having
ethylene-bridged ligands (Lphen3, Lphen3ꢀ, and Lphen2) with those of
methylene-bridged ones, the rotational barrier of the C(phenyl)–
CH2 bond seems to be much smaller for the ethylene-bridged
complexes, because of the reduced steric repulsion between the
metal fragments and the ethyl substituents due to the longer
carbon chains.
Experimental
General
Standard Schlenk and vacuum line techniques under N2 at-
mosphere were employed for the reactions. Acetone (molecular
sieves), acetonitrile (P2O5), and nitromethane (CaCl2) were treated
with appropriate drying agents, distilled, and stored under N2.
The metal reagents [Pd(C3H5)cod]BF4,16 [Rh(cod)2]BF4,17 and
1
Fig. 5 500 MHz VT H NMR spectra of the ethyl and aromatic region
of 3 at 338, 300, 273, 258 and 248 K.
17
[Rh(nbd)2]BF4 were prepared according to the published proce-
dures. 1H and 13C NMR spectra were recorded on Bruker AC-200,
JEOL GX-270, JEOL EX-400, and JEOL LA-500 spectrometers.
Solvents for NMR measurements were dried over molecular sieves,
degassed, and stored under N2. IR spectra were obtained on a
JASCO FT/IR 5300 spectrometer. ESI-MS and HRMS (FAB)
spectra were recorded on a ThermoQuest Finnigan LCQ Duo
mass spectrometer and a JEOL JMS-700 mass spectrometer,
Fig. 6 Possible conformational isomers observed at low temperature.
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Chart 1 NMR labeling scheme of the ligands and the corresponding tri- and dinuclear complexes.
respectively. Other chemicals were purchased and used as received.
JCH = 156 Hz, C1), 121.4 (d, JCH = 163 Hz, C16), 119.1 (d, JCH
=
3
1
In the following section, JHH and JCH are abbreviated as J and
CH, respectively. The NMR labeling scheme of the ligands and the
corresponding tri- and dinuclear complexes is given in Chart 1.
163 Hz, C14), 103.4 (d, JCH = 178 Hz, C11), 48.8 (t, JCH = 140 Hz,
C5), 25.4 (t, JCH = 126 Hz, C5), 22.1 (t, JCH = 126 Hz, C7), 14.8
(q, JCH = 128 Hz, C8), 14.5 (q, JCH = 127 Hz, C6). HRMS (FAB,
pos): m/z = 477.2763 (calcd for [M + H]+, C39H40N9 477.2767).
J
Preparation of Tri(chloromethyl)triethylbenzene
Lpypz3
.
(662 mg, 2.15 mmol) and 3-(2-pyridyl)pyrazole (1.03 g,
7.10 mmol) were dissolved in toluene (50 mL), and 40% NaOH aq
(7 mL) and 40% NBu4OH solution (a few drops) were added to
the solution. The mixture was heated at 90 ◦C for 7 h. The organic
layer was extracted with toluene and dried over MgSO4, filtered,
and rotary evaporated to dryness to yield the crude product. The
product was recrystallized from Et2O–pentane (white crystals,
1.25 g, 1.98 mmol, 92% yield). 1H NMR (400 MHz, acetone-d6):
d 8.40 (d, J = 4.1 Hz, 3 H, H13), 7.83 (d, J = 8.1 Hz, 3 H, H10),
7.61 (t, J = 7.7 Hz, 3 H, H11), 7.27 (d, J = 2.2 Hz, 3 H, H6), 7.08
(d, J = 7.6 Hz, 3 H, H12), 6.70 (d, J = 2.4 Hz, 3 H, H7), 5.46 (s,
6 H, H5), 2.83 (q, J = 7.6 Hz, 6 H, H3), 0.92 (t, J = 7.6 Hz, 9 H,
H4). 13C NMR (100 MHz, acetone-d6): d 153.5 (s, C9), 152.6 (s,
Preparation of Lphen3
. A THF solution of 2-methyl-1,10-
phenanthroline (440 mg, 2.59 mmol) was added to 1.2 equiv
of LDA–THF solution at −78 ◦C and stirred for 2 h at this
temperature. After addition of a tri(chloromethyl)triethylbenzene
(256 mg, 0.84 mmol)–THF solution, the solution was stirred at
−8 ◦C for 4 h and then at ambient temperature for 12 h. The
volatiles were removed under reduced pressure after the solution
was quenched with H2O (20 mL) and the reddish brown precipitate
was extracted with CH2Cl2 (50 mL × 3), washed with saturated
NaCl aq, dried with Na2SO4, and evaporated. The residual oil was
purified by column chromatography (silica, CH2Cl2 → CH2Cl2 :
MeOH = 9 : 1) and recrystallization with CH2Cl2–hexane to yield
L
phen3 as a reddish brown solid (260 mg, 0.33 mmol, 40%). 1H NMR
C1), 150.1 (d, JCH = 176 Hz, C13), 147.0 (s, C8), 137.1 (d, JCH
=
(400 MHz, CDCl3): d 9.20 (d, J = 4.1 Hz, 3 H, H18), 8.17 (d, J =
8.1 Hz, 3 H, H16), 8.10 (d, J = 8.3 Hz, 3 H, H9), 7.72–7.67 (m,
6 H, H12 + H13), 7.57–7.54 (m, 3 H, H17), 7.32 (d, J = 8.3 Hz,
3 H, H8), 3.45 (t, J = 8.3 Hz, 6 H, H5 or H6), 3.20 (t, J = 7.8 Hz,
H5 or H6), 2.68 (q, J = 7.2 Hz, 6 H, H3), 1.16 (t, J = 7.2 Hz, 9H,
160 Hz, C11), 131.5 (s, C2), 131.0 (d, JCH = 180 Hz, C6), 123.0
(d, JCH = 162 Hz, C12), 120.1 (d, JCH = 165 Hz, C10), 104.9 (d,
JCH = 177 Hz, C7), 50.6 (t, JCH = 140 Hz, C5), 24.0 (t, JCH
=
126 Hz, C3), 15.7 (q, JCH = 121 Hz, C4). HRMS (FAB, pos):
m/z = 634.3421 (calcd for [M + H]+, C39H40N9 634.3407).
H4). 13C NMR (100 MHz, CDCl3): d 162.5 (s, C7), 150.0 (d, JCH
=
179 Hz, C18), 146.0 (s, C15), 145.6 (s, C11), 139.4 (s, C1), 136.0
(d, JCH = 161 Hz, C9), 135.9 (d, JCH = 161 Hz, C16), 135.1 (s,
C2), 128.7 (s, C14), 127.0 (s, C10), 126.4 (d, JCH = 162 Hz, C13),
125.5 (d, JCH = 162 Hz, C12), 122.7 (d, JCH = 161 Hz, C8), 122.5
(d, JCH = 164 Hz, C17), 40.8 (t, JCH = 128 Hz, C5 or C6), 29.1
(t, JCH = 128 Hz, C5 or C6), 22.6 (t, JCH = 125 Hz, C3), 15.8 (q,
JCH = 127 Hz, C4). HRMS: calcd for [M + H]+: 781.4109, found
781.4042.
Preparation of Lpypz2
2.87 mmol) and 3-(2-pyridyl)pyrazole (834 mg, 5.74 mmol) were
dissolved in toluene (50 mL), and 40% NaOH aq (7 mL) and
40% NBu4OH solution (a few drops) were added to the solution.
. Di(bromomethyl)triethylbenzene (1.0 g,
◦
The mixture was heated at 90 C for 7 h. The organic layer was
extracted with toluene and dried over MgSO4, filtered, and rotary
evaporated to dryness to yield the crude product. The product
was recrystallized from CH2Cl2–hexane (white crystals, 848 mg,
1
1.78 mmol, 62% yield). H NMR (400 MHz, CDCl3): d 8.40 (d,
Preparation of Lphen2
.
The ligand was synthesized in a similar
J = 3.6 Hz, 2 H, H17), 7.81 (d, J = 7.8 Hz, 2 H, H14), 7.54 (t, J =
7.1 Hz, 2 H, H15), 7.03–7.00 (m, 3 H, H1 + H16), 6.89 (d, J =
2.2 Hz, 2 H, H10), 6.70 (d, J = 2.2 Hz, 2 H, H11), 5.38 (s, 4 H,
H9), 2.64 (q, J = 7.6 Hz, 2 H, H7), 2.56 (q, J = 7.6 Hz, 4 H, H5),
1.05 (t, J = 7.6 Hz, 6 H, H6), 0.90 (t, J = 7.6 Hz, 3 H, H8). 13C
NMR (100 MHz, CDCl3): d 151.5 (s, C13), 150.9 (s, C3), 148.5 (d,
manner as Lphen3 by treating 2-methyl-1,10-phenanthroline and 1.2
equiv of LDA with di(bromomethyl)triethylbenzene at a ratio of
2 : 1 (268 mg, 0.47 mmol, 14%). 1H NMR (400 MHz, CDCl3): d
9.20 (d, J = 4.1 Hz, 2 H, H18), 8.20 (d, J = 8.0 Hz, 2 H, H16),
8.08 (d, J = 8.3 Hz, 2 H, H9), 7.74–7.67 (m, 4 H, H12 + H13),
7.59–7.56 (m, 2 H, H17), 7.35 (d, J = 8.3 Hz, 2 H, H9), 6.91 (s,
1 H, H22), 3.37 (t, J = 7.6 Hz, 4 H, H5 or H6), 3.15 (t, J = 7.6 Hz,
4 H, H5 or H6), 2.69–2.60 (m, 6 H, H20 + H3), 1.20 (t, J = 7.6 Hz,
JCH = 178 Hz, C17), 144.6 (s, C4), 143.9 (s, C12), 135.6 (d, JCH
=
161 Hz, C15), 128.7 (d, JCH = 172 Hz, C10), 127.7 (s, C2), 127.2 (d,
1894 | Dalton Trans., 2008, 1888–1898
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6 H, H19), 1.09 (t, J = 7.6 Hz, 3 H, H4). 13C NMR (100 MHz,
CDCl3): d 162.4 (s, C7), 149.9 (d, JCH = 179 Hz, C18), 145.7 (s,
(brs, 6 H, H3), 1.15–1.22 (brs, 9 H, H4). 13C NMR (100 MHz,
CD3NO2): d 155.1 (d, JCH = 185 Hz, C13), 154.1 (s, C9), 151.8 (s,
C15), 145.4 (s, C10), 140.6 (s, C2), 140.2 (s, C21), 135.9 (d, JCH
=
C1), 149.3 (s, C8), 142.3 (d, JCH = 168 Hz, C11), 134.9 (d, JCH =
161 Hz, C9), 135.7 (d, JCH = 161 Hz, C16), 134.4 (s, C1), 128.5
(s, C14), 126.8 (s, C11), 126.3 (d, JCH = 157 Hz, C22), 126.2 (d,
193 Hz, C6), 130.7 (s, C2), 127.5 (d, JCH = 170 Hz, C12), 123.5 (d,
JCH = 169 Hz, C10), 119.8 (d, JCH = 165 Hz, C3H5), 106.4 (d, JCH
184 Hz, C7), 59.9, 67.0 (t, JCH = 155, 164 Hz, C3H5), 53.3 (t, JCH
=
=
JCH = 162 Hz, C13), 125.3 (d, JCH = 162 Hz, C12), 122.5 (d, JCH
=
161 Hz, C8), 122.4 (d, JCH = 163 Hz, C17), 40.3 (t, JCH = 128 Hz,
C5 or C6), 28.9 (t, JCH = 127 Hz, C5 or C6), 25.6 (t, JCH = 126 Hz,
C20), 22.3 (t, JCH = 125 Hz, C3), 15.8 (q, JCH = 126 Hz, C4), 15.3
(q, JCH = 127 Hz, C19). HRMS: calcd for [M + H]+: 575.3175,
found: 575.3175.
144 Hz, C5), 24.7 (t, JCH = 128 Hz, C3), 15.6 (q, JCH = 128 Hz,
C4). ESI-MS (MeCN): m/z = 781.2 [(Lpypz3)Pd(C3H5)]+, 1249.9
[(Lpypz3)Pd3(C3H5)3(BF4)2]+. Anal. calcd for C48H54B3F12N9Pd3: C,
43.13; H, 4.07; N, 9.43. Found: C, 42.90; H, 4.51; N, 9.61%.
Synthesis of 2.
A mixture of [Rh(cod)2]BF4 (198 mg,
Preparation of Lphen3ꢀ
.
The ligand was synthesized in a sim-
0.487 mmol) and Lpypz3 (100 mg, 0.157 mmol) in CH3NO2 (5 mL)
was stirred at ambient temperature for 2 h. After the solvent
was removed under vacuum, the product was washed with Et2O
(20 mL × 3), dried under vacuum to give 2 as orange crystalline
solid. 1H NMR (200 MHz, CD3NO2): d 8.11 (t, J = 7.6 Hz, 3 H,
H11), 7.97 (d, J = 7.4 Hz, 3 H, H10), 7.80 (d, J = 5.5 Hz, 3 H, H13),
7.55 (t, J = 6.1 Hz, 3 H, H12), 7.26 (s, 3 H, H6), 6.93 (d, J = 2.7 Hz,
ilar manner as Lphen3 by using 2,9-dimethyl-1,10-phenanthroline
(1.00 g, 4.80 mmol) with 1.2 equiv of LDA and tri(chloromethyl)-
triethylbenzene (492 mg, 1.60 mmol) to yield Lphen3ꢀ (329 mg,
1
0.40 mmol, 25%). H NMR (400 MHz, CDCl3): d 8.08–7.96 (m,
6 H, H9 + H16), 7.62–7.54 (m, 6 H, H12 + H13), 7.42–7.34 (m,
6 H, H8 + H17), 3.40 (t, J = 8.1 Hz, 6 H, H5 or H6), 3.22 (t, J =
8.0 Hz, 6 H, H5 or H6), 2.85 (brs, 9 H, H19), 2.83 (brs, 6 H, H3),
1.22 (t, J = 7.2 Hz, 9 H, H4). 13C NMR (100 MHz, CDCl3): d
161.6 (s, C7), 158.3 (s, C18), 144.6 (s, C15), 144.4 (s, C11), 138.9
(s, C1), 135.8 (d, JCH = 161 Hz, C9), 135.5 (d, JCH = 161 Hz, C16),
135.0 (s, C2), 126.5 (s, C14), 126.0 (s, C10), 124.8 (d, JCH = 162 Hz,
C13), 124.6 (d, JCH = 162 Hz, C12), 122.7 (d, JCH = 161 Hz, C8),
121.8 (d, JCH = 164 Hz, C17), 40.3 (t, JCH = 128 Hz, C5 or C6),
29.1 (t, JCH = 128 Hz, C5 or C6), 25.0 (q, JCH = 126 Hz, C19),
22.2 (t, JCH = 125 Hz, C3), 15.5 (q, JCH = 127 Hz, C4).
=
3 H, H7), 5.30 (s, 6 H, H5), 4.94 (s, 12 H, -CH CH- (cod)), 2.10–
2.62 (m, 30 H, H3 + -CH2- (cod)), 1.29 (t, J = 7.4 Hz, 9 H, H4). 13
C
NMR (100 MHz, CD3NO2): d 156.4 (s, C9), 153.0 (s, C1), 149.5 (s,
C8), 149.0 (d, JCH = 184 Hz, C13), 142.6 (d, JCH = 171 Hz, C11),
136.4 (d, JCH = 187 Hz, C6), 130.5 (s, C2), 127.3 (d, JCH = 174 Hz,
C12), 123.6 (d, JCH = 172 Hz, C10), 106.3 (d, JCH = 187 Hz,
=
=
C7), 84.8 (d, JCH = 150 Hz, -CH CH (cod)), 50.6 (t, JCH
=
=
144 Hz, C5), 31.6 (t, JCH = 130 Hz, -CH2- (cod)), 24.6 (t, JCH
128 Hz, C3), 15.7 (q, JCH = 128 Hz, C4). ESI-MS (MeCN): m/z =
844.8 [(L1)Rh(cod)]+, 1440.7 [(Lpypz3)Rh3(cod)3(BF4)2]+. Elemental
analysis data could not be obtained due to the instability of the
complex.
Preparation of Lbpy3
.
6-Methyl-2,2ꢀ-bipyridine was synthesized
according to the published method.18 The ligand Lbpy3 was
synthesized in a similar manner as Lphen3 by treating 1.62 g
(9.52 mmol) of 6-methyl-2,2ꢀ-bipyridine and 1.2 equiv of LDA
with tri(chloromethyl)triethylbenzene 500 mg (1.63 mmol) to yield
the ligand as a reddish brown solid (400 mg, 0.52 mmol, 32%). 1H
NMR (400 MHz, CDCl3): d 8.48 (d, J = 4.3 Hz, 3 H, H16), 8.42
(d, J = 7.8 Hz, 3 H, H13), 8.15 (d, J = 7.8 Hz, 3 H, H10), 7.54 (t,
J = 7.8 Hz, 3 H, H14), 7.52 (t, J = 7.8 Hz, 3 H, H9), 7.03–7.01 (m,
6 H, H8 + H15), 3.06, 3.00 (s, 12 H, H5 + H6), 2.85 (q, J = 7.0 Hz,
6 H, H3), 1.20 (t, J = 7.0 Hz, 9 H, H4). 13C NMR (100 MHz,
CDCl3): d 161.1 (s, C7), 156.5 (s, C11), 155.5 (s, C12), 149.0 (d,
JCH = 177 Hz, C16), 139.1 (s, C1), 137.2 (d, JCH = 161 Hz, C9),
136.8 (d, JCH = 161 Hz, C14), 135.6 (s, C2), 123.5 (d, JCH = 163 Hz,
C15), 122.4 (d, JCH = 161 Hz, C8), 121.0 (d, JCH = 165 Hz, C10),
118.3 (d, JCH = 165 Hz, C13), 40.1 (t, JCH = 128 Hz, C5 or C6),
29.8 (t, JCH = 128 Hz, C5 or C6), 22.6 (t, JCH = 125 Hz, C3), 15.9
(q, JCH = 127 Hz, C4).
Synthesis of 3. A CH3NO2 solution (5 mL) of 2 (200 mg,
0.131 mmol) was degassed by a freeze–pump–thaw procedure.
After an atmospheric pressure of CO gas was introduced, the
reaction mixture was cooled by ice bath and was stirred for
1 h. The resulting yellow solution was precipitated by addition
of Et2O. Then the precipitate was dissolved in CH3NO2, filtered
through celite and reprecipitated, and then dried under vacuum to
yield 3 as a reddish brown solid (144 mg, 0.104 mmol, 80% yield).
1H NMR (200 MHz, CD3NO2): d 8.78 (d, J = 5.6 Hz, 3 H, H13),
8.28 (d, J = 7.8 Hz, 3 H, H11), 8.09 (d, J = 7.6 Hz, 3 H, H10), 7.68
(t, J = 5.7 Hz, 3 H, H12), 7.49 (d, J = 2.3 Hz, 3 H, H6), 7.05 (d, J =
2.7 Hz, 3 H, H7), 5.81 (s, 6 H, H5), 2.78 (brs, 6 H, H3), 1.19 (brs,
9 H, H4). 13C NMR (100 MHz, CD3NO2): d 184.5 (d, JRh-C = 70 Hz,
CO), 154.0 (d, JCH = 184 Hz, C13), 155.3 (C9), 150.9 (s, C1), 148.8
(s, C8), 142.8 (d, JCH = 171 Hz, C11), 135.7 (d, JCH = 198 Hz, C6),
128.6 (s, C2), 126.9 (d, JCH = 172 Hz, C12), 122.8 (d, JCH = 172 Hz,
C10), 105.6 (d, JCH = 187 Hz, C7), 51.9 (t, JCH = 144 Hz, C5), 23.4
(t, JCH = 128 Hz, C3), 14.1 (q, JCH = 128 Hz, C4). IR (CH3NO2
solution) mCO = 2100, 2038 cm−1. ESI-MS (MeCN): m/z = 792.7
Synthesis of 1. Lpypz3 (46 mg, 73 lmol) and [Pd(C3H5)cod]BF4
(78 mg, 230 lmol) were dissolved in CH3NO2 (5 mL) and stirred
at ambient temperature for 1 h. The volatiles were evaporated and
the residual solid was washed with Et2O and hexane to remove
the free cod ligand. The solid was dried under vacuum to yield the
white solid, which was used without further purification (66 mg,
+
[(Lpypz3)Rh(CO)2]+, 1284.2 {[(L1)(Rh(CO)2)3](BF4)2} . Anal. calcd
for C45H39B3F12N9O6Rh3 + Me2CO: C, 40.34; H, 3.17; N, 8.82.
Found: C, 40.39; H, 3.43; N, 8.95%.
1
51 lmol, 70% yield). H NMR (200 MHz, CD3NO2): d 8.75 (d,
J = 4.9 Hz, 3 H, H13), 8.17 (t, J = 7.8 Hz, 3 H, H11), 8.07 (d,
J = 7.9 Hz, 3 H, H10), 7.58 (t, J = 6.5 Hz, 3 H, H12), 7.46 (d,
J = 2.7 Hz, 3 H, H6), 7.06 (d, J = 2.7 Hz, 3 H, H7), 6.02 (m, 3 H,
C3H5), 5.68 (m, 6 H, H5), 4.81, 4.54 (d, J = 5.9 Hz, 6 H, C3H5-
syn), 3.78, 3.51 (d, J = 12.4, 12.2 Hz, 6 H, C3H5-anti), 2.78–2.70
Synthesis of 4. To a CH2Cl2 solution of [Pd(C3H5)cod]BF4
(263 mg, 0.768 mmol), Lphen3 (100 mg, 0.256 mmol) was added and
the mixture immediately became cloudy. The solution was stirred
for 1 h and the white precipitate was collected by filtration. The
filtrate was washed with Et2O and hexane. Drying under vacuum
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©

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1
yielded 4 as a white solid (171 mg, 0.115 mmol, 45%). H NMR
(d, JCH = 166 Hz, C13), 128.1 (d, JCH = 168 Hz, C12), 127.2 (d,
(400 MHz, CD3NO2): d 9.30 (d, J = 5.2 Hz, 3 H, H18), 8.93 (d,
J = 8.3 Hz, 3 H, H16), 8.81 (d, J = 8.5 Hz, 3 H, H9), 8.25–8.20 (m,
6 H, H12 + H13), 8.13–8.10 (m, 3 H, H17), 7.98 (d, J = 8.5 Hz,
3 H, H8), 6.02 (m, J = 6.6 Hz, 3 H, C3H5), 4.63, 4.54 (d, J = 6.8,
7.1 Hz, 6 H, C3H5-syn), 3.81 (t, J = 7.8 Hz, 6 H, H5 or H6), 3.97,
3.58 (d, J = 13.2, 12.0 Hz, 6 H, C3H5), 3.46 (t, J = 7.9 Hz, 6 H, H5
or H6), 2.74 (q, J = 7.2 Hz, 6 H, H3), 1.23 (t, J = 7.2 Hz, 9 H, H4).
JCH = 168 Hz, C8), 126.6 (d, JCH = 170 Hz, C17), 64.2 (t, JCH =
153 Hz, C=C(nbd), 53.0 (d, JCH = 155 Hz, -CH2-(nbd)), 39.9 (t,
JCH = 128 Hz, C5 or C6), 29.9 (t, JCH = 129 Hz, C5 or C6), 24.4 (t,
JCH = 126 Hz, C3), 16.3 (q, JCH = 127 Hz, C4). ESI-MS (MeCN):
m/z = 976.0 [(Lphen3)Rh(nbd)]+, 1539.7 [(Lphen3)Rh3(nbd)3(BF4)2]+.
Synthesis of 7. Complex 6 (200 mg, 0.133 mmol) was dissolved
in CH3NO2 and 1 atm of CO gas was introduced into the reaction
vessel after pumping at 0 ◦C, and the color of the solution turned
from orange to yellow after stirring the reaction mixture at that
temperature for 1 h. Et2O was added to the solution and the
resulting precipitate was redissolved into CH3NO2 and filtered
through celite. The filtrate was concentrated, precipitation with
Et2O, and dried under vacuum to yield a reddish brown solid
13C NMR (100 MHz, CD3NO2): d 165.8 (s, C7), 155.0 (d, JCH
=
187 Hz, C18), 147.0 (s, C15), 146.5 (s, C11), 141.6 (d, JCH = 167 Hz,
C9), 141.0 (d, JCH = 167 Hz, C16), 140.9 (s, C1), 135.5 (s, C2), 131.7
(s, C14), 130.0 (s, C10), 128.9 (d, JCH = 167 Hz, C13), 127.9 (d,
JCH = 167 Hz, C12), 127.0 (d, JCH = 171 Hz, C8), 127.0 (d, JCH
=
170 Hz, C17), 119.8 (t, JCH = 163 Hz, C3H5), 67.6 (t, JCH = 162 Hz,
C3H5), 46.0 (t, JCH = 128 Hz, C5 or C6), 30.0 (t, JCH = 130 Hz,
C5 or C6), 24.3 (t, JCH = 128 Hz, C3), 16.2 (q, JCH = 129 Hz, C4).
ESI-MS(MeCN) m/z = 1162.8 [(Lphen3)Pd2(C3H5)2(BF4)]+, 1397.1
[(Lphen3)Pd3(C3H5)3(BF4)2]+. Anal. calcd for C63H63N6Pd3 + (BF4)3.
C; 50.99, H; 4.28, N; 5.66. Found: C; 50.54, H; 4.44, N; 5.54%.
1
(168 mg, 0.110 mmol, 83%). H NMR (400 MHz, CD3NO2): d
9.26 (d, J = 4.9 Hz, 3 H, H18), 8.83 (d, J = 8.3 Hz, 3 H, H16),
8.75 (d, J = 8.5 Hz, 3 H, H9), 8.19–8.17 (m, 6 H, H12 + H13),
8.13–8.02 (m, 3 H, H17), 7.88 (d, J = 8.3 Hz, 3 H, H8), 3.63 (t,
J = 7.6 Hz, 6 H, H5 or H6), 3.35 (t, J = 7.4 Hz, 6 H, H5 or H6),
2.62 (q, J = 7.4 Hz, 6 H, H3), 1.23 (t, J = 7.4 Hz, 9 H, H4). 13
C
Synthesis of 5. To a CH2Cl2 (2 mL) + MeCN (3 mL) solution
of (cod)PdMeCl (104 mg, 0.39 mmol), Lphen3 (100 mg, 0.128 mmol)
was added dropwise. After the solution was stirred at room
temperature, AgOTf (115 mg, 0.445 mmol) was added and the
mixture was stirred for another 1 h. The reaction mixture was
filtered through Celite and the volatiles of the filtrate were removed
under reduced pressure. The crude product was washed with
Et2O and CH2Cl2 to yield 5 as a yellowish brown solid (147 mg,
0.086 mmol, 67%). 1H NMR (400 MHz, CD3NO2): d 8.80 (d, J =
5.2 Hz, 3 H, H18), 8.61 (d, J = 7.6 Hz, 3 H, H16), 8.52 (d, J =
8.0 Hz, 3 H, H9), 7.91–8.00 (m, 6 H, H12 + H13), 7.83 (brs, 3 H,
H17), 7.57 (d, J = 7.8 Hz, 3 H, H8), 3.39 (brs, 6 H, H5 or H6), 3.22
(brs, 6 H, H5 or H6), 2.65 (brs, 6 H, H3), 2.25 (brs, 9 H, MeCN),
1.26 (brs, 9 H, Pd-Me), 1.04 (t, J = 7.1 Hz, 9 H, H4). 13C NMR
(100 MHz, CD3NO2): d 165.7 (s, C7), 150.3 (d, JCH = 168 Hz,
C18), 148.3 (s, C15), 144.9 (s, C11), 142.0 (d, JCH = 165 Hz, C9),
141.5 (d, JCH = 164 Hz, C16), 140.4 (s, C1), 136.4 (s, C2), 132.1
(s, C14), 129.8 (s, C10), 129.2 (d, JCH = 167 Hz, C13), 127.9 (d,
NMR (100 MHz, CD3NO2): d 184.4 (d, JRh-C = 72 Hz, CO), 155.6
(d, JCH = 190 Hz, C18), 167.7 (s, C7), 148.7 (s, C15), 148.0 (s,
C11), 143.2 (d, JCH = 169 Hz, C9), 143.0 (d, JCH = 161 Hz, C16),
141.9 (s, C1), 135.6 (s, C2), 132.4 (s, C14), 130.8 (s, C10), 129.5
(d, JCH = 168 Hz, C13), 128.6 (d, JCH = 168 Hz, C12), 127.6 (d,
JCH = 173 Hz, C8), 127.5 (d, JCH = 169 Hz, C17), 46.2 (t, JCH
=
128 Hz, C5 or C6), 29.9 (t, JCH = 129 Hz, C5 or C6), 24.3 (t,
JCH = 124 Hz, C3), 16.3 (q, JCH = 127 Hz, C4). ESI-MS (MeCN):
m/z = 939.9 [(Lphen3)Rh(CO)2]+, 1431.4 [(Lphen3)Rh3(CO)6(BF4)2]+.
IR (CH3NO2): mCO = 2096, 2034 cm−1.
Synthesis of 8. A mixture of Lpypz2 (104 mg, 0.22 mmol)
and [Pd(cod)allyl]BF4 (149 mg, 0.44 mmol) in CH2Cl2 (10 mL)
was stirred at ambient temperature for 0.5 h. The volatiles were
evaporated and the solid was precipitated by CH2Cl2–Et2O to
yield 8 as a white solid (122 mg, 0.13 mmol, 58% yield). 1H NMR
(200 MHz, CD3NO2): d 8.79 (d, J = 4.9 Hz, 2 H, H17), 8.20 (t,
J = 7.0 Hz, 2 H, H15), 8.09 (d, J = 7.6 Hz, 2 H, H14), 7.62 (t,
J = 6.1 Hz, 2 H, H16), 7.42 (s, 1 H, H1), 7.36 (d, J = 2.7 Hz, 2 H,
H10), 7.05 (d, J = 2.7 Hz, 2 H, H11), 6.05 (m, 2 H, C3H5), 5.68
(m, 4 H, H9), 4.82, 4.58 (d, J = 6.6 Hz, 4 H, C3H5-syn), 3.82, 3.54
(d, J = 12.4 Hz, 4 H, C3H5-anti), 2.75 (q, J = 7.6 Hz, 6 H, H5 +
H7), 1.23 (t, J = 7.6 Hz, 6 H, H8), 1.12 (t, J = 7.6 Hz, 3 H, H6).
13C NMR (100 MHz, CD3NO2): d 154.8 (d, JCH = 185 Hz, C17),
153.7 (s, C13), 151.6 (s, C3), 148.3 (s, C12), 146.2 (s, C2), 142.0
(d, JCH = 169 Hz, C15), 134.3 (d, JCH = 194 Hz, C10), 130.0 (d,
JCH = 157 Hz, C1), 128.1 (s, C4), 127.1 (d, JCH = 177 Hz, C16),
123.1 (d, JCH = 169 Hz, C14), 119.4 (d, JCH = 166 Hz, C3H5),
105.9 (d, JCH = 184 Hz, C11), 59.7, 66.6 (t, JCH = 162, 152 Hz,
C3H5), 52.5 (t, JCH = 144 Hz, C9), 27.0 (t, JCH = 128 Hz, C5), 23.9
JCH = 168 Hz, C12), 127.6 (d, JCH = 174 Hz, C8), 126.4 (d, JCH
163 Hz, C17), 41.5 (t, JCH = 128 Hz, C5 or C6), 29.9 (t, JCH
130 Hz, C5 or C6), 24.0 (t, JCH = 128 Hz, C3), 16.6 (q, JCH
=
=
=
121 Hz, C4), 7.5 (q, JCH = 139 Hz, MeCN), 3.7 (q, JCH = 136 Hz,
Pd-Me). ESI-MS (MeCN): m/z = 1413.4 [(Lphen3)Pd3Me(OTf)2]+,
1428.5 [(Lphen3)Pd3Me2(OTf)2]+, 1443.5 [(Lphen3)Pd3Me3(OTf)2]+.
Synthesis of 6. Lphen3 (200 mg, 0.256 mmol) was added to a
CH2Cl2 solution of [Rh(nbd)2]BF4 (287 mg, 0.770 mmol) and
stirred for 1 h. The precipitate in the reaction mixture was collected
and the solid was washed with Et2O and hexane, then dried under
vacuum to yield a reddish brown solid (229 mg, 0.141 mmol, 55%).
1H NMR (400 MHz, CD3NO2): d 8.77 (d, J = 8.3 Hz, 3 H, H16),
8.65 (d, J = 8.5 Hz, 3 H, H9), 8.15–8.10 (m, 6 H, H12 + H13),
8.00 (d, J = 5.2 Hz, 3 H, H18), 7.96–7.92 (m, 3 H, H17), 7.68 (d,
(t, JCH = 128 Hz, C7), 15.7 (q, JCH = 128 Hz, C4), 15.3 (q, JCH
=
128 Hz, C4). ESI-MS (MeCN): m/z = 624.1 [(Lpypz2)Pd(C3H5)]+,
858.4 [(Lpypz2)Pd2(C3H5)2(BF4)]+.
=
J = 8.3 Hz, 3 H, H8), 4.76 (12 H, -C CH (nbd)), 4.20 (6 H, -CH-
(nbd)), 3.26 (t, J = 8.3 Hz, 6 H, H5 or H6), 2.98 (t, J = 7.6 Hz, 6 H,
H5 or H6), 2.58 (q, J = 7.3 Hz, 6 H, H3), 1.65 (6 H, -CH2- (nbd)),
1.14 (t, J = 7.3 Hz, 9 H, H4). 13C NMR (100 MHz, CD3NO2): d
168.3 (s, C7) 149.5 (d, JCH = 186 Hz, C18), 148.4 (s, C15), 148.0 (s,
Synthesis of 9. [Rh(cod)2]BF4 (380 mg, 0.934 mmol) and Lpypz2
(222 mg, 0.467 mmol) were dissolved in CH3NO2 (5 mL) and
stirred at ambient temperature for 1 h. After the volatiles were
removed under reduced pressure, the product was washed with
Et2O (20 mL × 3), and dried under vacuum to give 9 as an orange
C11), 141.6 (d, JCH = 169 Hz, C9), 141.5 (s, C1), 141.4 (d, JCH
=
161 Hz, C16), 136.1 (s, C2), 131.6 (s, C14), 130.1 (s, C10), 129.2
1896 | Dalton Trans., 2008, 1888–1898
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©

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solid (450 mg, 0.420 mmol, 90% yield). 1H NMR (400 MHz,
CD3NO2): d 8.14 (t, J = 7.6 Hz, 2 H, H15), 7.99 (d, J = 7.4 Hz,
2 H, H14), 7.83 (d, J = 5.5 Hz, 2 H, H17), 7.57 (t, J = 6.1 Hz, 2 H,
H16), 7.40 (brs, 2 H, H10), 7.19 (s, 1 H, H1), 6.94 (d, J = 2.7 Hz,
C21), 141.3 (d, JCH = 166 Hz, C9), 141.2 (d, JCH = 168 Hz, C16),
134.7 (s, C2), 132.1 (s, C15), 130.4 (s, C10), 129.1 (d, JCH = 167 Hz,
C13), 128.6 (d, JCH = 157 Hz, C22), 128.1 (d, JCH = 167 Hz, C12),
127.4 (d, JCH = 171 Hz, C8), 127.2 (d, JCH = 170 Hz, C17), 120.0 (t,
=
2 H, H11), 5.26 (s, 4 H, H9), 4.97 (brs, 8 H, -CH CH- (cod)),
JCH = 165 Hz, C3H5), 66.7 (t, JCH = 162 Hz, C3H5), 45.7 (t, JCH
128 Hz, C5 or C6), 29.4 (t, JCH = 130 Hz, C5 or C6), 27.1 (t, JCH
=
=
2.65–2.08 (m, 22 H, H5 + H7 + -CH2- (cod)), 1.23 (t, J = 7.4 Hz,
9 H, H6 + H8). 13C NMR (100 MHz, CD3NO2): d 156.4 (s, C13),
153.0 (s, C3), 148.9 (d, JCH = 180 Hz, C17), 148.7 (s, C12), 146.3 (s,
C2), 142.6 (d, JCH = 169 Hz, C15), 136.2 (d, JCH = 195 Hz, C10),
130.3 (d, JCH = 157 Hz, C1), 128.1 (s, C4), 127.1 (d, JCH = 172 Hz,
C16), 123.6 (d, JCH = 171 Hz, C14), 106.1 (d, JCH = 184 Hz, C11),
127 Hz, C20), 23.8 (t, JCH = 126 Hz, C3), 16.3 (q, JCH = 127 Hz,
C4), 16.1 (q, JCH = 127 Hz, C19). ESI-MS (MeCN): m/z = 722.2
[(Lphen2)Pd2(C3H5)2(BF4)]+, 1190.8 [(Lphen2)Pd3(C3H5)3(BF4)2]+.
Synthesis of 12. Lphen2 (154 mg, 0.268 mmol) was added to
a CH2Cl2 solution of [Rh(nbd)2]BF4 (200 mg, 0.536 mmol) and
stirred at RT for 1 h. The resulting precipitate was collected by
filtration, extracted with CH3CN, and the volatile was removed
under reduced pressure. The solid was washed with Et2O and
hexane and drying under vacuum yielded a reddish brown solid
=
84.8 (d, JCH = 150 Hz, -CH CH-), 50.2 (t, JCH = 143 Hz, C9),
31.6 (t, JCH = 130 Hz, -CH2- (cod)), 27.2 (t, JCH = 127 Hz, C5),
24.1 (t, JCH = 128 Hz, C7), 16.1 (q, JCH = 127 Hz, C8), 15.5 (q,
JCH = 128 Hz, C6). ESI-MS (MeCN): 687.7 [(Lpypz2)Rh(cod)]+,
985.6 [(Lpypz2)Rh2(cod)2(BF4)]+. Elemental analysis data could not
be obtained due to instability of the complex.
1
(131 mg, 0.126 mmol, 47%). H NMR (400 MHz, CD3NO2): d
8.75 (d, J = 8.0 Hz, 2 H, H16), 8.57 (d, J = 8.5 Hz, 2 H, H9), 8.11
(m, 4 H, H12 + H13), 8.00 (d, J = 5.1 Hz, 2 H, H18), 7.94–7.90
(m, 2 H, H17), 7.60 (d, J = 8.5 Hz, 2 H, H8), 6.97 (s, 1 H, H22),
Synthesis of 10. A CH3NO2 solution (5 mL) of 9 (100 mg,
0.093 mmol) was degassed by a freeze–pump–thaw procedure
and an atmospheric pressure of CO gas was introduced. Then
the reaction mixture was cooled by an ice bath and stirred for
1 h. The resulting solution was precipitated by addition of Et2O
(20 mL). Then the precipitate was dissolved in CH3NO2, filtered
through celite and reprecipitated, then dried under vacuum to
=
4.73 (8 H, -CH CH- (nbd)), 4.13 (4 H, -CH- (nbd)), 3.25 (t, J =
8.3 Hz, 4 H, H5 or H6), 2.96 (t, J = 7.6 Hz, 4 H, H5 or H6),
2.67 (q, J = 7.6 Hz, 4 H, H3), 2.44 (q, J = 7.6 Hz, 4 H, H20),
1.58 (4 H, -CH2- (nbd)), 1.12 (t, J = 7.6 Hz, 9 H, H19 + H4).
13C NMR (100 MHz, CD3NO2): d 168.5 (s, C7), 149.3 (d, JCH
=
1
185 Hz, C18), 148.1 (s, C15), 147.8 (s, C11), 143.0 (s, C1), 142.3 (s,
C21), 141.4 (d, JCH = 170 Hz, C9), 141.2 (d, JCH = 170 Hz, C16),
134.7 (s, C2), 131.4 (s, C14), 129.9 (s, C10), 129.2 (d, JCH = 165 Hz,
C13), 128.5 (d, JCH = 154 Hz, C22), 127.9 (d, JCH = 166 Hz, C12),
127.6 (d, JCH = 168 Hz, C8), 126.6 (d, JCH = 172 Hz, C17), 64.4 (t,
JCH = 153 Hz, -CH2- (nbd)), 52.9 (d, JCH = 155 Hz, -CH- (nbd)),
39.3 (t, JCH = 129 Hz, C5 or C6), 29.5 (t, JCH = 129 Hz, C5 or C6),
27.1 (t, JCH = 127 Hz, C20), 23.9 (t, JCH = 126 Hz, C3), 16.3 (q,
JCH = 127 Hz, C4), 16.0 (q, JCH = 127 Hz, C19). ESI-MS (MeCN):
m/z = 769.8 [(Lphen2)Rh(nbd)]+, 1333.5 [(Lphen2)Rh3(nbd)3(BF4)2]+.
afford 10 as a yellow solid (68 mg, 0.070 mmol, 75% yield). H
NMR (270 MHz, CD3NO2): d 8.75 (d, J = 5.6 Hz, 2 H, H17), 8.28
(t, J = 7.7 Hz, 2 H, H15), 8.11 (d, J = 7.5 Hz, 2 H, H14), 7.69
(t, J = 5.6 Hz, 2 H, H16), 7.45 (s, 1 H, H1), 7.37 (d, J = 2.3 Hz,
2 H, H10), 7.06 (d, J = 2.7 Hz, 2 H, H11), 5.74 (s, 4 H, H9), 2.73
(q, J = 7.5 Hz, 6 H, H5 + H7), 1.23–1.14 (m, 9 H, H6 + H8).
13C NMR (100 MHz, CD3NO2): d 184.2 (d, JRh-C = 70 Hz, CO),
156.3 (s, C13), 155.2 (d, JCH = 185 Hz, C17), 152.1 (s, C3), 149.0
(s, C12), 146.6 (s, C2), 144.0 (d, JCH = 170 Hz, C15), 136.5 (d,
JCH = 196 Hz, C10), 130.3 (d, JCH = 158 Hz, C1), 128.1 (d, JCH
172 Hz, C16), 127.3 (C4), 124.0 (d, JCH = 171 Hz, C14), 106.7 (d,
JCH = 186 Hz, C11), 52.9 (t, JCH = 143 Hz, C9), 27.2 (t, JCH
128 Hz, C5), 24.2 (t, JCH = 126 Hz, C7), 16.2 (q, JCH = 127 Hz,
=
Crystal structure determination
=
Data for compounds Lpypz, 1, and 2 were collected on a RIGAKU
RAXIS-IV imaging plate area detector with a graphite monochro-
C8), 15.5 (q, JCH = 127 Hz, C6). IR (CH3NO2 solution) mCO
=
2100, 2038 cm−1. ESI-MS (MeCN): 635.5 [(Lpypz2)Rh(CO)2]+, 881.3
[(Lpypz2)Rh2(CO)4(BF4)]+. Anal. calcd for C34H32B2F8N6O4Rh2 +
Me2CO: C, 43.31; H, 3.73; N, 8.19. Found: C, 42.94; H, 3.98; N
8.79%.
˚
mated Mo-Ka radiation source (k = 0.71073 A) at 213 K. In
the reduction of data, Lorentz and polarization corrections were
made.19 The structures were solved by a combination of direct
methods (SHELXS-86)20 and Fourier synthesis (DIRDIF94).21
All calculations were performed using the CrystalStructure22
crystallographic software package except for refinement, which
was performed using SHELXL-97.20b Unless otherwise stated, all
non-hydrogen atoms were refined anisotropically, methyl hydrogen
atoms were refined using riding models and other hydrogen atoms
were fixed at the calculated positions. Lpypz3: All the hydrogen atoms
were refined isotropically and their positions were refined. 1: All
B and F atoms in the three independent BF4 anions were refined
isotropically. Two sets of disordered F atoms on the BF4 anions
were refined isotropically taking into account two components of
three of four F atoms, respectively (occupancies refined as 0.5714 :
0.4286 for B(1)F4, 0.5192 : 0.4808 for B(2)F4, 0.6409 : 0.3591 for
B(3)F4). Three CH3NO2 molecules were included and they were
refined isotropically. Hydrogen atoms on one of the nitromethane
molecule were not included in the refinement. 2: F atoms on
the B(3) atom were refined isotropically taking into account two
Synthesis of 11. Lphen2 (100 mg, 0.174 mmol) was added to
a CH2Cl2 solution of [(cod)Pd(C3H5)]BF4 (120 mg, 0.348 mmol)
and stirred at RT for 1 h. The resulting precipitate was collected by
filtration and extracted with CH3CN, and the volatile was removed
under reduced pressure. The resulting solid was washed with Et2O
and hexane and drying under vacuum yielded a white solid (73 mg,
0.070 mmol, 40%). 1H NMR (400 MHz, CD3NO2): d 9.24 (d, J =
5.2 Hz, 3 H, H18), 8.81 (d, J = 8.3 Hz, 2 H, H16), 8.66 (d, J =
8.5 Hz, 2 H, H9), 8.12–8.16 (m, 4 H, H12 + H13), 8.04–8.00 (m,
2 H, H17), 7.75 (d, J = 8.5 Hz, 2 H, H8), 6.98 (s, 1 H, H22), 6.09
(m, J = 6.6 Hz, 2 H, allyl-H), 4.59 (d, J = 6.8 Hz, 4 H, allyl-H,
syn), 3.76 (brs, allyl-H, anti), 3.60 (t, J = 7.3 Hz, 4 H, H5 or H6),
3.32 (t, J = 7.3 Hz, 4 H, H5 or H6), 2.60 (q, J = 7.2 Hz, 2 H, H3),
2.47 (q, J = 7.2 Hz, 4 H, H20), 1.15–1.09 (m, 9 H, H19 + H4).
13C NMR (100 MHz, CD3NO2): d 166.4 (s, C7), 155.4 (d, JCH
186 Hz, C18), 147.6 (s, C14), 147.2 (s, C11), 143.0 (s, C1), 142.4 (s,
=
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Dalton Trans., 2008, 1888–1898 | 1897
©

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components of three of four F atoms (occupancies refined as
0.5245 : 0.4755). Three CH3NO2 molecules were included, one
of the molecule was refined anisotropically and the rest were
refined isotropically. The N atom in one of the isotropically refined
CH3NO2 molecule is on the special position with its occupancy
0.5 and thus the occupancy of the whole molecule was fixed at 0.5.
Hydrogen atoms attached to the disordered part were not included
in the refinement.†
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Acknowledgements
This research was financially supported by the Japan Society for
Promotion of Science and Technology (Grant-in-Aid for Young
Scientists (B): No. 16750046, Grant-in-Aid for Scientific Research
(B): No. 15350032) and the Ministry of Education, Culture, Sports,
Science and Technology of the Japanese Government (Grant-
in-Aid for Scientific Research on Priority Areas, No. 18065009,
“Chemistry of Concerto Catalysis”), which are gratefully acknowl-
edged.
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1898 | Dalton Trans., 2008, 1888–1898
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The Royal Society of Chemistry 2008
©