Synthesis of dinuclear (μ-η3-Allyl)palladium(I) and -platinum(I) complexes supported by chelate-bridging ligands

Article abstract of DOI:10.1021/om400557p

Dinuclear (μ-η³-allyl)palladium(I) complexes supported by chelate-bridging ligands, (μ-η³-allyl)Pd₂(μ-L) (L = N,N′-bis[2-(diphenylphosphino)phenyl]formamidinate, N-(2-diphenylphosphino)phenyl-N′-8-quinolylformamidinate, N,N′-di-8-quinolylformamidinate, N,N′-di-8-quinolylacetamidinate), were synthesized, and some of them were characterized by X-ray crystallography. A dinuclear (μ-η³-allyl)platinum(I) complex, (μ-η³-allyl)Pt₂(μ-L), was also synthesized and crystallographically characterized.

Full text of DOI:10.1021/om400557p

Article
pubs.acs.org/Organometallics
3
Synthesis of Dinuclear (μ‑η ‑Allyl)palladium(I) and -platinum(I)
Complexes Supported by Chelate-Bridging Ligands
Yu Yamaguchi, Katsunori Yamanishi, Mitsuru Kondo, and Naofumi Tsukada*
†
‡
†,§
,†,§
†
‡
§
Department of Chemistry, Graduate School of Science, Graduate School of Science and Technology, and Research Institute of
Green Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
*
S Supporting Information
3
ABSTRACT: Dinuclear (μ-η -allyl)palladium(I) complexes
3
supported by chelate-bridging ligands, (μ-η -allyl)Pd (μ-L)
2
(
L = N,N′-bis[2-(diphenylphosphino)phenyl]formamidinate,
N-(2-diphenylphosphino)phenyl-N′-8-quinolylformamidinate,
N,N′-di-8-quinolylformamidinate, N,N′-di-8-quinolylacetami-
dinate), were synthesized, and some of them were
3
3
characterized by X-ray crystallography. A dinuclear (μ-η -allyl)platinum(I) complex, (μ-η -allyl)Pt (μ-L), was also synthesized
2
and crystallographically characterized.
INTRODUCTION
Chart 1. Chelate-Bridging Ligands
■
3
The structure and reactivity of mononuclear (η -allyl)-
palladium(II) complexes have been thoroughly investigated,
1
and catalysis via the allyl complex has been extensively utilized
2
in organic synthesis such as the Tsuji−Trost reaction. In
3
contrast, less attention has been paid to dinuclear (μ-η -
allyl)palladium(I) complexes, although the synthesis and
structure of the complexes were first reported more than 30
3
years ago. In particular, there have been few reports on their
3
a,4
reactivity,
even though they have the potential to exhibit
reactivities different from those of the mononuclear complexes
and work as a catalyst for the novel transformation of organic
5
molecules. For example, Hazari recently reported a novel
reactivity of the bridging allyl ligand and its application to a
catalytic transformation of carbon dioxide.
6
RESULTS AND DISCUSSION
The reaction of dpfamH with [(η -C H )PdCl] (1a) or [(η -
■
3
3
One of the reasons that the study of the reactivity and
catalytic use of palladium species is rare might be the easy
cleavage of dinuclear complexes into two mononuclear
3
5
2
3
C H )PdOAc] (1b) in the presence of TMEDA gave (μ-η -
3
5
2
C H )Pd (μ-dpfam) (2a) in high yields (Scheme 1). While the
3
5
2
3
a,4b,c
complexes.
Therefore, suppression of the cleavage gives
synthesis from 1b proceeded without TMEDA to give 2a in
similar yield, the addition of TMEDA was essential to the
synthesis from 1a. The reaction of dpfamH with 1b in the
absence of TMEDA or in the presence of other amines such as
3
new possibilities for the chemistry of dinuclear (η -allyl)-
palladium(I) complexes. One solution is the use of chelate-
bridging ligands, which hold two metal atoms in adjacent
positions. We previously reported the synthesis of various
dinuclear palladium(II) and platinum(II) complexes supported
(i-Pr)
include a trace amount of 2a. Complex 2a was also synthesized
NEt gave a mixture of unidentified complexes, which
2
1
b y t h e c h e l a t e - b r i d g i n g l i g a n d N , N ′ - b i s [ 2 -
from Pd(0) and Pd(II): the reaction of dpfamH with /
2
mol of
7
the dimer 1a and Pd (dba) ·CHCl afforded 2a in 72% yield.
(
diphenylphosphino)phenyl]formamidinate (dpfam), and this
2
3
3
8
The reaction of dpfamH with Pd (dba) ·CHCl and allyl
work was extended by Waymouth and co-workers. We also
reported organic transformations catalyzed by the dinuclear
2
3
3
chloride (3a) or allyl acetate (3b) also gave 2a in one step. In a
9
similar manner, the reaction of other chelate-bridging ligands
complexes. In the course of our study, dinuclear palladium(I)
with 1b in the presence of TMEDA gave the dinuclear
complexes having a metal−metal bond were also synthesized by
3
1
0
3
allylpalladium complexes (μ-η -C H )Pd (μ-dpqfam) (4; 85%
using dpfam. We report here the synthesis of dinuclear (μ-η -
allyl)palladium(I) and -platinum(I) complexes supported by
dpfam and the related chelate-bridging ligands N-(2-
diphenylphosphino)phenyl-N′-8-quinolylformamidinate
3
5
2
3
3
yield), (μ-η -C H )Pd (μ-qfam) (5; 55% yield), and (μ-η -
3
5
2
C H )Pd (μ-qaam) (6; 45% yield) (Chart 2). The correspond-
3
5
2
1
1
(
dpqfam), N,N′-di-8-quinolylformamidinate (qfam), and
N,N′-di-8-quinolylacetamidinate (qaam) (Chart 1).
Received: June 15, 2013
Published: August 22, 2013
©
2013 American Chemical Society
4837
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Article
Scheme 1. Synthesis of Dinuclear Allylpalladium(I) Complex
2
a
Figure 1. Molecular structure of 2a, showing 50% thermal ellipsoids.
Hydrogen atoms are omitted for clarity. The bridging allyl ligand is
disordered and occupies two sites. Only one site is depicted. Selected
bond lengths (Å) and angles (deg): Pd(1)−Pd(2) = 2.6073(3),
Pd(1)−C(38a) = 2.058(19), Pd(1)−C(39a) = 2.441(6), Pd(1)−P(1)
=
2.2450(8), Pd(1)−N(1) = 2.119(3), Pd(2)−C(39a) = 2.430(5),
Pd(2)−C(40a) = 2.07(3), Pd(2)−P(2) = 2.2629(7), Pd(2)−N(2) =
2.122(3); P(1)−Pd(1)−Pd(2) = 169.54(2), P(2)−Pd(2)−Pd(1) =
166.38(3).
Chart 2. Dinuclear Allylpalladium(I) Complexes Supported
by Chelate-Bridging Ligands
Figure 2. Molecular structure of 4, showing 50% thermal ellipsoids.
Hydrogen atoms and solvent molucules are omitted for clarity.
Selected bond lengths (Å) and angles (deg): Pd(1)−Pd(2) =
2
.5832(8), Pd(1)−C(30) = 2.324(10), Pd(1)−C(31) = 2.062(11),
Pd(1)−N(1) = 2.110(6), Pd(1)−N(2) = 2.112(8), Pd(2)−C(29) =
2
.066(12), Pd(2)−C(30) = 2.486, Pd(2)−N(3) = 2.140(8), Pd(2)−
P(1) = 2.2416(19); N(1)−Pd(1)−Pd(2) = 156.53(19), P(1)−Pd(2)−
Pd(1) = 160.54(6).
ing platinum complex 7 can be also synthesized by the reaction
3
of dpfamH with [(η -C H )PtCl] in dichloromethane (50%
3
5
4
3
yield). There have been few reports on dinuclear (η -allyl)
4c,12
platinum complexes.
slightly shorter than that of 2a, owing to the weak trans
influence of quinoline.
The compounds 2a, 4, and 6 were characterized by X-ray
crystallography (Figures 1−3, respectively). In all complexes,
the central carbon of the allyl ligand binds to both palladium
atoms, while the terminal carbons bind to different palladium
atoms. The bridging amidinate binds to palladium atoms only
through the nitrogen atoms. The palladium−amidinate carbon
distances are 3.011−3.061 Å, indicating that the carbon atoms
do not bind to palladium atoms. The palladium−center carbon
distances (2.360−2.486 Å) are similar to those in allyl
Compound 7 was also characterized by X-ray crystallography
(Figure 4). To the best of our knowledge, this is the first
3
example of a crystallographically characterized dinuclear (μ-η -
allyl)platinum(I) complex. The structure of 7 is similar to that
of the corresponding palladium complex 2a. The Pt−Pt
distance of 7 (2.6411 Å) is slightly longer than the Pd−Pd
distance of 2a (2.6073 Å). In contrast, the Pt−P distances are
slightly shorter than the Pd−P distances. There are no
significant differences between the Pt−allyl carbon distances
6a,c
complexes bridged by carboxylate ligands.
In contrast, the
1
3
palladium−terminal carbon distances (2.058−2.094 Å) are
longer than those of the carboxylate complexes (1.984−2.047
Å), perhaps due to the trans influence. The Pd−Pd distances
vary according to the coordinating atoms on the Pd−Pd axis.
The Pd−Pd distance of 2a (2.6073 Å), which has two
phosphine groups on the axis, is similar to those of reported
and the Pd−allyl distances.
The complexes bearing substituted allyl ligands, 2b−e, were
prepared in a similar manner using the corresponding
palladium dimers [(η -1-RC H )PdOAc] and [(η -2-RC H )-
3
3
3
4
2
3
4
PdOAc] (R = Me, Ph) in 46−73% yields (Chart 3). While
2
3
complex 2c was also obtained from dpfamH and [(η -2-
PhC H )PdCl] , the reaction of dpfamH and [(η -1-PhC H )-
PdCl] under similar conditions gave the A-frame complex (η -
1-PhC H ) Pd (μ-Cl)(μ-dpfam). Complexes 2d,e were ob-
3
3
dinuclear (μ-η -allyl)palladium(I) complexes having two
3
4
2
3
4
4
c,e,6a,c
1
phosphine ligands.
The Pd−Pd distance of 6 (2.526
2
7
Å), which has two nitrogen groups on the Pd−Pd axis, is
3
4 2
2
4
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did not change by heating at 60 °C for 20 h in C D . Osakada
6
6
and Yamamoto reported that alkenes promoted the isomer-
3
4b
ization of (μ-η -1-MeC H )Pd (μ-SPh)(PCy ) . Unexpect-
3
4
2
3 2
edly, the syn/anti ratio of 2e was not changed by the addition
of styrene or methyl acrylate. In contrast, tert-butyl isocyanide
was found to promote the isomerization of 2e: the isomer-
ization of a 10/90 (syn/anti) mixture of 2e in the presence of 5
equiv of tert-butyl isocyanide in C D at room temperature
6
6
resulted in a 49/51 equilibrium mixture of 2e. The isomer-
ization of 72/28 mixture of 2e by tert-butyl isocyanide also gave
a 49/51 mixture of 2e. Complex 2d was obtained as a 76/24
3
(
syn/anti) mixture by the reaction of [(η -1-MeC H )PdOAc]
3
4
2
and dpfamH. The ratio was reproducible, in contrast with the
case for 2e. The isomerization of 2d by tert-butyl isocyanide
resulted in a 29/71 equilibrium mixture. The anti preference of
Figure 3. Molecular structure of 6, showing 50% thermal ellipsoids.
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Pd(1)−Pd(2) = 2.526(2), Pd(1)−C(21) = 2.07(2),
Pd(1)−C(22) = 2.40(2), Pd(1)−N(1) = 2.090(14), Pd(1)−N(2) =
2
d,e is weaker than those of the reported dinuclear complexes
3
(
μ-η -1-RC H )(μ-X)Pd (PPh ) (R = Me, Ph, X = halogen,
3 4 2 3 2
4b,c
SPh).
2
.110(12), Pd(2)−C(22) = 2.36(2), Pd(2)−C(23) = 2.094(16),
3
In the reaction of [(η -1-PhC H )PdOAc] and dpfamH,
3
4
2
Pd(2)−N(3) = 2.095(14), Pd(2)−N(4) = 2.116(13); N(1)−Pd(1)−
Pd(2) = 162.1(4), N(4)−Pd(2)−Pd(1) = 164.1(4).
cinnamyl acetate (120%) was also generated along with 2e
65%) (Scheme 2). Phenylpropene and its isomers and dimers
(
Scheme 2. Generation of Cinnamyl Acetate in the Reaction
3
of [(η -1-PhC H )PdOAc] and dpfamH
3
4
2
Figure 4. Molecular structure of 7, showing 50% thermal ellipsoids.
Hydrogen atoms are omitted for clarity. The bridging allyl ligand is
disordered and occupies two sites. Only one site is depicted. Selected
bond lengths (Å) and angles (deg): Pt(1)−Pt(2) = 2.6411(5), Pt(1)−
C(38b) = 2.0645(4), Pt(1)−C(39b) = 2.4046(4), Pt(1)−P(1) =
were not observed by GC-MS. The result indicates that Pd(0)
is formed by reductive elimination of cinnamyl acetate from
3
[
(η -1-PhC H )PdOAc] . Although the precise mechanism for
3
4
2
the formation of the dinuclear complex 2 is unclear, it is likely
3
that 2 is formed by the reaction between Pd(0) and (η -
2
.2336(19), Pt(1)−N(1) = 2.108(7), Pt(2)−C(39b) = 2.4421(4),
Pt(2)−C(40b) = 2.0552(4), Pt(2)−P(2) = 2.2275(18), Pt(2)−N(2)
2.120(6); P(1)−Pt(1)−Pt(2) = 166.87(6), P(2)−Pt(2)−Pt(1) =
68.80(5).
3
RC H )Pd(dpfam), which is generated from dpfamH and [(η -
3
4
=
1
RC H )PdX] . As mentioned above, the addition of TMEDA
3 4 2
was essential for the synthesis of 2a from the chloride dimer 1a,
and (i-Pr) NEt did not work as well as TMEDA. TMEDA may
2
Chart 3. Dinuclear Palladium(I) Complexes Bridged by 1- or
-Substituted Allyl Ligands
function not only as a base to abstract hydrogen from dpfamH
and trap hydrogen chloride but also as a chelate ligand to
accelerate reductive elimination of allyl chloride.
2
Next, the stability and reactivity of dinuclear complexes 2 was
investigated. Expectedly, the chelate-bridging ligand suppresses
the cleavage to mononuclear complexes. No cleavage of
complex 2a was observed in the presence of excess
triphenylphosphine or dppe in benzene solution. Complexes
2a−e were not decomposed by heating at 200 °C for several
minutes or by exposure to air for several months. Complex 2a
was so unreactive that any transformation or decomposition
was not observed in the reaction with several organic
compounds in THF or benzene at 80 °C. Styrene, isoprene,
methyl acrylate, acetylacetone, and iodobenzene did not react
with 2a, while the reaction with methyl iodide gave a complex
mixture. Similarly to the dinuclear allyl complexes bridged by
tained as a mixture of syn/anti stereoisomers. The syn/anti
configurations were unambiguously established on the basis of
coupling constants, showing a value for the center proton−anti
proton coupling larger than that for the center proton−syn
4b,c
proton coupling.
Moreover, the configurations of syn
isomers of 2d,e were also confirmed by NOE experiments:
irradiation of the center proton resonance of syn-2d increased
the methyl resonance, and irradiation of the center proton of
syn-2e increased the phenyl resonance. The syn/anti ratio of 2e
was not reproducible between reactions (78/22 to 10/90) and
6c
carboxylates, CO (1 atm, room temperature) did not insert
2
into the palladium−allyl bond of 2a. Other small molecules
such as CO (20 atm, 100 °C) and H (1 atm, 80 °C) also did
2
not react with 2a.
4
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Article
Yield: 75 mg, 92%. In the reaction without the addition of TMEDA,
the yield was 91% (74 mg).
Method C. To a solution of dpfamH (56 mg, 0.10 mmol) in
CONCLUSION
■
In summary, we have synthesized and characterized new
3
dinuclear (μ-η -allyl)palladium(I) and -platinum(I) complexes
acetone (4 mL) was added Pd (dba) ·CHCl (52 mg, 0.050 mmol).
2
3
3
supported by several chelate-bridging ligands. Further studies
on the reactivity toward organic molecules and catalytic activity
of the dinuclear complexes are ongoing in our group.
After the mixture was stirred at room temperature for 0.5 h, 1a (18
mg, 0.050 mmol) and TMEDA (30 μL, 0.20 mmol) were added. The
reaction mixture was stirred at room temperature for 18 h to give a
yellow precipitate, which was collected by filtration after the addition
of water (2 mL) to the suspension, washed with methanol and diethyl
ether, and dried under reduced pressure. Yield: 59 mg, 72%.
EXPERIMENTAL SECTION
■
Method D. To a solution of dpfamH (56 mg, 0.10 mmol) and
All reactions were carried out using standard Schlenk techniques under
a nitrogen atmosphere. Dry solvents were purchased and used directly
as received. The chelate-bridging ligands dpfamH and dpqfamH were
Pd (dba) ·CHCl (104 mg, 0.10 mmol) in acetone (4 mL) were
2
3
3
added TMEDA (30 μL, 0.20 mmol) and 3a (8.2 μL, 0.10 mmol) or 3b
11 μL, 0.10 mmol). The mixture was stirred at room temperature
7,11
1
(
prepared according to literature methods.
H NMR spectra were
overnight to give a yellow precipitate, which was collected by filtration
after the addition of water (2 mL) to the suspension, washed with
methanol and diethyl ether, and dried under reduced pressure. Yield:
measured on a JEOL ECA-600 (600 MHz) spectrometer. Chemical
shifts were reported in the scale relative to tetramethylsilane (0 ppm).
1
3
1
C{ H} NMR spectra were measured on a JEOL ECA-600 (151
5
8 mg (72%) from 3a, 65 mg (80%) from 3b.
MHz) spectrometer. Chemical shifts were reported in the scale relative
3
31
1
Synthesis of (μ-η -2-MeC H )Pd (μ-dpfam) (2b). This com-
3 4 2 2
to CDCl (77.1 ppm) as an internal reference. P{ H} NMR spectra
3
plex was prepared by method B from dpfamH (56 mg, 0.10 mmol)
were measured on a JEOL ECA-600 (243 MHz) spectrometer.
Chemical shifts were reported in the scale relative to phosphoric acid
3
and [(η -2-MeC H )PdOAc] (44 mg, 0.10 mmol) and isolated as a
3
4
2
1
yellow powder (46 mg, 52%). H NMR (600 MHz, CDCl ): δ 10.17
3
(
0 ppm). High-resolution mass spectral analysis (HRMS) was carried
(
1
t, J = 2.4 Hz, 1H, NCHN), 7.57−7.49 (m, 10H, Ar), 7.36−7.30 (m,
P
out with a JEOL JMS-T100LP instrument.
Synthesis of qfamH and qaamH. A solution of 8-aminoquino-
line (0.72 g, 5.0 mmol), trimethyl orthoformate (0.55 mL, 5.0 mmol),
6H, Ar), 6.91 (t, J = 7.2 Hz, 2H, Ar), 3.39 (virtual t, J + J = 6.6 Hz,
P P′
3
1
1
2
H, syn-H), 1.71−1.69 (m, 5H, center-Me and anti-H). P{ H} NMR
(243 MHz, CDCl ): δ 18.83. Anal. Calcd for C H N P Pd : C,
3 41 36 2 2 2
and p-TsOH·H O (9.5 mg, 0.05 mmol) in benzene (2.5 mL) was
2
5
9.22; H, 4.36; N, 3.37. Found: C, 59.30; H, 4.51; N, 3.22.
gently refluxed for 18 h. After the mixture was cooled, benzene,
methanol, and excess trimethyl orthoformate were removed under
reduced pressure at room temperature. Diisopropyl ether (30−40 mL)
was added to the residue, and the mixture was refluxed until the solid
dissolved. After the mixture was cooled to room temperature, yellow
precipitates were collected by filtration, washed with a small amount of
3
Synthesis of (μ-η -2-PhC H )Pd (μ-dpfam) (2c). This complex
3
4
2
2
was prepared by method A from dpfamH (56 mg, 0.10 mmol) and
3
[
(η -2-PhC H )PdCl] (52 mg, 0.10 mmol) and isolated as a yellow
3 4 2
1
powder (41 mg, 46%). H NMR (600 MHz, CDCl ): δ 10.13 (t, J =
3
P
2
.6 Hz, 1H, NCHN), 7.63−7.58 (m, 4H, Ar), 7.51−7.46 (m, 6H, Ar),
7
.37−7.33 (m, 16H, Ar), 7.28−7.25 (m, 2H, Ar), 6.95−6.92 (m, 3H,
1
diisopropyl ether, and dried to yield 0.51 g (68%) of qfamH. H NMR
Ar), 6.90 (t, J = 7.4 Hz, 2H, Ar), 3.74 (virtual t, J + J = 7.7 Hz, 2H,
P
P′
(
600 MHz, CDCl ): δ 9.70 (br s, 1H, NH), 8.91 (br s, 2H, 2 × C2-H),
31
1
3
syn-H) 1.80 (s, 2H, anti-H). P{ H} NMR (243 MHz, CDCl ): δ
3
8
.65 (br s, 1H, NCHN), 8.18−8.14 (m, 2H, 2 × C4-H), 7.55−7.41
2
0.97. Anal. Calcd for C H N P Pd : C, 61.83; H, 4.29; N, 3.13.
13 1
46 38 2 2 2
(
m, 8H, 2 × C3-H, 2 × C5-H, 2 × C6-H, and 2 × C7-H). C{ H}
Found: C, 61.30; H, 4.30; N, 2.84.
NMR (151 MHz, CDCl ): δ 150−148 (br), 147.36, 135.97, 130−128
3
3
Synthesis of (μ-η -1-MeC H )Pd (μ-dpfam) (2d). This complex
3
4
2
2
(
br), 126.98, 124−118 (br), 121.5. HRMS (ESI): m/z calcd for
was prepared by method B from dpfamH (56 mg, 0.10 mmol) and
+
C H N [M + H] 299.1291, found 299.1295. Mp: 99 °C.
3
19
15
4
[
(η -1-MeC H )PdOAc] (44 mg, 0.10 mmol) and isolated as a yellow
3 4 2
Ligand qaamH was prepared analogously as a yellow powder (46%
1
powder (50 mg, 60%, syn/anti = 75/25). H NMR (600 MHz,
1
yield). H NMR (600 MHz, CDCl ): δ 9.25 (s, 1H, NH), 9.20 (d, J =
3
CDCl ): syn isomer, δ 10.01 (t, J = 2.0 Hz, 1H, NCHN), 3.06 (m,
3
P
7.6 Hz, 1H, C7-H), 8.89 (d, J = 2.1 Hz, 1H, C2-H), 8.80 (d, J = 2.8
1
H, syn-H), 2.87 (m, 1H, center-H), 2.32 (m, 1H, anti-H geminal to
Hz, 1H, C2-H), 8.16−8.12 (m, 2H, 2 × C4-H), 7.53−7.47 (m, 3H,
C5-H and 2 × C6-H), 7.43 (dd, J = 4.1, 8.3 Hz, 1H, C3-H), 7.38 (d, J
Me), 1.47 (dd, J = 6.2 Hz, J = 7.6 Hz, 3H, Me), 1.43 (br d, J = 12.4
P
Hz, 1H, anti-H); anti isomer, δ 10.14 (t, J = 2.4 Hz, 1H, NCHN),
P
=
8.3 Hz, 1H, C5-H), 7.35 (dd, J = 4.1. 8.3 Hz, 1H, C3-H), 7.21 (m,
3
.90 (m, 1H, syn-H geminal to Me), 3.19 (m, 1H, center-H), 2.86 (m,
1H, syn-H), 1.85 (br d, J = 13.1 Hz, 1H, anti-H), 0.81 (t, J = 5.5 Hz, JP
5.5 Hz, 3H, Me). Anal. Calcd for C H N P Pd : C, 59.22; H, 4.36;
13
1
1
1
1
1
3
H, C7-H), 2.09 (s, 3H, CH3). C{ H} NMR (151 MHz, CDCl ): δ
53.57, 149.35, 148.47, 147.43, 141.88, 138.55, 136.48, 136.23, 135.99,
29.36, 127.84, 127.80, 126.82, 121.61, 121.19, 120.82, 120.02, 119.27,
15.82, 20.04. HRMS (ESI): m/z calcd for C H N [M + H]
13.1448, found 313.1455. Mp: 139 °C.
3
=
41
36
2
2
2
N, 3.37. Found: C, 59.13; H, 4.41; N, 3.33.
+
3
20
17
4
Synthesis of (μ-η -1-PhC H )Pd (μ-dpfam) (2e). This complex
3 4 2 2
was prepared by method B from dpfamH (56 mg, 0.10 mmol) and
3
Synthesis of (μ-η -C H )Pd (μ-dpfam) (2a). Method A. To a
3
3
5
2
2
[(η -1-PhC H )PdOAc] (57 mg, 0.10 mmol) and isolated as a yellow
3
4
2
solution of dpfamH (0.28 g, 0.50 mmol) and TMEDA (0.15 mL, 1.0
mmol) in acetone (20 mL) was added 1a (0.18 g, 0.50 mmol). The
mixture was stirred at room temperature overnight to give a yellow
precipitate, which was collected by filtration after the addition of water
powder (65 mg, 73%, syn/anti = 64/36). The syn/anti ratio was not
1
reproducible. H NMR (600 MHz, CDCl ): syn isomer, δ 9.92 (s, 1H,
3
NCHN), 3.50 (m, 1H, center-H), 3.35 (br d, J = 11.7 Hz, anti-H
geminal to Ph), 3.13 (m, 1H, syn-H), 1.55 (br d, J = 13.1 Hz, 1H, anti-
(
15 mL) to the suspension, washed with methanol and diethyl ether,
H); anti isomer, δ 10.13 (s, 1H, NCHN), 4.56 (ddd, J = 8.6 Hz, J =
P
1
and dried under reduced pressure. Yield: 0.36 g, 88%. H NMR (600
2.7, 11.3 Hz, 1H, syn-H geminal to Ph), 3.26 (m, 1H, center-H), 2.65
MHz, CDCl ): δ 10.13 (t, J = 2.0 Hz, 1H, NCHN), 7.54−7.48 (m,
(dt, J = 2.7, 8.9 Hz, J = 8.9 Hz, 1H, syn-H), 2.23 (m, 1H, anti-H).
3
P
P
1
0H, Ar), 7.36−7.32 (m, 16H, Ar), 6.91 (t, J = 7.2 Hz, 2H, Ar), 3.18
Anal. Calcd for C H N P Pd : C, 61.83; H, 4.29; N, 3.13. Found: C,
46
38
2
2
2
(
m, 2H, syn-H), 3.12 (m, 1H, center-H), 1.56 (d, J = 13.2 Hz, 2H,
61.66; H, 4.32; N, 3.14.
31
1
3
anti-H). P{ H} NMR (243 MHz, CDCl ): δ 20.81. Anal. Calcd for
Synthesis of (μ-η -C H )Pd (μ-dpqfam) (4). This complex was
3
3 5 2 2
C H N P Pd : C, 58.77; H, 4.19; N, 3.43. Found: C, 58.82; H, 4.29;
prepared by method B from dpqfamH (0.29 g, 0.53 mmol) and 1b
40
34
2
2
2
1
N, 3.36.
(0.22 g, 0.53 mmol) and isolated as a yellow powder (0.31 g, 85%). H
Method B. To a solution of dpfamH (56 mg, 0.10 mmol) and
TMEDA (30 μL, 0.20 mmol) in acetone (4 mL) was added 1b (41
mg, 0.10 mmol). The mixture was stirred at room temperature
overnight to give 2a as a yellow precipitate, which was collected by
filtration after the addition of water (2 mL) to the suspension, washed
with methanol and diethyl ether, and dried under reduced pressure.
NMR (600 MHz, CDCl ): δ 10.13 (d, J = 2.1 Hz, 1H, NCHN), 9.02
3
P
(ddd, J = 1.4 Hz, J = 4.8, 1.4 Hz, 1H, C2-H), 8.23 (dd, J = 8.2, 1.4 Hz,
P
1H, C4-H), 7.68 (d, J = 8.3 Hz, 1H, C7-H), 7.59 (dd, J = 8.9, 4.8 Hz,
1H, Ar) 7.58−7.53 (m, 4H, Ar), 7.50 (t, J = 8.3 Hz, 1H, C6-H), 7.46
(dd, J = 8.2, 4.8 Hz, 1H, C3-H), 7.40−7.35 (m, 5H, C5-H and Ar),
7.35−7.29 (m, 4H, Ar), 6.95 (t, J = 7.6 Hz, 1H, Ar), 3.78 (m, 1H,
4
840
dx.doi.org/10.1021/om400557p | Organometallics 2013, 32, 4837−4842

Organometallics
Article
center-H), 3.04 (d, J = 8.2 Hz, 1H, syn-H), 2.98 (m, 1H, syn-H), 1.95
Information). The quality of the structure is lower due to the the
small size of the crystals.
(
d, 13.0 Hz, 1H, anti-H), 1.30 (dd, J = 1.4, 12.4 Hz, 1H, anti-H).
3
1
1
P{ H} NMR (243 MHz, CDCl ): δ 17.19.
Recrystallization of 6 by vapor diffusion of n-pentane into a solution
of benzene afforded an orange plate. Data collection was carried out
on a Rigaku CCD Mercury system fitted with a monochromatic Mo
Kα radiation source (λ = 0.71070 Å) at room temperature. Eighteen
preliminary data frames were measured at 0.5° increments of ω, to
assess the crystal quality and preliminary unit cell parameters. The
intensity images were also measured at 0.5° intervals of ω. The
intensity images were integrated using the Crystal Clear program
package. The structure was solved by direct methods (SHELX97). All
non-hydrogen atoms were refined anisotropically by full-matrix least-
squares techniques. All hydrogen atoms were placed in idealized
positions and were included but not refined. Crystal data and
refinement details are summarized in Table S1 (Supporting
Information). The quality of the structure is lower due to the small
size of the crystals.
3
3
Synthesis of (μ-η -C H )Pd (μ-qfam) (5). This complex was
3
5
2
2
prepared by method B from qfamH (0.26g, 0.86 mmol) and 1b (0.36
1
g, 0.86 mmol) and isolated as a red powder (0.24 g, 51%). H NMR
(
600 MHz, CDCl ): δ 10.14 (s, 1H, NCHN), 8.99 (dd, J = 1.4, 4.8 Hz,
3
2
2
2
1
2
1
H, C2-H), 8.24 (dd, J = 1.4, 8.2 Hz, 2H, C-4H), 7.74 (d, J = 7.6 Hz,
H, C7-H), 7.51 (t, J = 7.6 Hz, 2H, C6-H), 7.46 (dd, J = 4.8, 8.2 Hz,
H, C3-H), 7.35 (d, J = 7.6 Hz, 2H, C5-H), 4.38 (tt, J = 7.6, 13.1 Hz,
H, center-H), 2.86 (d, J = 7.6 Hz, 2H, syn-H), 1.63 (d, J = 13.1 Hz,
H, anti-H). Anal. Calcd for C H N Pd : C, 47.93; H, 3.29; N,
22
18
4
2
0.16. Found: C, 47.95; H, 3.33; N, 10.34.
3
Synthesis of (μ-η -C H )Pd (μ-qaam) (6). This complex was
3
5
2
2
prepared by method B from qaamH (31 mg, 0.10 mmol) and 1b (41
1
mg, 0.10 mmol) and isolated as a red powder (25 mg, 45%). H NMR
(
600 MHz, CDCl ): δ 8.90 (dd, J = 1.4, 4.8 Hz, 2H, C2-H), 8.25 (dd, J
3
=
1.4, 8.2 Hz, 2H, C4-H), 7.48 (t, J = 7.6 Hz, 2H, C6-H), 7.45 (dd, J =
Recrystallization of 7 by vapor diffusion of diethyl ether into a
solution of dichloromethane afforded a pale yellow prism. Data
collection was carried out on a Rigaku CCD Mercury system fitted
with a monochromatic Mo Kα radiation source (λ = 0.71070 Å) at
room temperature. Eighteen preliminary data frames were measured at
4
7
.8, 8.2 Hz, 2H, C3-H), 7.42 (d, J = 7.6 Hz, 2H, C7-H), 7.33 (d, J =
.6 Hz, 2H, C5-H), 4.38 (tt, J = 7.6, 12.4 Hz, 1H, center-H), 2.69 (d, J
=
7.6 Hz, 2H, syn-H), 1.56 (d, J = 12.4 Hz, 2H, anti-H). Anal. Calcd
for C H N Pd : C, 48.87; H, 3.57; N, 9.91. Found: C, 48.88; H, 3.59;
23
20
4
2
0
.5° increments of ω, to assess the crystal quality and preliminary unit
N, 10.08.
Synthesis of (μ-η -C H )Pt (μ-dpfam) (7). To a solution of
dpfamH (56 mg, 0.10 mmol) and TMEDA (30 μL, 0.20 mmol) in
3
cell parameters. The intensity images were also measured at 0.5°
intervals of ω. The intensity images were integrated using the Crystal
Clear program package. The structure was solved by direct methods
3
5
2
2
3
dichloromethane (4 mL) was added [(η -C H )PtCl] (54 mg, 0.050
3
5
4
(
SIR92). All non-hydrogen atoms were refined anisotropically by full-
mmol). After the mixture was stirred at room temperature for 4 h,
volatiles were removed under reduced pressure. The residue was
dissolved in hexane/dichloromethane (1/1) and passed through a
short silica gel pad. After the solvents were removed under reduced
pressure, the residue was washed with diethyl ether, collected by
matrix least-squares techniques. All hydrogen atoms were placed in
idealized positions and were included but not refined. Crystal data and
refinement details are summarized in Table S1 (Supporting
Information).
1
filtration, and dried under reduced pressure. Yield: 50 mg, 50%. H
NMR (600 MHz, CDCl ): δ 11.40 (t, J = 3.4 Hz, J = 124 Hz, 1H,
ASSOCIATED CONTENT
Supporting Information
3
P
Pt
■
NCHN), 7.62−7.51 (m, 10H, Ar), 7.44 (m, 2H, Ar), 7.39−7.30 (m,
*
S
1
4H, Ar), 6.94 (t, J = 7.6 Hz, 2H, Ar), 3.11 (m, 1H, center-H), 2.85
31
1
A table and CIF files giving crystallographic data for 2a, 4, 6,
(
m, 2H, syn-H), 1.62 (m, 2H, anti-H). P{ H} NMR (243 MHz,
CDCl ): δ 33.19 ( J = 3703 Hz, J = 46 Hz, J = 99 Hz). Anal.
1
1
2
3
14
and 7 and figures giving the H NMR spectrra for qfamH,
3
Pt
Pt
P
31
qaamH, 2a−e, and 4−7 and the P NMR spectrum for 7. This
material is available free of charge via the Internet at http://
pubs.acs.org.
Calcd for C H N P Pt : C, 48.29; H, 3.44; N, 2.82. Found: C, 48.30;
40
34
2
2
2
H, 3.50; N, 2.73.
Crystallographic Structural Determination. Recrystallization of
a by vapor diffusion of diethyl ether into a solution of dichloro-
2
methane afforded a yellow block. Data collection was carried out on a
Rigaku ValiMax with a Saturn diffractometer using a multilayer mirror
monochromatic Mo Kα radiation source (λ = 0.71075 Å) at −99.8 °C.
Eighteen preliminary data frames were measured at 0.5° increments of
ω, to assess the crystal quality and preliminary unit cell parameters.
The intensity images were also measured at 0.5° intervals of ω. The
intensity images were integrated using the Crystal Clear program
package. The structure was solved by direct methods (SIR92). The
allyl ligand, which was disordered at two positions, was located in the
difference Fourier map and then refined with restrained (SHELX-97)
C−C bond distances (SADI and SAME). All non-hydrogen atoms
were refined anisotropically by full-matrix least-squares techniques. All
hydrogen atoms except the allyl ligand were placed in idealized
positions and were included but not refined. Crystal data and
refinement details are summarized in Table S1 (Supporting
Information).
AUTHOR INFORMATION
Corresponding Author
E-mail for N.T.: sntsuka@ipc.shizuoka.ac.jp.
■
*
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by a Grant-in-Aid for Scientific
Research (No. 20550091) from MEXT and carried out using
instruments of the Center for Instrumental Analysis of
Shizuoka University.
REFERENCES
■
Recrystallization of 4 by vapor diffusion of n-pentane into a solution
of benzene afforded a yellow block (4·C H ). Data collection was
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program package. The structure was solved by direct methods
(
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full-matrix least-squares techniques. All hydrogen atoms were placed in
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