Propargylic substitution reaction catalyzed by group IV(Ti, Zr, Hf)-Ru heterobimetallic complexes

Article abstract of DOI:10.1021/om200292p

A series of heterobimetallic complexes consisting of group IV metallocenyl diphosphines and Ru were synthesized and structurally characterized. Most of them work as catalysts toward propargylic substitution reaction of 1,1-diphenyl-2-propyn-1-ol (4) with EtOH. The stoichiometric reactions of the heterobimetallic complexes [MCl₂(μ-η⁵: η¹-C₅H₄PEt₂) ₂RuClCp*] (M = Zr, Hf) with 4 and NaBAr^F₄ afforded key reactive intermediate allenylidene complexes [MCl2(μ- η⁵:η¹-C₅H₄PEt ₂)₂RuCp*(=C=C=CPh₂)]BAr^F ₄, whose molecular structures were confirmed by X-ray analyses. A plausible reaction pathway for the catalytic reaction is proposed where group IV metal chloride and Ru moieties work cooperatively.

Full text of DOI:10.1021/om200292p

ARTICLE
pubs.acs.org/Organometallics
Propargylic Substitution Reaction Catalyzed by Group IV
(Ti, Zr, Hf)ꢀRu Heterobimetallic Complexes
Takamasa Miyazaki, Yoshiaki Tanabe, Masahiro Yuki, Yoshihiro Miyake, and Yoshiaki Nishibayashi*
Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
S Supporting Information
b
ABSTRACT: A series of heterobimetallic complexes consisting of
group IV metallocenyl diphosphines and Ru were synthesized and
structurally characterized. Most of them work as catalysts toward
propargylic substitution reaction of 1,1-diphenyl-2-propyn-1-ol (4)
with EtOH. The stoichiometric reactions of the heterobimetallic
complexes [MCl2(μ-η5:η1-C5H4PEt2)2RuClCp*] (M = Zr, Hf) with
4 and NaBArF4 afforded key reactive intermediate allenylidene com-
plexes [MCl2(μ-η5:η1-C5H4PEt2)2RuCp*(dCdCdCPh2)]BArF ,
4
whose molecular structures were confirmed by X-ray analyses.
A plausible reaction pathway for the catalytic reaction is proposed
where group IV metal chloride and Ru moieties work cooperatively.
’ INTRODUCTION
bearing group IV metallocenyl diphosphine moieties is summarized
in Scheme 1. The TiꢀRu heterobimetallic complex [TiCl2-
(μ-η5:η1-C5H4PEt2)2RuClCp*] (1c) was prepared by a similar meth-
od to the preparation of [ZrCl2(μ-η5:η1-C5H4PEt2)2RuClCp*]
(1a) and [HfCl2(μ-η5:η1-C5H4PEt2)2RuClCp*] (1b), which we
previously reported.7 Introduction of methyl groups to the cyclo-
pentadienylphosphines was also found to be accomplished when
the bis(1-diethylphosphino-2,3,4,5-tetramethylcyclopentadienyl)
group IV metal dichloride [MCl2(η5-C5Me4PEt2)2] (M = Zr, Hf)
was reacted with [Cp*Ru(μ3-Cl)]4 to afford [ZrCl2(μ-η5:
η1-C5Me4PEt2)2RuClCp*] (2a) or [HfCl2(μ-η5:η1-C5Me4PEt2)2-
RuClCp*] (2b). Furthermore, substitution of the RuCp* moiety of 1a
with RuCp was feasible by changing the reactant from [Cp*Ru(μ3-
Cl)]4 to [CpRuCl(PPh3)2] to obtain [ZrCl2(μ-η5:η1-C5H4PEt2)2-
RuClCp] (3a). Formation of these complexes was confirmed by 1H
NMR and 31P NMR spectra, and their detailed structures were con-
firmed by X-ray analyses (see Supporting Information for details).
Propargylic Substitution Reaction of Propargylic Alcohol
Catalyzed by Heterobimetallic Complexes. We next examined
the catalytic activity of these complexes in the propargylic
substitution reaction of 1,1-diphenyl-2-propyn-1-ol (4) with
EtOH. Typical results are shown in Table 1. All the reactions
were carried out in the presence of catalytic amounts of catalyst
(10 mol %) and NaBArF (10 mol %) (BArF = tetrakis[3,
Multinuclear transition-metal complexes are expected to supply
new reactivity that cannot be accomplished by mononuclear ones,
although useful reactions distinctive to multinuclear complexes are
limited in number.1 Meanwhile, we have already reported the syn-
thesis of thiolato-bridged diruthenium complexes and their unique
capabilities toward catalytic propargylic substitution reactions of
propargylic alcohols with nucleophiles,2 where the possible electron
transfer between two ruthenium atoms plays an important role to
promote the reaction.3 As an extension of our study on the pre-
paration and reactivity of thiolato-bridged diruthenium complexes,
we have reported the synthesis of the analogous diruthenium
complexes where chloride ligands or bridging thiolato ligands were
substituted by other atoms (Br, I,4 P5,6), which demonstrated that the
reactivity of diruthenium complexes is significantly affected by halide
ligands or bridging ligands coordinated to Ru atoms.
On the other hand, we have quite recently reported the dehy-
drogenation of amineꢀboranes catalyzed by ZrꢀRu heterobi-
metallic complexes bearing zirconocenyl diphosphines as aux-
iliary ligands, where cooperative activation of amineꢀboranes by
both of the metals is the key to facilitate the reaction.7 In the
course of the investigation of other reactivity of the ZrꢀRu hete-
robimetallic complexes, we have envisaged that electron transfer
between heterometal atoms can occur when both of the metals
are fixed in close proximity because metalꢀmetal bonded ZrꢀRu
heterobimetallic complexes were indeed isolated.7 Herein, we
wish to report the application of ZrꢀRu heterobimetallic com-
plexes and their HfꢀRu and TiꢀRu analogues to the catalytic
propargylic substitution reaction.
4
4
5-bis(trifluoromethyl)phenyl]borate). The ZrꢀRu heterobime-
tallic complex 1a as well as HfꢀRu complex 1b and TiꢀRu
complex 1c showed catalytic activity toward propargylic sub-
stitution reaction to afford the corresponding propargylic sub-
stituted product (5) in moderate yields (Table 1, runs 1ꢀ3). Here,
1a showed almost the same catalytic activity as 1c, while 1b showed
a slightly higher catalytic activity than 1a and 1c. Interestingly, 2a
’ RESULTS AND DISCUSSION
Received: April 5, 2011
Published: May 10, 2011
Preparation and Characterization of Heterobimetallic Com-
plexes. Preparation of a series of heterobimetallic complexes
r
2011 American Chemical Society
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Scheme 1
Scheme 2
Table 1. Catalytic Propargylic Substitution Reaction of 4 with
EtOHa
run
catalyst
yield (%)
1
1a
1b
1c
2a
2b
3a
57
71
56
4
2
3
4
5
18
55
9
6
7
[(η5-C5H4PEt2)2ZrCl2]
8
[Cp*RuCI(depe)]
0
9b
10b
7a
53
7b
71
a Reaction of 4 (0.30 mmol) with EtOH (7.5 mL) in the presence of
Figure 1. ORTEP drawing of 6a. Thermal ellipsoids are shown at the
50% probability level. Hydrogen atoms and BArF anion are omitted
catalyst (0.03 mmol) and NaBArF (0.03 mmol) at 60 °C for 72 h.
4
4
b Reaction was carried out without NaBArF .
for clarity. Selected interatomic distances (Å) and angles (deg):
4
Zr(1) Ru(1), 3.9745(9); Zr(1)ꢀCl(1), 2.4782(19); Zr(1)ꢀCl(2),
3 3 3
2.410(3); Ru(1)ꢀCl(1), 2.4942(17); Ru(1)ꢀP(1), 2.3270(19);
Ru(1)ꢀP(2), 2.3511(19); Cl(1)ꢀZr(1)ꢀCl(2), 95.55(7); Ru(1)ꢀCl-
(1)ꢀZr(1) 106.13(7); Cl(1)ꢀRu(1)ꢀP(1), 90.86(7); Cl(1)ꢀ
Ru(1)ꢀP(2), 88.36(6); P(1)ꢀRu(1)ꢀP(2), 95.26(7).
and 2b, bearing a tetramethyl-substituted metallocenyl diphosphine
moiety, showed much less catalytic activity than 1a and 1b, res-
pectively (Table 1, runs 4, 5), while 3a, bearing a cyclopentadienyl
(Cp) moiety on Ru, showed almost the same catalytic activity as 1a
(Table 1, run 6). Both mononuclear Zr complex [(η5C5H4PEt2)2-
ZrCl2] (Table 1, run 7) and Ru complex [Cp*RuCl(depe)] (Table 1,
run 8) were not catalytically active at all.
The catalytic activity of 1a is apparently much higher than
mononuclear complexes [(η5-C5H4PEt2)2ZrCl2] and [Cp*Ru-
Cl(depe)] (depe = 1,2-bis(diethylphosphino)ethane), indicating
that both Zr and Ru moieties in 1a participate in the catalysis.
The significant decrease of the catalytic activity of 2a in compar-
ison with 1a clarified that substituents of the cyclopentadienyl
moiety of the zirconocenyl diphosphine directly affect the
catalytic activity. In contrast, 3a showed almost the same
reactivity as 1a, suggesting that substituents of the cyclopenta-
dienyl moiety of Ru have less influence on the catalytic activity.
Unfortunately, other propargylic alcohols bearing a terminal
alkyne moiety such as 1-phenyl-2-propyn-1-ol,8 1,1-bis(4-
methylphenyl)-2-propyn-1-ol,9 and propargylic alcohol bearing
an internal alkyne moiety such as 1,1-diphenyl-2-propyn-
3-phenyl-1-ol8 were not applicable to this catalytic reaction.
Isolation and Characterization of Heterobimetallic
Allenylidene Complexes as Reactive Intermediates. To get some
information about the reaction pathway of this catalytic reaction, we
investigated stoichiometric reactions of the heterobimetallic com-
plexes 1a and 1b with 4. Treatment of 1a with NaBArF
4
afforded [ZrCl(μ-η5:η1-C5H4PEt2)2(μ-Cl)RuCp*]BArF (6a) in
4
67% yield, which further reacted with 4 to give the corresponding
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Scheme 3
Scheme 4
Figure 2. ORTEP drawing of 7a. Thermal ellipsoids are shown at the
50% probability level. Hydrogen atoms and BArF4 anion are omitted for
clarity. Selected interatomic distances (Å) and angles (deg): Zr(1)
3 3 3
Ru(1), 4.9464(8); Zr(1)ꢀCl(1), 2.4377(17); Zr(1)ꢀCl(2), 2.4262(16);
Ru(1)ꢀP(1), 2.3175(13); Ru(1)ꢀC(16), 1.901(5); C(16)ꢀC(17),
1.243(8); C(17)ꢀC(18), 1.358(8); Cl(1)ꢀZr(1)ꢀCl(2), 97.46(6);
P(1)ꢀRu(1)ꢀC(16), 92.20(12); Ru(1)ꢀC(16)ꢀC(17) 170.9(5);
C(16)ꢀC(17)ꢀC(18), 175.1(6); C(17)ꢀC(18)ꢀC(19), 117.6(5);
C(17)ꢀC(18)ꢀC(23), 122.9(5); C(19)ꢀC(18)ꢀC(23), 119.5(4);
P(1)ꢀRu(1)ꢀP(1)*, 95.30(4).
ZrꢀRu heterobimetallic allenylidene complex [ZrCl2(μ-η5:
η1-C5H4PEt2)2RuCp*(dCdCdCPh2)]BArF (7a) in 67% yield.
4
Complex 7a could also be prepared directly by treatment of 1a with
1.1 equiv of 4 in the presence of 1 equiv of NaBArF4 in 57% yield.
Similarly, the HfꢀRu heterobimetallic allenylidene complex
[HfCl2(μ-η5:η1-C5H4PEt2)2RuCp*(dCdCdCPh2)]BArF (7b)
4
was obtained in 67% yield (Scheme 2). Thus, formation of the
allenylidene complexes 7 should proceed via the formation of the
chloride-bridged complexes 6 as intermediates.
1
Complexes 6a, 7a, and 7b were characterized by H and 31P
NMR spectra as well as X-ray analyses. As shown in Figures 1 and
2, the configuration around the Ru center in both 6a and 7a adopts
a three-legged piano stool coordination geometry, typical of
coordinatively saturated cyclopentadienyl Ru(II) bis(phosphine)
complexes.10 As for 6a, the interatomic distance between Zr and
Ru atoms (3.9745(9) Å) is too long to draw a metalꢀmetal single
bond,11 where the chloride ligand bridges Zr and Ru atoms. The
interatomic distance between Zr and Ru (4.9464(8) Å) in 7a is
comparable to that of 1a (5.0017(4) Å),7 suggesting that there is
also no metalꢀmetal bond. Moreover, the almost linear angles
(Ru(1)ꢀC(16)ꢀC(17), 170.9(5)°; C(16)ꢀC(17)ꢀC(18),
175.1(6)°) and the bond distances in the allenylidene moiety
(C(16)ꢀC(17), 1.243(8) Å; C(17)ꢀC(18), 1.358(8) Å) in 7a
are comparable to those reported for cationic ruthenium alleny-
lidene complexes.12 These structural features as well as NMR and
IR spectroscopic observations (νCdCdC = 1914 cmꢀ1) strongly
support the formation of the allenylidene complex 7a. It should be
noted that the complex 7a offers a rare example of multinuclear
allenylidene compounds with only a terminal allenylidene ligand
on the heterobimetallic center.13
activity as the corresponding heterobimetallic complexes 1a and
1b.14 Moreover, propargylic alcohol bearing an internal alkyne
moiety is not applicable to this reaction, as shown in the previous
section, suggesting that the formation of the Ru allenylidene moi-
ety is necessary for the catalytic reaction to proceed. Meanwhile,
we have also investigated the reaction of 2a with 1.1 equiv of 4 in
the presence of 1 equiv of NaBArF in order to obtain the cor-
4
responding allenylidene complex, which resulted in no formation
of the desired allenylidene complex. Taking into consideration this
result as well as the low catalytic activity of 2 (Table 1, runs 4, 5), it
is suggested that the formation of the Ru allenylidene moiety is
indeedrequisitefor thecatalyticreaction. Thus, these results stron-
gly support that our catalytic reaction proceeds via the formation
of allenylidene complexes 7 as reactive intermediates.
Next, we investigated catalytic reactions of 7a and 7b. Treat-
ment of 4 with a catalytic amount of 7a or 7b (10 mol %) afforded
5 in 53% and 71% yields, respectively (Table 1, runs 9, 10),
demonstrating that 7a and 7b show almost the same catalytic
In order to gain more information about our heterobimetallic
catalysis, we have newly prepared the FeꢀRu heterobimetallic
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complex [Cp*RuCl(depf)] (8; depf = 1,10-bis(diethylphosphino)-
ferrocene) and investigated the catalytic activity of 8 toward the
propargylic substitution reaction of 4 with EtOH, as shown in
Scheme 3. Treatment of [Cp*Ru(μ3-Cl)]4 with 4 equiv of depf
afforded 8 in 73% yield. Next, we investigated the reaction of 4
with catalytic amounts of 8 (10 mol %) and NaBArF4 (10 mol %).
As a result, no formation of 5 was observed in the reaction,
while the formation of the corresponding allenylidene complex
[Cp*Ru(dCdCdCPh2)(depf)]BArF4 (9) was observed in situ,
confirmed by NMR and IR spectra. Indeed, 9 was successfully
isolated by the reaction of 8 with 1 equiv of 4 in the presence of
’ EXPERIMENTAL SECTION
1
General Procedures. H NMR (270 MHz) and 31P NMR (109
MHz) spectra were recorded on a JEOL Excalibur 270 spectrometer in
suitable solvents. 31P NMR chemical shifts were quoted relative to an
external standard of 85% H3PO4. Elemental analyses were performed at
the Microanalytical Laboratory of The University of Tokyo or on an
Exeter Analytical CE-440 elemental analyzer. IR spectra were recorded on
a JASCO FT/IR 4100 Fourier transform infrared spectrophotometer. All
reactions were carried out under a dry nitrogen atmosphere or in an argon-
filled glovebox. Solvents were dried by general methods and degassed be-
fore use. [Cp*Ru(μ3-Cl)]4,15 [CpRuCl(PPh3)2],16 [Cp*RuCl(depe)],17
1 equiv of NaBArF in 77% yield (Scheme 3). These results
NaBArF ,18 depf,19 Na[C5H4PEt2], [(η5-C5H4PEt2)2ZrCl2], 1a, and 1b7
4
4
clearly indicate that group IV metallocenyl diphosphine moieties
are essential to the catalytic reaction.
were prepared according to the literature procedures. Na[C5Me4PEt2] was
synthesized according to the slightly modified procedure of the preparation
of Na[C5H4PEt2], using LiC5Me4H instead of CpLi. Other reagents were
purchased commercially and used as received.
Plausible Reaction Pathway. A plausible reaction pathway is
shown in Scheme 4. First, 1 reacts with 4 in the presence of
NaBArF to form a vinylidene complex (A). Subsequent de-
Preparation of [TiCl2(μ-η5:η1-C5H4PEt2)2RuClCp*] (1c). To
a slurry of Na[C5H4PEt2] (367 mg, 2.08 mmol) in toluene (25 mL) and
a trace amount of THF (0.1 mL) was added [TiCl4(thf)2] (332 mg,
0.994 mmol), and the mixture was stirred at room temperature for 4 h.
Then, [Cp*Ru(μ3-Cl)]4 (272 mg, 0.250 mmol) was added to the
reaction mixture and stirred for a further 12 h. The resulting reaction
mixture was filtered through a pad of Celite, and solvent was removed
from the filtrate in vacuo. The resulting brown residue was washed with
hexane (7 mL ꢁ 3) and Et2O (7 mL ꢁ 2), then recrystallized from
4
hydration of A leads to the formation of allenylidene complex 7.
Next, nucleophilic attack of EtOH to the Cγ atom of the
allenylidene ligand results in the formation of an alkynyl complex
(B), then the hydrogen atom shifts into the Cβ atom on the
ligand to give another vinylidene complex (C). Complex C is
then transformed into the η2-coordinated propargylic ether
tautomer (D), which liberates 5 with the formation of the
chloride-bridged heterobimetallic complex 6. Finally, 6 reacts
with another 4 to regenerate the vinylidene complex A. In the
previously reported propargylic substitution reactions catalyzed
by thiolato-bridged diruthenium complexes, it was revealed that
the electron transfer between two ruthenium atoms is the key
step to facilitate catalysis.3 In contrast, the distances between
heterometals in the present catalysts such as complexes 1 and 7
are too long to interact with, as shown in Figure 2. At present, we
consider that the formation of the chloride-bridged complex 6 is
the key step that promotes the dissociation of 5 from D.
However, the difference of catalytic activity between 1a (or 1c)
and 1b may suggest that the electronic nature of the group IV
metal may affect the catalytic activity; that is, the possibility that
electronic transfer between heterometals facilitates catalysis
cannot be ruled out. The significant decrease of the catalytic
activity of 2a compared to those of 1a, 3a, and 5a is probably
due to the steric repulsion between methyl substituents of
the zirconocene moiety and the pentamethylcyclopentadienyl
ligand on Ru, which prevents not only the facile transformation
of D into 6 but also subsequent formation of the allenylidene
complex 7.
In summary, novel heterobimetallic complexes 1c, 2a, 2b, 3a,
and 6a consisting of group IV metallocenyl diphosphines and Ru
were synthesized and structurally characterized. It was demon-
strated that complexes 1 and 3a work as catalysts toward the
propargylic substitution reaction of 4 with EtOH to obtain 5 in
moderate yields, whereas complex 2, bearing tetramethyl-substi-
tuted metallocenyl diphosphine as an auxiliary ligand, did not
work as a catalyst at all. Treatment of the heterobimetallic com-
plexes 1a and 1b with 4 in the presence of NaBArF4 afforded the
corresponding heterobimetallic allenylidene complexes 7a and
7b, respectively, as reactive intermediates, and their molecular
structures were confirmed by X-ray analyses. Studies on the reac-
tion pathway revealed that both group IV metallocenyl dipho-
sphine dichloride moieties and the Ru allenylidene moiety work
cooperatively in the catalytic reaction. Further work is currently
in progress to develop other useful and intriguing reactions
distinctive to our heterobimetallic system.
benzeneꢀhexane to afford 1c 1.5C6H6 as brown blocks. Crystals of
3
1c 1.5C6H6 are effluorescent and gave off benzene to afford a brown
3
powder of 1c (242 mg, 0.347 mmol, 35% isolated yield) after drying in
vacuo. 1H NMR (C6D6): δ 7.84 (br, 2H, C5H4), 7.03 (br, 2H, C5H4),
5.50 (br, 2H, C5H4), 2.35 (br, 2H, PCH2), 1.81 (br, 6H, PCH2), 1.43
(s, 15H, Cp*), 1.08 (br t, 3JHH = 7.6 Hz, 6H, CH2Me), 0.61 (br t, 3JHH
=
7.8 Hz, 6H, CH2Me). 31P{1H} NMR (C6D6): δ 37.7 (s). Anal. Calcd for
C28H43Cl3P2TiRu: C, 48.26; H, 6.22. Found: C, 47.97; H, 6.03.
Preparation of [ZrCl2(μ-η5:η1-C5Me4PEt2)2RuClCp*] (2a).
To a slurry of Na[C5Me4PEt2] (1.03 g, 4.43 mmol) in toluene (50 mL)
and a trace amount of THF (0.2 mL) was added [ZrCl4(thf)2] (773 mg,
2.05 mmol), and the mixture was stirred at room temperature for 3 h.
Then, [Cp*Ru(μ3-Cl)]4 (557 mg, 0.512 mmol) was added to the reaction
mixture, and the mixture was stirred for a further 6 h. The resulting
reaction mixture was filtered through a pad of Celite, and solvent was
removed from the filtrate in vacuo. The resulting orange residue was
washed with hexane (10 mL ꢁ 4) to afford 2a as an orange solid (1.09 g,
1.28 mmol, 62% isolated yield). Orange plates of 2a 1.5C6H6 suitable for
3
X-ray crystallography were obtained by layering hexane onto a benzene
solution of 2a. 1H NMR (C6D6): δ 2.62ꢀ2.51 (m, 2H, PCH2), 2.09ꢀ
1.97 (m, 30H, C5Me4 and PCH2), 1.53 (s, 15H, Cp*), 1.03 (dt, 3JHP
=
15.9 Hz, 3JHH = 7.3 Hz, 6H, CH2Me), 0.63 (dt, 3JHP = 13.2 Hz, 3JHH = 7.3
Hz, 6H, CH2Me). 31P{1H} NMR (C6D6): δ 40.3 (s). Anal. Calcd for
C36H59Cl3P2RuZr: C, 50.72; H, 6.98. Found: C, 51.01; H, 7.27.
Preparation of [HfCl2(μ-η5:η1-C5Me4PEt2)2RuClCp*] (2b).
To a slurry of Na[C5Me4PEt2] (100 mg, 0.431 mmol) in toluene (10 mL)
and a trace amount of THF (0.1 mL) was added [HfCl4(thf)2] (95.1 mg,
0.205 mmol), and the mixture was stirred at room temperature for 3 h.
Then, [Cp*Ru(μ3-Cl)]4 (55.7 mg, 0.0512 mmol) was added to the reaction
mixture, and the mixture was stirred for a further 6 h. The resulting reaction
mixture was filtered through a pad of Celite; then solvent was removed from
the filtrate in vacuo. The resulting orange residue was washed with hexane
(3 mL ꢁ 3) to afford 2b as an orange solid (80.5 mg, 0.0857 mmol, 42%
isolated yield). Red blocks of 2b suitable for X-ray crystallography were
obtained by layering hexane onto a benzene solution of 2b, which was
1
then kept cooled at 0 °C. H NMR (C6D6): δ 2.71 (br, 2H, PCH2),
2.16ꢀ1.99 (m, 30H, C5Me4 and PCH2), 1.54 (s, 15H, Cp*), 1.15 (dt,
3
3JHP = 16.5 Hz, JHH = 7.3 Hz, 6H, CH2Me), 0.61 (dt, 3JHP = 12.7 Hz,
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3JHH = 7.0 Hz, 6H, CH2Me). 31P{1H} NMR (C6D6): δ 41.2 (s). Anal.
Calcd for C36H59Cl3HfP2Ru: C, 46.01; H, 6.33. Found: C, 45.96; H, 6.33.
Preparation of [ZrCl2(μ-η5:η1-C5H4PEt2)2RuClCp] (3a). To a
slurry of [CpRuCl(PPh3)2] (1.41 g, 1.94 mmol) in toluene (25 mL) was
added [(η5-C5H4PEt2)2ZrCl2] (1.00 g, 2.13 mmol), and the mixture
was refluxed overnight. Then, solvent was removed in vacuo, and the
resulting orange residue was washed with Et2O (10 mL ꢁ 4) to afford 3a
asanorangesolid(904 mg, 1.35 mmol, 69%isolatedyield). Redneedlesof
3a suitable for X-ray crystallography were obtained by layering hexane
onto a toluene solution of 3a. 1H NMR (C6D6): δ 7.99 (br, 2H, C5H4),
6.69(br, 2H, C5H4), 6.61ꢀ6.59 (m, 2H, C5H4), 5.74 (br, 2H, C5H4), 4.40
(s, 5H, Cp), 2.26ꢀ2.11 (m, 2H, PCH2), 1.90ꢀ1.79 (m, 4H, PCH2),
1.71ꢀ1.52 (m, 2H, PCH2), 0.78ꢀ0.62 (m, 12H, CH2Me). Anal. Calcdfor
C23H33Cl3P2RuZr: C, 41.22; H, 4.96. Found: C, 41.09; H, 4.91.
Preparation of [Cp*RuCl(depf)] (8). To a slurry of [Cp*Ru-
(μ3-Cl)]4 (227 mg, 0.209 mmol) in THF (7.5 mL) was added depf
(303 mg, 0.837 mmol), and the mixture was stirred at room temperature for
18 h. Then, solvent was removed in vacuo, and the resulting orange residue
was extracted with CH2Cl2 and filtered through a pad of Celite. After
solvent was removed from the filtrate, the resulting orange-yellow residue
was washed with hexane (5 mL ꢁ 4) to afford 8 as a yellow solid (389 mg,
0.614 mmol, 73% isolated yield). 1H NMR (C6D6): δ 5.31 (br, 2H, C5H4),
4.04 (br, 2H, C5H4), 4.01 (br, 2H, C5H4), 3.91 (br, 2H, C5H4), 2.45 (br,
2H, PCH2), 1.90 (br, 4H, PCH2), 1.90 (br, 2H, PCH2), 1.57 (s, 15H, Cp*),
1.13ꢀ0.97 (m, 12H, CH2Me). 31P{1H} NMR (C6D6): δ 34.2 (s). Anal.
Calcd for C28H43ClFeP2Ru: C, 53.05; H, 6.84. Found: C, 52.49; H, 6.82.
Preparation of [Cp*Ru(dCdCdCPh2)(depf)]BArF4 (9). To a
solution of 8 (127 mg, 0.200 mmol) in ClCH2CH2Cl (4 mL) were added
NaBArF4 (177 mg, 0.200 mmol) and 4 (43.6 mg, 0.209 mmol), and the
mixture was heated at 60 °C and stirred for 24 h. The resulting reaction
mixture was filtered, and all the volatiles were removed in vacuo. The
resulting reddish-purple residue was then recrystallized from CH2Cl2ꢀhex-
ane and kept cooled at ꢀ35 °C to afford 9 as red blocks (252 mg, 0.153
Preparation of [ZrCl(μ-η5:η1-C5H4PEt2)2(μ-Cl)RuCp*]BArF
4
(6a). To a solution of 1a (92.7 mg, 0.125 mmol) in C6H5F (5 mL) was
added NaBArF (111 mg, 0.125 mmol), and the mixture was heated at
4
60 °C and stirred for 8 h. The resulting reaction mixture was filtered, and
hexane was layered onto the filtrate to afford 6a as red plates (132 mg,
0.0842 mmol, 67% isolated yield). 1H NMR (CD2Cl2): δ 7.66 (br, 8H,
BArF ), 7.50 (br, 4H, BArF ), 7.07 (br, 2H, C5H4), 6.54 (br, 2H, C5H4),
1
mmol, 77% isolated yield). H NMR (CD2Cl2): δ 7.73ꢀ7.58 (m, 14H,
BArF and CPh), 7.50 (br, 4H, BArF ), 7.44ꢀ7.38 (m. 4H, CPh), 4.36
4
4
4
4
(br, 4H, C5H4), 4.13 (br, 2H, C5H4), 4.03 (br, 2H, C5H4), 2.18ꢀ2.05 (m,
2H, PCH2), 1.90 (br, 2H, PCH2), 1.81 (s, 15H, Cp*), 1.73ꢀ1.63 (m, 2H,
PCH2), 1.48 (br, 2H, PCH2), 1.17 (dt, 3JHP = 14.0 Hz, 3JHH = 7.0 Hz, 6H,
CH2Me), 0.77 (dt, 3JHP = 17.0 Hz, 3JHH = 7.6 Hz, 6H, CH2Me). 31P{1H}
NMR (CD2Cl2): δ 45.7 (s). IR (KBr, cmꢀ1): 1911 (s, νCdCdC). Anal.
Calcd for C75H65BF24FeP2Ru: C, 54.53; H, 3.97. Found: C, 54.33; H, 4.07.
Catalytic Propargylic Substitution Reaction of 4 with
EtOH. A typical experimental procedure for the reaction of 4 with
EtOH catalyzed by 1a is described as follows. Compounds 1a (22.2 mg,
6.22 (br, 2H, C5H4), 6.12 (br, 2H, C5H4), 2.49ꢀ2.06 (m, 6H, PCH2),
1.96ꢀ1.84 (m, 2H, PCH2), 1.64 (s, 15H, Cp*), 1.10 (dt, 3JHP = 17.8 Hz,
3JHH = 7.6 Hz, 6H, CH2Me), 0.91 (dt, 3JHP = 14.3 Hz, 3JHH = 7.3 Hz, 6H,
CH2Me). 31P{1H} NMR (CD2Cl2): δ 20.7 (s). Anal. Calcd for
C60H55Cl3BCl2F24P2RuZr: C, 45.96; H, 3.54. Found: C, 45.76; H, 3.64.
Preparation of [ZrCl2(μ-η5:η1-C5H4PEt2)2RuCp*(dCdCd
CPh2)]BArF (7a). Method A. To a solution of 1a (110.3 mg,
4
0.149 mmol) in ClCH2CH2Cl (3 mL) was added NaBArF (133 mg,
4
0.150 mmol) and 4(34.5 mg, 0.166 mmol), and the mixture was heated and
stirred at 60 °C for 8 h. The resulting reaction mixture was filtered, and all
the volatiles were removed in vacuo. The resulting reddish-purple residue
was recrystallized from CH2Cl2ꢀhexane and kept cooled at ꢀ35 °C to
afford 7a as dark orange plates (150 mg, 0.0853 mmol, 57% isolated yield).
Method B. To a solution of 6a (108.5 mg, 0.0692 mmol) in ClCH2CH2Cl
(2.5 mL) was added 4 (14.4 mg, 0.0691 mmol); then the mixture was
heated at 60 °C and stirred for 8 h. The resulting reaction mixture was
filtered, and all the volatiles were removed in vacuo. The resulting reddish-
purple residue was recrystallized from CH2Cl2ꢀhexane and kept cooled
at ꢀ35 °C to afford 7a as dark orange plates (81.0 mg, 0.0461 mmol, 67%
isolated yield). 1H NMR (CD2Cl2): δ7.68ꢀ7.67 (m, 14H, BArF4 and CPh),
0.030 mmol), NaBArF (26.6 mg, 0.030 mmol), and 4 (62.5 mg, 0.30
4
mmol) were placed in a 20 mL flask. Anhydrous EtOH (7.5 mL) was
added, and then the mixture was stirred at 60 °C for 72 h. After the
solvent was removed in vacuo, the resulting reddish-purple residue was
extracted with hexane (1 mL ꢁ 3) and purified by column chromatog-
raphy (SiO2) with EtOAcꢀn-hexane (1/9) to give 5 as a pale yellow oil.
’ ASSOCIATED CONTENT
S
Supporting Information. CIF file with X-ray crystallo-
b
graphic data for 1c 1.5C6H6, 2a 1.5C6H6, 2b, 3a, 7b, and 9. This
material is available free of charge via the Internet at http://pubs.
acs.org.
3
3
7.66 (br, 4H, BArF ), 7.65ꢀ7.40 (m. 4H, CPh), 6.89 (br, 2H, C5H4), 6.75
4
(br, 4H, C5H4), 5.79 (br, 2H, C5H4), 2.27ꢀ2.18 (m, 2H, PCH2), 2.03ꢀ1.95
(m, 2H, PCH2), 1.86 (s, 15H, Cp*), 1.77ꢀ1.67 (m, 2H, PCH2), 1.61ꢀ1.54
(m, 2H, PCH2), 1.25 (dt, 3JHP = 15.7 Hz, 3JHH = 7.8 Hz, 6H, CH2Me), 0.61
(dt, 3JHP = 17.8 Hz, 3JHH = 7.4 Hz, 6H, CH2Me). 31P{1H} NMR (CD2Cl2):
δ 39.0 (s). IR (KBr, cmꢀ1): 1914 (s, νCdCdC). Anal. Calcd for
C75H65BCl2F24P2RuZr: C, 51.23; H, 3.73. Found: C, 50.76; H, 3.92.
Preparation of [HfCl2(μ-η5:η1-C5H4PEt2)2RuCp*(dCdCd
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: ynishiba@sogo.t.u-tokyo.ac.jp.
CPh2)]BArF (7b). To a solution of 1b (124 mg, 0.150 mmol) in
’ ACKNOWLEDGMENT
4
ClCH2CH2Cl (3 mL) was added NaBArF4 (133 mg, 0.150 mmol) and 4
(34.6 mg, 0.166 mmol), and the mixture was heated at 60 °C and stirred for
8 h. The resulting reaction mixture was filtered, and all the volatiles were
removed in vacuo. The resulting reddish-purple residue was recrystallized
from CH2Cl2ꢀhexane and kept cooled at ꢀ35 °C to afford 7b as red
needles (185 mg, 0.100 mmol, 67% isolated yield). 1H NMR (CD2Cl2): δ
This work was supported by a Grant-in-Aid for the Scientific
Research for Young Scientist (S) (No. 19675002) from the
Ministry of Education, Culture, Sports, Science and Technology
of Japan and Funding Program for Next Generation World-
Leading Researchers (GR025). Y.N. thanks Ube Industries LTD.
T.M. acknowledges the Global COE program for Chemistry
Innovation. We also thank the Research Hub for Advanced Nano
Characterization at The University of Tokyo for X-ray analysis.
7.67ꢀ7.65 (m, 14H, BArF4 and CPh), 7.63 (br, 4H, BArF ), 7.50ꢀ7.40 (m.
4
4H, CPh), 6.79 (br, 2H, C5H4), 6.67 (br, 2H, C5H4), 6.63 (br, 2H, C5H4),
5.68 (br, 2H, C5H4), 2.31ꢀ2.14 (m, 2H, PCH2), 2.04ꢀ1.93 (m, 2H,
PCH2), 1.86 (s, 15H, Cp*), 1.78ꢀ1.70 (m, 2H, PCH2), 1.69ꢀ1.54 (m, 2H,
PCH2), 1.25 (dt, 3JHP = 15.7 Hz, 3JHH = 7.8 Hz, 6H, CH2Me), 0.58 (dt,
3JHP = 18.1 Hz, 3JHH = 7.4 Hz, 6H, CH2Me). 31P{1H} NMR (CD2Cl2):
δ40.6(s).IR(KBr, cmꢀ1):1914(s,νCdCdC). Anal. Calcd for C75H65BCl2F24-
HfP2Ru: C, 48.81; H, 3.55. Found: C, 48.38; H, 3.70.
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