Carbon-carbon bond formation involving a vinylidene ligand and ferrocenyl substituent in cationic ruthenium complexes

Article abstract of DOI:10.1021/om900775r

A formal intramolecular olefin metathesis process between the C=C double bond of a vinylidene ligand and a pendant vinyl group in several ruthenium complexes, each with a ferrocenyl group, is followed by an additional intramolecular C-C bond formation between a Cp ligand of the ferrocenyl substituent and the vinylidene ligand. The regioselectivity of the C-C bond formation reaction at either the substituted or the nonsubstituted Cp group of the ferrocenyl group is possibly influenced by a steric effect between the neighboring substituent near the ferrocenyl group and the phosphine ligand on the ruthenium metal center. The structure of one ruthenium complex resulting from such a C-C bond formation has been fully characterized by a single-crystal X-ray diffraction analysis.

Full text of DOI:10.1021/om900775r

1092 Organometallics 2010, 29, 1092–1099
DOI: 10.1021/om900775r
Carbon-Carbon Bond Formation Involving a Vinylidene Ligand and
Ferrocenyl Substituent in Cationic Ruthenium Complexes
Li-Han Chang, Cheng-Wei Yeh, Hao-Wei Ma, Shu-Yu Liu, Ying-Chih Lin,*
Yu Wang, and Yi-Hong Liu
Department of Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China
Received September 6, 2009
A formal intramolecular olefin metathesis process between the CdC double bond of a vinylidene
ligand and a pendant vinyl group in several ruthenium complexes, each with a ferrocenyl group, is
followed by an additional intramolecular C-C bond formation between a Cp ligand of the ferrocenyl
substituent and the vinylidene ligand. The regioselectivity of the C-C bond formation reaction at
either the substituted or the nonsubstituted Cp group of the ferrocenyl group is possibly influenced by
a steric effect between the neighboring substituent near the ferrocenyl group and the phosphine ligand
on the ruthenium metal center. The structure of one ruthenium complex resulting from such a C-C
bond formation has been fully characterized by a single-crystal X-ray diffraction analysis.
Introduction
vinylidene derivatives.5 Vinylidene on a metal is considered
as an electron-withdrawing ligand stabilized by electron-rich
metal fragments.6 The reactivity of the metal vinylidene
complex is rationalized by taking the electrophilicity of
vinylidene CR, the nucleophilicity of Cβ, and the highly
unsaturated features of the ligand into consideration. Thus,
the formation of metal vinylidene intermediate has been used
to promote a new carbon-carbon bond-forming reaction by
the addition of carbon nucleophile to the electrophilic vinyli-
dene CR atom.7 Ferreocene8 displayed versatile reactivities of
carbon-carbon bond forming reactions and has become
very attractive from a commercial point of view.9 Ferro-
cenophane ring systems in which the two Cp groups are
Metal vinylidene complexes have attracted a great deal of
attention, because these compounds offer the possibility for
developing new types of organometallic intermediates that
could have various interesting and unusual reactivities.
Recently, the importance of metal vinylidene intermediates
in catalysis,1 particularly that of ruthenium vinylidene com-
plexes,2 has been pointed out. The most straightforward
route to a metal vinylidene complex arises from the activa-
tion of a terminal alkyne.3,4 The addition reaction at Cβ of a
σ-alkynyl complex using various electrophilic reagents
has also been described as a versatile method to prepare
*To whom correspondence should be addressed. E-mail: yclin@
ntu.edu.tw.
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Published on Web 02/04/2010
2010 American Chemical Society

Article
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joined by an atomic or a molecular bridge as well as
substituted ferrocene have also been developed10,11 as build-
ing blocks for metal-based polymers12 and also in bio-
organometallic chemistry.13 With both vinylidene and ferro-
cene groups showing C-C bond forming reactivity, a study
has been initiated to explore the intramolecular reactions of a
ruthenium vinylidene complex containing a ferrocenyl
group. In this study, we use the allenylidene complex14 with
a ferrocenyl group as the starting material for the prepara-
tion of the vinylidene complex, since the reactivity of the
allenylidene complex is also governed by the electron-defi-
cient character of both CR and Cγ atoms.15 Grignard reagent
is thus used as a nucleophile to add to Cγ of the allenylidene
complex, readily prepared from ferrocenyl-substituted pro-
pargylic alcohols, to yield an acetylide complex. This is
followed by the electrophilic addition of organic halide to
synthesize a variety of specialized vinylidene complexes, each
containing a ferrocenyl group and an allylic group at Cγ.
Previously, we observed a formal metathesis process, as
shown in Scheme 1 for similar vinylidene complexes with
an allylic group at Cγ.16 In this work our study on these
ferrocenyl complexes reveals the same reactivity. In addition,
a facile C-C bond formation reaction between the vinyli-
dene and the ferrocenyl groups is also observed. This pro-
vides a direct approach to ferrocenophane compounds under
mild conditions.
Scheme 1
Scheme 2
The complexes [Ru0]dCdCdCH(Fc)[PF6] (2a0) and
[Ru]dCdCdCPh(Fc)[PF6] (2b) were similarly prepared from
1a and 1b, respectively. These allenylidene derivatives, each
with a ferrocenyl group, are air-stable solids, are readily
soluble in most polar solvents such as THF, CH2Cl2, chloro-
form, acetone, and methanol, and have poor solubility in
diethyl ether and are insoluble in hexane. The 31P NMR
spectrum of 2a displays a singlet peak at δ 48.15 assigned to
PPh3. Complex 2a0 also shows a singlet resonance at δ 82.9 in
the 31P NMR spectrum. These are different from the Tp-
substituted congener Tp(PPh3)2RudCdCdCPh(Fc)[SbF6],
where Tp is the tris(pyrazolyl)borate ligand, which exists as
two isomers at room temperature.18 Hartmann et al. proposed
that the major isomer of the Tp congener has the less bulky
phenyl substituent oriented toward the PPh3 ligands along the
RudCdCdC axis. However, for 2a, the energy barrier for the
rotation of the allenylidene moiety is probably not high enough
to allow observation of two different rotamers at ambient
temperatures. The same phenomenon was also observed in 2a0
and 2b.
Results and Discussion
Allenylidene, Acetylide, and Vinylidene Complexes. Two
ferrocenyl-substituted propargylic alcohols, FcC(OH)-
(R1)CtCH (1a, R1 = H; 1b, R1 = Ph; Fc = CpFe(C5H4)),
were prepared by following the literature method.17 The
synthesis of allenylidene complexes containing either an
[Ru] (=Cp(PPh3)2Ru) or [Ru0] (=Cp(dppe)Ru) moiety
using 1a or 1b is straightforward. Namely, the reaction of
[Ru]-Cl with 1a in methanol in the presence of KPF6 gave the
cationic allenylidene complex [Ru]dCdCdCH(Fc)[PF6] (2a)
as an intensely deep green solid in good yield (see Scheme 2).
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1
Complex 2a displays downfield broad H resonances at
δ 5.21 and 4.90 assigned to the protons of the substituted Cp
group of the ferrocenyl moiety bound to Cγ of the allenyli-
dene ligand. The singlet resonance at δ 8.92 assigned to the
allenylidene proton is consistent with the structure. The 13C
NMR spectrum of 2a shows a triplet downfield resonance at
δ 269.4 with JPC = 19.7 Hz and two singlet resonances at δ
180.4 and 153.8 assigned to CR, Cβ, and Cγ, respectively. The
ESI mass spectrum of 2a displaying a parent ion at m/z 913.1
is consistent with the formula of the proposed allenylidene
complex. Recently the chemical reactivity of a metal complex
bearing a ferrocenyl group has attracted attention in orga-
nometallic chemistry. For example, Dixneuf et al. described
the synthesis of heterobimetallic Fe-Ni and Fe-Pd oligo-
mers using diynylferrocene derivatives as precursors.19
Fischer et al. demonstrated a regioselective insertion of a
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H.; Wang, Y. J. Am. Chem. Soc. 2007, 129, 14974–14980. (b) Yen, Y. S.;
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hedron 2002, 58, 9785–9792. (b) Tappe, K.; Knochel, P. Tetrahedron:
Asymmetry 2004, 15, 91–102. (c) Skibar, W.; Kopacka, H.; Wurst, K.;
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Organometallics 1996, 15, 1530–1531.

1094 Organometallics, Vol. 29, No. 5, 2010
Chang et al.
CtC triple bond into Cβ-Cγ of an allenylidene ligand in a
bis(ferrocenyl)-substituted metal complex.20
Scheme 3
Nucleophilic addition of the Grignard reagent
BrMgCH2CHdCH2 to Cγ of the allenylidene ligand of 2a
at -78 °C afforded the neutral acetylide complex [Ru]-
CtCCH(Fc)CH2CHdCH2 (3a) as a brown-yellow solid in
reasonable yield. Similarly, the complexes [Ru0]-CtC-
CH(Fc)CH2CHdCH2 (3a0) and [Ru]-CtCCPh(Fc)CH2-
CHdCH2 (3b) were prepared from 2a0 and 2b, respectively,
using the same Grignard reagent. The regiospecific nucleo-
philic addition takes place exclusively at Cγ of the cumulenic
skeleton. This shows that the steric hindrance between the
phosphine ligand and the Grignard reagent disfavors addi-
tion at CR. The light yellow acetylide complex is air stable
and is soluble in benzene, diethyl ether, acetone, and CH2Cl2
but insoluble in methanol. Spectroscopic data of 3a
support the proposed formula. Two doublet resonances at
2
δ 51.3 and 51.1 with JP-P = 38.2 Hz in the 31P NMR
spectrum of 3a with a stereogenic carbon center at Cγ appear
in the region of a regular ruthenium acetylide complex. In the
1H NMR spectrum of 3a three multiplet resonances at δ 5.91,
4.89, and 4.79 are assigned to the terminal vinyl group. The
multiplet resonances in the region of δ 4.43-4.03 are as-
signed to the Cp moiety bound to Cγ of the allenylidene
ligand. Multiplet resonances at δ 2.42 - 2.30 are assigned
to two methylene protons. The ESI mass spectrum of 3a
showing parent ions at m/z 955.2 is consistent with the
proposed formula.
methanol by NaOMe immediately formed the acetylide
complex 3a0.
Intramolecular C-C Bond Formation. Interestingly, com-
plex 4a displays interesting reactivity owing to the presence
of the allylic and the ferrocenyl groups in the vinylidene
ligand. As depicted in Scheme 3, a skeletal rearrangement of
4a is followed by C-C bond formation between Cβ of the
vinylidene ligand and Cp of the ferrocenyl group, producing
the vinylidene complex 7a in CH2Cl2 or MeOH at room
temperature (see Scheme 3). When the transformation was
monitored by the 31P NMR spectra, a broad resonance at δ
44.20 attributed to the intermediate [Ru]dCdCH-
CH2CH(Fc)CHdCH2 (5a) was observed before two doublet
resonances at δ 43.5 and 42.8 with 2JP-P = 27.2 Hz assigned
to 7a appeared. 5a diminished at the end of the reaction.
The 1H NMR spectrum of 7a displays multiplet reso-
nances at δ 5.89, 5.02, and 5.06 assigned to the vinyl group,
and their coupling patterns reveal that there is no neighbor-
ing methylene group. The proton signals of the ferrocenyl
group give 6 resonances at δ 4.27, 4.20, 4.17, 4.06, 4.02, and
3.81 with the integral ratio of 1:1:2:2:1:1, and the 10 singlet
13C signals in the region δ 87.62-67.54 are assigned to two
Cp rings of the ferrocenyl group. Both indicate that all
hydrogen and carbon atoms on the two Cp rings of the
ferrocenyl group are in different chemical environments,
signifying that both Cp ligands of the ferrocenyl group are
Protonation reactions of the acetylide complexes 3a, 3a0,
and 3b with HBF4 in diethyl ether at 0 °C afforded the
corresponding cationic vinylidene complexes [M]dCdC-
HC(R1)(Fc)CH2CHdCH2[BF4] (4a, R1 = H, [M] = [Ru];
4a0, R1 = H, [M] = [Ru’]; 4b, R1 = Ph, [M] = [Ru]), which
are all red-brown solids. The 1H NMR spectrum of the
vinylidene complex 4b is broad even at low temperature.
The formal metathesis reaction described below probably
occurred immediately when the vinylidene complex was
dissolved in solvent.16 Fortunately, complex 4a with no
1
phenyl group at Cγ gives a clear high-resolution H NMR
spectrum at room temperature if the NMR experiment is
quickly conducted in a short period of time for the
freshly prepared complex 4a. The 31P NMR spectrum of 4a
shows two doublet resonances at δ 44.6 and 43.4 with
2JP-P = 26.5 Hz which are in the region of a regular
ruthenium vinylidene complex, indicating the presence of
1
the stereogenic center at Cγ. The H NMR spectrum of 4a
displays multiplet resonances at δ 6.12, 5.32, and 5.28
assigned to the vinyl group. The resonance of the vinylidene
proton appears at δ 4.69. The multiplet resonances
in the region of δ 4.24-4.07 are assigned to the Cp moiety
of the ferrocenyl group bound at Cγ, and multiplet reso-
nances at δ 2.82-2.35 are assigned to two methylene pro-
substituted. The two 13C resonances at δ 344.6 with 2JP-C
=
15.2 Hz and at δ 119.8 assigned to CR and Cβ, respectively,
reveal the ruthenium vinylidene character. In the 2D HMBC
NMR spectrum of 7a, both resonances of CR and Cβ are
1
correlated to the H resonances at δ 2.54-2.51 assigned to
the unique methylene group. The two 13C resonances at δ
87.3 and 78.6 assigned to two tertiary carbons of the ferro-
cenyl group are both correlated to the methylene protons at
Cγ. This implies that the two Cp rings of the ferrocenyl group
are separately bonded to Cβ and Cδ of the vinylidene ligand.
The ESI mass spectrum of 7a showing the parent peak at m/z
953.17 is also consistent with the proposed vinylidene com-
plex. The HSQC, HMBC, and COSY 2D NMR spectra with
the 1H and 13C NMR chemical shifts and coupling patterns
clearly reveal the carbon chain of the ligand of 7a. It is
inferred that the transformation of complex 4a proceeds via
the vinylidene intermediate 5a to yield complex 7a. However,
1
tons. The H NMR spectrum of 4a0 also displays a broad
signal possibly due to a fast transformation of 4a0 to 5a0.
Characterization of the vinylidene complex 4a0 relies on the
ESI mass and 31P NMR data. The 31P NMR spectrum
displays two doublet resonances at δ 78.8 and 78.7 with
2JP-P = 19.5 Hz in the region of a regular ruthenium dppe
vinylidene complex. The ESI mass spectrum of 4a0 showing
parent ions at m/z 829.1 is consistent with the proposed
vinylidene formula. Moreover, deprotonation of 4a0 in
(20) Haas, T.; Oswald, S.; Niederwieser, A.; Bildstein, B.; Kessler, F.;
Fischer, H. Inorg. Chim. Acta 2009, 362, 845–854.

Article
Organometallics, Vol. 29, No. 5, 2010 1095
a high-resolution 1H NMR spectrum of 5a was not obtained,
even at low temperature. This is ascribed to the ongoing
formal metathesis reaction occurring for 5a in solution. To
indirectly corroborate the structure of the vinylidene inter-
mediate 5a, subsequent addition of NaOMe to a mixture of
5a and 7a afforded the neutral acetylide complex
[Ru]-CtCCH2CH(Fc)CHdCH2 (6a) in the reaction mix-
ture. Complex 6a was separated from the mixture by column
chromatography. The 31P NMR spectrum of 6a displays a
broad resonance at δ 51.1 in the region of a regular ruthe-
nium acetylide complex. The broad singlet resonance is
ascribed to the relatively long separation between the stereo-
genic carbon center and the two phosphine ligands. The
C-C bond formation in the transformation of 5a to 7a
provides a direct approach to a ferrocenophane compound
under mild conditions. Werner and co-workers reported the
reaction of methyl Grignard reagent with a chlororhodium
vinylidene complex bearing a ferrocenyl group at Cβ, leading
to an interesting C-C coupling reaction mainly due to the
steric effect of the ferrocenyl group.21
Scheme 4
complex 4b showed two doublet resonances at δ 42.8 and
43.5 with 2JP-P = 26.6 Hz. In 2 days a broad resonance at δ
43.8 assigned to 5b appeared, and the peaks attributed to 4b
disappeared completely. Finally, the signal of 5b was con-
verted to two other sets of two doublet resonances at δ 45.8
Complexes with dppe Ligand and with Phenyl-Substituted
Enyne. The unusual transformation of 4a to 7a is interesting;
thus, we carried out further studies of the reaction of the
dppe analogue 4a0. Complex 4a0 in solution is gradually
converted to the vinylidene complex 5a0 by the same intra-
molecular formal metathesis reaction of the two CdC dou-
ble bonds, leading to an equilibrium with a 4a0:5a0 ratio of
about 1:2 (see Scheme 4).
2
and 42.9 with JP-P = 26.2 Hz and δ 46.1 and 42.6 with
2JP-P = 26.4 Hz in a ratio of 2:1. These are attributed to
diastereoisomers of the intramolecular cyclization product
7b. The ESI mass spectrum of 7b agrees with the proposed
vinylidene cyclization complex with a parent peak at m/z
1029.20. The 1H NMR spectrum also supports the proposed
structure. One isomer shows a doublet of doublets signal at δ
6.27 with 3JH-H(trans) = 17.0 Hz and 3JH-H(cis) = 10.5 Hz
assigned to the internal vinyl proton. From the COSY
spectrum, two corresponding doublet signals at δ 5.24 with
3J = 10.5 Hz and at δ 5.07 with 3J = 17.0 Hz are assigned to
two terminal vinyl protons. The other vinyl signals of the
1
All resonances of the H NMR spectrum of 5a0 are also
broad. Addition of NaOMe to the mixture containing 5a0
again afforded the neutral acetylide complex 6a0. The 1H and
31P NMR spectra of 6a0 indirectly reveal the change of the
carbon chain in the transformation of 4a0 to 5a0. The formal
metathesis reaction from 4 to 5 is most probably controlled
by a steric effect. The steric hindrance between the dppe and
ferrocenyl groups of 4a0 is expected to be less than that of the
corresponding groups in 4a. As a result, the driving force for
the formal metathesis process in 4a0 is not as effective.
Interestingly, no further C-C bond formation reaction
occurred for the dppe vinylidene complex 5a0 in solution,
even for a long period of time or at higher temperature. The
more electron-donating character of dppe probably makes
Cβ more electron rich, thus disfavoring the nucleophilic
addition of the ferrocenyl Cp group to Cβ.
3
minor isomer appear at δ 5.79 and 4.90 with J = 10.3 Hz
and at δ 4.56 with 3J = 17.1 Hz. These diastereoisomers are
due to the presence of a stereogenic center at Cγ and the
chiral cyclopentadienyl plane in 7b. On the basis of the
structure of 7b described below, it is reasonable to assume
that the major product is the one where the ferrocenyl group
and the neighboring phenyl group are in an anti form with
less steric hindrance. The minor product should have the
ferrocenyl group and the phenyl group in a syn form.
To explore the scope of this novel process, the reaction of
the vinylidene complex 4b containing a slightly different
vinylidene fragment with a phenyl group and the same
ferrocenyl substituent at Cγ was explored. Surprisingly, 4b,
with a phenyl group replacing hydrogen at Cγ of 4a, under-
went the same formal metathesis reaction but was followed
by a dissimilar C-C bond forming reaction between the
ferrocenyl Cp group and Cβ (see Scheme 3). Complex 4b in
CH2Cl2 or MeOH at room temperature gradually trans-
formed to the metathesis product 5b and finally converted
cleanly to the intramolecular cyclization product 7b in 7
days. Again, addition of NaOMe to the solution containing
5b led to the isolation of the neutral acetylide complex
[Ru]-CtCCH2C(Fc)(Ph)CHdCH2 (6b). Spectroscopic
data of 6b reveal the expected carbon chain. This sequential
formation of complexes 5b and 7b from 4b in solution was
observed clearly in the 31P NMR spectra. At the beginning,
Single crystals of the major isomer of complex 7b were
obtained by vapor diffusion at -5 °C in CH2Cl2/ether. This
major isomer of complex 7b has been further characterized
by a single-crystal X-ray crystallographic study. An ORTEP
view of 7b is shown in Figure 1, and selected bond distances
and angles are given in Table 1. The molecular structure
shows a pseudo-octahedral three-legged piano-stool coordi-
nation around the ruthenium atom. The Ru(1)-C(1) dis-
˚
tance of 1.852(4) A is a typical RudC double bond, with the
Ru(1)-C(1)-C(2) bond angle of 171.2(4)° showing almost
linear geometry. In agreement with the sp2 hybridization at
C(2), the bond angle C(1)-C(2)-C(3) is 126.2(4)°. Also, the
bond angle C(4)-C(5)-C(6) is 125.6(8)°, indicating the sp2
hybrid of C(5) and double-bond character of C(5)-C(6).
The transformation from 4a to 5a could be interpreted by
a formal metathesis process between the terminal vinyl group
and the CRdCβ bond of the vinylidene ligand of 4a, as shown
in Scheme 5.15 This mechanism is proposed on the basis
(21) Wiedemann, R.; Fleischer, R.; Stalke, D.; Werner, H. Organo-
metallics 1997, 16, 866–870.

1096 Organometallics, Vol. 29, No. 5, 2010
Chang et al.
˚
Table 1. Selected Bond Lengths (A) and Angles (deg) for 7b
˚
Bond Lengths (A)
Ru(1)-C(1)
C(1)-C(2)
C(2)-C(3)
C(2)-C(13)
1.852(4)
1.305(6)
1.541(6)
1.470(6)
C(4)-C(5)
C(4)-C(14)
C(5)-C(6)
1.490(9)
1.513(7)
1.406(12)
Bond Angles (deg)
Ru(1)-C(1)-C(2)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
171.2(4)
126.2(4)
104.7(4)
C(1)-C(2)-C(13)
C(13)-C(2)-C(3)
C(4)-C(5)-C(6)
128.8(4)
105.0(3)
125.6(8)
Scheme 5
Figure 1. ORTEP drawing of the cationic complex 7b. For
clarity, aryl groups of the triphenylphosphine ligands on Ru
except for ipso carbons and PF6- are omitted (thermal ellipsoids
are set at the 30% probability level).
of many stoichiometric and catalytic reactions of enynes
reported in the literature.16,22 The ruthenium vinylidene
complex 4 could first undergo a cyclization to give the
carbocationic cyclohexenyl complex A or directly proceed
via a metal-assisted regiospecific [2 þ 2] cycloaddition of two
double bonds to yield C. The [3.1.0] bicyclic intermediate B
possibly formed via a 1,2-alkyl shift then serves as a bridge
for the transformation between A and C. Formation of similar
bicyclic structures as reaction intermediates has been postu-
lated in many Pt- or Au-catalyzed reactions of enynes.23
Similarly, a further 1,2-alkyl shift brings about the formation
of D and E. Finally, ring opening of the carbocationic cyclo-
hexenyl complex E yields complex 5a. Alternatively, retro-
cycloaddition of the four-membered ring of C also directly
gives 5a. A complex with a four-membered-ring structure has
been reported by Gimeno and co-workers for a ruthenium
vinylidene complex containing an allylphosphine ligand which
performed a cycloaddition similar to that in 4a.22b
On the basis of the structure of the product 7b, it is likely
that the transformation from 5 to 7 may evolve H2 gas. An
oxidative carbon-carbon bond formation with efficient
reductive H2 evolution has been observed in a photocatalytic
system containing colloidal ZnS, water, and organic sub-
strates such as triethylamine, tetrahydrofuran, and metha-
nol.24 Interestingly, the transformation of 5 to 7 does not
require photo energy. The product was obtained from the
reaction carried out in a flask covered with aluminum foil.
The C-C bond forming reaction may thus be considered as a
coupling of two sp2 carbons induced by the thermal energy.
Friedel-Craft alkylation or acylation of the Cp ligand
commonly observed in many ferrocenyl systems may shed
light on the transformation of 5 to 7 involving cationic
species. A mechanism for the formation of 7b is proposed
as shown in Scheme 6. The vinylidene complex 5b could
undergo a 1,3-hydride shift to give a hydride acetylide
intermediate. An alternative access to this intermediate is
the formation of a η2-coordinated alkyne intermediate fol-
lowed by oxidative addition of the C-H bond to the metal
center. Then C-C bond formation between the substituted
Cp of the ferrocenyl group and Cβ leads to the formation of
the cyclic structure, giving the final product 7b. On the other
hand, C-C bond formation could take place at the η2-
coordinated electrophilic alkyne ligand. The transformation
from 5a to 7a is similar but involves the nonsubstituted Cp. It
is clear that the presence of the phenyl group of 5b alters the
reaction path. It could be the steric hindrance between the
ferrocenyl group and the phenyl group or an electronic effect
that drives the substituted Cp of the ferrocenyl group to
move closer to Cβ for the C-C bond formation. It is not yet
clear how two hydrogen atoms are eliminated.
Since the transformation from 4 to 7 proceeds via the
intermediate 5, with the ferrocenyl group at Cδ, it is inter-
esting to see if other vinylidene complexes bearing a ferro-
cenyl group at Cδ could undergo the same intramolecular
C-C bond formation. Therefore, we prepared 5c and 5d, two
analogues of 5a, and the propargyl-substituted vinylidene
complex 4e as shown in Scheme 7 and explored their
chemical reactivity. The reaction of [Ru]-Cl and 1c17 in the
presence of NH4PF6 in methanol at room temperature
afforded complex 5c, a vinylidene complex with a ferrocenyl
group at Cδ. Another terminal alkyne, 1d, with a methoxy
group and a ferrocenyl group bonded at Cδ, was synthesized
by the reaction of 1c with methanol and HCl. Reaction
of [Ru]-Cl with 1d in the presence of NH4PF6 gave the
~
~
(22) (a) Nieto-Oberhuber, C.; Munoz, M. P.; Bunuel, E.; Nevado, C.;
ꢁ
Cardenas, D. J.; Echavarren, A. M. Angew. Chem., Int. Ed. 2004, 43,
2402–2406. (b) Alvarez, P.; Lastra, E.; Gimeno, J.; Bassetti, M.; Falvello, L.
R. J. Am. Chem. Soc. 2003, 125, 2386–2387.
€
(23) (a) Mamane, V.; Gress, T.; Krause, H.; Furstner, A. J. Am.
Chem. Soc. 2004, 126, 8654–8655. (b) Eckert, M.; Monnier, F.; Shchetnikov,
ꢁ
G. T.; Titanyuk, I. D.; Osipov, S. N.; Toupet, L.; Derien, S.; Dixneuf, P. H.
ꢁ
~
Org. Lett. 2005, 7, 3741–3743. (c) Jimenez-Nꢁunez, E.; Echavarren, A. M.
Chem. Rev. 2008, 108, 3326–3350. (d) Buzas, A.; Gagosz, F. J. Am. Chem.
Soc. 2006, 128, 12614–12615. (e) Boyer, F. D.; Goff, X. L.; Hanna, I. J. Org.
Chem. 2008, 73, 5163–5166. (f) Luzung, M. R.; Markham, J. P.; Toste, F. D.
J. Am. Chem. Soc. 2004, 126, 10858–10859.
(24) Yanagida, S.; Azuma, T.; Kawakami, H.; Kizumoto, H.;
Sakurai, H. J. Chem. Soc., Chem. Commun. 1984, 1, 21–22.

Article
Organometallics, Vol. 29, No. 5, 2010 1097
Scheme 6
methods and were distilled under nitrogen before use. All
reagents were obtained from commercial suppliers and were
used without further purification. NMR spectra were recorded
on a Bruker AC-300, Bruker Avance-400, or a DMX-500
FT-NMR spectrometer. 1H NMR and 13C NMR spectra were
obtained in CDCl3 at ambient temperature, and chemical shifts
are expressed in δ. Proton chemical shifts are referenced to
δ 7.26 (CHCl3), and carbon chemical shifts are referenced to
δ 77.0 (CDCl3). 31P (121 MHz) NMR spectra were referenced
relative to external 85% phosphoric acid. Both 13C{1H} and
31P{1H} spectra were proton decoupled. FAB mass spectra were
recorded on a JEOL SX-102A spectrometer. According to the
literature methods, [Ru]Cl ([Ru] = Cp(PPh3)2Ru)25 and [Ru0]Cl
([Ru0] = Cp(dppe)Ru)26 were prepared from RuCl3 xH2O,
3
which was purchased from Steam Chemicals. Compounds 1a,
1b, and 1c were also prepared according to the literature
method.14
Scheme 7
Synthesis of 1-Ferrocenyl-1-methoxy-3-butyne (1d). In a
Schlenk flask charged with 1-ferrocenyl-3-propyn-1-ol (0.10 g,
0.39 mmol) and 1 mL of HCl (0.1 M), methanol (30 mL) was
added via a syringe. Then the solution was heated to reflux for
1/2 h. The solution turned from yellow to red. Then the solution
was dried under vacuum, and the mixture was purified by silica
gel chromatography with diethyl ether-hexane (1:5) as eluent to
obtain a yellow solution. Removal of the solvent yielded the
yellow powder as 1d (0.05 g, 47%). Spectroscopic data of 1d are
as follows. 1H NMR (CDCl3): δ 4.22 (m, 1H, FcCH), 4.20, 4.19,
4.18, 4.17 (m, 4 ꢀ 1H, CH of Cp), 4.14 (s, 5H, Cp), 3.36 (s, 3H,
OMe), 2.85-2.69 (m, 2H, CH2), 2.09 (s, 1H, tCH). 13C NMR
(CDCl3): δ 87.8 (tCH), 81.9 (tC), 77.8 (COMe), 68.8 (5C, Cp),
70.1, 68.3, 67.7, 66.1 (4C, CH of Cp), 56.9 (OMe), 25.6 (CH2 of
allyl). Anal. Calcd for C15H16FeO: C, 67.19; H, 6.01. Found: C,
67.32; H, 6.14.
vinylidene complex 5d in reasonable yield. We also synthe-
sized the acetylide complex [Ru]CtCCH(Fc)CH2CtCH
(3e) using a procedure similar to that for 3a. Then proton-
ation of 3e with HBF4 afforded the corresponding cationic
vinylidene complex [Ru]dCdCHCH(Fc)CH2CtCH[BF4]
(4e).
Unfortunately, all three vinylidene complexes 5c, 5d, and
4e would not undergo transformation to give the desired
alkylation product in solution. Complexes 5c, 5d, and 4e are
all thermally stable. Attempts to conduct the dehydration of
complex 5c also failed, even at 80 °C. Complex 5d is also
stable in solution at 80 °C. Therefore, it is clear that the
terminal vinyl group of 5a and 5b plays an important role in
the transformation of 5 to 7.
Synthesis of [Ru]dCdCdCH(Fc)[PF6] (2a). In a Schlenk
flask charged with [Ru]Cl (0.25 g, 0.35 mmol), KPF6 (0.11 g,
0.62 mmol), and 1a (0.10 g, 0.42 mmol), CH2Cl2 (20 mL) was
added via a syringe. The mixture was stirred for 30 h at room
temperature. The solution turned from red to deep green. The
mixture was filtered through Celite. Further purification was
performed by three successive precipitations from CH2Cl2/
hexane. The deep green powder was filtered and washed with
ether (5 mL) and hexane (10 mL) and then dried under vacuum
to afford 2a (0.26 g, 83%). Spectroscopic data of 2a are as
follows. 1H NMR (CDCl3): δ 8.92 (s, 1H, dCH), 7.35-7.13 (m,
30H, Ph), 5.21 (m, 2H, CpFc), 4.90 (m, 2H, CpFc), 4.86 (s, 5H,
CpFc), 4.17 (s, 5H, Cp). 13C NMR (CDCl3): δ 269.4 (t, 2JP-C
=
19.7 Hz, CR), 180.4 (Cβ), 153.8 (Cγ), 135.8-128.2 (Ph), 91.7
(Cp), 72.9, (5C, CpFc), 90.7, 79.0, 76.3 (CpFc). 31P NMR
(CDCl3): δ 48.1 (s, PPh3), -143.62 (heptet, 1JP-F = 712.7 Hz,
PF6). ESI-MS (m/z): 913.1 (Mþ). Anal. Calcd for C54H45F6Fe-
P3Ru: C, 61.32; H, 4.29. Found: C, 61.16; H, 4.39.
Concluding Remarks
In several ruthenium vinylidene complexes, each with a
substituted ferrocenyl group and an allyl group at Cγ, a
formal intramolecular olefin metathesis process between the
CdC double bond of the vinylidene ligand and the terminal
vinyl group was observed. The extent of such a metathesis
process possibly depends on steric effects between the sub-
stituted group of the vinylidene ligand and the phosphine on
the metal. An additional intramolecular C-C bond forma-
tion between the Cp ligand of the ferrocenyl substituent and
the vinylidene ligand gave the cyclization product. Steric
effects between the neighboring substituent and phosphine
ligand on Ru or possibly the electronic effects of the sub-
stituent changed the regioselectivity of the C-C bond form-
ing reaction.
Synthesis of [Ru0]dCdCdCH(Fc)[PF6] (2a0). Complex 2a0
was similarly prepared from [Ru’]Cl (1.01 g, 1.66 mmol),
NH4PF6 (0.55 g, 3.33 mmol), and 1a (0.48 g, 1.99 mmol) in
methanol (20 mL) for 60 h at room temperature. The deep green
powder was dried under vacuum to afford 2a0 (1.06 g, 81%).
1
Spectroscopic data of 2a0 are as follows. H NMR (CDCl3): δ
8.07 (s, 1H, dCH), 7.56-7.11 (m, 30H, Ph), 5.21 (s, 5H, Cp),
4.95 (m, 2H, CpFc), 4.43 (m, 2H, CpFc), 3.95 (s, 5H, CpFc),
2.96-2.92 (m, 4H, dppe). 13C NMR (CDCl3): δ 270.9 (t, 2JP-C
= 19.2 Hz, CR), 180.4 (Cβ), 151.0 (Cγ), 138.3-128.3 (Ph), 89.7
(Cp), 72.2 (5C, CpFc), 77.9, 68.9, 66.4 (CpFc), 29.0 (dppe). 31P
NMR (CDCl3): δ 82.9 (s, dppe). ESI-MS (m/z): 787.4 (Mþ).
Anal. Calcd for C44H39F6FeP3Ru: C, 56.73; H, 4.22. Found: C,
56.79; H, 4.02.
Experimental Section
(25) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R.; Ittel, S.
D. Inorg. Synth. 1990, 28, 270–272.
(26) Alonso, A. G.; Reventos, L. B. J. Organomet. Chem. 1988, 338,
249–254.
General Procedures. The manipulations were performed un-
der an atmosphere of dry nitrogen using vacuum-line and
standard Schlenk techniques. Solvents were dried by standard
ꢁ

1098 Organometallics, Vol. 29, No. 5, 2010
Chang et al.
Synthesis of [Ru]dCdCdC(Fc)(Ph)[PF6] (2b). Complex 2b
(0.15 g, 65% yield) was similarly prepared from [Ru]Cl (0.25 g,
0.34 mmol), NH4PF6 (0.17 g, 1.04 mmol), and 1b (0.22 g, 0.70
mmol). Spectroscopic data of 2b are as follows. 1H NMR
(CDCl3): δ 7.56-7.05 (m, 35H, Ph), 5.34 (m, 2H, CpFc), 5.20
(m, 2H, CpFc), 4.92 (s, 5H, Cp), 4.29 (s, 5H, CpFc). 13C NMR
(CDCl3): δ 263.2 (CR), 182.3 (Cβ), 166.0 (Cγ), 143.2-128.1 (Ph),
91.5, 78.8, 73.6 (CpFc), 73.4 (5C, CpFc). 31P NMR (CDCl3): δ
(CDCl3): δ 7.49-7.06 (m, 30H, Ph), 4.52 (m, 1H, CH of CpFc),
4.28 (m, 1H, CH of CpFc), 4.27 (s, 5H, Cp), 4.21 (s, 5H, CpFc),
4.06, 4.05 (m, 2 ꢀ 1H, CH of CpFc), 3.88 (m, 1H, CH(Fc)),
2.47-2.39 (m, 2H, CH2), 1.92 (t, 4JH-H = 2.4 Hz, 1H, tCH).
13C NMR (CDCl3): δ 134.1-127.1 (Ph), 110.9 (Cβ), 94.1 (t,
2JC-P = 24.4 Hz, CR), 93.2 (tC), 85.0 (Cp), 84.8 (tCH), 69.3,
68.9 (5C, CpFc), 68.4, 67.5, 67.0, 66.8 (Fc), 35.2 (Cγ), 29.2 (CH2).
31P NMR (CDCl3): δ 51.3 (s). Anal. Calcd for C57H48FeP2Ru:
C, 71.92; H, 5.08. Found: C, 71.77; H, 4.92.
Synthesis of [Ru]dCdCHCH(Fc)CH2CHdCH2[BF4] (4a). A
Schlenk flask was charged with 3a (0.10 g, 0.10 mmol) in diethyl
ether (15 mL) under nitrogen. Then HBF4 (54% in diethyl ether)
was added drop by drop at 0 °C to the solution. Immediately,
green precipitates formed, and the addition of HBF4 was
continued until no further solid was formed. The precipitates
were filtered, washed with diethyl ether (3 ꢀ 10 mL), and dried
under vacuum to give a brown-yellow powder of 4a (0.08 g, ca.
77%) with a trace amount of 5a revealed by NMR. Spectro-
scopic data of 4a are as follows. 1H NMR (CDCl3): δ 7.50-6.97
(m, 30H, Ph), 6.12 (m, 1H, dCH), 5.32 (m, 1H, dCH2), 5.28 (m,
1H, dCH2), 5.13 (s, 5H, Cp), 4.69 (m, 1H, dCH), 4.24 (m, 1H,
CH of CpFc), 4.19 (m, 1H, CH of CpFc), 4.14 (m, 1H, CH of
CpFc), 4.08 (s, 5H, CpFc), 3.95 (m, 1H, CH of CpFc), 3.42 (m, 1H,
C(Fc)(H)), 2.83-2.36 (m, 2H, CH2 of allyl). 31P NMR (CDCl3):
δ 45.0, 43.5 (two d, 2JP-P = 26.6 Hz). ESI MS (m/z): 955.19 (Mþ
- BF4). Anal. Calcd for C57H51BF4FeP2Ru: C, 65.72; H, 4.93.
No elemental analysis was carried out for 4a, since the sample is
contaminated with a trace amount of 5a.
Synthesis of [Ru0]dCdCHCH(Fc)CH2CHdCH2[BF4] (4a0).
Complex 4a0 (0.17 g, ca. 84% yield) was similarly prepared from
3a0 (0.20 g, 0.24 mmol) and HBF4 (54% in diethyl ether).
Spectroscopic data of 4a0 are as follows. 31P NMR (CDCl3): δ
79.1, 79.0 (two d, 2JP-P = 19.5 Hz). ESI MS (m/z): 829.1 (Mþ -
BF4). Anal. Calcd for C47H45BF4FeP2Ru: C, 61.66; H, 4.95. No
elemental analysis was carried out for 4a0, since the sample is
contaminated with 5a0.
Synthesis of [Ru]dCdCHC(Fc)(Ph)CH2CHdCH2[BF4] (4b).
Complex 4b (0.16 g, 80% yield) was similarly prepared from 3b
(0.20 g, 0.19 mmol) and HBF4 (54% in diethyl ether). Spectro-
scopic data of 4b are as follows. 31P NMR (C6D6): δ 43.5, 43.1 (2
d, 2JP-P = 26.8 Hz). ESI MS (m/z): 1031.2 (Mþ - BF4). Anal.
Calcd for C63H55BF4FeP2Ru: C, 67.69; H, 4.96. No elemental
analysis was carried out for 4b, since the sample is contaminated
with 5b.
1
47.2 (s, PPh3), -144.03 (heptet, JP-F = 712.7 Hz, PF6). IR
(CH2Cl2):
ν
1946 cm-1 (ν(CdCdC)). Anal. Calcd for
C60H49F6FeP3Ru: C, 63.56; H, 4.36. Found: C, 63.33; H, 4.24.
Synthesis of [Ru]CtCCH(Fc)CH2CHdCH2 (3a). A 20 mL
THF solution of 2a (0.20 g, 0.22 mmol) was treated with
allylmagnesium bromide (0.43 mL, 1 M, 0.43 mmol) at room
temperature. The solution turned from deep green to brown
immediately, and then 2 mL of water was added to quench the
reaction. The resulting solution became brown-green and was
dried under vacuum. The solid residue was extracted by diethyl
ether, and then the filtered solution was washed with two
portions of water. The combined organic extracts were dried
over MgSO4 and then filtered. The solid MgSO4 was washed
with diethyl ether until the solvent was colorless, and the solvent
of the combined extracts was removed by rotary evaporation.
Further purification was performed by flash neutral aluminum
oxide chromatography (CH2Cl2-hexane 2:1) to give 3a as a
yellow powder (0.14 g, 67%). Spectroscopic data of 3a are as
follows. 1H NMR (CDCl3): δ 7.48-7.04 (m, 30H, Ph), 5.91 (m,
1H, dCH), 4.89 (d, 3JH-H (trans) = 17.7 Hz, 1H, dCH2), 4.79
3
(d, JH-H (cis) = 10.2 Hz, 1H, =CH2), 4.43 (m, 1H, CH of
CpFc), 4.35 (m, 1H, CH of CpFc), 4.25 (s, 5H, CpFc), 4.19 (s, 5H,
Cp), 4.14 (m, 1H, CH of CpFc), 4.03 (m, 1H, CH of CpFc), 3.69
(m, 1H, C(Fc)(H)), 2.42-2.30 (m, 2H, CH2 of allyl). 13C NMR
(CDCl3): δ 139.7-127.0 (Ph), 139.0 (dCH), 114.2 (dC), 112.0
(Cβ), 91.8 (t, 2JC-P = 24.8 Hz, CR), 85.0 (Cp), 68.6 (5C, CpFc),
69.4, 68.3, 66.9, 66.7, 66.5 (Fc), 43.3 (Cγ), 35.7 (CH2). 31P NMR
(CDCl3): δ 51.3, 51.1 (two d, 2JP-P = 38.2 Hz). MS (ES): m/z
955.2 (Mþ). Anal. Calcd for C57H50FeP2Ru: C, 71.77; H, 5.28.
Found: C, 71.62; H, 5.49.
Synthesis of [Ru0]CtCCH(Fc)CH2CHdCH2 (3a0). Complex
3a0 (0.13 g, 62% yield) was similarly prepared from 2a0 (0.20 g,
0.25 mmol) and allylmagnesium bromide (0.40 mL, 1 M, 0.40
mmol). Spectroscopic data of 3a0 are as follows. 1H NMR
(CDCl3): δ 8.03-7.27 (m, 30H, Ph), 5.49 (m, 1H, dCH), 4.81
(s, 5H, Cp), 4.70 (m, 1H, dCH2), 4.65 (d, 1H, dCH2), 4.00 (s,
5H, CpFc), 3.90, 3.89, 3.78, 3.77 (m, 4 ꢀ 1H, CH of CpFc), 3.05
(m, 1H, CH(Fc)), 2.78-2.33 (m, 4H, dppe), 1.89-1.68 (m, 2H,
CH2 of allyl). 13C NMR (CDCl3): δ 143.3-127.3 (Ph), 138.9
(dCH), 113.6 (dC), 110.0 (Cβ), 92.9 (t, 2JC-P = 26.0 Hz, CR),
82.0 (Cp), 68.5 (5C, CpFc), 68.4, 67.7, 66.5, 66.3, 66.1 (Fc), 43.6
(Cγ), 35.1 (CH2), 27.8 (m, dppe). 31P NMR (CDCl3): δ 87.9, 87.5
(two d, JP-P = 20.8 Hz). Anal. Calcd for C47H44FeP2Ru: C,
68.20; H, 5.36. Found: C, 68.39; H, 5.41.
Synthesis of [Ru]dCdCHCH(Fc)CH2CtCH[BF4] (4e).
Complex 4e (0.08 g, 84% yield) was similarly prepared from
3e (0.10 g, 0.11 mmol) and HBF4 (54% in diethyl ether).
1
Spectroscopic data of 4e are as follows. H NMR (CDCl3): δ
7.39-6.99 (m, 30H, Ph), 5.18 (s, 5H, Cp), 4.74 (d, 3JH-H = 9.5
Hz, 1H, dCH), 4.15, 4.14 (m, 2 ꢀ 1H, CH of CpFc), 4.06 (s, 5H,
CpFc), 3.98, 3.91 (m, 2 ꢀ 1H, CH of CpFc), 3.54 (m, 1H,
4
C(Fc)(H)), 2.89-2.59 (m, 2H, CH2 of allyl), 2.39 (t, JH-H
=
Synthesis of [Ru]CtCC(Fc)(Ph)CH2CHdCH2 (3b). Complex
3b (0.15 g, 72% yield) was similarly prepared from 2b (0.20 g,
0.20 mmol) and allylmagnesium bromide (0.30 mL, 1 M, 0.30
mmol). Spectroscopic data of 3b are as follows. 1H NMR
(C6D6): δ 7.96-6.83 (m, 35H, Ph), 6.08 (m, 1H, dCH), 4.99
(d, JH-H = 17.3 Hz, 1H, dCH2), 4.82 (d, JH-H = 10.4 Hz, 1H,
dCH2), 4.43 (s, 5H, Cp), 4.33, 4.21, 4.13 (m, 3 ꢀ 1H, CH of
CpFc), 4.10 (s, 5H, CpFc), 3.96 (m, 1H, CH of CpFc), 3.18 (m, 2H,
CH2 of allyl). 13C NMR (C6D6): δ 153.5-124.3 (Ph), 138.8
(dCH), 115.2 (dC), 113.4 (Cβ), 93.9 (t, 2JC-P = 23.8 Hz, CR),
85.6 (Cp), 69.2 (5C, CpFc), 68.6, 67.5, 62.2, 66.7, 66.1 (Fc), 50.3
2.1 Hz, 1H, tCH). 31P NMR (CDCl3): δ 44.9, 43.3 (two d,
2JP-P = 26.4 Hz). Anal. Calcd for C57H49BF4FeP2Ru: C, 65.85;
H, 4.75. Found: C, 66.07; H, 5.01.
Synthesis of [Ru]dCdCHCH2CH(Fc)(OH)][PF6] (5c). A
Schlenk flask was charged with [Ru]Cl (0.27 g, 0.37 mmol), 1c
(0.10 g, 0.39 mmol), and NH4PF6 (0.26 g, 1.59 mmol) under
nitrogen. Then 20 mL of methanol was added via a syringe. The
solution was stirred for 12 h at room temperature, and the
solution turned from orange to yellow. When the reaction
ended, a light yellow powder was formed as a precipitate, and
the precipitate was filtered, washed with methanol (3 ꢀ 10 mL),
and dried under vacuum to give a light yellow powder of 5c
(0.25 g, 72%). Spectroscopic data of 5c are as follows. 1H NMR
(CD2Cl2): δ 7.47-6.89 (m, 30H, Ph), 4.86 (s, 5H, Cp), 4.44 (m,
1H, dCH), 4.27 (m, 1H, CH of CpFc), 4.24 (m, 1H, OH), 4.11
(m, 1H, CH of CpFc), 4.11 (s, 5H, CpFc), 3.95, 3.52 (m, 2 ꢀ 1H,
CH of CpFc), 3.34 (m, 1H, CH(Fc)), 2.34-1.87 (m, 2H, CH2).
(Cγ), 35.7 (CH2). 31P NMR (C6D6): δ 50.9, 50.3 (two d, JP-P
=
37.8 Hz). Anal. Calcd for C63H54FeP2Ru: C, 73.47; H, 5.28.
Found: C, 73.62; H, 5.03.
Synthesis of [Ru]CtCCH(Fc)CH2CtCH (3e). Complex 3e
(0.14 g, 68% yield) was similarly prepared from 2a (0.20 g,
0.22 mmol) and propargylmagnesium bromide (0.80 mL, 0.5 M,
0.40 mmol). Spectroscopic data of 3e are as follows. 1H NMR
2
13C NMR (CD2Cl2): δ 295.1 (t, JP-c = 13.7 Hz, CR),

Article
Organometallics, Vol. 29, No. 5, 2010 1099
136.9-128.5 (Ph), 96.2 (Cβ), 91.5 (Cp), 80.2 (COH), 71.0, 70.3,
70.1, 66.6, 62.1 (Fc), 69.4 (5C, CpFc), 28.2 (CH2). 31P NMR
(CD2Cl2): δ 47.0, 46.7 (two d, 2JP-P = 29.6 Hz). ESI MS (m/z):
945.1 (Mþ - PF6). Anal. Calcd for C55H49F6FeOP3Ru: C,
60.62; H, 4.53. Found: C, 60.47; H, 4.79.
2JP-P = 27.2 Hz). ESI MS (m/z): 953.17 (Mþ - BF4). Anal.
Calcd for C57H49BF4FeP2Ru: C, 65.85; H, 4.75. Found: C,
66.15; H, 4.94.
Synthesis of Complex 7b. Complex 4b (0.10 g, 0.10 mmol) was
dissolved in dried CH2Cl2 (10 mL) under nitrogen in a Schlenk
flask. The solution was stirred at room temperature for 1 week.
The solution changed from brown to red. Then, the solution was
concentrated to 2 mL under vacuum, and the resulting solution
was purified by precipitation from CH2Cl2-diethyl ether.
Further purification was performed by flash column chromato-
graphy using neutral aluminum oxide with CH2Cl2-acetone 2:1
as eluent. A red powder identified as 7b (0.06 g) was obtained in
64% yield. The reaction with no fluorescent light gave no
isolable product. For 7b, two isomers are observed in the 31P
NMR spectrum, giving two AB patterns in a 2:1 ratio. For the
NMR monitoring reaction carried out in CD2Cl2, an intermedi-
ate showing a 31P singlet resonance at δ 43.8 attributed to 5b was
observed. Single crystals of the major isomer were obtained by
vapor diffusion of ether into a solution of 7b in CH2Cl2 at -5 °C.
Attempts to get the pure minor isomer failed. Spectroscopic data
of 7b are as follows. Major isomer: 1H NMR (CDCl3) δ
Synthesis of [Ru]dCdCHCH2CH(Fc)(OMe)[PF6] (5d). A
Schlenk flask was charged with [Ru]Cl (0.15 g, 0.20 mmol), 1d
(0.05 g, 0.19 mmol), and NH4PF6 (0.15 g, 0.92 mmol) under
nitrogen. Then 20 mL of methanol was added via a syringe. The
solution was stirred for 12 h at room temperature, and the
solution turned from orange to yellow. When the reaction
ended, a light yellow powder was formed as a precipitate, which
was filtered, washed with methanol (3 ꢀ 10 mL), and dried
under vacuum to give a light yellow powder of 5d (0.13 g, 66%).
Spectroscopic data of 5d are as follows. 1H NMR (CD3CN): δ
7.46-7.10 (m, 30H, Ph), 5.11 (s, 5H, Cp), 4.89 (m, 1H, dCH),
4.28, 4.23, 4.22, 4.12 (m, 4 ꢀ 1H, CH of CpFc), 4.03 (s, 5H, CpFc),
4.02 (m, 1H, CH(Fc)), 3.38 (s, 3H, OMe), 2.94-2.68 (m, 2H,
CH2). 31P NMR (CD3CN): δ 44.8, 44.4 (2 d, 2JP-P = 29.6 Hz).
ESI MS (m/z): 959.0 (Mþ - PF6). Anal. Calcd for C56H51-
F6FeOP3Ru: C, 60.93; H, 4.66. Found: C, 60.79; H, 4.54.
Synthesis of [Ru]CtCCH2CH(Fc)CHdCH2 (6a). A Schlenk
flask was charged with 4a (0.10 g, 0.10 mmol) in methanol
(10 mL). The solution was stirred for 2 days at room temperature.
Then NaOMe was added to the solution. A brown precipitate
was formed immediately. The mixture was stirred for 30 min. Then
the solution was dried under vacuum, and CH2Cl2 was added to
extract the product. The combined extract solution was filtered
through Celite. The filtrate was dried under vacuum. The solid was
washed with methanol (3 mL) and dried under vacuum to afford 6a
(0.08 g, 82%). Spectroscopic data of 6a are as follows. 1H
NMR (CDCl3): δ 7.51-7.06 (m, 30H, Ph), 6.07 (m, 1H, dCH),
4.93 (m, 1H, dCH2), 4.89 (m, 1H, dCH2), 4.21 (s, 5H, Cp), 4.19,
4.13 (m, 2 ꢀ 1H, CH of CpFc), 4.11 (s, 5H, CpFc), 4.04, 4.02
(m, 2 ꢀ 1H, CH of CpFc), 3.05 (m, 1H, CH(Fc)), 2.87-2.67
(m, 2H, CH2 of allyl). 31P NMR (CDCl3): δ 51.1 (s, PPh3). Anal.
Calcd for C57H50FeP2Ru: C, 71.77; H, 5.28. Found: C, 71.92;
H, 5.19.
3
7.50-6.68 (m, 35H, Ph), 6.28 (dd, JH-H(trans) = 17.0 Hz,
3
3JH-H(cis) = 10.5 Hz, 1H, dCH), 5.26 (d, JH-H(cis) = 10.7
Hz, 1H, dCH2), 5.09 (br, 6H, dCH2, Cp), 4.28 (m, 2H, CH of
CpFc, CH2), 4.25 (s, 5H, Cp of Fc), 4.16 (d, 1H, 3JH-H = 2.24
Hz, CH of CpFc), 3.81 (d, 1H, 3JH-H = 2.29 Hz, CH of CpFc),
2.82 (d, 1H, 2JH-H = 13.0 Hz, CH2); 31P NMR (CDCl3) δ 45.8,
2
42.9 (two d, JP-P = 26.2 Hz). The minor isomer was only
observed in NMR: 1H NMR (CDCl3) δ 7.50-6.68 (m, 35H, Ph),
5.79 (dd, JH-H(trans) = 16.7 Hz, JH-H(cis) = 10.0 Hz, 1H,
3
3
3
dCH), 5.04 (s, 5H, Cp), 4.88 (d, JH-H(cis) = 10.8 Hz, 1H,
3
dCH2), 4.58 (d, JH-H(trans) = 17.5 Hz, 1H, dCH2),
4.29-4.01 (m, 4H, CH2, CH of CpFc), 3.91 (s, 5H, Cp), 2.71
(d, 1H, 2JH-H = 13.4 Hz, CH2); 31P NMR (CDCl3) δ 46.1, 42.6
(two d, 2JP-P = 26.4 Hz). ESI MS (m/z): 1029.20 (Mþ - BF4).
Anal. Calcd for the major isomer, C63H53BF4FeP2Ru: C, 67.82;
H, 4.79. Found: C, 67.69; H, 5.01.
Single-Crystal X-ray Diffraction Analysis of 7b. Single crystals
of the major isomer of 7b suitable for an X-ray diffraction study
were grown as mentioned above. A single crystal of dimensions
0.20 ꢀ 0.15 ꢀ 0.10 mm3 was glued to a glass fiber and mounted
on an SMART CCD diffractometer. The diffraction data were
collected using 3 kW sealed-tube Mo KR radiation (T = 295 K).
The exposure time was 5 s per frame. SADABS27 (Siemens area
detector absorption) absorption correction was applied, and
decay was negligible. Data were processed, and the structure was
solved and refined by the SHELXTL28 program. The structure
was solved using direct methods and confirmed by Patterson
methods refined on intensities of all data to give R1 = 0.0568
and wR2 = 0.1291 for 13 493 unique observed reflections (I >
2σ(I)). Hydrogen atoms were placed geometrically using the
riding model with thermal parameters set to 1.2 times those for
the atoms to which the hydrogens are attached and 1.5 times
those for the methyl hydrogens.
Synthesis of [Ru0]CtCCH2CH(Fc)CHdCH2 (6a0). Complex
6a0 (0.16 g, 81%) was similarly prepared from 4a0 (0.20 g, 0.24
mmol). Spectroscopic data of 6a0 are as follows. 1H NMR
(CD3COCD3): δ 8.00-7.28 (m, 30H, Ph), 5.53 (m, 1H, dCH),
4.68 (s, 5H, Cp), 4.58 (m, 1H, dCH2), 4.53 (m, 1H, dCH2), 3.97
(s, 5H, CpFc), 3.91, 3.79, 4.76, 4.74 (m, 4 ꢀ 1H, CH of CpFc),
2.50-2.32 (m, 4H, dppe), 2.20 (m, 1H, CH(Fc)), 1.76-1.60 (m,
2H, CH2 of allyl). 31P NMR (CD3COCD3): δ 87.1, 86.9 (2 d,
JP-P = 22.1 Hz). Anal. Calcd for C47H44FeP2Ru: C, 68.20; H,
5.36. Found: C, 67.97; H, 5.49.
Synthesis of Complex 7a. A Schlenk flask was charged with 4a
(0.10 g, 0.10 mmol) in dried CH2Cl2 (10 mL) under nitrogen. The
solution was stirred for 1 week at room temperature. The
solution changed from brown to red. Then, the solution was
concentrated to 2 mL under vacuum, and to the resulting
solution was added diethyl ether to give a precipitate, which
was filtered. Further purification was performed by flash neu-
tral aluminum oxide chromatography (CH2Cl2-acetone 2:1) to
give a red-brown powder of 7a (0.07 g, 70%). Spectroscopic data
of 7a are as follows. 1H NMR (CDCl3): δ 7.66-6.94 (m, 30H,
Ph), 5.89 (m, 1H, dCH), 5.13 (s, 5H, Cp), 5.06 (m, 1H, dCH2),
5.02 (m, 1H, dCH2), 4.27, 4.21 (m, 2 ꢀ 1H, CH of CpFc), 4.17,
4.06 (m, 2 ꢀ 2H, CH of CpFc), 4.02, 3.81 (m, 2 ꢀ 1H, CH of
CpFc), 2.89 (m, 1H, CH(Fc)), 2.54-2.51 (m, 2H, CH2 of allyl).
Acknowledgment. We thank the National Science Council
of Taiwan, Republic of China, for financial support.
Supporting Information Available: A CIF file giving complete
crystallographic data for 7b. This material is available free of
charge via the Internet at http://pubs.acs.org.
2
13C NMR (CDCl3): δ 344.6 (t, JP-C = 15.2 Hz, CR), 139.7
(27) The SADABS program is based on the method of Blessing; see:
Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33–38.
(28) SHELXTL: Structure Analysis Program, version 5.04; Siemens
Industrial Automation Inc., Madison, WI, 1995.
(dCH), 134.5-128.2 (Ph), 119.8 (Cβ), 115.2 (dCH2), 94.1 (Cp),
87.3, 78.6, 70.8, 70.7, 70.2, 69.6, 69.5, 69.2, 68.3, 67.5 (Fc), 40.2
(CH(Fc)), 39.5 (CH2). 31P NMR (CDCl3): δ 43.5, 42.8 (2 d,