Unusual activation of 1-ethynyl-1-cyclohexanol by [RuCl(η5-C9H7)-(PPh3) 2]: Synthesis and reactivity of the allenylidene derivative [Ru{=C=C=C(C13H20)}(η5-C9H 7)(PPh3)2][PF6]

Article abstract of DOI:10.1039/a904744a

The reaction of [RuCl(η⁵-C₉H₇)(PPh₃) ₂] with an excess of 1-ethynyl-1-cyclohexanol and NaPF₆ in refluxing methanol yielded the allenylidene complex [Ru{=C=C=C(C₁₃H₂₀)}(η⁵-C₉H ₇)(PPh₃)₂][PF₆] 1 via an unprecedented coupling of two molecules of the propargyl (prop-2-ynyl) alcohol derivative. Complex 1 can also be obtained by reaction of the vinylvinylidene derivative [Ru{=C=C(H)R}(η⁵-C₉H₇)(PPh ₃)₂][PF₆] 2 (R = 1-cyclohexenyl) with 1-ethynyl-1-cyclohexanol or 1-ethynylcyclohexene in refluxing methanol. The behaviour of 2 towards other 1-alkyn-3-ols has been studied but only the replacement of the vinylidene moiety by the propargyl alcohols, via an η¹-vinylidene-η²-alkyne tautomerization process, to generate both vinylvinylidene [Ru{=C=C(H)R}(η⁵-C₉H₇)(PPh ₃)₂][PF₆] (R = 1-cyclopentenyl, 1-cycloheptenyl or 1-cyclooctenyl) or allenylidene [Ru(=C=C=CR₂)(η⁵-C₉H₇)(PPh ₃)₂][PF₆] (R = Ph or R₂=2,2′-biphenyldiyl) complexes along with 1-ethynylcyclohexene was observed. A similar 1,3-enyne elimination also takes place in the reaction of 2 with phenylacetylene or acetonitrile to afford [Ru{=C=C(H)Ph}(η⁵-C₉H₇)(PPh ₃)₂][PF₆] and [Ru(N≡CMe)(η⁵-C₉H₇)(PPh ₃)₂][PF₆], respectively. On the basis of these observations a mechanism for the formation of 1 is proposed. The allenylidene complex 1 regioselectively reacts with NaR, in THF at -20°C, to yield the neutral σ-alkynyl derivatives [Ru{C≡CC(C₁₃H₂₀)R}(η⁵-C ₉H₇)(PPh₃)₂] (R = C≡N or OMe). Protonation of the R = CN derivative with HBF₄·Et₂O, in diethyl ether at -20°C, afforded the cationic vinylidene complex [Ru{=C=C(H)C(C₁₃H₂₀)C≡N}(η⁵-C ₉H₇)(PPh₃)₂][BF₄]. In contrast, protonation with R = OMe gives back the starting allenylidene derivative 1. The Royal Society of Chemistry 1999.

Full text of DOI:10.1039/a904744a

View Article Online / Journal Homepage / Table of Contents for this issue
Unusual activation of 1-ethynyl-1-cyclohexanol by [RuCl(ꢀ5-C9H7)-
(PPh3)2]: synthesis and reactivity of the allenylidene derivative
[Ru{᎐C᎐C᎐C(C H )}(ꢀ5-C H )(PPh ) ][PF ]
᎐ ᎐ ᎐
13 20
9
7
3 2
6
Victorio Cadierno, M. Pilar Gamasa, José Gimeno* and Elena Lastra
Departamento de Química Orgánica e Inorgánica, Instituto Universitario de Química
Organometálica ‘Enrique Moles’ (Unidad Asociada al C.S.I.C.), Universidad de Oviedo,
E-33071 Oviedo, Spain. E-mail: jgh@sauron.quimica.uniovi.es
Received 14th June 1999, Accepted 15th July 1999
The reaction of [RuCl(η5-C9H7)(PPh3)2] with an excess of 1-ethynyl-1-cyclohexanol and NaPF6 in refluxing methanol
᎐ ᎐ ᎐
yielded the allenylidene complex [Ru{᎐C᎐C᎐C(C H )}(η5-C H )(PPh ) ][PF ] 1 via an unprecedented coupling of
13 20
9
7
3
2
6
two molecules of the propargyl (prop-2-ynyl) alcohol derivative. Complex 1 can also be obtained by reaction of the
vinylvinylidene derivative [Ru{᎐C᎐C(H)R}(η5-C H )(PPh ) ][PF ] 2 (R = 1-cyclohexenyl) with 1-ethynyl-1-cyclo-
᎐ ᎐
9
7
3
2
6
hexanol or 1-ethynylcyclohexene in refluxing methanol. The behaviour of 2 towards other 1-alkyn-3-ols has been
studied but only the replacement of the vinylidene moiety by the propargyl alcohols, via an η1-vinylidene–η2-alkyne
᎐ ᎐
᎐ ᎐ ᎐
tautomerization process, to generate both vinylvinylidene [Ru{᎐C᎐C(H)R}(η5-C H )(PPh ) ][PF ] (R = 1-cyclo-
9
7
3
2
6
pentenyl, 1-cycloheptenyl or 1-cyclooctenyl) or allenylidene [Ru(᎐C᎐C᎐CR )(η5-C H )(PPh ) ][PF ] (R = Ph or
2
9
7
3
2
6
R2 = 2,2Ј-biphenyldiyl) complexes along with 1-ethynylcyclohexene was observed. A similar 1,3-enyne elimination
also takes place in the reaction of 2 with phenylacetylene or acetonitrile to afford [Ru{᎐C᎐C(H)Ph}(η5-C H )-
᎐ ᎐
9
7
5
᎐
(PPh ) ][PF ] and [Ru(N᎐CMe)(η -C H )(PPh ) ][PF ], respectively. On the basis of these observations a mechanism
᎐
3
2
6
9
7
3
2
6
for the formation of 1 is proposed. The allenylidene complex 1 regioselectively reacts with NaR, in THF at Ϫ20 ЊC,
5
᎐
᎐
to yield the neutral σ-alkynyl derivatives [Ru{C᎐CC(C H )R}(η -C H )(PPh ) ] (R = C᎐N or OMe). Protonation
᎐
᎐
13 20
9
7
3 2
of the R = CN derivative with HBF4ؒEt2O, in diethyl ether at Ϫ20 ЊC, afforded the cationic vinylidene complex
5
᎐
[Ru{᎐C᎐C(H)C(C H )C᎐N}(η -C H )(PPh ) ][BF ]. In contrast, protonation with R = OMe gives back the
᎐ ᎐
᎐
13 20
9
7
3
2
4
starting allenylidene derivative 1.
process through a formal [1,3]-H shift (Chart 1; Path II) to the
thermodynamically more stable vinylvinylidene derivatives.9,10
In the course of these studies we have found that the activ-
ation of 1-ethynyl-1-cyclohexanol by the metal fragment
[Ru(η5-C9H7)(PPh3)2]ϩ proceeds through a different pathway.
Thus, we have preliminarily reported the formation of an
allenylidene moiety containing a spiro-bicyclic fragment 1
which results from the metal promoted double dehydration of
two molecules of the 1-alkyn-3-ol, see eqn. (1).11
Introduction
The chemistry of ruthenium() complexes containing unsatur-
ated carbene ligands [Ru]᎐(C᎐) CR (“metallacumulenes”) has
᎐
᎐
n
2
received increasing attention in recent years. In particular,
important developments have been achieved by using the ability
of vinylidene derivatives (the simplest members of the series,
n = 1)1 to promote selective carbon–carbon coupling reactions.2
They have also been shown to be active species in several cat-
alytic transformations involving terminal alkynes,3 and useful
catalysts for ring opening metathesis polymerization (ROMP)
and ring closing-metathesis (RCM) of cyclic or acyclic olefins.3
In contrast, the chemistry of the higher members of this series
has been less developed in spite of their potential utility in
synthesis due to the presence of a cumulene system and the
metal–carbon double bond.1 In this context, ruthenium()
allenylidene complexes [Ru]᎐C᎐C᎐CR developed4 are excellent
᎐ ᎐ ᎐
2
substrates for regio- and/or stereo-selective C–C and carbon–
heteroatom coupling processes.5 More recently, Dixneuf
and co-workers6 have found that the cationic allenylidene
ruthenium() derivatives [Ru(Cl)(᎐C᎐C᎐CR )(PR )(η6-arene)]ϩ
are appropriate catalysts for the RCM of olefins.
In order to ascertain the scope of this unexpected reaction
and explore the reactivity of the unprecedented allenylidene
complex 1, we have now studied (a) alternative synthetic
approaches to 1 and (b) its utility as a source of functional-
ized alkynyl (A) and vinylidene derivatives (B) (Chart 2). A
mechanistic account of the formation of complex 1 is pro-
posed and a series of exchange processes of the cyclohexenyl-
᎐ ᎐ ᎐
2
3
Following the well established Selegue methodology,7 we
have recently reported the synthesis of a large variety of
indenylruthenium() allenylidene complexes using propargyl
(prop-2-ynyl) alcohol derivatives as a source of the unsaturated
carbene moiety (Chart 1; Path I).8 We have also shown that
vinylvinylidene complexes can be selectively obtained from
1-ethynyl-1-cycloalkanols, via the initial formation of unstable
allenylidene species which rapidly undergo a tautomerization
vinylidene moiety in the complex [Ru{᎐C᎐C(H)R}(η5-C H )-
᎐ ᎐
9
7
(PPh3)2][PF6] 2 (R = 1-cyclohexenyl) leading to the formation
of other unsaturated carbene complexes is also reported.
J. Chem. Soc., Dalton Trans., 1999, 3235–3243
This journal is © The Royal Society of Chemistry 1999
3235

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Chart 1
Compound 1 is soluble in chlorinated solvents and tetra-
hydrofuran and has been characterized by microanalysis, con-
ductance measurements, mass spectrometry (FAB), IR and
1
NMR (31P-{1H}, H and 13C-{1H}) spectroscopy (details are
given in the Experimental section). The structure has been con-
firmed unequivocally by X-ray crystallography.11 Complex 1
consists of a cationic indenylruthenium() allenylidene contain-
ing
a spiro(bicyclo[3.3.1]non-2-en-9-ylidene–4-cyclohexane)
moiety, with the 9-carbon atom being Cγ of the unsaturated
chain (see Scheme 1 for numbering of the bicyclic skeleton).
The IR spectrum (KBr) exhibits, in addition to the expected
absorption for the hexafluorophosphate anion (839 cmϪ1), a
Chart 2
strong ν(C᎐C᎐C) band (asymmetric stretching vibration) at
Results
᎐ ᎐
1940 cmϪ1. The 1H and 13C-{1H} NMR spectra also support the
formation of the spiro-bicyclic allenylidene moiety (see the
Experimental section). In particular the following features are
noted: (i) the typical carbene Ru᎐C low-field resonance in the
Synthesis and characterization of [Ru{᎐C᎐C᎐C(C H )}-
᎐ ᎐ ᎐
13 20
(ꢀ5-C9H7)(PPh3)2][PF6] 1
The reaction of [RuCl(η5-C9H7)(PPh3)2] with an excess of 1-
ethynyl-1-cyclohexanol, in refluxing methanol (ca. 12 h) and in
the presence of NaPF6, results in the formation of the cationic
᎐
α
13C-{1H} NMR spectrum which appears as a virtual triplet at
δC 304.48 (2J(CP) = 2J(CPЈ) = 19.4 Hz), and (ii) the expected
singlet resonances of the Cβ and Cγ carbons at δC 186.83 and
191.07.
allenylidene complex [Ru{᎐C᎐C᎐C(C H )}(η5-C H )(PPh ) ]-
᎐ ᎐ ᎐
13 20
9
7
3 2
[PF6] 1 which has been isolated as an air-stable orange solid
(55% yield) (Scheme 1; method A).
Complex 1 is also formed (69% yield) by treatment of the
Scheme 1
3236
J. Chem. Soc., Dalton Trans., 1999, 3235–3243

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vinylvinylidene complex [Ru{᎐C᎐C(H)R}(η5-C H )(PPh ) ]-
᎐ ᎐
mixtures (Scheme 2). No products resulting from a formal
9
7
3 2
[PF6] 2 (R = 1-cyclohexenyl) with an excess of 1-ethynyl-1-
cyclohexanol (ca. 3:1) in refluxing methanol (ca. 12 h) (Scheme
1; method B). It is worth mentioning that on monitoring this
reaction by 31P-{1H} NMR spectroscopy no intermediate
species was observed. Since complex 2 is generated by the treat-
ment of [RuCl(η5-C9H7)(PPh3)2] with 1-ethynyl-1-cyclohexanol
in refluxing methanol (ca. 30 min),9 it is apparent that 2 is a
transient species in the formation of 1, eqn. (1), being able to
activate the formal addition and the dehydration of a second
molecule of the alkynol. Allenylidene complex 1 can be also
obtained (71% yield) by reaction of 2 with the 1,3-enyne 1-
ethynyl-1-cyclohexene which actually is acting as the dehy-
drated species of the parent 1-ethynyl-1-cyclohexanol (Scheme
1; method C). Similarly, the reaction of the neutral σ-enynyl
coupling between 2 and the cyclic alkynols analogous to 1 were
observed even when a longer reaction time was used.
The novel vinylvinylidene complex 4c (81% yield) has been
fully characterized by elemental analysis, IR and NMR (31P-
{1H}, 1H and 13C-{1H}) spectroscopy, showing similar spectro-
scopic properties to those reported for 2 and 4a,4b.9 In particu-
lar, the most remarkable features of the NMR spectra are: (i)
(1H) the singlet and triplet resonances at δH 4.82 and 5.27
(J(HH) = 8.4 Hz) of the Ru᎐C᎐CH and ᎐CH protons, re-
᎐ ᎐
᎐
spectively, and (ii) (13C-{1H}) the typical low-field triplet
resonance of the carbenic atom Ru᎐C at δ 355.29 (2J(CP) =
᎐
α
C
16.5 Hz) as well as the expected Cβ and olefinic singlet
resonances at δC 120.99 (C ), 125.81 (᎐CH) and 126.44 (᎐C).
᎐
᎐
β
The proposed structure for 4c was also assessed by studying
its reactivity. Thus, the acidic vinylidene proton can easily be
5
9
᎐
complex [Ru(C᎐CR)(η -C H )(PPh ) ] 3 (R = 1-cyclohexenyl)
᎐
9
7
3 2
with 1-ethynyl-1-cyclohexanol, in refluxing methanol and in
the presence of MgSO4 and NaPF6, also gives complex 1 (63%
yield) (Scheme 1; method D).
abstracted by treatment of a dichloromethane solution with
᎐
Al O to afford the neutral σ-enynyl derivative [Ru(C᎐CR)-
᎐
2
3
(η5-C9H7)(PPh3)2] 5 (R = 1-cyclooctenyl) which is isolated
(89% yield) as an air-stable orange solid (Scheme 2). The
presence of the enynyl group in 5 is clearly confirmed by the
Attempts to form similar allenylidene complexes from
[RuCl(η5-C9H7)(PPh3)2] using an excess of analogous 1-ethynyl-
appearance of (i) a ν(C᎐C) absorption band at 2067 cmϪ1 in the
᎐
᎐
᎐
1-cycloalkanols HC᎐CC(OH)CH CH (CH ) CH (n = 1 or 3),
᎐
2
2
2
n
2
IR spectrum (KBr), and (ii) typical resonances for the Ru-Cα,
under similar reaction conditions, have been unsuccessful
(Scheme 1). The reactions lead instead to the formation of the
᎐ ᎐
Cβ and Cγ carbon atoms in the 13C-{1H} NMR spectra at
δC 103.82 (2J(CP) = 25.4 Hz), 116.99 and 129.68, respectively,
corresponding vinylvinylidene complexes [Ru{᎐C᎐C(H)R}(η5-
the ᎐CH carbon resonance falling within the aromatic
᎐
C9H7)(PPh3)2][PF6] (R = 1-cyclopentenyl 4a or 1-cycloheptenyl
4b) in good yields.9
region.
The lability of the cyclohexenylvinylidene moiety in complex
2 is confirmed by reactions with 1,1-diphenyl-2-propyn-1-ol
and 9-ethynyl-9-fluorenol which generate the previously
Reactions of [Ru{᎐C᎐C(H)R}(ꢀ5-C H )(PPh ) ][PF ] 2 (R ؍
᎐ ᎐
9
7
3
2
6
1-cyclohexenyl) with 1-alkyn-3-ols
reported allenylidene derivatives [Ru(᎐C᎐C᎐CR )(η5-C H )-
᎐ ᎐ ᎐
2
9
7
Since the direct synthetic approach for allenylidene complexes
analogous to 1 from [RuCl(η5-C9H7)(PPh3)2] is only suitable
for 1-ethynyl-1-cyclohexanol, an alternative procedure was
envisaged. Thus, given that the vinylvinylidene complex 2 is
an intermediate in the formation of complex 1, being able to
couple one further molecule of 1-ethynyl-1-cyclohexanol, its
reaction was tested with other 1-ethynyl-1-cycloalkanols in
order to achieve analogous mixed coupling reactions. However,
the processes proceed through a different pathway showing that
the vinylidene moiety in 2 is remarkably labile being easily
replaced by the 1-alkyn-3-ol derivatives (Scheme 2).
(PPh3)2][PF6] (R = Ph 6a (78% yield), R2 = 2,2Ј-biphenyldiyl 6b
(69% yield))8a (Scheme 2).
Reactivity of [Ru{᎐C᎐C᎐C(C H )}(ꢀ5-C H )(PPh ) ][PF ] 1:
᎐ ᎐ ᎐
13 20
9
7
3
2
6
5
᎐
Synthesis of ꢁ-alkynyl complexes [Ru{C᎐CC(C H )R}(ꢀ -
᎐
13 20
᎐
C H )(PPh ) ] (R ؍ C᎐N 7a or OMe 7b) and the vinylidene
᎐
9
7
3 2
5
᎐
complex [Ru{᎐C᎐C(H)C(C H )C᎐N}(ꢀ -C H )(PPh ) ][BF ] 8
᎐ ᎐
᎐
13 20
9
7
3
2
4
The allenylidene complex [Ru{᎐C᎐C᎐C(C H )}(η5-C H )-
᎐ ᎐ ᎐
13 20
9
7
(PPh3)2][PF6] 1 regioselectively reacts with an equimolar
᎐
amount of NaR (R = C᎐N or OMe), in THF at Ϫ20 ЊC to
᎐
᎐
Thus, the treatment of complex 2 with an excess of 1-ethynyl-
1-cyclopentanol, -1-cycloheptanol or -1-cyclooctanol (ca. 10:1)
in refluxing methanol (ca. 3 h) results in clean formation of the
afford the neutral σ-alkynyl derivatives [Ru{C᎐CC(C H )R}-
᎐
13 20
5
᎐
(η -C H )(PPh ) ] (R = C᎐N 7a or OMe 7b) isolated in 53 and
᎐
9
7
3 2
68% yield, respectively (Scheme 3).
vinylvinylidene derivatives [Ru{᎐C᎐C(H)R}(η5-C H )(PPh ) ]-
Complexes 7a,7b have been analytically and spectro-
scopically characterized. The formation of the alkynyl chain is
clearly confirmed by the appearance in the IR spectra (KBr) of
᎐ ᎐
9
7
3 2
[PF6] (R = 1-cyclopentenyl 4a,9 1-cycloheptenyl 4b9 or 1-cyclo-
octenyl 4c) (65–85% yield). The concomitant elimination of 1-
ethynylcyclohexene was detected by GC of the crude reaction
a ν(C᎐C) absorption at 2082 7a and 2056 cmϪ1 7b. The 31P-{1H}
᎐
᎐
Scheme 2
J. Chem. Soc., Dalton Trans., 1999, 3235–3243
3237

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Scheme 3
NMR spectra display two doublet signals (AB system) (7a:
heptenyl) which are rapidly formed in refluxing methanol by
δ 51.11 and 51.52 (2J(PP) = 31.4 Hz); 7b: 50.30 and 52.43 ppm
(2J(PP) = 31.3 Hz)). The non-equivalence of the phosphorus
nuclei is due to the presence of stereogenic centres on the
the reaction of [RuCl(η5-C9H7)L2] with cyclic alkynols
᎐
HC᎐CC(OH)CH CH (CH ) CH (n = 1, 2 or 3) in the presence
᎐
2
2
2
n
2
of NaPF6.9 Although a longer treatment does not affect the
process with the cyclic pentanol and heptanol derivatives, none-
theless the reaction of [RuCl(η5-C9H7)(PPh3)2] with 1-ethynyl-
1-cyclohexanol in refluxing methanol for 12 h gives the novel
allenylidene complex 1 containing the spiro-bicyclic fragment
[3.3.1]non-2-en-9-ylidene (Scheme 1). The formation of 1 is
the result of the formal addition of two dehydrated molecules
of 1-ethynyl-1-cyclohexanol to the metal auxiliary [Ru(η5-
C9H7)(PPh3)2]ϩ via an unusual metal-promoted double de-
hydration of the alkynol, eqn. (1).
1
spiro-bicyclic fragment. The H and 13C-{1H} NMR spectra
are consistent with the proposed formulations (details in the
Experimental section). The most remarkable features in the
13C-{1H} NMR spectra are: (i) the characteristic virtual triplet
resonance (ca. 2J(CP) = 2J(CPЈ) = 24 Hz) for the Ru–Cα carbon
nucleus (δC 98.34 7a and 90.71 7b), and (ii) the singlet reson-
ances of Cβ (δC ca. 109 7a and 114.85 7b), Cγ (δC ca. 40.00 7a
᎐
and 74.51 7b), as well as C᎐N (7a, δ 123.44) and OMe (7b,
᎐
C
δC 47.63) carbon nuclei.
Addition of electrophiles to the Cβ of σ-alkynyl complexes
has been described as one of the most versatile entries into
vinylidene derivatives.1 Thus, the protonation of 7a with an
excess of HBF4ؒEt2O, in diethyl ether at Ϫ20 ЊC, yields the
At present we are unable to give a plausible explanation for
this unprecedented and selective transformation of 1-ethynyl-1-
cyclohexanol which does not occur for the rest of the cyclic
alkynols. Apparently, this coupling reaction is controlled by
the thermodynamic stability of the allenylidene complex 1
which in contrast seems to be less favourable with respect to the
formation of the corresponding vinylvinylidene complex for the
analogous cyclic alkynols. This is confirmed by the selective
formation of 1 starting either from the cyclohexenylvinyl-
monosubstituted cationic vinylidene complex [Ru{᎐C᎐C(H)C-
᎐ ᎐
5
᎐
(C H )C᎐N}(η -C H )(PPh ) ][BF ] 8 (76% yield) (Scheme
᎐
13 20
9
7
3
2
4
3). Analytical and spectroscopic data are in accord with the
proposed formulation (see the Experimental section). In par-
ticular, the presence of the vinylidene moiety was identified,
as usual, on the basis of: (i) (1H NMR) the singlet resonance of
the Ru᎐C᎐CH proton (δ 4.14), and (ii) (13C-{1H} NMR) the
idene complex [Ru{᎐C᎐C(H)R}(η5-C H )(PPh ) ][PF ] 2 (R =
᎐ ᎐
9
7
3
2
6
᎐ ᎐
H
1-cyclohexenyl) (Scheme 1; methods B and C) or the σ-enynyl
5
low-field resonance of the carbene carbon Ru᎐C (δ 340.90)
᎐
᎐
α
which appears as a virtual triplet (2J(CP) = 2J(CPЈ) = C15.7 Hz).
In contrast, the treatment of 7b with HBF4ؒEt2O gives back the
precursor allenylidene derivative 1 in almost quantitative yield
(Scheme 3). It is interesting that the elimination of methanol
also occurs in the reactions of the analogous indenylruthen-
derivative [Ru(C᎐CR)(η -C H )(PPh ) ] 3 (R = 1-cyclohexenyl)
᎐
9
7
3 2
(Scheme 1; method D). These transformations are rapid and
thermodynamically favourable since by monitoring the reactions
by 31P-{1H} NMR no transient species other than the starting
and final complexes are observed. They shed light on the first
steps of the reaction pathway (see below).
5
᎐
ium() methoxyalkynyl complexes [Ru{C᎐CC(OMe)Ph }(η -
᎐
2
It is apparent that mixed coupling reactions between the
C9H7)L2] with acids.12
cyclohexenylvinylidene complex
2
and cyclic alkynols
᎐
HC᎐CC(OH)CH CH (CH ) CH (n = 1, 3 or 4) are also
᎐
2
2
2
n
2
thermodynamically disfavoured (Scheme 2). They proceed
through dehydration of the parent alcohol leading to the
formation of vinylvinylidene complexes 4a–4c and 1-ethynyl-
cyclohexene. These processes can be described as a formal
Discussion
Reactions with 1-ethynyl-1-cycloalkanols
The activation of cyclic or acyclic propargylic alcohols
1
2
᎐
HC᎐CC(OH)R R by ruthenium() chloride derivatives is a
exchange of the cyclohexenylvinylidene moiety ᎐C᎐C(H)(C H )
᎐
᎐ ᎐
6
9
well known synthetic methodology for either vinylvinylidene
or allenylidene complexes which are selectively formed de-
pending on the nature of the alcohol. To date a wide series
of derivatives such as trans-[RuCl2L2] (L2 = dppm or dppe),13
[RuCl(η5-C5R5)L2]5f,k,7,10a,c and [RuCl(η5-C9H7)L2]8,9 have been
shown to promote such a type of transformation. In par-
ticular, we have reported the synthesis of vinylvinylidene
by the analogous ᎐C᎐C(H)R (R = 1-cyclopentenyl, 1-cyclo-
heptenyl or 1-cyclooctenyl). Similarly, 2 undergoes an analo-
᎐ ᎐
gous exchange process by the allenylidene moiety ᎐C᎐C᎐CR to
᎐ ᎐ ᎐
2
give allenylidene complexes 6a,6b and 1-ethynylcyclohexene by
᎐
reactions with acyclic alkynols HC᎐CC(OH)R (R = 2Ph or
᎐
2
2
2,2Ј-biphenyldiyl). Although no intermediate products could be
detected by 31P-{1H} NMR spectroscopy, the formation of
complexes 4a–4c and 6a,6b may be understood (Scheme 4)
assuming that, in refluxing methanol, the vinylvinylidene
complexes
[Ru{᎐C᎐C(H)R}(η5-C H )L ][PF ]
᎐ ᎐
(L = PPh3,
9
7
2
6
L2 = dppe; R = 1-cyclopentenyl, 1-cyclohexenyl or 1-cyclo-
3238
J. Chem. Soc., Dalton Trans., 1999, 3235–3243

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Scheme 4
derivative 2 is in equilibrium with undetectable concentrations
2
2
5
᎐
of its η -co-ordinated 1,3-enyne tautomer [Ru(η -HC᎐CR)(η -
᎐
C9H7)(PPh3)2][PF6] (R = 1-cyclohexenyl)2b,8b,14† which under-
goes rapid substitution of the 1-ethynylcyclohexene ligand
by the 1-alkyn-3-ol present in the reaction media to afford the
2
5
᎐
corresponding [Ru(η -HC᎐CC(OH)R )(η -C H )(PPh ) ][PF ]
᎐
2
9
7
3
2
6
complex. The typical [1,2]-H shift to give the corresponding
hydroxyvinylidene complex, followed by a spontaneous dehy-
dration of this intermediate, generates the final vinylvinylidene
4a–4c or allenylidene 6a,6b derivatives. Probably, the favourable
exchange of the η2-co-ordinated 1,3-enyne by the incoming
alkynol is the driving force of the overall process.
In accord with the lability of the cyclohexenylvinylidene
moiety based on an η1-vinylidene to η2-alkyne tautomerization,
the vinylidene unit in complex 2 can be also replaced by other
ligands such as phenylacetylene or acetonitrile to yield the
known vinylidene complex [Ru{᎐C᎐C(H)Ph}(η5-C H )-
᎐ ᎐
9
7
5
(PPh3)2][PF6] 916 and the nitrile derivative [Ru(N᎐CMe)(η -
᎐
᎐
C9H7)(PPh3)2][PF6] 10,15 respectively. It should be noted that
these complexes as well as 4a–4c and 6a,6b are quantitatively
formed. Nevertheless, the addition of an excess (ca. 10:1) of
1-ethynyl-1-cyclohexanol or 1-ethynylcyclohexene to refluxing
solutions of compounds 4a–4c, 9 and 10 in methanol leads to
quantitative formation of 2 as monitored by 31P-{1H} and H
1
NMR spectroscopy (see Scheme 4).
Mechanistic proposal for the formation of [Ru{᎐C᎐C᎐C(C H )}-
᎐ ᎐ ᎐
13 20
(ꢀ5-C9H7)(PPh3)2][PF6] 1
With all these precedents in mind we can conclude that the
allenylidene complex 1 results from the coupling between vinyl-
vinylidene 2 and 1-ethynylcyclohexene. A mechanistic proposal
is shown in Scheme 5. We assume that the first step involves
transfer of the acidic vinylidene proton from 2 to the carbon–
carbon double bond of the 1,3-enyne which generates the
neutral σ-enynyl derivative 39 and the transient carbocation
species I. A carbon–carbon coupling reaction between both
intermediates rapidly takes place to form the allenylidene
derivative II. The final formation of complex 1 is likely to be
Scheme 5
based on the acidic character of the proton on the Cδ of the
allenylidene fragment in II. Thus, an initial proton loss gen-
erates the neutral σ-enynyl intermediate III which undergoes an
intramolecular C–C coupling process between the alkenyl and
terminal alkyne functionalities to form the zwitterionic
allenylidene IV. The final protonation of IV gives the observed
spiro-bicyclic allenylidene complex 1. It should be noted that
related intermolecular coupling reactions between allenylidene
complexes containing hydrogen atoms on the Cδ and σ-enynyl
derivatives to yield dinuclear cyclic allenylidene species have
been reported.5a,b,d,f
† The existence of this equilibrium is confirmed in the reaction of
complex 2 with PPh3 in refluxing methanol which leads to the alkenyl-
phosphonioderivative(E)-[Ru{C(H)᎐C(PPh3)R}(η5-C9H7)(PPh3)2][PF6]
᎐
(R = 1-cyclohexenyl) via nucleophilic addition of PPh3 on the co-
2
᎐
ordinated C᎐C bond of the corresponding η -1,3-enyne tautomer. See
᎐
ref. 9. Ab initio molecular orbital (MO) calculations on the model
[Ru(᎐C᎐CH2)(η5-C9H7)(PH3)2]ϩ show that the energy barrier for
᎐
᎐
tautomerization of vinylidene to π-alkyne is only 22.9 kcal molϪ1. This
relatively low value can readily be overcome under the reaction
conditions.15
J. Chem. Soc., Dalton Trans., 1999, 3235–3243
3239

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We assume that the key step of this mechanism is the attack
of complex 3 on the propargylic cation I simultaneously
generated from the starting materials under the reaction con-
ditions. This is consistent with the reaction of 3 with 1-ethynyl-
1-cyclohexanol using MgSO4 as a Lewis acid to activate the
alcohol which readily leads to the formation of 1 (63%)
(Scheme 1; method D) while no reaction is observed in the
absence of the Lewis acid, showing that the formation of the
activated species I is required.
atom to give the alkynyl derivatives 7a,7b (Scheme 3). It is
apparent that the electrophilic Cα atom is effectively pro-
tected and remains inaccessible with respect to the Cγ atom
in spite of this site being relatively sterically crowded. There-
fore, these are additional examples which confirm the utility
of indenylruthenium() allenylidene complexes for the syn-
thesis of functionalized alkynyl derivatives in a regioselective
manner.
Taking into account that the generation of propargylic
cations from both 1-alkyn-3-ols or 1,3-enynes is favoured by
co-ordination to transition metal complexes,17 a ruthenium-
mediated formation of carbocation I cannot be discarded
(see Scheme 6). Thus, the initial proton transfer from 2 can
Conclusion
The reaction of the vinylvinylidene complex [Ru{᎐C᎐C(H)R}-
᎐ ᎐
(η5-C9H7)(PPh3)2][PF6] 2 (R = 1-cyclohexenyl) with 1-ethynyl-1-
cyclohexanol to yield the spiro-bicyclic allenylidene derivative
[Ru{᎐C᎐C᎐C(C H )}(η5-C H )(PPh ) ][PF ] 1 provides a new
᎐ ᎐ ᎐
13 20
9
7
3
2
6
type of selective carbon–carbon coupling process in the well
known chemistry of transition metal vinylidene systems.1
Furthermore, we have demonstrated that this unprecedented
process is based on an initial ruthenium-promoted dehydration
of the 1-alkyn-3-ol derivative, involving an η1-vinylidene–η2-
alkyne tautomerism at ruthenium, and subsequent coupling
between the resulting 1,3-enyne and the vinylvinylidene moiety
of 2. Unfortunately, the scope of this unusual coupling reaction
is limited and small differences in the nature of the propargyl
alcohol derivative lead only to replacement of the vinylidene
moiety in 2.
In addition, the allenylidene complex 1 proved to be an
excellent precursor for the regioselective synthesis of func-
5
᎐
tionalized σ-alkynyl derivatives [Ru{C᎐CC(C H )R}(η -
᎐
13 20
᎐
C H )(PPh ) ] (R = C᎐N 7a or OMe 7b) through its reaction
᎐
9
7
3 2
with nucleophiles. The utility of these new derivatives in
organic synthesis is assured since we have previously reported a
general and useful methodology for liberation of the organic
fragment on related indenylruthenium() complexes.15
Experimental
Scheme 6
General methods
The reactions were performed under an atmosphere of dry
nitrogen using vacuum-line and standard Schlenk techniques.
All reagents were obtained from commercial suppliers and used
without further purification. Solvents were dried by standard
methods and distilled under nitrogen before use. The com-
take place not on the free 1-ethynylcyclohexene molecule, but
2
5
᎐
instead on the transient complex [Ru(η -HC᎐CR)(η -C H )-
᎐
9
7
(PPh3)2][PF6] (R = 1-cyclohexenyl) to afford the neutral σ-
enynyl derivative 3 and the stabilized propargylic cation IЈ. A
carbon–carbon coupling process between both intermediates
followed by co-ordination of 1-ethynylcyclohexene present in
the reaction media can afford II regenerating the starting
vinylvinylidene 2.
pounds [RuCl(η5-C9H7)(PPh3)2],20 [Ru{᎐C᎐C(H)R}(η5-C H )-
᎐ ᎐
9
7
5
(R = 1-cyclohexenyl)9 and [Ru(C᎐CR)(η -
᎐
(PPh3)2][PF6]
2
᎐
C9H7)(PPh3)2] 3 (R = 1-cyclohexenyl)9 were prepared by the
literature methods. Infrared spectra were recorded on a Perkin-
Elmer 1720-XFT spectrometer. The conductivities were
measured at room temperature, in ca. 10Ϫ3 mol dmϪ3 acetone
solutions, with a Jenway PCM3 conductimeter. The C, H and
N analyses were carried out with a Perkin-Elmer 240-B micro-
analyser. Mass spectra (FAB) were recorded using a VG
Autospec spectrometer, operating in the positive mode; 3-nitro-
benzyl alcohol was used as the matrix. The GC analyses were
carried out on a Perkin-Elmer 8600 gas chromatograph,
equipped with a 12 m AQ2 capillary column (0.22 mm) and a
flame ionization detector; quantification was achieved with a
Perkin-Elmer Nelson 1020 integrator. The NMR spectra were
recorded on a Bruker AC300 instrument at 300 (1H), 121.5 (31P)
or 75.4 MHz (13C) using SiMe4 or 85% H3PO4 as standards.
DEPT Experiments have been carried out for all the complexes.
Abbreviations used: s, singlet; br, broad; d, doublet; dd, doublet
of doublets; t, triplet; vt, virtual triplet; m, multiplet.
Reactivity of the allenylidene complex [Ru{᎐C᎐C᎐C(C H )}-
᎐ ᎐ ᎐
13 20
(ꢀ5-C9H7)(PPh3)2][PF6] 1
Although the reactivity of transition-metal allenylidene com-
plexes has only sparsely been investigated, there is ample
experimental1,5,13 and theoretical5e,8a,18 evidence to conclude
that the Cα and Cγ atoms of the unsaturated chain are electro-
philic centres and that Cβ is nucleophilic. During the last few
years we have demonstrated that the regioselectivity of the
nucleophilic additions on indenylruthenium() allenylidene
complexes can be controlled by appropriate selection both of
the substituents in the allenylidene chain and of the ancillary
ligands.8,9,12,19 Thus, we have found that allenylidene com-
plexes containing the [Ru(η5-C9H7)(PPh3)2] moiety exhibit an
efficient steric protection of the Cα atom due to the preferred
cis orientation of the indenyl group with respect to the un-
saturated chain and to the presence of the bulky ancillary
triphenylphosphine ligands. In contrast, the Cγ atom is more
accessible and nucleophiles can be added at this position to
yield functionalized σ-alkynyl derivatives.8a,9,12,19 In accordance,
complex 1 undergoes readily nucleophilic additions at the Cγ
3240
J. Chem. Soc., Dalton Trans., 1999, 3235–3243

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Preparations
5.27 (t, J(HH) = 8.4, ᎐CH), 5.54 (d, 2 H, J(HH) = 2.5, H-1,3),
5.81 (m, 2 H, H-4,7 or H-5,6), 5.87 (t, 1 H, J(HH) = 2.5 Hz,
H-2) and 6.78–7.48 (m, 32 H, Ph and H-4,7 or H-5,6);
δC(CDCl3) 25.92, 26.18, 26.27, 28.41, 29.70 and 30.25 (s, CH2),
81.84 (s, C-1,3), 99.29 (s, C-2), 116.35 (s, C-3a,7a), 120.99
(s, Cβ), 123.21 and 130.22 (s, C-4,7 and C-5,6), 125.81 (s,
᎐
[Ru{᎐C᎐C᎐C(C H )}(ꢀ5-C H )(PPh ) ][PF ] 1. Method A.
᎐ ᎐ ᎐
13 20
9
7
3
2
6
The salt NaPF6 (0.08 g, 0.5 mmol) and 1-ethynyl-1-cyclo-
hexanol (0.06 g, 0.5 mmol) were added to a solution of
[RuCl(η5-C9H7)(PPh3)2] (0.15 g, 0.2 mmol) in MeOH (45 cm3).
The reaction mixture was heated under reflux for 12 h. The
solvent was then removed under vacuum, the crude product
extracted with CH2Cl2 (ca. 20 cm3), and the extract filtered.
Concentration of the resulting solution (ca. 5 cm3) followed by
the addition of diethyl ether (ca. 50 cm3) precipitated an orange
solid, which was washed with diethyl ether (2 × 20 cm3) and
dried in vacuo. Yield: 0.12 g, 55% (Found: C, 66.58; H, 5.32.
᎐CH), 126.44 (s, ᎐C), 128.40–133.61 (m, Ph) and 355.29 (t,
᎐
᎐
2J(CP) = 16.5 Hz, Ru᎐Cα); ∆δ(C-3a,7a) = Ϫ14.35.
᎐
5
᎐
[Ru(C᎐CR)(ꢀ -C H )(PPh ) ]
5
(R ؍ 1-cyclooctenyl).
A
᎐
9
7
3 2
mixture of the vinylvinylidene complex 4c (0.30 g, 0.3 mmol)
and neutral Al2O3 (excess, 5 cm3) in CH2Cl2 (20 cm3) was stirred
at room temperature for 2 h. The solvent was then removed
under vacuum, and the solid residue extracted with diethyl
ether (ca. 50 cm3) and filtered. Evaporation of the solvent
gave the σ-enynyl complex 5 as an orange solid. Yield: 0.23 g,
C61H57F6P3Ru requires C, 66.72; H, 5.23%). Conductivity
Ϫ
(acetone, 20 ЊC): 118 ΩϪ1 cm2 molϪ1. νmax
˜
/cmϪ1 (PF6 ) 839s,
(C᎐C᎐C) 1940s (KBr). δ (CD Cl ) 49.56 (br); δ (CD Cl ) 1.20–
᎐ ᎐
P
2
2
H
2
2
2.17 (m, 16 H, CH2), 2.60 and 2.86 (s, 1 H each one, CH), 4.91
(m, 1 H, H-2), 5.39 (m, 2 H, H-1 and H-3), 5.43 (m, 1 H,
89% (Found: C, 75.39; H, 5.85. C55H50P2Ru requires C,
᎐
75.58; H, 5.76%). νmax
˜
/cmϪ1 (C᎐C) 2067m (KBr). δ (C D )
᎐
P
6
6
᎐CHCH), 5.90 (d, 1 H, J(HH) = 9.6 Hz, ᎐CH), 6.34 and 6.51
᎐
᎐
52.67s; δH(C6D6) 1.60 (m, 6 H, CH2), 1.68, 2.32 and 2.55 (m,
2 H each one, CH2), 4.69 (d, 2 H, J(HH) = 2.4, H-1,3),
5.50 (t, J(HH) = 2.4, H-2), 5.97 (t, 1 H, J(HH) = 8.3 Hz,
(m, 1 H each, H-4, H-5, H-6 or H-7) and 6.96–7.39 (m, 32 H, Ph
and H-4, H-5, H-6 or H-7); δC(CD2Cl2) 18.32, 22.08, 22.84,
26.27, 32.83, 34.24, 35.25 and 39.97 (s, CH2), 46.11 (s, C), 52.27
and 58.42 (s, CH), 86.11 and 86.94 (s, C-1 and C-3), 97.12 (s,
C-2), 110.72 and 112.26 (s, C-3a and C-7a), 123.18–140.07
᎐CH), 6.35 and 6.68 (m, 2 H each, H-4,7 and H-5,6) and
᎐
6.90–7.53 (m, 30 H, Ph); δC(C6D6) 26.63, 27.30, 27.62, 29.31,
31.63 and 31.99 (s, CH2), 74.91 (s, C-1,3), 95.56 (s, C-2),
103.82 (t, 2J(CP) = 25.4 Hz, Ru–Cα), 109.21 (s, C-3a,7a),
116.99 (s, Cβ), 123.10 and 125.87 (s, C-4,7 and C-5,6), 129.68
(m, Ph, CH᎐CH, C-4, C-5, C-6 and C-7), 186.83 and 191.07 (s,
᎐
C and C ) and 304.48 (vt, 2J(CP) = 2J(CPЈ) = 19.4 Hz, Ru᎐C );
᎐
β
γ
α
∆δ(C-3a,7a) = Ϫ19.16 (average). m/z (FAB) 953 (Mϩ) and 691
(s, ᎐C) and 127.00–139.08 (m, Ph and ᎐CH); ∆δ(C-3a,7a) =
᎐
᎐
(Mϩ Ϫ PPh3).
Ϫ21.49.
Method B. A solution of the vinylvinylidene complex 2 (0.15
g, 0.2 mmol) and 1-ethynyl-1-cyclohexanol (0.07 g, 0.6 mmol)
in methanol (40 cm3) was heated under reflux for 12 h. The
solvent was then removed under vacuum and the resulting
solid residue washed with diethyl ether (2 × 15 cm3) to afford
1 in 69% yield (0.15 g).
Method C. As described in method B, complex 1 was ob-
tained in 71% yield (0.154 g) starting from 2 (0.15 g, 0.2 mmol)
and 1-ethynylcyclohexene (0.07 ml, 0.6 mmol).
Method D. A mixture of the σ-enynyl complex 3 (0.169 g, 0.2
mmol), 1-ethynyl-1-cyclohexanol (0.07 g, 0.6 mmol), NaPF6
(0.05 g, 0.3 mmol) and MgSO4 (0.12 g, 1 mmol) in methanol
(40 cm3) was heated under reflux for 12 h. The solvent was then
removed under vacuum, the crude product extracted with
CH2Cl2 (ca. 20 cm3), and the extract filtered. Concentration of
the resulting solution (ca. 5 cm3) followed by the addition of
diethyl ether (ca. 50 cm3) precipitated 1, which was washed with
diethyl ether (2 × 20 cm3) and dried in vacuo. Yield: 0.14 g,
63%.
5
᎐
᎐
᎐
[Ru{C᎐CC(C13H20)R}(ꢀ -C9H7)(PPh3)2] (R ؍ C᎐N 7a or
᎐
OMe 7b). General procedure. A solution of the allenylidene
complex 1 (1.09 g, 1 mmol) in THF (50 cm3) was treated, at
Ϫ20 ЊC, with the corresponding NaR reagent (1 mmol). The
mixture was allowed to warm to room temperature, and the
solvent then removed under vacuum. The solid residue was
extracted with diethyl ether (for 7a) or hexane (for 7b) and
filtered. Evaporation of the solvent gave the σ-alkynyl com-
plexes 7a,7b as yellow-orange solids. Complex 7a was purified
by column chromatography (neutral Al2O3; activity grade I)
collecting the orange band eluted with hexane–diethyl ether
(4:1): 0.52 g, 53% (Found: C, 76.29; H, 6.06; N, 1.34. C62H57-
᎐
NP2Ru requires C, 76.05; H, 5.86; N, 1.43%); νmax
˜
/cmϪ1 (C᎐C)
᎐
2
᎐
2082m, (C᎐N) 2221w (KBr); δP(C6D6) 51.11 (d, J(PP) = 31.4,
PPh3) and 51.52 (d, J(PP) = 31.4 Hz, PPh3); δH(C6D6) 1.26–
᎐
2
1.84 (m, 13 H, CH2), 2.03 (m, 3 H, CH2), 2.26 and 2.45 (m, 1 H
each one, CH), 4.48 and 4.62 (m, 1 H each, H-1 and H-3), 5.37
(m, 1 H, H-2), 5.50 (dd, 1 H, J(HH) = 10.0, 6.0, ᎐CHCH), 5.80
᎐
(d, 1 H, J(HH) = 10.0 Hz, ᎐CH), 6.18 and 6.60 (m, 2 H each,
᎐
Reactions of [Ru{᎐C᎐C(H)R}(ꢀ5-C H )(PPh ) ][PF ] 2 (R ؍
H-4, H-5, H-6 and H-7) and 6.93–7.36 (m, 30 H, Ph); δC(C6D6)
17.29, 22.72, 22.87, 25.61, 26.74, 26.82, 36.24 and 37.51 (s,
CH2), 39.13 and 40.38 (s, C and Cγ), 41.57 and 41.66 (s, CH),
᎐ ᎐
9
7
3
2
6
1-cyclohexenyl) with propargyl alcohol derivatives: [Ru{᎐C᎐C-
᎐ ᎐
(H)RЈ}(ꢀ5-C9H7)(PPh3)2][PF6] (RЈ ؍ 1-cyclopentenyl 4a, 1-cyclo-
2
2
heptenyl 4b or 1-cyclooctenyl 4c) and [Ru(᎐C᎐C᎐CR )(ꢀ5-C H )-
73.43 (d, J(CP) = 6.1, C-1 or C-3), 73.91 (d, J(CP) = 5.6, C-1
᎐ ᎐ ᎐
2
9
7
2
(PPh3)2][PF6] (R2 ؍ 2Ph 6a or C12H8 6b). General procedure. A
solution of the vinylvinylidene complex 2 (0.99 g, 1 mmol) and
the corresponding propargyl alcohol (10 mmol for complexes
4a–4c and 3 mmol for complexes 6a,6b) in MeOH (50 cm3) was
heated under reflux for 3 h. The solvent was then removed
under vacuum, and the solid residue extracted with CH2Cl2 (ca.
30 cm3) and filtered. Concentration of the resulting solution
(ca. 5 cm3) followed by addition of diethyl ether (ca. 50 cm3)
precipitated a brown (4a–4c) or violet (6a,6b) solid, which was
washed with diethyl ether (2 × 20 cm3) and dried in vacuo. The
31P-{1H} and 1H NMR data obtained for complexes 4a,4b
(65 and 85% yield, respectively) and 6a,6b (78 and 69% yield,
respectively) were in agreement with those previously re-
ported.8a,9 Complex 4c: 0.82 g, 81% (Found: C, 64.21; H, 5.08.
or C-3), 95.22 (s, C-2), 98.34 (vt, J(CP) = 2J(CPЈ) = 23.8 Hz,
Ru–Cα), 108.51, 109.42 and 109.73 (s, C-3a, C-7a and Cβ),
123.06, 123.67, 124.50, 125.84, 126.06 and 138.48 (s, C-4, C-5,
᎐
C-6, C-7, ᎐CHCH and ᎐CH), 123.44 (s, C᎐N) and 127.37–
᎐
᎐
᎐
138.92 (m, Ph). Complex 7b: 0.67 g, 68% (Found: C, 75.28; H,
6.02. C62H60OP2Ru requires C, 75.66; H, 6.14%). νmax
/cmϪ1
(C᎐C) 2056m (KBr); δ (C D ) 50.30 (d, J(PP) = 31.3, PPh )
˜
2
᎐
᎐
P
6
6
3
2
and 52.43 (d, J(PP) = 31.3 Hz, PPh3); δH(C6D6) 0.93–2.11 (m,
17 H, CH2 and CH), 2.41 (m, 1 H, CH), 2.80 (s, 3 H, OCH3),
4.42 and 4.58 (m, 1 H each, H-1 and H-3), 5.43 (m, 1 H, H-2),
5.57 (dd, 1 H, J(HH) = 9.9, 6.3, ᎐CHCH), 5.76 (d, 1 H,
᎐
J(HH) = 9.9 Hz, ᎐CH), 5.93 and 6.40 (m, 2 H each, H-4, H-5,
᎐
H-6 and H-7) and 6.65–7.18 (m, 30 H, Ph); δC(C6D6) 16.30,
21.32, 21.65, 23.35, 25.70, 35.52 and 35.91 (s, CH2), 39.16 (s, C),
39.37 and 40.89 (s, CH), 47.63 (s, OCH3), 71.90 (d, 2J(CP) = 7.4,
C-1 or C-3), 73.40 (d, 2J(CP) = 7.0, C-1 or C-3), 74.51 (s,
Cγ), 90.71 (vt, 2J(CP) = 2J(CPЈ) = 23.9 Hz, Ru-Cα), 94.69 (s,
C-2), 107.31 and 109.58 (s, C-3a and C-7a), 114.85 (s, Cβ) and
C55H51F6P3Ru requires C, 64.76; H, 5.04%); conductivity
Ϫ
(acetone, 20 ЊC) 109 ΩϪ1 cm2 molϪ1; νmax
˜
/cmϪ1 (PF6 ) 837s
(KBr); δP(CDCl3) 37.22s; δH(CDCl3) 1.48 (m, 6 H, CH2), 1.65,
1.91 and 2.08 (m, 2 H each one, CH ), 4.82 (s, 1 H, Ru᎐C᎐CH),
᎐ ᎐
2
J. Chem. Soc., Dalton Trans., 1999, 3235–3243
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M. Oliván, J. C. Huffman, O. Eisenstein and K. G. Caulton,
121.48–138.69 (m, Ph, C-4, C-5, C-6, C-7, ᎐CHCH and ᎐CH);
∆δ(C-3a,7a) = Ϫ22.25 (average).
᎐
᎐
Organometallics, 1998, 17, 4700; (m) Y.-H. Lo, Y.-C. Lin, G.-H. Lee
and Y. Wang, Organometallics, 1999, 18, 982; (n) C. Slugovc,
K. Mereiter, R. Schmid and K. Kirchner, Organometallics, 1999, 18,
1011.
5
᎐
[Ru{᎐C᎐C(H)C(C H )C᎐N}(ꢀ -C H )(PPh ) ][BF ] 8.
A
᎐ ᎐
᎐
13 20
9
7
3
2
4
solution of the σ-alkynyl complex 7a (0.98 g, 1 mmol) in diethyl
ether (100 cm3), at Ϫ20 ЊC, was treated dropwise stirring
vigorously with a dilute solution of HBF4ؒEt2O in diethyl ether.
Immediately, an insoluble solid precipitated but the addition
was continued until no further solid formed. The solution was
then decanted and the brown solid washed with diethyl ether
(3 × 20 cm3) and vacuum dried. Yield: 0.81 g, 76% (Found: C,
68.89; H, 5.19; N, 1.24. C62H58BF4NP2Ru requires C, 69.79; H,
5.48; N, 1.31%). Conductivity (acetone, 20 ЊC): 110 ΩϪ1 cm2
3 C. Bruneau and P. H. Dixneuf, Acc. Chem. Res., 1999, 32, 311 and
refs. therein.
4 J. R. Lomprey and J. P. Selegue, Organometallics, 1993, 12, 616;
R. F. Winter and F. M. Hornung, Organometallics, 1997, 16, 4248;
M. I. Bruce, P. Hinterding, P. J. Low, B. W. Skelton and A. H. White,
J. Chem. Soc., Dalton Trans., 1998, 467; P. Haquette, D. Touchard,
L. Toupet and P. Dixneuf, J. Organomet. Chem., 1998, 565, 63;
R. F. Winter, Chem. Commun., 1998, 2209; D. Touchard, P.
Haquette, A. Daridor, L. Toupet and P. H. Dixneuf, J. Am. Chem.
Soc., 1994, 116, 11157; D. Peron, A. Romero and P. H. Dixneuf,
Gazz. Chim. Ital., 1994, 124, 497.
Ϫ
molϪ1. νmax
˜
/cmϪ1 (BF ) 1060s, (C᎐N) 2232w (KBr). δ (CDCl )
᎐
᎐
4
P
3
2
2
5 (a) J. P. Selegue, J. Am. Chem. Soc., 1983, 105, 5921; (b) M. I. Bruce,
P. Hinterding, E. R. T. Tiekink, B. W. Skelton and A. H. White,
J. Organomet. Chem., 1993, 450, 209; (c) L. P. Barthel-Rosa,
K. Maitra, J. Fischer and J. H. Nelson, Organometallics, 1997, 16,
1714; (d) M. A. Jímenez Tenorio, M. Jímenez Tenorio, M. C. Puerta
and P. Valerga, Organometallics, 1997, 16, 5528; (e) M. A.
Esteruelas, A. V. Gómez, A. M. López, J. Modrego and E. Oñate,
Organometallics, 1997, 16, 5826; ( f ) I. de los Rios, M. Jiménez
Tenorio, M. C. Puerta and P. Valerga, J. Organomet. Chem., 1997,
549, 221; (g) M. A. Esteruelas, A. V. Gómez, A. M. López, E. Oñate
and N. Ruiz, Organometallics, 1998, 17, 2297; (h) M. A. Esteruelas,
A. V. Gómez, A. M. López and E. Oñate, Organometallics, 1998, 17,
3567; (i) M. A. Esteruelas, A. V. Gómez, A. M. López, M. C. Puerta
and P. Valerga, Organometallics, 1998, 17, 4959; (j) M. A.
Esteruelas, A. V. Gómez, A. M. López, J. Modrego and E. Oñate,
Organometallics, 1998, 17, 5434; (k) M. I. Bruce, P. J. Low and
E. R. T. Tiekink, J. Organomet. Chem., 1999, 572, 3; (l) B. Buriez,
I. A. Burns, A. F. Hill, A. J. P. White, D. J. Williams and J. D. E. T.
Wilton-Ely, Organometallics, 1999, 18, 1504; (m) C. Bianchini,
M. Peruzzini, F. Zanobini, C. Lopez, I. de los Rios and A.
Romerosa, Chem. Commun., 1999, 443; (n) M. A. Esteruelas, A. V.
Gómez, A. M. López, E. Oñate and N. Ruiz, Organometallics,
1999, 18, 1606; (o) B. Buriez, D. J. Cook, K. J. Harlow, A. F. Hill,
T. Welton, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely,
J. Organomet. Chem., 1999, 578, 264.
6 A. Fürstner, M. Picquet, C. Bruneau and P. H. Dixneuf, Chem.
Commun., 1998, 1315; M. Picquet, C. Bruneau and P. H. Dixneuf,
Chem. Commun., 1998, 2249; M. Picquet, D. Touchard, C. Bruneau
and P. H. Dixneuf, New J. Chem., 1999, 141; A. Fürstner, A. F. Hill,
M. Liebl and J. D. E. T. Wilton-Ely, Chem. Commun., 1999, 601;
B. M. Trost and J. A. Flygare, J. Am. Chem. Soc., 1992, 114, 5476.
7 J. P. Selegue, Organometallics, 1982, 1, 217.
8 (a) V. Cadierno, M. P. Gamasa, J. Gimeno, M. González-Cueva,
E. Lastra, J. Borge, S. García-Granda and E. Pérez-Carreño,
Organometallics, 1996, 15, 2137; (b) M. P. Gamasa, J. Gimeno,
C. González-Bernardo, J. Borge and S. García-Granda,
Organometallics, 1997, 16, 2483; (c) P. Crochet, B. Demerseman,
M. I. Vallejo, M. P. Gamasa, J. Gimeno, J. Borge and S. García-
Granda, Organometallics, 1997, 16, 5406.
9 V. Cadierno, M. P. Gamasa, J. Gimeno, J. Borge and S. García-
Granda, Organometallics, 1997, 16, 3178.
10 (a) J. P. Selegue, B. A. Young and S. L. Logan, Organometallics,
1991, 10, 1972; (b) D. Touchard, N. Pirio and P. H. Dixneuf,
Organometallics, 1995, 14, 4920; (c) M. A. Esteruelas, A. V. Gómez,
F. J. Lahoz, A. M. López, E. Oñate and L. A. Oro, Organometallics,
1996, 15, 3423.
11 V. Cadierno, M. P. Gamasa, J. Gimeno, E. Lastra, J. Borge and
S. García-Granda, Organometallics, 1994, 13, 745.
12 V. Cadierno, M. P. Gamasa, J. Gimeno, M. C. López-González,
J. Borge and S. García-Granda, Organometallics, 1997, 16, 4453.
13 D. Touchard and P. H. Dixneuf, Coord. Chem. Rev., 1998, 178–180,
409 and refs. therein.
14 P. Nombel, N. Lugan and R. Mathieu, J. Organomet. Chem., 1995,
503, C22; C. Slugovc, V. N. Sapunov, P. Wiede, K. Mereiter,
R. Schmid and K. Kirchner, J. Chem. Soc., Dalton Trans., 1997,
4209; C. Bianchini, G. Purches, F. Zanobini and M. Peruzzini, Inorg.
Chim. Acta, 1998, 272, 1; M. Martín, O. Gevert and H. Werner,
J. Chem. Soc., Dalton Trans., 1996, 2275.
38.42 (d, J(PP) = 22.4, PPh3) and 39.23 (d, J(PP) = 22.4 Hz,
PPh3); δH(CDCl3) 1.37–2.03 (m, 16 H, CH2), 2.13 and 2.30 (m,
1 H each, CH), 4.14 (s, 1 H, Ru᎐C᎐CH), 5.30–5.81 (m, 5 H,
᎐ ᎐
H-1, H-2, H-3, ᎐CHCH and ᎐CH), 5.97 and 6.20 (m, 1 H each,
᎐
᎐
H-4, H-5, H-6 or H-7) and 6.64–7.51 (m, 32 H, Ph and H-4,
H-5, H-6 or H-7); δC(CDCl3) 16.51, 22.15, 25.57, 25.68, 26.21,
35.60 and 37.36 (s, CH2), 37.87 and 39.14 (s, C), 39.95 and 41.97
(s, CH), 82.90 (d, 2J(CP) = 5.1, C-1 or C-3), 85.03 (d,
2J(CP) = 3.3, C-1 or C-3), 98.43 (s, C-2), 112.76 and 118.36 (s,
᎐
C-3a and C-7a), 118.07 (s, C ), 123.16 (s, C᎐N), 122.08–137.59
᎐
β
(m, Ph, C-4, C-5, C-6, C-7, ᎐CHCH and ᎐CH) and 340.90 (vt,
᎐
᎐
2J(CP) = 2J(CPЈ) = 15.7 Hz, Ru᎐C ); ∆δ(C-3a,7a) = Ϫ15.14
᎐
α
(average).
Reaction of complex 2 with phenylacetylene: [Ru{᎐C᎐C-
᎐ ᎐
(H)Ph}(ꢀ5-C9H7)(PPh3)2][PF6] 9. This complex has been pre-
pared analogously to 4a–4c and 6a,6b starting from 2 (0.15 g,
0.2 mmol) and phenylacetylene (0.2 ml, 2 mmol). Yield: 0.17 g,
1
86%. The 31P-{1H} and H NMR spectra were in agreement
with the literature.16
5
᎐
Reaction of complex 2 with acetonitrile: [Ru(N᎐CMe)(ꢀ -
᎐
C9H7)(PPh3)2][PF6] 10. A solution of the vinylvinylidene com-
plex 2 (0.05 g, 0.05 mmol) in acetonitrile (10 cm3) was heated
under reflux for 1 h. The solvent was then removed under
vacuum, and the yellow solid residue washed with diethyl ether
(2 × 5 cm3) and dried in vacuo. Yield: 0.04 g, 81%. The 31P-{1H}
and 1H NMR data obtained for complex 10 were in agreement
with those previously reported.15
Acknowledgements
This work was supported by the Ministerio de Educación y
Cultura of Spain (DGICYT, Project PB96-0558) and the EU
(Human Capital Mobility programme, Project ERBCHRXCT
940501). V. C. thanks the Fundación para la Investigación
Científica y Técnica de Asturias (FICYT) for a fellowship.
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