The influence of phosphane ligands on the versatility of ruthenium-indenylidene complexes in metathesis

Article abstract of DOI:10.1002/chem.201000659

The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy3 with phosphanes of varying elect

Full text of DOI:10.1002/chem.201000659

FULL PAPER
DOI: 10.1002/chem.201000659
The Influence of Phosphane Ligands on the Versatility of Ruthenium–
Indenylidene Complexes in Metathesis
Julie Broggi,[a] Cꢀsar A. Urbina-Blanco,[a] Hervꢀ Clavier,[a, c] Anita Leitgeb,[b]
Christian Slugovc,[b] Alexandra M. Z. Slawin,[a] and Steven P. Nolan*[a]
Abstract: The aim of the present study
is to develop readily available and
stable pre-catalysts that could be easily
prepared on large scale from simple
starting materials. Based on the hy-
pothesis that substitution of classical
PCy3 with phosphanes of varying elec-
tron-donating properties could be a
straightforward manner to improve cat-
alytic activity, a methodical study deal-
ing with the effect of phosphane fine-
tuning in ruthenium–indenylidene cata-
lysts was performed. Challenged to es-
tablish how the electronic properties of
para-substituted phosphane ligands
translate into catalyst activity, the ver-
satile behaviour of these new rutheni-
um–indenylidene complexes was inves-
tigated for a number of metathesis re-
actions.
Keywords: N-heterocyclic
car-
benes · metathesis · phosphanes ·
ruthenium–indenylidene
Introduction
came with the synthesis of more active mixed phosphane–
NHC complexes, so-called second-generation catalysts, such
In a quest to synthesise ever better performing, well defined,
ruthenium-based catalysts for olefin metathesis,[1] design ef-
forts have focused on modulation of the organic fragments
around the Ru centre. The first significant breakthrough in
this area appeared with the introduction of N-heterocyclic
carbenes (NHC)[2] on ruthenium–benzylidene complexes by
Herrmann et al. in 1998.[3] Although they were found in
some instances to be more active, these two NHC-contain-
ing complexes were in most cases less efficient than their bi-
sphosphane analogues. The real breakthrough, however,
as 1[4]
.
These early examples clearly illustrate the crucial role
played by the NHC ligand.[5,6] Since then, numerous pre-cat-
alysts have permitted the evolution of metathesis reactions
into a powerful carbon–carbon double-bond-forming tool
and as a consequence numerous industrial and therapeutic
applications have benefited from this success story.[7]
[a] Dr. J. Broggi, C. A. Urbina-Blanco, Dr. H. Clavier,
Prof. Dr. A. M. Z. Slawin, Prof. Dr. S. P. Nolan
School of Chemistry, University of St Andrews
KY16 9ST, St Andrews (UK)
Mechanistic and computational studies of 1 and the relat-
ed complexes [Ru(X)2ACTHUNGTRENNN(UG SIMes)AHCUTNRTGEGN(NUN PR3)ACHTNGUTREN(NUGN =CHR)] (SIMes=
Fax : (+44)1334-463808
E-mail: snolan@st-andrews.ac.uk
N,N’-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, X=hal-
ogen, PR3 =aryl- or alkylphosphane, =CHR = alkylidene)
have revealed that ancillary ligands dramatically affect the
rates of initiation and propagation in olefin metathesis reac-
tions.[8,9] Recently, variations on the core architecture of
ruthenium complexes have consisted mainly in the introduc-
tion of new NHCs[6,10] and in the modification of the alkyli-
dene ligand[11] in order to produce new metathesis catalysts
with improved stability, activity, selectivity and functional
group tolerance.[12] Among the latter modification type,
ruthenium–indenylidene complexes, such as 2, have emerged
[b] A. Leitgeb, Dr. C. Slugovc
Institute for Chemistry and Technology of Materials
Graz University of Technology
Stremayrgasse 16, 8010 Graz (Austria)
[c] Dr. H. Clavier
Present address: Institut des Sciences Molꢀculaires de Marseille
Universitꢀ Aix-Marseille, UMR CNRS 6263
Av. Escadrille Normandie Niemen
13397 Marseille Cedex 20 (France)
Supporting information for this article (additional synthetic proce-
dures and compound characterisation details) is available on the
WWW under http://dx.doi.org/10.1002/chem.201000659.
Chem. Eur. J. 2010, 16, 9215 – 9225
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
9215

Table 1. Synthesis of phosphane-tuned SIMes–Ru–indenylidene com-
plexes.
as efficient tools for olefin metathesis transformations and
are an attractive alternative to benzylidene congeners.[13]
These pre-catalysts are straightforwardly synthesised in
large scale with readily available and stable precursors, and
demonstrate an enhanced stability to harsh reaction condi-
tions and exhibit catalytic activity equal to/or better than
their benzylidene counterparts.[14] Similarly to other rutheni-
um families, the main research activity in ruthenium–indeny-
lidene chemistry has focused on modifying the carbene
moiety,[13,15] or on substituting the phosphane by other li-
gands, such as, for example, Schiff bases[16] or pyridine,[17] un-
derlining the poor attention paid to the effects of varying
the phosphane ligand. This is intriguing as, ever since
Tolman quantified their electronic and steric parameters,[18]
the variation of phosphane ligands on metal centres has
become a valuable approach to modulate the catalytic activ-
ity of catalytic systems[19] and metathesis is no exception. By
using magnetisation transfer experiments to investigate the
first step of the olefin metathesis mechanism, studies of
Grubbs et al. have demonstrated that changing the phos-
phane bound to the ruthenium centre affects phosphane dis-
sociation and recoordination of free PR3 to ruthenium and,
therefore, has a profound and complex influence on the cat-
alytic activity.[8b,20] Hence, first-generation catalysts require
more electron-donating phosphanes,[21] whereas second-gen-
eration catalysts benefit from the use of poorer coordinating
ligands.[8,20] On the other hand, although first-generation cat-
alysts have higher phosphane exchange rates than second-
generation complexes, the latter are more active. This obser-
vation was rationalised by the higher affinity of NHC-con-
taining catalysts for olefin coordination compared to rebind-
ing of the phosphane leading to a higher rate of propagation
into the catalytic cycle. Earlier work from our group on
first- and second-generation benzylidene systems showed
that replacing tricyclohexylphosphane (PCy3) with triphenyl-
phosphane (PPh3)[5a] or phosphabicyclononane (Phoban)[22]
resulted in more rapid ring-closing metathesis (RCM). Nev-
ertheless, even though faster phosphane exchange was ob-
served with PPh3,[20] its high lability and its lack of bulkiness
translated into a decrease in stability of the corresponding
complex.[5a] Thus, PCy3 still appeared as a more viable
ligand and has been predominantly used in spite of its cost.
Recently, Verpoort and co-workers have reported a compa-
rative study of ruthenium–indenylidene complexes 2, 3 and
[a]
[a]
Complex
PR3
Yield [%]
sP
pKa
4
5
6
7
8
9
PPh3
P(p-CH3OC6H4)3
P(p-CH3C6H4)3
78
75
77
90
90
73
0
2.73
4.57
3.84
1.97
À0.27
À0.17
0.06
0.23
0.52
P
P
ACHTUNGTRENNUNG
A
1.03
[b]
P(p-CF3C6H4)3
[a] Values taken from reference [20]. [b] Unknown.
multistep synthesis with low overall yields. As part of our
ongoing research towards the development of more active
metathesis systems, we aimed to develop readily available
and stable pre-catalysts that could be prepared easily on
large scale and did not require elaborate and/or expensive
starting materials. Based on the hypothesis that the substitu-
tion of classical PCy3 by phosphanes with different electron-
donating properties could be an efficient and easy way to
improve the catalytic activity, we also decided to explore in
a methodical approach the effect of phosphane modification
in ruthenium–indenylidene catalysts. Challenged to establish
how the electronic properties of para-substituted phosphane
ligands translate into catalyst activity, the versatile behav-
iour of these new ruthenium–indenylidene complexes was
investigated for a number of metathesis reactions: RCM of
dienes or enynes, ring-rearrangement metathesis (RRM),
cross-metathesis (CM) and ROMP.
Results and Discussion
Synthesis and structural characterisation: Keeping in mind
that increased initiation would permit higher catalysis rate,
lower catalyst loadings and reaction temperatures, five new
ruthenium–indenylidene complexes were synthesised and
fully characterised. These have the general formula [RuCl2-
4
(Table 1) versus first-, second- and third-generation
ACHTUNGTNER(UNNG SIMes)ACHTUNRGTEG(NNNU PR3)ACHTGUNTREN(NUGN Ind)] (Ind=3-phenylindenylid-1-ene) and
Grubbsꢂ catalysts.[23] The replacement of the PCy3 ligand
with the more labile PPh3 ligand drastically improved the
catalytic performance as 4 displayed similar activities as
second-generation catalysts for RCM and initiated ring-
opening metathesis polymerisation (ROMP) significantly
faster. This is in line with our original observations on the
second-generation ruthenium–benzylidene system.
bear less electron-donating phosphanes than PCy3. A para-
substituted triphenylphosphane ligand series was selected as
it possesses members displaying different electronic proper-
ties that should influence the phosphane dissociation/rebind-
ing rates (Table 1). Of note, these phosphanes all have the
same cone angle of 1458, whereas PCy3 has a cone angle of
1708.
The choice of the ancillary ligand remains a crucial pa-
rameter in finding the adequate compromise between labili-
ty of the dissociating ligand and stabilisation of the pre-cata-
lyst. The aforementioned modifications to NHC ligands or
alkylidene moiety often involve complicated and expensive
Ruthenium–mono pyridine adducts have proven to be
versatile precursors in the synthesis of new complexes by
facile ligand substitution reactions.[15b,20,23,24] Starting from
the commercially available [RuCl
2ACHTUNGRTEN(UNGN SIMes)ACHUTNRTGENN(GUN pyridine)ACHTUNGTRENNUNG(Ind)]
(3), complexes 4–9 were obtained in one step through ex-
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Chem. Eur. J. 2010, 16, 9215 – 9225

Ruthenium–Indenylidene Complexes in Metathesis
FULL PAPER
change of pyridine by the appropriate phosphane at room
temperature (Table 1). They were isolated on scales that
reached up to 1.5 g with good yields and high purity by
simple precipitation and/or washing. Of note, the same pre-
viously reported steric and electronic limitations were en-
countered while attempting to use phosphane ligands that
are bulky (such as ortho-substituted phosphanes) or electron
poor such as PACHTUNGTRENNUNG
(C6F5)3.[24] 1H NMR spectra of 4–9 showed a
characteristic resonance at d=4 ppm for the imidazolidine
protons. 13C NMR spectra displayed characteristic low-field
resonances for N-heterocylic carbenic carbons around d=
2
215 ppm with J
N
dicated a mutually trans arrangement of the phosphane and
NHC ligands. In each case, the signal at d=300 ppm is char-
2
acteristic of a Ru=C carbenic carbon with J
N
indicating, this time, relative cis arrangement to the phos-
phane. 31P NMR spectra showed single resonances between
d=22 and 27 ppm. Elemental analysis also confirmed the
composition and bulk purity of the new compounds. Com-
plexes 4–9 were found to be perfectly stable in the solid
state and could be easily handled in air. In
[D2]dichloromethane (CD2Cl2) under N2 at 408C, analysis of
the NMR spectra showed that all complexes were stable for
more than 4 h and complete decomposition was not ob-
served after 24 h. In [D8]toluene under N2 at 808C, major
degradation occurred within 1 h and was complete after 4 h
for 4, 5, 6 and 7, but not for complexes 8 and 9 that showed
improved stability and were not entirely degraded after 4 h
under these conditions. Complexes 8 and 9 could also be
kept several days in CD2Cl2 under N2 at room temperature
without any sign of decomposition.
Figure 2. Ball-and-stick representation of 6. Hydrogen atoms are omitted
À
for clarity. Selected bond lengths [ꢃ] and angles [8]: Ru(1) C(24)
À
À
À
1.867(6), Ru(1) C(1) 2.090(6), Ru(1) P(1) 2.4069(16), Ru(1) Cl(1)
À
2.3750(17), Ru(1) Cl(2) 2.4035(18); C(24)-Ru(1)-C(1) 105.4(2), C(1)-
Ru(1)-P(1) 162.71(17), Cl(1)-Ru(1)-Cl(2) 162.84(5).
tures of 5 and 6 are quite similar, despite containing differ-
ent phosphane ligands. Bond distances were all within the
expected range of similar Ru–benzylidene,[20] including 1,
NHC
and Ru–indenylidene complexes[15a] (Ru C
ꢀ2.09 ꢃ,
À
Ind
À
Ru C ꢀ1.86 ꢃ). They show the expected distorted
square-pyramidal geometry around the metal centre with a
slight tilt of the NHC (C(1)-Ru(1)-P(1) =164 and 1628, re-
spectively). Bond angles in these SIMes-containing Ru–in-
denylidenes were more closely related to those reported for
The structures of the Ru–indenylidene complexes 5 and 6
were unambiguously confirmed by X-ray crystallography
and are graphically presented in Figures 1 and 2 with a se-
lection of bond distances and angles. The solid-state struc-
(Ind)][15a] bearing the 1,3-bis(2,6-diiso-
[RuCl2ACHTUNGERTG(NUNN SIPr)ACHUTNRTGEG(NNUN PCy3)ACHTNUGTRENNUGN
propylphenyl)-4,5-dihydroimidazol-2-ylidene (SIPr) ligand
than for those found in SIMes–Ru–benzylidenes,[20] under-
lining the important effect of the alkylidene group on the
geometry of the complex.
Catalytic activity in ring-closing metathesis (RCM): The re-
activity of the catalysts series 4–9 was investigated for a
number of metathesis reactions (RCM, RRM, CM and
ROMP) and compared to the second-generation benzyli-
dene catalyst 1, the second-generation indenylidene catalyst
2 and the third-generation catalyst 3. Benchmarks, as well
as, original substrates featuring diverse functional groups
and steric encumbrance were studied. Catalytic activities of
1–9 were first evaluated in the ring-closing metathesis of
allyl malonate substrates with low (10) or high (12) steric
hindrance (Table 2). As expected for RCM of 10, the novel
catalysts 4–9 bearing more labile phosphanes were all more
active than the commercially available complexes 1, 2 and 3,
affording complete conversion to 11 in shorter reaction
times. Within the indenylidene class, a drastic difference in
term of efficiency was observed between alkyl (2, 82% in
5 h) and aryl phosphanes (4–9, >99% in 0.5–1.5 h). Hence,
it appears clear that dissociation/rebinding rates of aryl
phosphanes, associated to their stereoelectronic parameters,
allow for more rapid kinetics in RCM. The catalytic activity
Figure 1. Ball-and-stick representation of 5. Hydrogen atoms are omitted
À
for clarity. Selected bond lengths [ꢃ] and angles [8]: Ru(1) C(24)
À
À
À
1.870(5), Ru(1) C(1) 2.086(5), Ru(1) P(1) 2.3975(15), Ru(1) Cl(1)
À
2.3619(16), Ru(1) Cl(2) 2.4040(16), C(24)-Ru(1)-C(1) 104.3(2), C(1)-
Ru(1)-P(1) 164.73(15), Cl(1)-Ru(1)-Cl(2) 161.28(5).
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S. P. Nolan et al.
Table 2. Comparison of pre-catalysts 1–9 in ring closing metathesis with
Table 3. Catalytic performance of complexes 4 and 9 in RCM of di-
model substrates.[a]
enes.[a]
Entry
Substrate
Product
[Ru]
t [h]
Conv. [%]
Entry Substrate
Product
[Ru] t [h] Yield [%]
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1.5
5
5
0.75
1.5
1.25
0.75
0.75
0.5
>99
82
38
>99
>99
>99
>99
>99
>99
1
2
4
9
0.75
0.5
97
97
3
4
4
9
0.5
0.25
98
98
5
6
4
9
1
0.5
95
95
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
7
8
9
30
58
10
18
22
21
22
22
23
7
8
4
9
3
1
82
84
5[b]
9
10
4
9
0.25
0.25
95
95
11
12
4
9
1.5
1
95
94
[a] Reaction conditions: substrate (0.5 mmol), [Ru] complex (1 mol%),
CH2Cl2 (0.1m), N2, RT. [b] [Ru] complex (5 mol%), toluene (0.1m), N2,
808C.
13
14
4
9
1.5
0.75
93
94
found is the following: 2 (Cy) < 5 (OCH3) < 6 (CH3) < 4
(H) ꢀ 7(F) ꢀ 8 (Cl) < 9 (CF3) and correlates with the de-
creasing phosphane pKa or the increasing Hammett constant
(sp) of the aryl substituent.[2] Complex 9 bearing the ex-
tremely electron-poor phosphane P(p-CF3C6H4)3 was the
most active pre-catalyst for RCM of 10. Interestingly, an op-
posite trend was obtained in the case of the encumbered
substrate 12, since PCy3-containing 2 afforded the highest
conversion (58%) outperforming by far its benzylidene
counterpart 1 (30%). The higher thermal stability of 2 is no
doubt the cause for the ability to perform under harsh reac-
tion conditions. Of note, the successful formation of chal-
lenging tetrasubstituted olefins is usually reached with Hov-
eyda–Grubbs catalysts requiring multistep and low-yielding
synthesis.[10e,25] All triarylphosphane-bearing complexes (4–
9) exhibited the same low reactivity at this temperature.
Even though third-generation catalyst 3 with an indenyli-
dene scaffold has been reported to surpass the best third-
generation Grubbs catalyst, its performance in RCM is
quite inferior to second-generation complexes.[23]
Highly active complex 9 was then subjected to a represen-
tative set of RCM reactions in order to study its scope and
compatibility with functional groups or ring sizes (Table 3).
For comparison, metathesis reactions were also accom-
plished with 4 bearing the economical PPh3. By using only
1 mol% of ruthenium at room temperature, all dienes were
completely converted to the corresponding cyclic product
with excellent yields (82–98%) in short reaction times
(0.25–3 h). The effect of the more labile P(p-CF3C6H4)3
ligand on the catalytic activity translated into a more active
complex 9 that performed twice as fast as 4. Ester, ether,
amine, nitrile and amide functional groups were well tolerat-
ed and did not affect the catalytic outcome. Complete con-
versions to di- or trisubstituted cycloalkenes were obtained
15
16
4
9
1
0.5
90
91
17
18
4
9
1.0
0.5
97
97
19
20
4
9
1.5
0.75
95
96
21
22
4
9
3
91[b]
1.5 92[b]
[a] Reaction conditions: substrate (0.5 mmol), [Ru] complex (1 mol%),
CH2Cl2 (0.1m), N2, RT. [b] CH2Cl2 (0.05m).
starting either from terminal, 1,2-, 2,2’-disubstituted or
1,1’,2-trisubstituted olefins. As generally encountered in
RCM, the only problematic substrates were tetrasubstituted
dienes that lead to poor yields (Table 2). The straightfor-
ward formation of five-, six- and seven-membered rings that
are mono- or bicyclic was also achieved. During the progress
of the study of the scope, the formation of self-cross-meta-
thesis products was not observed. Nonetheless, RCM of
diene 31 leading to the seven-membered bicyclic ring 32 had
to be carried out under higher dilution conditions to avoid
polymer formation (Table 3, entries 21 and 22).
The reactivity profile of pre-catalysts 4–9 also proved to
be very attractive in the ring-closing metathesis of enynes as
outlined in Table 4. Comparison of substrates 33 and more
hindered 35 revealed analogies to the RCM of dienes
(Table 4, entries 1–18). All triarylphosphane-bearing com-
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Ruthenium–Indenylidene Complexes in Metathesis
FULL PAPER
Table 4. Catalytic performance of pre-catalysts 1–9 in RCM of enynes.[a]
Ring-rearrangement metathesis (RRM): Ring-rearrange-
ment metathesis, combining ring-opening/ring-closing meta-
thesis steps, allows for the straightforward construction of
complex scaffolds.[26] Ruthenium–indenylidene complexes
were already established in RRM reactions allowing for a
large spectrum of rearrangements.[27] A brief examination of
catalyst activity revealed that 9 lead to the best perfor-
mance. OxabicycloACTHNUTRGNEUNG[2.2.1]heptene and norbornene exo-deriv-
atives were subjected to ring rearrangement by using
1 mol% of 4 or 9 in a diluted solution (Table 5). To avoid
Entry
Substrate
Product [Ru] t [h] Conv. (Yield) [%]
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
0.5
24
24
0.75
3
0.75
1.25
0.75
0.3
>99
63
12
>99 (95)
>99
>99
>99
>99
>99 (96)
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
7
8
9
75
74
5
Table 5. Catalytic performance of pre-catalysts 4 and 9 in RRM.[a]
Entry Substrate
Product
[Ru]
t
Yield
38 (32)
42
5[b]
[h] [%]
37
22
55
1
2
4
9
5
80
1.5 92
52 (50)
19
20
4
9
0.5
0.3
>99 (95)
>99 (95)
3
4
4
9
0.25 91
0.25 96
21
22
4
9
24
24
<2
<2
5
6
4
9
5
1
56[b]
42[b]
23
24
4
9
5
5
57 (53)
40 (37)
7
8
4
9
5
5
53[c]
66[c]
[a] Reaction conditions: substrate (0.5 mmol), [Ru] complex (1 mol%),
CH2Cl2 (0.1m), N2, RT. [b] [Ru] complex (5 mol%), toluene (0.1m),
808C.
[a] Reaction conditions: substrate (0.5 mmol), [Ru] complex (1 mol%),
CH2Cl2 (0.01m), N2, RT. [b] Polymer accounts for mass balance. [c] Re-
action products are an inseparable mixture of the expected product and
1
the starting material. H NMR conversion.
plexes 4–9, particularly 9, performed significantly faster and
more competently than 2 at room temperature whereas the
stability of tricyclohexylphosphane benefited 2 under harsh-
er conditions. Interestingly, the alkylidene appears to also
play a crucial role in enabling smooth reactions, as Ru–ben-
zylidene 1 (Table 4, entry 1) performed much better than 2
(Table 4, entry 2). Despite complex 1 contains PCy3, its effi-
ciency was found comparable to the arylphosphane com-
plexes. In the case of the encumbered substrate 35, no per-
formance difference was observed between the two catalysts
(Table 4, entries 10 and 11). The reaction scope of 4 and 9
was then extended to the synthesis of selected exocyclic 1,3-
dienes. For substrates 33 and 37, excellent yields were ob-
tained at room temperature in 20 min by using 1 mol% of 9
(Table 4, entries 9 and 20). On the other hand, the cyclisa-
tion of 39 was found to be problematic, and the desired
product could not be isolated (Table 4, entries 21 and 22),
whereas RCM carried out on a similar substrate 41, possess-
ing two additional methyl groups, by using the same reaction
conditions led to the formation of 53% and 37% of 42, re-
spectively (Table 4, entries 23 and 24). Surprisingly, in this
latter case, complex 4 performed better than 9.
polymerisation during low-pressure solvent reduction, the
completed reactions were quenched with ethyl vinyl
ether.[28] The formation of five- and six-membered rings was
easily achieved in good yields and short reaction times
(Table 5, entries 1–4). On the other hand, RRM leading to
the seven-membered ring product 48 was hindered by poly-
merisation side reactions (Table 5, entries 5 and 6). In this
particular case, pre-catalyst 4, which has a lower activity in
RRM, permitted a reduction in polymer formation by slow-
ing the reaction rate (Table 5, entry 5). Substitution of the
exocyclic C=C bond engendered a significant increase in the
reaction time leading to a decrease in the yield (Table 5, en-
tries 7 and 8 vs. entries 1 and 2).
Cross-metathesis (CM): Complexes 1–9 (1 mol%) were then
compared in the cross-metathesis reaction of but-3-enyl ben-
zoate (51) with 2 equivalents of methyl acrylate at room
temperature (Table 6). Once again, our series of triarylphos-
phane-containing Ru catalysts 4–9 was more active and ste-
reoselective than complexes 1, 2 and 3. The exchange of
Chem. Eur. J. 2010, 16, 9215 – 9225
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S. P. Nolan et al.
Table 6. Comparison of pre-catalysts 1–9 in cross-metathesis.[a]
(Table 7, entries 5 and 6) or amide groups (Table 7, en-
tries 17 and 18) conjugated to the C=C double bond were
found more problematic. The use of cross-metathesis dimers
as partners was also successful (Table 7, entries 9–12). Even
the 1,2-disubstituted olefin 74 could be coupled (Table 7, en-
tries 25 and 26), CM of the more challenging y,y-disubsti-
tuted olefin 76 with methyl acrylate failed with both cata-
lysts and only starting materials were recovered even when
the reaction was conducted under harsher reaction condi-
tions (Table 7, entries 27 and 28). Finally, comparison of
pre-catalysts 4 and 8 on the entire screening scope shows
that both complexes are equipotent for cross-metathesis re-
actions. In all cases, similar yields were achieved in the same
time range and with high regioselectivity, underlining the
weak influence of the nature of the phosphane in CM com-
pared to its influence in RCM.
[Ru]
PR3
Conv.
[%]
52
E/Z
ratio
52 (dimer)
[%][b]
[%][b]
1
2
3
4
5
6
7
8
9
PCy3
PCy3
–
PPh3
P(p-CH3OC6H4)3
P(p-CH3C6H4)3
80
29
8
80
77
82
81
81
75
69
26
5
73
60
74
74
77
69
>20:1
16:1
7:1
>20:1
>20:1
>20:1
>20:1
>20:1
>20:1
11
3
3
7
17
8
7
4
6
P
P
U
P(p-CF3C6H4)3
[a] Reaction conditions: substrate 51 (0.5 mmol), methyl acrylate
(1 mmol), [Ru] (1 mol%), CH2Cl2 (0.1m), N2, RT, 5 h. [b] 1H NMR con-
version.
Ring-opening metathesis polymerisation (ROMP): Im-
proved initiation has significant implications in metathesis
polymerisation giving access to higher control over polymer
molecular weights, therefore, the scope of 4–9 as initiators
in ring-opening metathesis polymerisation was evaluated.
For this purpose, we used two norbornene derivatives,
PCy3 for a more labile phosphane provided a radical im-
provement in terms of conversion and stereoselectivity. Al-
though CM by using 1 or 4–9 resulted in similar high conver-
sions of the starting material, a favoured distribution for the
cross-metathesis product 52 over the self-metathesis dimer
of 52 was found with Ru–indenylidenes (except with 5).
Unexpectedly, the activity trend found for CM is: 2 (Cy)
< 5 (OCH3) < 9 (CF3) < 4 (H) < 6 (CH3) ꢀ 7 (F) < 8
(Cl), which does not fit to the electronic properties of the
phosphanes and strongly differed with the trend observed in
namely dimethyl bicyclo
ACHTUNGTRENNUNG
(78) and 5,6-bis(methoxymethyl)bicyclo
AHCTUNGTRENNUNG
(79). Catalysts (or initiators, in the polymerisation jargon) 2
and 3 were selected as reference initiators because of their
extremely different initiation behaviour, providing a reason-
able benchmark for all initiators under investigation. In a
first approximation, the average number molecular weight
(Mn) is determined by the ratio of initiation rate to propaga-
tion rate (ki/kp) of a given initiator and monomer combina-
tion. Provided that no secondary metathesis reaction affects
the double bonds of the formed polymer (i.e., back-biting),
determination of Mn will allow for an indirect, qualitative
comparison of ki/kp for the initiators under investigation.[29]
For example, 3 shows fast and complete initiation with most
monomers (estimation for ki/kp > 10–1000 depending on
the monomer) and thus, every initiator molecule starts a
growing chain. Therefore, polymers characterised by low Mn
values and low polydispersity indices (PDIs) are obtained.[30]
In contrast, slow and incomplete initiation is a characteristic
feature of 2 in ROMP (estimation for ki/kp < 1–0.01 de-
pending on the monomer), resulting in high Mn and high
PDI values of the corresponding polymers.[30]
RCM. [RuCl2ACHTUNGTRENNUNG(SIMes)PACHTNUTREGGNN(UN p-ClC6H4)3ACHTNUGTRENN(UGN Ind)] (8) was, under the
studied conditions, the most efficient and selective pre-cata-
lyst within the series. The overall stability of the catalyst in
the reaction medium is probably the most important factor
dictating catalyst efficiency in such time-demanding CM.
We then extended the scope of cross-metathesis reactions
to a wider range of benchmark and original substrates by
using 1 mol% of 4 or 8 under mild conditions (Table 7).
Special attention was paid to functional group tolerance, as
well as, to the influence of chain length and olefin substitu-
tion. Optimisation of the reaction conditions revealed that
the coupling preceded better in more concentrated solution
and favoured the CM product. Hence, compared to conver-
sions reported in Table 6, cross-product 52 was obtained
with 82 and 90% yields by using 4 and 8, respectively, in a
1m dichloromethane solution and only traces of 51 or the
dimer of 52 were observed (Table 7, entries 1 and 2). As for
the RCM, the Ru–indenylidene catalysts were robust and
tolerant to several polar substituents including esters, silyl
ethers, ethers, aryl halides, alcohols, acids and phosphonates,
leading to the synthesis of the corresponding products in
moderate to good yields. Unfortunately, compound 65 bear-
ing an unprotected amide was produced in low yields along
with a significant amount of dimer (Table 7, entries 15 and
16). The examination of several unactivated olefin partners
bearing various functionalities indicated a strong substrate
dependence of our catalytic systems. Whereas ester-,
ketone-, alcohol-, acetate- and acid-containing olefins led to
good yields and high E/Z ratios, the coupling of aldehyde
The initiator 2–9 (1 equiv) were treated with monomers
78 or 79 (300 equiv) and results are summarised in Table 8
and Figure 3. All polymerisations were completed in 1h;
except for catalysts 5 (2 h) and 9 (30 min). Mn values range
from
102100–356200 gmolÀ1
and
from
88700–
302800 gmolÀ1 for polymers obtained from monomer 78
and 79, respectively. A correlation between donor property
of the phosphane (expressed by their electronegativity c or
Hammett constant sp)[31,20] and the experimental Mn values
are depicted in Figure 4 and Figure 5. Correlations in the
linear fits are not perfect but show the same general trends
for both monomers, confirming the above-established trend
9220
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ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 9215 – 9225

Ruthenium–Indenylidene Complexes in Metathesis
FULL PAPER
Table 7. Scope of cross-metathesis reactions for pre-catalysts 4 and 8.[a]
initiation rates. This trend is
also illustrated by the PDI
values of the polymers. Elec-
Entry Substrate
Product
[Ru] t [h] Yield [%] E/Z ratio
Yield
AHCTUNGTRENNUNG
tron-rich
phosphane-bearing
1
2
4
8
2
2
82
90
>20:1
>20:1
–
–
complexes afford polymers with
high PDIs, whereas the PDI
values decrease with an increas-
ing c of the phosphane.[30] All
initiators under investigation
showed improved initiation effi-
ciency when compared to 2,
which bears PCy3, and produce
polymers with lower Mn and
PDI values with both mono-
3
4
4
8
7
7
66
69
>20:1
>20:1
–
–
5
6
4
8
2
2
25
26
>20:1
>20:1
–
–
7
8
4
8
3
3
50
52
>20:1
>20:1
39
42
mers
(see
Table 8
and
Figure 3).[30] Complex 9 featur-
ing the most electron-withdraw-
ing group, that is, the CF3
group, showed the best results.
Regardless of the phopshane
used, none of the complexes
under investigation outperform
the pyridine bearing initiator 3
in this respect. The presented
results are in line with previous
work carried out by Grubbs
et al. who compared initiation
constants in polymerisation of
1,4-cyclooctadiene (COD) with
analogous benzylidene com-
plexes.[32]
9
10
4
8
3
3
65
63
9:1
9:1
–
–
11
12
4
8
1
1
71
74
9:1
9:1
19
26
13
14
4
8
3
3
76
72
>20:1
>20:1
16
16
15
16
4
8
2
2
3
10
>20:1
>20:1
10
23
17
18
4
8
2
2
23
20
8:2
8:2
<2
<2
19
20
4
8
3
3
75
76
>20:1
>20:1
25
24
Conclusion
It is now well established that
there is no universal catalyst for
all categories of metathesis re-
actions. Considering the sub-
strate dependence on catalysis,
we investigated various phos-
21
22
4
8
2
2
84
81
>20:1
>20:1
–
–
23
24
4
8
3
3
35
33
>20:1
>20:1
32
27
phane-bearing
ruthenium–in-
denylidene complexes in model
reactions and examined which
was their preferred niche. By
25
26
4
8
2
2
58
50
>20:1
>20:1
21
21
using
modify the phosphane around
the SIMes–Ru–indenylidene
scaffold, a toolbox of catalysts
featuring different stability, dis-
sociation rate and activity in
olefin metathesis was readily
achieved. As an overall trend,
a
simple method to
27[b]
28[b]
4
8
5
5
–
–
–
–
–
–
[a] Reaction conditions: substrate (0.5 mmol), cross partner (1–2 equiv), [Ru] (1 mol%), CH2Cl2 (1m), N2,
RT.[b] [Ru] (5 mol%), toluene (0.1m), 808C.
[RuCl
ACHTUNGTREN(NUGN Ind)] bearing an extremely electron-poor phosphane was
found to be the most active catalyst for poorly hindered sub-
strates in diene and enyne RCM, RRM and ROMP, whereas
2ACHTUNGTRENUN(GN SIMes){P(p-CF3C6H4)3}-
for RCM. Electron-poor PPh3 derivatives show an easier
dissociation, leading to high initiation rates, whereas com-
plexes bearing electron-rich phosphane ligands exhibit lower
Chem. Eur. J. 2010, 16, 9215 – 9225
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9221

S. P. Nolan et al.
Table 8. Electronic parameters (electronegativity, c) of the phosphane li-
gands and results from ROMP of monomers 78 and 79.[a]
[c]
[c]
[Ru]
c
Mn
PDI[c]
Yield
[%][b]
Mn
PDI[c]
Yield
[%][b]
2
3
4
5
6
7
8
9
1.4
654400
45400
2.0
1.1
1.4
1.5
1.5
1.3
1.3
1.3
89
72
74
84
78
61
87
67
967200
64700
2.3
1.1
1.4
1.8
1.5
1.4
1.4
1.3
87
74
66
85
86
96
70
68
n.a.
13.25
10.5
11.5
17.5
16.8
20.5
155000
356200
273900
151400
129200
102100
177800
302800
296000
170200
140000
88700
Figure 5. Correlation between the Hammett constant (sp) of the phos-
phane substituent and the Mn values of the polymers obtained from 79.
[a] Reaction conditions:
c , monomer/initiator=300:1,
Mon =0.2 molLÀ1
CH2Cl2, RT, quenching with ethyl vinyl ether. [b] Isolated yield after re-
peated precipitation from methanol. [c] Determined by GPC relative to
polystyrene standards, THF.
reaction types examined. Since such a significant effect is
obtained by simply modulating the para-functional group of
the phenyl group on a triphenylphosphane scaffold, we are
currently examining the effects of further modifications on
this and related architectures.
Experimental Section
General considerations: All reagents were used as received. Dichlorome-
thane was dispensed from a solvent purification system from Innovative
Technology. Catalyst syntheses were performed in an MBraun glovebox
containing dry argon and less than 1 ppm oxygen. Flash column chroma-
tography was performed on silica gel 60 (230–400 mesh). 1H, 31P, 19F and
13C NMR spectra were recorded on a Bruker Avance 300 or Bruker
Avance II 400 Ultrashield NMR spectrometers. High-resolution mass
spectrometry (HRMS) analyses were performed by the Mass Spectrome-
try Service of the University of St Andrews and by EPSRC National
Mass Spectrometry Service Centre (Swansea University). Complexes 2
and 3 are commercially available from Umicore AG or Strem Chemicals
Inc. Substrates 10,[13c] 12,[13c] 14,[13c] 16,[13c] 20,[33] 21,[34] 23,[13c] 25,[13c] 27,[35]
29,[13c] 31,[13c] 33,[13c] 35,[5d] 37,[13c] 39,[13c] 41,[13c] 43,[27] 45,[27] 47,[27] 49,[27]
51,[36] 54,[37] 58,[38] 76,[36] 78[29] and 79[39] have previously been described in
the literature.
Figure 3. Mn values of the polymers obtained from 78 (black bars) and 79
(grey bars) by using initiators 2–9.
AHCTUNTGREN[GUNN RuCl2ACHNUTRTGEG(NNNU SIMes)ACHTNGUTERN(NUGN PPh3)(3-phenylinden-1-ylidene)] (4): In a glovebox, com-
plex 3 (1.5 g, 2.0 mmol) and PPh3 (526 mg, 2.0 mmol, 1 equiv) were dis-
solved in dichloromethane (10 mL) and stirred for 3 h at room tempera-
ture. The volatiles were removed in vacuum and the residue was recrys-
tallised from dichloromethane/hexane (1:5, 18 mL). Filtration and wash-
ing with methanol (10 mL) and pentane (2ꢄ10 mL) afforded the rutheni-
1
um complex 4 as an ochre coloured solid (1.45 g, 78%). H and 31P NMR
were similar to the literature data.[23] 1H NMR (300 MHz, CD2Cl2): d=
7.78 (d, J=7.2 Hz, 1H; HInd), 7.46–7.38 (m, 3H; HAr), 7.30–7.26 (m, 2H;
HAr), 7.18–7.11 (m, 4H; HAr), 7.02–6.87 (m, 16H; HAr), 6.47 (s, 1H; m-
CHSIMes), 6.32 (s, 1H; m-CHSIMes), 5.94 (s, 1H; m-CHSIMes), 4.02–3.95 (m,
2H; CH2-CH2), 3.84–3.70 (m, 2H; CH2-CH2), 2.60 (s, 3H; CH3SIMes), 2.57
(s, 3H; CH3SIMes), 2.39 (s, 3H; CH3SIMes), 2.05 (s, 3H; CH3SIMes), 1.93 (s,
3H; CH3SIMes), 1.76 ppm (s, 3H; CH3SIMes); 31P NMR (121 MHz, CD2Cl2):
d=25.96 ppm.
Figure 4. Correlation between the Hammett constant (sp) of the phos-
phane substituent and the Mn values of the polymers obtained from 78.
AHCTUNTGREN[GUNN RuCl2ACHNUTRTGEG(NNNU SIMes)(PACHTNUGERTN(NUGN p-MeOPh)3)(3-phenylinden-1-ylidene)] (5): In a glove-
box, complex 3 (1.0 g, 1.34 mmol) and tris(p-methoxyphenyl)phosphane
(490 mg, 1.4 mmol, 1.05 equiv) were dissolved in dichloromethane
(10 mL) and stirred for 3 h at room temperature. The volatiles were re-
moved in vacuum and the residue was washed with methanol (10 mL)
and pentane (2ꢄ10 mL), affording the ruthenium complex 5 as a burgun-
dy solid (1.03 g, 75%). 1H NMR (300 MHz, CD2Cl2): d=7.93 (d, J=
its bulkier PCy3-containing congener was highly efficient for
encumbered substrates. On the other hand, in cross-meta-
thesis similar conversions were achieved by using the new
series of catalysts. [RuCl
2ACHTUNGTREN(UGNN SIMes)AHCTUNRTEGGNUN(N PPh3)ACTHNUGTRENN(UGN Ind)] appeared as
middle-of-the-road catalyst giving good results in all olefin
9222
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Chem. Eur. J. 2010, 16, 9215 – 9225

Ruthenium–Indenylidene Complexes in Metathesis
FULL PAPER
7.2 Hz, 1H; HInd), 7.54–7.46 (m, 3H; HAr), 7.36 (t, J=7.4 Hz, 2H; HAr),
7.24 (td, J=7.3, 0.9 Hz, 1H; HAr), 7.13 (bs, 2H; HAr), 7.06–6.92 (m, 8H;
HAr), 6.58 (dd, J=8.8, 1.5 Hz, 6H; HAr), 6.49 (s, 1H; m-CHSIMes), 6.40 (s,
1H; m-CHSIMes), 6.02 (s, 1H; m-CHSIMes), 4.11–4.04 (m, 2H; CH2-CH2),
3.95–3.78 (m, 2H; CH2-CH2), 3.71 (s, 9H; OCH3), 2.72 (s, 3H; CH3SIMes),
2.65 (s, 3H; CH3SIMes), 2.49 (s, 3H; CH3SIMes), 2.12 (s, 3H; CH3SIMes), 2.04
(s, 3H; CH3SIMes), 1.84 ppm (s, 3H; CH3SIMes);. 13C NMR (75.5 MHz,
ACHTUNGTERN[UNGN RuCl2ACHNUTRTGEG(NNUN SIMes)(PACHTUNGTNER(NUGN p-ClPh)3)(3-phenylinden-1-ylidene)] (8): In a glovebox,
complex 3 (1.5 g, 2.0 mmol) and tris(p-chlorophenyl)phosphane (770 mg,
2.1 mmol, 1.05 equiv) were dissolved in dichloromethane (10 mL) and
stirred for 3 h at room temperature. The volatiles were removed in
vacuum and the residue dissolved in hexane (20 mL). The red solution
was cooled and filtrated to remove insoluble impurities. After evapora-
tion of solvent in vacuum, the remaining solid was washed with methanol
(10 mL) and pentane (2ꢄ10 mL), affording the ruthenium complex 8 as a
dark red solid (1.86 g, 90%). 1H NMR (400 MHz, CD2Cl2): d=7.83 (d,
J=7.2 Hz, 1H; HInd), 7.57–7.34 (m, 6H; HAr), 7.27–7.20 (m, 2H; HAr),
7.10–6.97 (m, 14H; HAr), 6.52 (s, 1H; m-CHSIMes), 6.42 (s, 1H; m-
CHSIMes), 6.05 (s, 1H; m-CHSIMes), 4.07 (t, J=10.0 Hz, 2H; CH2-CH2),
3.93–3.78 (m, 2H; CH2-CH2), 2.67 (s, 3H; CH3SIMes), 2.63 (s, 3H;
CH3SIMes), 2.50 (s, 3H; CH3SIMes), 2.14 (s, 3H; CH3SIMes), 2.02 (s, 3H;
CH3SIMes), 1.84 ppm (s, 3H; CH3SIMes); 13C NMR (100.6 MHz, CD2Cl2):
CD2Cl2): d=299.0 (d, JACHTUNGTRENNUNG(C,P)=12.9 Hz, C), 216.1 (d, JACHTUNGTERN(NUGN C,P)=86.3 Hz, C),
160.9 (3C), 143.4 (C), 141.4 (C), 140.6 (C), 139.9 (C), 139.5 (C), 138.6
(C), 138.3 (C), 138.2 (C), 137.3 (C), 137.0 (C), 136.9 (CH), 136.7 (C),
136.1 (CH), 136.0 (3CH), 135.8 (3CH), 130.1 (CH), 130.0 (CH), 129.3
(CH), 129.2 (3CH), 129.0 (CH), 128.9 (CH), 128.2 (CH), 126.6 (4C),
123.9 (CH), 123.3 (CH), 116.4 (CH), 113.3 (3CH), 113.2 (3CH), 55.4
(3CH3), 52.7 (CH2), 52.4 (CH2), 21.5 (CH3), 21.0 (CH3), 20.6 (CH3), 20.4
(CH3), 18.9 (CH3), 18.7 ppm (CH3); 31P NMR (121 MHz, CD2Cl2): d=
22.41 ppm; elemental analysis calcd (%) for C57H57Cl2N2O3PRu
(1021.02): C 67.05, H 5.63, N 2.74; found: C 66.98, H 5.70, N 2.75.
d=301.1 (d, JACTHNUTRGENN(UG C,P)=12.5 Hz, C), 214.7 (d, JACHUTNGTREN(NNGU C,P)=88.2 Hz, C), 143.3
(C), 141.7 (C), 141.2 (C), 139.9 (C), 139.6 (C), 139.0 (C), 138.3 (C), 138.2
(C), 137.5 (C), 136.9 (2C), 136.5 (2C), 136.1 (C), 135.8 (3CH), 135.7
(3CH), 130.08 (CH), 130.04 (CH), 129.9 (CH), 129.5 (CH), 129.45
(3CH), 129.4 (CH), 129.3 (CH), 129.1 (CH), 129.0 (CH), 128.8 (CH),
128.7 (CH), 128.2 (3CH), 128.1 (3CH), 126.6 (4C), 116.8 (CH), 52.7 (d,
ACHTUNGTRENNUNG[RuCl2ACHTUNGTRENNUNG(SIMes)(PACHTUNGTRENNUNG(p-Tolyl)3)(3-phenylinden-1-ylidene)] (6): In a glovebox,
complex 3 (1.0 g, 1.34 mmol) and tri-p-tolylphosphane (427 mg, 1.4 mmol,
1.05 equiv) were dissolved in dichloromethane (10 mL) and stirred for
2 h at room temperature. The volatiles were removed in vacuum and the
residue was recrystallised from dichloromethane/cold pentane (1:5,
18 mL) at À208C. Of note, the complex is soluble in pentane at room
temperature. After cold filtration, the orange-red solid was dissolved in
cyclohexane (30 mL) and filtered to remove insoluble impurities. After
evaporation of solvent in vacuum, the ruthenium complex 6 was obtained
as a orange-red solid (1.00 g, 77%). 1H NMR (300 MHz, CD2Cl2): d=
7.93 (d, J=7.2 Hz, 1H; HInd), 7.53–7.22 (m, 6H; HAr), 7.12–6.85 (m, 16H;
HAr), 6.43 (s, 1H; m-CHSIMes), 6.39 (s, 1H; m-CHSIMes), 6.03 (s, 1H; m-
CHSIMes), 4.07 (t, J=7.2 Hz, 2H; CH2-CH2), 3.83 (sextuplet, J=7.2 Hz,
2H; CH2-CH2), 2.72 (s, 3H; CH3SIMes), 2.64 (s, 3H; CH3SIMes), 2.49 (s, 3H;
CH3SIMes), 2.24 (s, 9H; p-CH3), 2.09 (s, 3H; CH3SIMes), 2.04 (s, 3H;
CH3SIMes), 1.84 ppm (s, 3H; CH3SIMes); 13C NMR (100.6 MHz, CD2Cl2):
JACHTNUTRGENNU(G C,P)=3.5 Hz, CH2), 52.5 (d, JCAHTUNGTERN(NUGN C,P)=1.8 Hz, CH2), 21.4 (CH3), 21.0
(CH3), 20.5 (CH3), 20.4 (CH3), 18.8 (CH3), 18.6 ppm (CH3); 31P NMR
(162 MHz, CD2Cl2): d=25.82 ppm; elemental analysis calcd for
C54H48Cl5N2PRu (MW 1034.28): C 62.71, H 4.68, N 2.71; found: C 62.40,
H 4.60, N 2.76.
AHCTUNGRTEG[NUNN RuCl2AHCUTNRTGEG(NUNN SIMes)(PACTHNGURTEN(NUGN p-CF3Ph)3)(3-phenylinden-1-ylidene)] (9): In a glove-
box, complex 3 (1.14 g, 1.53 mmol) and tris(p-fluoromethylphenyl)phos-
phane (750 mg, 1.61 mmol, 1.1 equiv) were dissolved in dichloromethane
(10 mL) and stirred for 3 h at room temperature. The volatiles were re-
moved in vacuum and the residue dissolved in hexane (20 mL). The red
solution was cooled and filtrated to remove insoluble impurities. After
evaporation of solvent in vacuum, the remaining solid was purified by
silica gel chromatography (hexane/diethyl ether 8:2) affording the ruthe-
nium complex 9 as a dark red solid (1.27 g, 73%). 1H NMR (300 MHz,
CD2Cl2): d=7.74 (d, J=7.0 Hz, 1H; HInd), 7.58–7.52 (m, 1H; HAr), 7.44–
7.34 (m, 10H; HAr), 7.27–7.11 (m, 9H; HAr), 6.99–6.93 (m, 2H; HAr), 6.49
(s, 1H; m-CHSIMes), 6.42 (s, 1H; m-CHSIMes), 6.05 (s, 1H; m-CHSIMes),
4.13–4.06 (m, 2H; CH2-CH2), 3.96–3.78 (m, 2H; CH2-CH2), 2.68 (s, 3H;
CH3SIMes), 2.65 (s, 3H; CH3SIMes), 2.49 (s, 3H; CH3SIMes), 2.14 (s, 3H;
CH3SIMes), 2.01 (s, 3H; CH3SIMes), 1.83 ppm (s, 3H; CH3SIMes); 13C NMR
d=299.4 (d, JACHTUNGTRENNUNG(C,P)=13.1 Hz, C), 215.9 (d, JACHUTNGTREN(NNGU C,P)=85.7 Hz, C), 143.4
(C), 141.4 (C), 140.6 (C), 139.9 (3C), 139.5 (C), 138.7 (C), 138.3 (C),
138.2 (C), 137.3 (C), 137.1 (C), 136.9 (CH), 136.7 (C), 136.0 (C), 134.5
(3CH), 134.4 (3CH), 130.1 (CH), 130.0 (CH), 129.3 (CH), 129.2 (CH),
129.17 (2CH), 129.0 (CH), 128.99 (CH), 128.8 (CH), 128.6 (CH), 128.5
(3CH), 128.4 (3CH), 128.1 (2CH), 126.6 (4C), 116.4 (CH), 52.7 (CH2),
52.5 (CH2), 21.5 (CH3), 21.3 (3CH3), 21.0 (CH3), 20.6 (CH3), 20.4 (CH3),
18.9 (CH3), 18.6 ppm (CH3); 31P NMR (121 MHz, CD2Cl2): d=
24.08 ppm; elemental analysis calcd (%) for C57H57Cl2N2PRu (973.03): C
70.36, H 5.90, N 2.88; found: C 70.29, H 5.94, N 3.08.
(100.6 MHz, CD2Cl2): d=302.6 (d, J
(C,P)=89.9 Hz, C), 143.3 (C), 142.4 (C), 141.1 (C), 140.1 (C), 139.8 (C),
139.1 (C), 138.3 (C), 137.7 (C), 137.0 (d, J(C,F)=2.3 Hz, CH), 136.8
(CH), 135.8 (C), 135.7 (C), 135.5 (C), 135.1 (CH), 135.0 (3CH), 134.9
(3CH), 131.9 (q, J(C,F)=33,6 Hz, 3C-CF3), 130.3 (CH), 130.2 (CH),
129.5 (CH), 129.4 (3CH), 129.37 (CH), 129.1 (CH), 129.0 (CH), 128.9
(CH), 126.6 (4C), 124.9–124.7 (m, 6CH), 124.2 (d, J(C,F)=272.5 Hz,
3CF3), 117.0 (CH), 52.7 (d, J(C,P)=3.6 Hz, CH2), 52.4 (d, J(C,P)=
ACHTUNGTNER(NUNG C,P)=12.8 Hz, C), 214.0 (d, J-
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG[RuCl2ACHTUNGTRENNUNG(SIMes)(PACHTUNGTRENNUNG(p-FPh)3)(3-phenylinden-1-ylidene)] (7): In a glovebox,
AHCTUNGTRENNUNG
complex 3 (1 g, 1.34 mmol) and tris(p-fluorophenyl)phosphane (444 mg,
1.4 mmol, 1.05 equiv) were dissolved in dichloromethane (10 mL) and
stirred for 2 h at room temperature. The volatiles were removed in
vacuum and the residue was washed with methanol (10 mL) and pentane
(2ꢄ10 mL), affording the ruthenium complex 7 as a maroon solid (1.18 g,
90%). 1H NMR (300 MHz, CD2Cl2): d=7.83 (d, J=7.4 Hz, 1H; HInd),
7.57–7.51 (m, 3H; HAr), 7.40 (t, J=7.5 Hz, 2H; HAr), 7.24 (t, J=7.2 Hz,
1H; HAr), 7.09–6.97 (m, 10H; HAr), 6.78 (td, J=8.8, 1.4 Hz, 6H; HAr),
6.58 (s, 1H; m-CHSIMes), 6.43 (s, 1H; m-CHSIMes), 6.04 (s, 1H; m-CHSIMes),
4.11–4.04 (m, 2H; CH2-CH2), 3.95–3.76 (m, 2H; CH2-CH2), 2.66 (s, 6H;
CH3SIMes), 2.48 (s, 3H; CH3SIMes), 2.17 (s, 3H; CH3SIMes), 2.00 (s, 3H;
CH3SIMes), 1.82 ppm (s, 3H; CH3SIMes); 13C NMR (100.6 MHz, CD2Cl2):
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
1.6 Hz, CH2), 21.2 (CH3), 21.0 (CH3), 20.6 (CH3), 20.5 (CH3), 18.8 (CH3),
18.6 ppm (CH3); 31P NMR (121 MHz, CD2Cl2): d=26.98 ppm; 19F NMR
(282 MHz, CD2Cl2): d=À63.86 ppm; elemental analysis calcd for
C57H48Cl2F9N2PRu (MW 1134.94): C 60.32, H 4.26, N 2.47; found: C 60.40,
H 4.52, N 2.31.
General procedure for RCM reactions: A Schlenk flask under nitrogen
was charged with the substrate (0.5 mmol) and dry dichloromethane
(5 mL, c=0.1m), then pre-catalyst 4 or 9 (5ꢄ10À6 mol) was added. The
reaction mixture was magnetically stirred at room temperature and the
progress of the reaction was monitored by TLC. After completion of the
reaction, the volatiles were removed under vacuum and the crude residue
was purified by flash column chromatography (pentane/ether 9:1) to
yield the pure product.
d=300.8 (d, J
(C,F)=250.6 Hz, 3C), 143.4 (C), 141.3 (C), 141.2 (C), 139.8 (C), 139.7
(C), 138.9 (C), 138.2 (C), 137.5 (C), 137.0 (C), 136.7 (d, J(C,F)=11.5 Hz,
3CH), 136.6 (d, J(C,F)=11.6 Hz, 3CH), 136.2 (C), 135.8 (C), 130.09
(CH), 130.06 (CH), 129.4 (CH), 129.35 (3CH), 129.3 (CH), 129.1 (CH),
129.0 (CH), 128.7 (CH), 128.6 (CH), 127.6 (d, J(C,F)=3.2 Hz, CH), 127.2
(d, J(C,F)=3.2 Hz, CH), 126.6 (4C), 116.8 (CH), 115.2 (d, J(C,F)=
10.7 Hz, 3CH), 114.9 (d, J(C,F)=10.6 Hz, 3CH), 52.7 (d, J(C,P)=3.5 Hz,
CH2), 52.4 (d, J(C,P)=2.3 Hz, CH2), 21.4 (CH3), 21.0 (CH3), 20.5 (CH3),
ACHTUNGTRENNUNG(C,P)=12.4 Hz, C), 215.0 (d, JACHTUNGTNER(NUGN C,P)=88.3 Hz, C), 164.0 (d,
JACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
General procedure for ring-rearrangement metathesis reactions:
A
A
ACHTUNGTRENNUNG
Schlenk flask, fitted with a magnetic stir bar, under nitrogen, was charged
with the substrate (0.5 mmol) and dry dichloromethane (50 mL, c=
0.01m). The pre-catalyst 4 or 9 (5ꢄ10À6 mol) was then added. The reac-
tion mixture was stirred at room temperature and the progress was moni-
tored by TLC. After completion, ethyl vinyl ether (0.1 mL) was added
ACHTUNGTRENNUNG
20.4 (CH3), 18.8 (CH3), 18.7 ppm (CH3); 31P NMR (121 MHz, CD2Cl2):
d=24.89 ppm. 19F NMR (376 MHz, CD2Cl2): d=À111.82 ppm; elemental
analysis calcd for C54H48Cl2F3N2PRu (MW 984.92): C 65.85, H 4.91, N
2.84; found: C 65.64, H 4.72, N 2.63.
Chem. Eur. J. 2010, 16, 9215 – 9225
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9223

S. P. Nolan et al.
and the solution was further stirred 30 min. The volatiles were removed
under vacuum and the crude product was purified by flash column chro-
matography to yield the pure product.
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General procedure for cross-metathesis reactions: A Schlenk flask, under
nitrogen, was charged with the substrate (0.5 mmol), the olefin partners
(1 mmol unless otherwise stated) and dry dichloromethane (0.5 mL, c=
1m). The pre-catalyst 4 or 7 (5ꢄ10À6 mol) was then added. The reaction
mixture was magnetically stirred at room temperature and the progress
of the reaction was monitored by TLC. After completion of the reaction,
the solvent was removed under vacuum and the crude residue was puri-
fied by flash column chromatography (pentane/ether 1:1) to yield the
pure product.
General procedure for ROMP reactions: The initiator 2–9 (1 equiv) was
weighed into a Schlenk flask with a stirring bar and dissolved in dry and
degassed CH2Cl2 (1 mL). Monomer 78 or 79 (300 equiv) was dissolved in
the corresponding amount of solvent to reach a total concentration of
0.2 molLÀ1. The monomer solution was added to the initiator solution.
The reaction mixture was stirred until polymerisation was complete,
which was monitored by thin layer chromatography. After completion,
the polymerisation reaction was quenched by addition of an excess of
ethyl vinyl ether (200 mL). After 15 min of additional stirring, the solvent
was reduced to approximately 1 mL. The reaction mixture was then
slowly added to vigorously stirred, cold methanol to precipitate the poly-
mer, which was collected and dried in vacuum. Provided yields refer to
the amount of isolated polymer. A sample of each polymer was subjected
to GPC for analysis of Mn and PDI.
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Acknowledgements
We are grateful to the EC for funding through the seventh framework
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mass analyses as is Umicore AG for the generous gift of materials.
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Chem. Eur. J. 2010, 16, 9215 – 9225

Ruthenium–Indenylidene Complexes in Metathesis
FULL PAPER
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Received: March 15, 2010
Published online: July 7, 2010
Chem. Eur. J. 2010, 16, 9215 – 9225
ꢁ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
9225