Synthesis and reactivity of novel ruthenium carbene catalysts. X-ray structures of [RuCl2(=CHSC6H5)(Pir 3)2] and [RuCl2(CHCH2CH2-C,N-2-C5H 4N)(Pir3)]

Article abstract of DOI:10.1016/S0022-328X(00)00289-8

Two novel classes of very air-stable ruthenium carbene complexes have been developed. The arylthio substituted ruthenium carbenes containing two bulky phosphines are deep purple solids, whereas the 2-pyridylethanyl substituted ruthenium carbene complexes contain only one bulky phosphine and are light-brown colored. One member of each class has been characterized with X-ray crystallography. The metathesis activity of these complexes has been investigated in the polymerization of dicyclopentadiene. Several excellent catalysts were identified. Desired geltimes and initiation temperatures could be easily tuned by changing the substitution pattern on the pendant ligand in the 2-pyridylethanyl substituted ruthenium carbenes.

Full text of DOI:10.1016/S0022-328X(00)00289-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 606 (2000) 65–74
Synthesis and reactivity of novel ruthenium carbene catalysts.
X-ray structures of [RuCl2(ꢀCHSC6H5)(PiPr3)2] and
[RuCl2(CHCH2CH2-C,N-2-C5H4N)(PiPr3)]
Paul A. van der Schaaf *, Roman Kolly, Hans-Ju¨rg Kirner, Francois Rime,
Andreas Mu¨hlebach, Andreas Hafner
Ciba Specialty Chemicals, CH-4002 Basel, Switzerland
Received 2 February 2000; received in revised form 27 April 2000
Abstract
Two novel classes of very air-stable ruthenium carbene complexes have been developed. The arylthio substituted ruthenium
carbenes containing two bulky phosphines are deep purple solids, whereas the 2-pyridylethanyl substituted ruthenium carbene
complexes contain only one bulky phosphine and are light-brown colored. One member of each class has been characterized with
X-ray crystallography. The metathesis activity of these complexes has been investigated in the polymerization of dicyclopentadi-
ene. Several excellent catalysts were identified. Desired geltimes and initiation temperatures could be easily tuned by changing the
substitution pattern on the pendant ligand in the 2-pyridylethanyl substituted ruthenium carbenes. © 2000 Elsevier Science S.A.
All rights reserved.
Keywords: Ruthenium; Catalyst; Carbenes; Metathesis; ROMP; Dicyclopentadiene
we describe two novel classes of ruthenium carbene
catalysts and their first application in the polymeriza-
tion of dicyclopentadiene (DCPD).
1. Introduction
In the last years of the 2nd millennium, the use of
ruthenium carbene catalysts for olefin metathesis reac-
tions has dramatically increased in the field of organic
and polymer chemistry. Primarily, this was caused by
the development of well-defined ruthenium carbene cat-
alysts by Grubbs group at CalTech [1]. Their pioneer-
ing work was followed by many others who ‘fine-tuned’
the catalyst system to increase stability and/or activity,
improved catalyst syntheses, and, last but not least,
incorporated the olefin metathesis chemistry in their
strategies to develop novel synthetic routes to, or via
classical routes not available, complex organic
molecules [2].
2. Results and discussion
2.1. Catalysts
Recently we published our first results on the solvent-
free polymerization of DCPD using [RuCl2(p-
cymene)(PCy3)] as catalyst precursor [3b]. With this
one-component initiator, DCPD was polymerized in
the presence of a wide variety of filler materials like
quartz powder, alumina, and pigments to obtain mate-
rials with outstanding mechanical and electrical proper-
ties. Solutions of 0.3 wt% of this catalyst in DCPD are
very latent, whereas upon raising the temperature to
80°C a fast and complete polymerization took place.
We think that in the activation mechanism the p-
cymene moiety is liberated and the ‘half-naked’ ruthe-
nium is transformed into a more reactive ruthenium
carbene complex. Most probably this transformation
Our long standing interest in olefin metathesis chem-
istry [3] led us to investigate the use of well-defined
ruthenium carbene catalysts intensively. In this paper
* Corresponding author. Tel.: +41-61-6365433; fax: +41-61-
6364011.
E-mail address: paul.van der schaaf@cibasc.com (P.A. van der
–
–
Schaaf).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00289-8

66
P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
Scheme 1.
into a carbene is accelerated by the presence of some
acetylenic impurities present in DCPD [4]. We could
decrease the catalyst concentration significantly by us-
ing Grubbs’ well-defined ruthenium carbene catalysts.
However, the drawback of these highly reactive cata-
lysts is the moderate latency. After solubilizing the
catalyst in DCPD, the polymerization takes place al-
most immediately without any control of the rate of
polymerization [5]. We tried to modify chemically this
catalyst system in such a way that we could control the
initiation rate of the polymerization. Surprisingly, we
found that hetero atom substituted ruthenium carbenes
[6] are also active catalysts for olefin metathesis reac-
tions. Especially, arylsulfur substituted ruthenium car-
benes appear to be very efficient catalysts [7]. This new
class of catalysts can be easily prepared either via the
reaction of Grubbs’ benzylidene catalyst with an aryl
vinyl thioether or via our one-pot procedure for the
synthesis of ruthenium carbenes starting from
[RuCl2(1,5-cyclooctadiene)] via a ruthenium hydride
species [8], see Scheme 1. In contrast to known proce-
dures from the literature in which ruthenium hydrides
are the key intermediates in the synthesis of ruthenium
carbenes [9], this synthetic procedure generates a very
reactive ruthenium hydride species in situ in boiling
isopropanol without the use of hydrogen gas.
Fig. 1. ORTEP drawing of the molecular structure of
[RuCl2(ꢀCHSPh)(PiPr3)2] (2a) (thermal ellipsoids at 50% probability).
Table 1
i
,
Selected bond lengths (A) and angles (°) for [RuCl2(ꢀCHSPh)(P Pr3)2]
(2a)
The catalysts 2a and 2b are purple, air-stable solids.
By introducing the para-methyl group in 2b, the solu-
bility of the catalyst in apolar solvents, and dicyclopen-
tadiene, was drastically increased. To elucidate the
stereochemistry of these complexes an X-ray structure
determination on 2a was carried out. Suitable crystals
were grown from a hot toluene solution. Fig. 1 shows
the ORTEP drawing of 2a together with the adopted
numbering scheme. Selected bond distances and angles
are given in Table 1.
Bonds lengths
Ru(1)ꢁCl(1)
Ru(1)ꢁCl(2)
Ru(1)ꢁC(1)
Ru(1)ꢁP(1)
Ru(1)ꢁP(2)
C(1)ꢁS(1)
2.3898(12)
2.3884(12)
1.837(4)
2.4196(10)
2.4184(11)
1.706(4)
S(1)ꢁC(2)
1.782(4)
Bond angles
Surprisingly, the presence of the sulfur atom on the
carbene moiety does not significantly influence the
structural properties of this carbene complex with re-
spect to the crystal structure of the Grubbs benzylidene
[1c]. This is also nicely reflected in the high metathesis
activity of these compounds, see below. The activation
mechanism of 2a and 2b is assumed to be similar to
that for the ruthenium benzylidene complexes. This
activation mechanism, as proposed by Grubbs et al.
[10], is a dissociative mechanism in which one of the
two phosphines dissociates from the ruthenium center
Cl(1)ꢁRu(1)ꢁCl(2)
P(1)ꢁRu(1)ꢁP(2)
Ru(1)ꢁC(1)ꢁS(1)
C(1)ꢁS(1)ꢁC(2)
P(1)ꢁRu(1)ꢁC(1)
P(2)ꢁRu(1)ꢁC(1)
Cl(1)ꢁRu(1)ꢁC(1)
Cl(2)ꢁRu(1)ꢁC(1)
P(1)ꢁRu(1)ꢁCl(1)
P(1)ꢁRu(1)ꢁCl(2)
P(2)ꢁRu(1)ꢁCl(1)
P(2)ꢁRu(1)ꢁCl(2)
173.92(5)
162.76(3)
129.0(2)
102.07(18)
98.96(11)
98.25(11)
92.67(12)
93.40(12)
89.40(4)
89.91(4)
90.79(4)
88.07(4)

P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
67
Scheme 2.
2.2. ROMP of DCPD
upon binding an olefin. Presumably the liberated phos-
phine remains in the proximity of the ruthenium center
of coordinately unsaturated reactive intermediates.
However, this reversible binding of the phosphine lig-
and also lowers the overall catalyst activity. Experimen-
tal evidence for the latter is provided by the fact that
the addition of CuCl to capture liberated phosphine
results in higher catalyst activity. Also the addition of
acid to the reaction mixture produces an increased
activity of the catalyst because of protonation of the
free phosphine [11]. We approached this problem in a
different way, and developed a new class of ruthenium
carbene complexes in which a potentially coordinating
ligand is directly bonded to the carbene moiety of the
catalyst [12]. A very efficient group of catalysts are the
2-pyridylethanyl substituted ruthenium carbene com-
plexes 4a–f. Also this new class of catalyst can be easily
prepared, either via the reaction of Grubbs benzylidene
catalyst with a 2-(3-butenyl)pyridine or directly via our
one-pot procedure for the synthesis of ruthenium carbe-
nes starting from [RuCl2(1,5-cyclooctadiene)] via a
ruthenium hydride species, see Scheme 2.
The metathesis activity of these new classes of cata-
lysts has been tested on the polymerization of dicy-
clopentadiene (DCPD), see Scheme 3. In a first test we
screened the activity of our catalysts in a differential
Fig. 2. ORTEP drawing of the molecular structure of
[RuCl2(ꢀCHCH2CH2-C,N-2-C5H4N)(PiPr3)] (4a) (thermal ellipsoids
at 50% probability).
These classes of catalysts are monophosphine com-
plexes in which the carbene moiety is substituted with
an intramolecularly coordinating pyridyl group [13].
The possibility of substitution of the pyridyl ring en-
abled us to fine-tune the reactivity of these catalysts,
vide infra. The catalysts 4a–f are light-brown, air-stable
solids. To elucidate the stereochemistry of these com-
plexes an X-ray structure determination of 4a was
carried out. Suitable crystals were grown from a hot
toluene solution. Fig. 2 shows the ORTEP drawing of 4a
together with the adopted numbering scheme. Selected
bond distances and angles are given in Table 2.
Again, the bond length of the ruthenium carbene
moiety is closely related to that of Grubbs benzylidene
catalyst and 2a. The main difference of the structural
properties of 4a with the latter structures is the signifi-
cant smaller ClꢁRuꢁCl angle of 155°, which is probably
a consequence of a combination of electronic and steric
factors that accompany the formation of the six-mem-
bered chelate ring by replacing one bulky phosphine.
Table 2
,
Selected bond lengths (A) and angles (°) for [RuCl2(ꢀCHCH2CH2-
C,N-2-C5H4N)(PiPr3)] (4a)
Bonds lengths
Ru(1)ꢁCl(1)
Ru(1)ꢁCl(2)
Ru(1)ꢁC(8)
Ru(1)ꢁP(1)
Ru(1)ꢁN(1)
2.3521(7)
2.3471(7)
1.810(3)
2.3423(7)
2.1542(19)
Bond angles
Cl(1)ꢁRu(1)ꢁCl(2)
P(1)ꢁRu(1)ꢁN(1)
Ru(1)ꢁC(8)ꢁC(7)
P(1)ꢁRu(1)ꢁC(8)
N(1)ꢁRu(1)ꢁC(8)
Cl(1)ꢁRu(1)ꢁC(8)
Cl(2)ꢁRu(1)ꢁC(8)
P(1)ꢁRu(1)ꢁCl(1)
P(1)ꢁRu(1)ꢁCl(2)
N(1)ꢁRu(1)ꢁCl(1)
N(1)ꢁRu(1)ꢁCl(2)
155.27(3)
172.80(6)
126.5(2)
96.08(9)
91.10(10)
100.34(9)
103.72(9)
91.67(2)
91.36(2)
86.63(6)
87.31(6)

68
P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
Scheme 3.
be at ca. 90°C whereas this for 4f is ca. 70°C, see Figs.
6 and 7.
scanning calorimetry (DSC) apparatus. The results of
this screening are given in Table 3.
These results clearly show that both arylthio substi-
tuted ruthenium carbenes 2a and 2b are very efficient
initiators as well as the 2-pyridylethanyl substituted
carbenes 4a, 4b, and 4f. All of these catalysts gave
poly(DCPD) with a glass transition temperature (Tg)
far above 120°C (which indicates high conversions of
\98%). The vinyl substituted Grubbs catalyst 6 ap-
peared to be a better initiator in this screening than the
benzylidene catalyst 5. These experiments also clearly
show the very good latency of the 2-pyridylethanyl
substituted ruthenium carbenes. Catalysts 4a, 4b and 4f
have all geltimes greater than 40 min. These high
geltimes are needed for good handling of the DCPD/
catalyst formulation.
The interesting candidates of this first screening were
subsequently tested in a plate polymerization experi-
ment. For this setup we used a heatable steel mold
(0.4×30×30 cm). In an experiment a freshly prepared
solution of the catalyst in DCPD ([DCPD]/[catalyst]=
4700:1) was poured into the preheated mold and the
temperature was monitored. With this setup curing
profiles and processing parameters were studied. Figs. 3
and 4 show the thermographs of the polymerization of
DCPD initiated by 2a, 2b, and 4a, 4b, 4f, respectively
with a fixed mold temperature of 60°C.
The exotherms of the reactions with 2a and 2b are
both higher than 180°C and the reactions are completed
after ca. 1 min. With the catalysts 4b and 4f exotherms
reach 165 and 178°C, respectively, and the reactions
take ca. 2 min for completion. With catalyst 4a no
exotherm was measured and the DCPD was only
slightly gelled after 4 min. However, by changing the
initial mold temperature, the polymerization profiles
changed drastically. Figs. 5–7 show the thermograph of
the polymerization initiated by 2b, 4a and 4f, respec-
tively, at different mold temperatures (note: for a better
comparison the y-axis shows the DT (°C) with respect
to the mold temperature).
3. Conclusion
Two novel classes of ruthenium carbene complexes
have been prepared. Polymerization experiments show
that these new ruthenium carbene complexes are excel-
lent initiators for the solvent-free catalytic polymeriza-
Table 3
Results of the catalyst screening for the polymerization of DCPD a
Catalyst
Tg (°C) b
Gel time (min) c
2a
2b
4a
4b
4c
4d
4e
4f
149
142
135
140
102
No reaction
78
149
68
10
12
\60
44
\60
\60 (no reaction)
\60
51
2
5 d
6 e
147
3
a Experimental conditions. A solution of catalyst in 5 g DCPD was
prepared and degassed in vacuum ([DCPD]/[catalyst]=12 000:1). A
sample of 20–30 mg of this solution was taken and a DSC scan was
recorded (0–200°C with 10°C min−1).
b The glass transition temperature (Tg) was determined in a second
run.
c The gel time was determined as the time needed for the 5 g
solution to flow like a honey.
d [RuCl2(ꢀCHPh)(PiPr3)2].
e [RuCl2(ꢀCHꢁCHꢀCMe2)(PiPr3)2].
Fig. 5 clearly shows that a mold temperature of 50°C
is not sufficient for the polymerization of DCPD ini-
tiated with 2b, whereas with a mold temperature of
60°C, a high exotherm is observed with a peak maxi-
mum at 45 s. At higher mold temperatures the polymer-
ization peak maximums of 20 s were reached (however,
polymer properties like Tgs tend to decrease at very
high polymerization rates). The optimum mold temper-
ature for the polymerization initiated by 4a appeared to
Fig. 3. Thermograph of the polymerization of DCPD with 2a (1) and
2b (2) at 60°C.

P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
69
tuned by changing the substitution pattern on the pen-
dant ligand in the 2-pyridylethanyl substituted ruthe-
nium carbenes. Experiments of using these novel
catalysts in other applications are currently in progress.
4. Experimental
All reactions were carried out in an atmosphere of
argon using standard Schlenk techniques when neces-
sary. Solvents were used directly from the bottle
(Fluka, puriss). Dicyclopentadiene was obtained from
BF Goodrich (Ultrene 99) and liquefied with 3% MTD
(methyl tetracyclododecene). Triisopropyl phosphine
was prepared according to a known procedure [14]. All
other chemicals were purchased from Fluka and used
as supplied. Screening polymerization experiments were
carried out in a DSC30 apparatus (differential scanning
calorimetry) of Mettler Toledo equipped with a TC15
TA controller. Preparation of poly(DCPD) plates were
performed in an in-house build, heatable mold (0.4×
30×30 cm), with online temperature recording. 1H-
and 31P-NMR spectra were recorded on a Bruker
AC250 or AC300 spectrometer in CDCl3 at 25°C. The
X-ray crystal structure analyses were carried out by the
BENEFRI-small molecule crystallography service, In-
stitute of Chemistry, University of Neuchaˆtel, Switzer-
Fig. 4. Thermograph of the polymerization of DCPD with 4a (1), 4b
(2) and 4f (3) at 60°C.
land
(http://www.unine.ch/chim/chp2/smcs/SMCS.
html).
4.1. Ligand synthesis
Fig. 5. Thermograph of the polymerization of DCPD with 2b
([DCPD]/[catalyst]=4700:1) at 80 (1), 70 (2), 60 (3) and 50°C (4).
Ligand 1a was prepared according to a modified
literature procedure [15]. In this procedure thiophenol
is deprotonated with sodium ethanolate, reacted with
1,2-dibromoethane, and dehydrobrominated with
sodium ethanolate. Surprisingly, for the synthesis of 1b,
no desired product was obtained when the alkylation
was performed with dibromoethane, followed by a de-
Fig. 6. Thermograph of the polymerization of DCPD with 4a
([DCPD]/[catalyst]=4700:1) at 100 (1), 90 (2), 80 (3), 70 (4) and 60°C
(5).
tion of DCPD. We were able to perform so-called
‘one-shot-full-cure’ polymerizations in
a preheated
mold with polymerization times of less than 1 min.
Desired geltimes and initiation temperatures can be
Fig. 7. Thermograph of the polymerization of DCPD with 4f
([DCPD]/[catalyst]=4700:1) at 80 (1), 70 (2), 60 (3) and 50°C (4).

70
P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
Scheme 5. Changing the solvent from THF to diethyl
ether improved the selectivity of the deprotonation
reaction dramatically [17], and the desired product was
obtained in good quality in 79% yield.
4.2. Synthesis of 1a
Thiophenol (110 g, 1 mol)) was added in small
portions to a solution of sodium ethanolate (prepared
by dissolving 23 g of sodium in 400 ml ethanol) over a
period of 20 min. The resulting clear reaction mixture is
then added dropwise, over a period of 2 h, to 1,2-dibro-
moethane (272 g, 1.4 mol) at r.t. After addition, the
reaction mixture is allowed to stir an additional hour at
r.t. A second solution of sodium ethanolate (prepared
by dissolving 40 g sodium in 800 ml ethanol) was added
dropwise over a period of 1 h. The resulting reaction
mixture was heated to reflux overnight. The reaction
mixture was then cooled to r.t. and filtered. The ethanol
solution was concentrated in vacuum (60°C, 200 mbar),
and was treated with 300 ml tert-butyl methyl ether and
200 ml water. The organic layer was separated, and the
water layer was then extracted twice with tert-butyl
methyl ether (2×50 ml). The combined organic layers
were washed with a saturated aqueous sodium chloride
solution (ca. 20%) until pH is neutral, and afterwards
dried over magnesium sulfate. The organic layer was
concentrated in vacuum, and the product was obtained
pure by distillation (103°C, 40 mbar). The product was
obtained in 46% yield (63 g) as a yellowish liquid [18].
Scheme 4.
hydrobromination reaction. Instead, quantitative yields
of (2-ethoxyethyl)-para-thiocresol were obtained. How-
ever, by using 2-chloroethanol as alkylating agent fol-
lowed by reaction of HCl and dehydrochlorination, the
product was obtained in good yield, see Scheme 4.
The 2-(3-butenyl)pyridines 3a–f were synthesized ac-
cording to a modified literature procedure [16]. All
desired products were obtained in good yield when we
deprotonated the ortho-methyl pyridines in THF at
low-temperature (ca. −70°C) with butyl lithium, re-
acted the in situ formed lithiated species with allylbro-
mide, warmed the reaction mixture to room
temperature (r.t.) and then performed the work-up.
However, such a reaction procedure is not economically
feasible to perform on a larger scale. When we opti-
mized the reaction procedure for 1a we performed the
deprotonation with butyl lithium in THF at ca. 0°C
and quenched the reaction with allyl chloride. After
work-up the desired product was obtained with a good
quality in 81% yield. However, when we used the same
procedure for the preparation of 3f a 60:40 mixture of
the para- and ortho-alkylated product was obtained, see
1
Purity \98% by GC. H-NMR: l 7.3 (5H, m, aryl-H);
6.53 (1H, CHꢀCH2); 5.34 (2H, CHꢀCH2).
4.3. Synthesis of 1b
A 2.4 g of sodium (104 mmol), cut in small pieces,
were added to 100 ml ethanol. After all sodium was
Scheme 5.

P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
71
dissolved, para-thiocresol (12.4 g, 100 mmol) were
added as a solid which rapidly dissolved. After 30 min
stirring at r.t., 6.7 ml (100 mmol) 2-chloroethanol were
added and the reaction mixture was heated to reflux for
3.5 h. During this step the reaction mixture went first
opaque and then a white precipitate formed. The reac-
tion mixture was cooled to r.t. and 60 ml fuming
hydrogen chloride were added dropwise over a period
of 10 min. The resulting reaction mixture was stirred
for 15 h at r.t. and then heated to reflux for 4.5 h. The
reaction mixture was then cooled to r.t. and diluted
with 100 ml water. This mixture was extracted with
tert-butyl methyl ether (7×40 ml). The combined or-
ganic phases were washed with 80 ml water, 80 ml of a
10% aqueous solution of NaOH, and 80 ml of a
saturated aqueous solution of sodium chloride (ca.
20%), successively, and dried over sodium sulfate. After
the solvents were removed in vacuum, the crude inter-
mediate product was obtained as a yellow liquid in a
quantitative yield (18.7 g). This product was used in the
following steps without further purification.
purple solid was washed with methanol (3×10 ml),
and dried in vacuum. This reaction procedure yielded
1
4.3 g pure product (78% yield). H-NMR: l 17.66 (s, 1,
carbene-H); 7.4–7.1 (m, 5, SPh); 2.8 (m, 6,
P(CHMe2)3); 1.2 (m, 36, P(CHMe2)3). 31P-NMR: l
42.3.
4.5. Synthesis of 2b
The reaction was performed in a similar way as
described for 2a. Using para-tolyl vinyl sulfide (ligand
1b), the desired product was obtained in 72% yield.
1H-NMR: l 17.62 (s, 1, carbene-H); 7.24 and 7.09 (dd,
4, SPh); 2.8 (m, 6, P(CHMe2)3); 2.28 (s, 3, para-Me);
1.2 (m, 36, P(CHMe2)3). 31P-NMR: l 42.2
4.6. Synthesis of 3a
A total of 400 ml butyllithium (2.5 M sol. in toluene,
1 mol) was added dropwise over a period of 2.5 h to a
cooled solution of 2-methylpyridine (93.13 g, 1 mol) in
320 ml THF of 0°C. The temperature of the reaction
mixture was kept between 0 and 5°C during the addi-
tion of the butyllithium solution. After addition, the
clear orange reaction mixture was stirred for an addi-
tional 30 min at 0°C. This orange reaction mixture was
kept at 0°C and added dropwise over a period of 30
min to a cooled solution of allyl chloride (76.53 g, 1
mol) in 320 ml THF. During the addition of the
organolithium intermediate, the temperature was kept
between 0 and 5°C. After addition, the final reaction
mixture was stirred for an additional 30 min. A total of
80 ml of isopropanol was added (to quench the remain-
ing organolithium species) keeping the reaction mixture
between 0 and 5°C. The reaction mixture, a yellow
suspension, was warmed to r.t. and 320 ml of a satu-
rated sodium chloride solution in water (ca. 20 wt%)
were added. The resulting suspension was filtered over
Celite®, and the filtercake was extracted with tert-butyl
methyl ether (3×200 ml). The organic phase was sepa-
rated from the combined reaction mixture with the
ethereal washings and dried over sodium sulfate. The
organic phase was concentrated in vacuo giving the
crude product. The product was purified by distillation
(42–50°C, 0.015 mbar), and obtained as a colorless
A total of 18.7 g of crude intermediate were added to
a 100 ml solution in ethanol containing 11.2 g of
potassium hydroxide. The resulting reaction mixture
was heated to reflux for 16 h, and a precipitate formed
upon heating. After cooling the reaction mixture to r.t.,
it was filtered, and the filtercake was extracted with
ethanol (3×30 ml). The combined ethanolic solutions
were concentrated in vacuum to give the crude product
as a yellow oil. After addition of some polymerization
inhibitor [17], the product was purified by distillation
(90–95°C, 18 mbar) giving the product as a colorless
1
liquid in 53% yield. Purity \98% by GC. H-NMR: l
7.28 and 7.13 (4H, dd, aryl-H); 6.50 (1H, CHꢀCH2);
5.26 (2H, CHꢀCH2); 2.33 (3H, para-CH3).
4.4. Synthesis of 2a
A total of 2.5 g [RuCl2(COD)] were suspended in 90
ml isopropanol (degassed to remove oxygen) 2.5 ml
triethylamine and 3.6 ml PiPr3 were added, and then the
reaction mixture was refluxed under argon for 3 h
resulting in a clear, dark red solution. This red solution
was cooled to −25°C and a light orange suspension
formed. 17.8 ml of a 1.0 M HCl solution in diethyl
ether were added in one portion (temperature raised to
−17°C), and the reaction mixture was stirred for an
additional 5 min keeping the temperature between −20
to −15°C. At −20°C 2.1 ml 1-hexyne were added in
one portion (color became more brown). The reaction
mixture was stirred for 1.5 h keeping the temperature
between −20 and −15°C to yield a purple suspension.
A total of 4.7 ml phenyl vinyl sulfide was then added
and the temperature was raised to r.t. At this tempera-
ture the reaction mixture was stirred for an additional
30 min. The purple suspension was filtered and the fine
1
liquid in 81% yield (108 g). Purity: \98% (GC). H-
NMR: l 8.50, 7.54 and 7.07 (4, py-H); 5.84 (1,
CH2CH2CHꢀCH2); 4.97 (2, CH2CH2CHꢀCH2); 2.85
(CH2CH2CHꢀCH2); 2.44 (2, CH2CH2CHꢀCH2).
4.7. Synthesis of 3b
The reaction was performed in a similar way as
described for 3a. Starting from 2,6-dimethyl pyridine,
the product was obtained after distillation (29–31°C,
0.013 mbar) in 80% yield with a purity of \97% by

72
P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
GC. 1H-NMR: l 7.44 and 6.90 (3, py-H); 5.82 (1,
CH2CH2CHꢀCH2); 4.97 (2, CH2CH2CHꢀCH2); 2.81 (2,
CH2CH2CHꢀCH2); 2.49 (3, 6-Me py); 2.41 (2,
CH2CH2CHꢀCH2).
keeping the reaction mixture between 0 and 5°C. The
reaction mixture, a yellow suspension, was warmed to
r.t. and 150 ml of a saturated sodium chloride solution
in water (ca. 20 wt%) were added. The resulting suspen-
sion was filtered over Celite®, and the organic phase
was separated. The filtercake was extracted with tert-
butyl methyl ether (3×100 ml). The combined organic
phase was dried over sodium sulfate. The organic phase
was concentrated in vacuo giving the crude product.
The product was purified by distillation (42–45°C, 0.02
mbar), and obtained as a colorless liquid in 79% yield
(41 g). Purity: \95% by GC (contains ca. 3% sym-col-
4.8. Synthesis of 3c
The reaction was performed in a similar way as
described for 3a, however, the lithiation and alkylation
with allylbromide were performed in diethyl ether at
−70°C. Starting from 2,5-dimethylpyridine, the
product was obtained after flash distillation in 65%
1
yield with a purity of \95% by GC. H-NMR: l 8.23,
lidine). 1H-NMR:
l
6.75 (2, py-H); 5.84 (1,
7.26 and 6.90 (3, py-H); 5.74 (1, CH2CH2CHꢀCH2);
4.88 (2, CH2CH2CHꢀCH2); 2.70 (2, CH2CH2CHꢀCH2);
2.38 (2, CH2CH2CHꢀCH2); 2.16 (3, 5-Me py).
CH2CH2CHꢀCH2); 4.99 (2, CH2CH2CHꢀCH2); 2.77 (2,
CH2CH2CHꢀCH2); 2.45 (2, CH2CH2CHꢀCH2); 2.45 (3,
6-CH3 py); 2.24 (3, 4-CH3 py).
4.9. Synthesis of 3d
4.12. Synthesis of 4a
The reaction was performed in a similar way as
described for 3c. Starting with 2,4-dimethyl pyridine,
the product was obtained in 72% yield with a purity of
\95% by GC. 1H-NMR: l 8.33, 6.92 and 6.88 (3,
py-H); 5.82 (1, CH2CH2CHꢀCH2); 5.00 (2,
CH2CH2CHꢀCH2); 2.79 (2, CH2CH2CHꢀCH2); 2.41 (2,
CH2CH2CHꢀCH2); 2.27 (3, 4-Me py).
A total of 4.4 g [RuCl2(COD)] were suspended in 150
ml isopropanol, degassed to remove oxygen, 4.4 ml
triethylamine and 6.4 ml PiPr3 were then added. The
reaction mixture was refluxed under argon for 3 h
resulting in a clear, dark-red solution. This red solution
was cooled to −20°C to yield a light-orange suspen-
sion. A total of 31.5 ml of a 1.0 M HCl solution in
diethyl ether were added over a period of 15 min, and
the reaction mixture was stirred for an additional 15
min keeping the temperature between −20 and −
15°C. A total of 6.2 ml of 1-hexyne were added in one
portion at −20°C (color changed to brown). The
reaction mixture was stirred for 1.5 h keeping the
temperature between −20 and −15°C leading to a
4.10. Synthesis of 3e
The reaction was performed in a similar way as
described for 3c. Starting with 2,3-dimethyl pyridine,
the product was obtained in 62% yield with a purity of
\95% by GC. 1H-NMR: l 8.25, 7.27 and 6.90 (3,
py-H); 5.80 (1, CH2CH2CHꢀCH2); 4.88 (2,
CH2CH2CHꢀCH2); 2.76 (2, CH2CH2CHꢀCH2); 2.36 (2,
CH2CH2CHꢀCH2); 2.18 (3, 3-Me py).
purple suspension.
A
total of 2.7
g
2-(3-bu-
tenyl)pyridine were added at −15°C. The temperature
was slowly raised to r.t. and the reaction mixture was
stirred for an additional 2 h. The brown colored sus-
pension was concentrated in vacuum leaving a brown-
ish crude product. Stirring the crude product with 20
ml chilled methanol gave a brown suspension. This
suspension was filtered and a fine brown powder was
obtained as the product. This product was washed with
chilled methanol (3×10 ml), and dried in vacuum. This
procedure yielded 4.8 g of pure product (yield 68%).
4.11. Synthesis of 3f
A total of 200 ml butyllithium (1.6 M solution in
hexane, 0.32 mol) was added dropwise over a period of
80 min to a cooled solution of 2,4,6-trimethylpyridine
(38.8 g, 0.32 mol) in 250 ml diethyl ether at 0°C. The
temperature of the reaction mixture was kept between 0
and 5°C during the addition of the butyllithium solu-
tion. After addition, the clear orange solution was
stirred for an additional hour at 0°C.
This orange reaction mixture was kept at 0°C and
added over a period of 15 min to a cooled solution of
allyl chloride (25.0 g, 0.32 mol) in 100 ml diethyl ether
of 0°C. During the addition of the pyridylmethyl
lithium reaction mixture, the temperature was kept
between 0 and 5°C. After addition, the final reaction
mixture was stirred for an additional hour at this
temperature. A total of 30 ml of isopropanol were
added (to quench the remaining alkyllithium species)
3
1H-NMR: l 19.41 (dt, 1, carbene-H, JPH=11.7 Hz);
8.70, 7.58, 7.19 (4, py-H); 3.60 (m, 2, ꢀCHCH2CH2); 2.5
(m, 5, ꢀCHCH2CH2 and P(CHMe2)3); 1.4 (m, 18,
P(CHMe2)3). 31P-NMR: l 44.3.
4.13. Synthesis of 4b
The reaction was performed in a similar way as
described for 4a. Using 2-(3-butenyl)-6-methylpyridine
(ligand 3b) the desired product was obtained as a
1
light-brown powder in 65% yield. H-NMR: l 19.77
3
(dt, 1, carbene-H, JPH=13.0 Hz); 7.50, 7.04 (3, py-H);

P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
73
3.40 (m, 2, ꢀCHCH2CH2); 3.22 (s, 3, 6-methyl); 2.93
(m, 2, ꢀCHCH2CH2); 2.65 (m, 3, P(CHMe2)3); 1.4 (m,
18, P(CHMe2)3). 31P-NMR: l 42.5.
reflections (Rint=0.063), 3116 were considered ob-
served [I\2|(I)], final R=0.0341, wR2=0.0476 (ob-
served data), goodness of fit 0.698, residual density
−3
,
max./min. 0.341 (near the Ru atom) /−0.340 e A
.
4.14. Synthesis of 4c
Absorption coefficient v=0.802 mm−1; no correction
for absorption was applied. Intensity data were col-
lected at r.t. on a Stoe image plate diffraction system
using Mo Ka graphite monochromated radiation. Im-
age plate distance 70 mm, ƒ scans 0–200°, step Dƒ=
The reaction was performed in a similar way as
described for 4a. Using 2-(3-butenyl)-5-methylpyridine
(ligand 3c) the desired product was obtained as a brown
1
,
powder in 61% yield. H-NMR: l 19.44 (dt, 1, carbene-
1°, 2q range 3.27–52.1°, dmax–dmin=12.45–0.8 1 A.
3
H, JPH=11.9 Hz); 8.47, 7.40, 7.08 (3, py-H); 3.53 (m,
The structure was solved by direct methods using the
program SHELXS-97 [19]. The refinement and all further
calculations were carried out using SHELXL-97 [20]. All
of the H-atoms were included in calculated positions
and treated as riding atoms using SHELXL-97 default
parameters. The non-H atoms were refined anisotropi-
cally, using weighted full-matrix least-squares on F2.
2, ꢀCHCH2CH2); 2.50 (m, 3, P(CHMe2)3); 2.39 (m, 2,
ꢀCHCH2CH2); 2.26 (s, 3, 5-methyl); 1.4 (m, 18,
P(CHMe2)3). 31P-NMR: l 44.0.
4.15. Synthesis of 4d
The reaction was performed in a similar way as
described for 4a. Using 2-(3-butenyl)-4-methylpyridine
(ligand 3d) the desired product was obtained as a
4.19. Crystal structure of 4a
1
brown powder in 65% yield. H-NMR: l 19.48 (dt, 1,
Suitable crystals of 4a were grown from a hot toluene
solution as dark red blocks. C17H30Cl2NPRu, triclinic,
3
carbene-H, JPH=11.8 Hz); 8.57, 7.24, 7.07 (3, py-H);
(
3.53 (m, 2, ꢀCHCH2CH2); 2.60 (m, 3, P(CHMe2)3);
2.46 (m, 2, ꢀCHCH2CH2); 2.36 (s, 3, 4-methyl); 1.4 (m,
18, P(CHMe2)3). 31P-NMR: l 42.8.
space group, P1 a=8.2949(5), b=8.8564(5), c=
,
15.7133(8) A, h=92.908(4), i=102.328(6), k=
114.821(5)°, Z=2, calc=1.483 6805
D
g
cm−3
,
reflections collected, 3754 independent reflections
(Rint=0.0249), 3412 were considered observed [I\
2|(I)], final R=0.0249, wR2=0.0567 (observed data),
4.16. Synthesis of 4e
The reaction was performed in a similar way as
described for 4a. Using 2-(3-butenyl)-3-methylpyridine
(ligand 3e) the desired product was obtained as a brown
goodness of fit 1.101, residual density max./min. 0.373/
−3
,
−0.379
e
A
. Absorption coefficient v=1.116
mm−1; no correction for absorption was applied. In-
tensity data were collected at r.t. on a Stoe AED2
4-circle diffractometer using Mo Ka graphite
monochromated radiation, using 2q/ꢀ scans in the
range 4–51° in 2q. The structure was solved by direct
methods using the program SHELXS-97 [19]. The refine-
ment and all further calculations were carried out using
SHELXL-97 [20]. The H-atoms of the organic ligand
were located from difference maps and refined isotropi-
cally. The H-atoms of the tris(isopropyl)phosphine lig-
and were included in calculated positions and treated as
riding atoms using SHELXL-97 default parameters. The
non-H atoms were refined anisotropically, using
weighted full-matrix least-squares on F2.
1
powder in 60% yield. H-NMR: l 19.45 (dt, 1, carbene-
3
H, JPH=11.5 Hz); 8.58, 7.44, 7.08 (3, py-H); 3.53 (m,
2, ꢀCHCH2CH2); 2.97 (m, 2, ꢀCHCH2CH2); 2.55 (m, 3,
P(CHMe2)3); 2.34 (s, 3, 3-methyl); 1.4 (m, 18,
P(CHMe2)3). 31P-NMR: l 44.6.
4.17. Synthesis of 4f
The reaction was performed in a similar way as
described for 4a. Using 2-(3-butenyl)-5-methylpyridine
(ligand 3f) the desired product was obtained as a brown
1
powder in 55% yield. H-NMR: l 19.75 (dt, 1, carbene-
3
H, JPH=13.1 Hz); 6.85, 6.82 (2s, 2, py-H); 3.29 (m, 2,
ꢀCHCH2CH2); 3.11 (s, 3, 6-methyl); 2.86 (m, 2,
ꢀCHCH2CH2); 2.61 (m, 3, P(CHMe2)3); 2.24 (s, 3,
4-methyl); 1.4 (m, 18, P(CHMe2)3). 31P-NMR: l 42.3
5. Supplementary material
4.18. Crystal structure of 2a
The crystallographic CIF files have been deposited
with the Cambridge Crystallographic Data Center (de-
position numbers: CCDC 138602 (2a); CCDC 138603
(4a)). Copies of this information may be obtained free
of charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
Suitable crystals of 2a were grown from a hot toluene
solution as very small dark-red rods. C25H48Cl2P2RuS,
(
triclinic, space group, P1, a=8.7596(7), b=9.7255(9),
,
c=18.7729(18) A, h=76.75(1), i=81.61(1), k=
3
,
75.19(1)°, V=1498.5(2) A , Z=2, Dcalc=1.362 g
cm−3, 11 668 reflections collected, 5358 independent

74
P.A. 6an der Schaaf et al. / Journal of Organometallic Chemistry 606 (2000) 65–74
rain, R.H. Grubbs, Organometallics 16 (1997) 4001. (d) C.
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