Novel ruthenium(II)2 carboxylates as catalysts for alkene metathesis

Article abstract of DOI:10.1002/1521-3765(20010702)7:13<2842::AID-CHEM2842>3.0.CO;2-O

The reactions of [Ru(=CHR)Cl₂(PCy₃)₂] (1: R = Ph; 1a: R = -CH=CPh₂) with silver salts of carboxylic acids afforded new dimeric complexes of the general formula [Ru₂(=CHR)₂(R′CO₂)₂ (μ-R′CO₂)₂(PCy₃)₂ (-H₂O)] (2: R = Ph, R′ = CF₃; 3: R = Ph, R′ = C₂F₅; 4: R = -CH=CPh₂, R′ = CF₃; 5: R = Ph, R′ = C₆F₅; 6: R = -CH=CPh₂, R′ = C₆F₅; 7: R = -CH=CPh₂, R′ = CCl₃) in good yields. With R′ = CF₃, C₂F₅ or CCl₃ these complexes are active catalysts for metathesis of acyclic alkenes, including unsaturated fatty acid esters, as well as for ring closing metathesis. The reactivity of these complexes with bases and weak donor solvents has been studied and their half-life times in several media were determined.

Full text of DOI:10.1002/1521-3765(20010702)7:13<2842::AID-CHEM2842>3.0.CO;2-O

FULL PAPER
Novel Ruthenium(ii)2 Carboxylates as Catalysts for Alkene Metathesis
Wlodzimierz Buchowicz,[a] Florent Ingold,[a] Johannes C. Mol,*[a] Martin Lutz,[b] and
Anthony L. Spek[b]
ˆ
Abstract: The reactions of [Ru-
R' ˆ C6F5; 6: R ˆ CH CPh2, R' ˆ C6F5;
complexes are active catalysts for meta-
thesis of acyclic alkenes, including un-
saturated fatty acid esters, as well as for
ring closing metathesis. The reactivity of
these complexes with bases and weak
donor solvents has been studied and
their half-life times in several media
were determined.
ˆ
ˆ
( CHR)Cl2(PCy3)2] (1: R ˆ Ph; 1a: R ˆ
7: R ˆ -CH CPh2, R' ˆ CCl3) in good
ˆ
CH CPh2) with silver salts of carboxylic
yields. With R' ˆ CF3, C2F5 or CCl3 these
acids afforded new dimeric complexes of
ˆ
the general formula [Ru2( CHR)2-
Keywords: alkenes ´ homogeneous
catalysis ´ metathesis ´ ruthenium
carbenes
(R'CO2)2(m-R'CO2)2(PCy3)2(m-H2O)] (2:
R ˆ Ph, R' ˆ CF3; 3: R ˆ Ph, R' ˆ C2F5;
ˆ
4: R ˆ CH CPh2, R' ˆ CF3; 5: R ˆ Ph,
Since the discovery of well-defined, single-component and
efficient metal-carbene catalysts by Schrock and co-work-
ers[2±4] and by Grubbs and co-workers,[5±7] the metathesis
reaction can be conveniently carried out in a chemical
laboratory at reasonable cost. In particular, the ruthenium
Introduction
Alkene metathesis is a powerful method for the cleavage and
formation of carbon ± carbon double bonds.[1] Various types of
olefins, such as acyclic olefins [Eq. (1), R1 and R2 ˆ alkyl or
H], diolefins [e.g. Eq. (2): ring-closing metathesis, RCM], and
cycloolefins [Eq. (3): ring-opening metathesis polymerization,
ROMP], undergo metathesis through contact with a suitable
catalyst resulting in a wide variety of possible products.
[6, 7]
ˆ
carbene complex [Ru( CHPh)Cl2(PCy3)2] (1)
became a
reagent of choice for numerous applications in organic
synthesis.[8±10] So far, attempts to improve the catalytic
performance of 1 have focused on replacing at least one of
the phosphines by nucleophilic N-heterocyclic carbene li-
gands.[11±18] Attempts to modify the anionic ligands in ruthe-
nium-carbene complexes of the type of 1 are less com-
mon.[19±22]
2 R1CH=CHR2
R1CH=CHR1 R2CH=CHR2
+
(1)
In our group we sought to substitute the chloride ligands in
1 with other anionic groups, such as carboxylates, as a possible
route for the development of an immobilised metathesis
catalyst. In a preliminary communication the synthesis,
properties and metathesis activity of a dimeric complex,
ˆ
(2)
+
CH2=CH2
namely
[Ru2( CHPh)2(CF3CO2)2(m-CF3CO2)2(PCy3)2(m-
H2O)] (2), are described.[23] The synthesis of this new type
of organometallic dimers has now been extended to other
carboxylates (see Scheme 1) and their metathesis activity has
been investigated.
n
(3)
n
represents a hydrocarbon chain with or without a heteroatom
Results and Discussion
[a] Dr. J. C. Mol, Dr. W. Buchowicz, Dr. F. Ingold
Institute of Molecular Chemistry, Faculty of Science
Universiteit van Amsterdam
Synthesis of dimers: All reactions of dimer formation
(Scheme 1) were performed at temperatures ranging from
308C to 08C using hexane as a solvent for 1 or 1a and THF
for the silver salt. Complexes 2 ± 7 were isolated as green (R ˆ
Nieuwe Achtergracht 166, 1018 WV Amsterdam (The Netherlands)
Fax : (‡31) 20-5256456
E-mail: jcmol@anorg.chem.uva.nl
[b] Dr. M. Lutz, Dr. A. L. Spek
ˆ
Ph) or yellow (R ˆ -CH CPh2) solids by crystallisation, after
Bijvoet Center for Biomolecular Research
Department of Crystal and Structural Chemistry
Utrecht University, Padualaan 8, 3584 CH Utrecht (The Netherlands)
filtering off AgCl and [AgClPCy3].[23] Complex 1 also reacts
with salts such as AgO2CCH3, TlO2CCH3 or AgO3SR (R ˆ
2842
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Chem. Eur. J. 2001, 7, No. 13

2842±2847
R'
C
O
O
O
'R
H
C
C
R'
H
PCy3
Ru
O
O
O
Cl
Cl
H
O
H
CHR
4 R'CO2Ag
C
Ru
Ru
C
+
2
- AgCl
- AgClPCy3
R
R
O
O
PCy3
PCy3
Cy3P
C
1: R = Ph
1a: R = -CH=CPh2
R'
2: R = Ph, R' = CF3
3: R = Ph, R' = C2F5
4: R = -CH=CPh2, R' = CF3
5: R = Ph, R' = C6F5
6: R = -CH=CPh2, R' = C6F5
7: R = -CH=CPh2, R' = CCl3
Scheme 1. Synthesis of complexes 2 ± 7: Hexane, THF, 30 to 08C.
Figure 1. Displacement ellipsoid plot (30% probability level) of com-
pound 3 in the crystal. The hexane solvent molecule and the hydrogen
atoms bound to carbons are omitted for clarity. Only one conformation of
the disordered pentafluoropropionate ion at O31 is displayed.
CF3, C6H4Me). Despite several attempts with these reagents
we could not isolate any organometallic complex under
similar experimental conditions. We conclude that the pKa of
the corresponding acid must lie between 7 and ‡3 to
stabilise the carbene ligand.
Table 1. Selected bond lengths [Š] and angles [8] for 3 with estimated
standard deviation in parentheses.
The most noticeable spectroscopic feature for complexes
2 ± 7 is the presence of the carbene proton resonance as a
doublet (for R ˆ Ph) in the range of d ˆ 20.6 ± 21.1 (3JPH ˆ 5 ±
bond length
Ru1 C1
Ru1 P1
Ru1 O1
Ru1 O31
Ru1 O51
Ru1 O62
1.852(4)
2.3619(11)
2.184(3)
2.103(3)
2.248(3)
2.075(3)
Ru2 C2
Ru2 P2
Ru2 O1
Ru2 O41
Ru2 O52
Ru2 O61
1.864(4)
2.3383(11)
2.227(3)
2.088(3)
2.089(2)
2.276(3)
ˆ
7 Hz), or as a doublet of doublets (for R ˆ -CH CPh2) in the
3
range of d ˆ 19.7 ± 20.2 (3JPH ˆ 5 ± 7 Hz, JHH ˆ 12 Hz). The
hydrogen atoms of the bridging water molecule are observed
as a singlet in the range of d ˆ 11.8 ± 12.6. 31P NMR spectra of
these complexes consist of only one singlet (d ˆ 43.2 ± 46.6),
while 19F NMR spectra contain two sets of peaks in accord
with the presence of two different carboxylate ligands.
bond angle
C1-Ru1-P1
C1-Ru1-O1
P1-Ru1-O1
C1-Ru1-O31
C1-Ru1-O51
C1-Ru1-O62
O31-Ru1-O51
O62-Ru1-O51
Ru1-O1-Ru2
89.28(12)
100.17(14)
170.26(8)
86.76(15)
169.59(15)
94.34(15)
84.62(11)
94.66(11)
123.05(12)
C2-Ru2-P2
C2-Ru2-O1
P2-Ru2-O1
C2-Ru2-O41
C2-Ru2-O52
C2-Ru2-O61
O41-Ru2-O61
O61-Ru2-O52
91.16(13)
93.12 (14)
175.56(7)
100.15(14)
82.98(14)
170.28(14)
82.96(10)
94.70(10)
The IR spectra of complexes 3 ± 7 in KBr pellets have the
characteristic vibrations of the tricyclohexylphosphine, the
carboxylic group and the phenyl ring of the carbene moiety.
The solid state structure, with bridging coordination mode of
the carboxylates, was destroyed in KBr, because only one
1
unidentate carboxylate stretch is observed at 1651 ± 1696cm
for the nas(CO2) and 1381 ± 1202cm for the ns(CO2).
1
The mass spectra (FD, MALDI-TOF) contain a molecular
peak only in the case of complex 4; the next fragment
observed in its FD mass spectrum is formed by abstraction of
the water molecule and two carboxylic groups (similar to the
previously reported MALDI-TOF MS of 2). For complexes 5
2 CH3(CH2)7CH=CH(CH2)7COOCH3 (8)
(4)
‡
CH3(CH2)7CH=CH(CH2)7CH3 + CH3OOC(CH2)7CH=CH(CH2)7COOCH3
and 6 [M H2O] fragments were detected. Complex 5 shows
also fragmentation involving loss of the carbene ligand that is
not observed with the other dimers.
The structure of dimer 3 was unambiguously confirmed by
X-ray crystallography (Figure 1, Table 1). The molecular
structure of 3 closely resembles that of 2.[23] Ruthenium
Within the experimental error, the most active among our
new compounds, that is, 3 and 7, show the same activity as 1.
The vinylalkylidene carbene complex 4 is slightly less efficient
than the corresponding benzylidene carbene complex 2. This
can be attributed to a slower initiation step of the bulkier
carbene 4.[7] No correlation is found between the pKa of the
corresponding acid and the conversion obtained with com-
plexes 2 ± 7 since both 3 and 7 display higher activity than 2.
We conclude that both electronic and steric properties of R'
influence the metathesis activity.
ˆ
coordination is distorted octahedral with the two Ru C(car-
bene) bond lengths 1.852(4) Š and 1.864(4) Š.
Metathesis activity: Table 2 summarises the catalytic activity
of dimers 3 ± 7 for the metathesis of internal alkenes, including
unsaturated fatty acid esters, such as methyl oleate (8)
[Eq. (4)]. For comparison, data for the starting compound 1
and the previously described dimer 2 are also shown.
Chem. Eur. J. 2001, 7, No. 13
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2843

J. C. Mol et al.
FULL PAPER
Table 2. Activity of Ru carbenes for the metathesis of alkenes.
Catalyst Substrate
Reaction time [h] Conversion [%]
(CH2)7CH=CH(CH2)7CH3
(CH2)7
(CH2)7
CH(CH2)7CH3
HC
HC
+
O
24[23]
36[23]
20[23]
33
O
2
2
2
3
3
3
4
4
5
6
7
1
1
1
trans-4-decene
4
4
4
4
CH(CH2)7CH3
methyl oleate[a]
methyl elaidate[b]
trans-4-decene
methyl oleate
(CH2)7CH=CH(CH2)7CH3
(6)
10
11
4
40
diethyl diallylmalonate[c]
trans-4-decene
methyl oleate
trans-4-decene
trans-4-decene
trans-4-decene
trans-4-decene
methyl oleate
0.5
4
30
19
An associative mechanism of alkene metathesis is not possible
with dimers 2 ± 7 because the ruthenium centre is already six-
coordinated. The first elemental reaction must be a dissoci-
ation of one ligand: the bridging coordination mode of the
carboxylate is easily broken as shown in Scheme 2. This
4
28
24
0
24
4
4
4
4
0
33
36[37]
40[37]
36[37]
methyl elaidate
General reaction conditions except for [c]: 3 mm solution in CH2Cl2, molar
ratio substrate:catalyst ˆ 550:1, 208C. [a] Methyl cis-9-octadecenoate.
[b] Methyl trans-9-octadecenoate. [c] 5 mm solution in CH2Cl2, molar ratio
substrate:catalyst ˆ 20:1, 208C.
Ar
Ar
HC
Cy3P
O
O
O
O
O
HC
Cy3P
O
O
H
O
PCy3
H
O
PCy3
Ru
Ru
Ar
Ru
Ru
Ar
O
O
O
CH
H
O
H
O
CH
O
O
Complexes 5 and 6 do not generate any active species for
the metathesis of internal alkenes. The bond order of the
carboxylate in 5 and 6 is lower than in all other dimers (see
O
O
+ 2 S
O
1
Experimental Section: ns(CO2) ˆ 1654 and 1651cm for 5
1
and 6, respectively, instead of 1690 Æ 5cm for 3, 4 and 7).
Ar
O
Ar
Therefore, the oxygen atoms in C6F5CO2 are less electron
rich than in the other halogenated carboxylates R'CO2 (with
R' ˆ CF3, C2F5 and CCl3). The ruthenium centre has lower
electron density in 5 and 6 than in the other dimers and was
inert towards olefin metathesis.[24]
O
HC
S
O
HC
Cy3P
S
H
O
Cy3P
O
PCy3
Ru
Ru
Ru
S
_ H2O
O
O
O
O
CH
H
O
Ar
O
RCM of diethyl diallylmalonate (9) [Eq. (5)] in the
presence of complex 1 (molar ratio substrate:catalyst 20:1)
proceeds to 95% conversion in 30 min. Under similar
conditions complex 3 gave 30% conversion in 30 min in
CH2Cl2 and 25% conversion in benzene. The catalyst was not
longer active after 30 min. As observed earlier with complex
2, in a polar solvent such as THF the catalytic activity was
dramatically lower (5% conversion after 2 h). Both the
1H NMR spectrum and GC show that the formation of the
cyclopentene needs an initiation time, thereafter the reaction
is fast for 15 min and a maximum conversion of 30% is
reached within 30 min.
O
With S = olefin
Ar
Cy3P
H
O
O
Ar
O
Ru
O
H
O
O
O
Cy3P
H
PCy3
Ru
O
Ru
O
H
O
O
H
Ar
O
O
Olefin + ruthenium carbene
EtO2C
CO2Et
EtO2C
CO2Et
Scheme 2. Proposed mechanism of the reaction of complexes 2 ± 4 and 7
with olefins or weak donor ligands.
-C2H4
(5)
9
reaction generates a water-bridged complex, which may form
a ruthenium metallacycle or, as observed in experiments with
donor solvents (see below), the water is removed from the
metal to form a 16-electron, five-coordinate (monomeric)
complex. Intermediates of this type have been postulated by
Grubbs and co-workers in the catalytic cycle involving
complex 1.[20] Moreover, a ruthenium carbene complex with
one tricyclophosphine ligand was isolated from a reaction of 1
with a substituted cyclobutene.[25]
To demonstrate the usefulness of our catalyst for the
construction of large rings, RCM of oleon (10) using 3 as
catalyst was examined. This reaction afforded a 1.2:1 trans/cis
mixture of 9-cycloheptadecen-1-one (11) [Eq. (6)]. The cis
isomer of 11 is civetone, an important base material in the
perfume industry.
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Chem. Eur. J. 2001, 7, No. 13

Alkene Metathesis
2842±2847
Reactions of 3 and 5 with weak s donor ligands: In the course
of our studies of the metathesis activity we became interested
in the stability of these dimers towards bases and weak donor
solvents (Table 3). In contrast to 1,[7] dimer 3 is not stable in a
these complexes are highly active for the metathesis of linear
olefins and for ring-closing metathesis. Reactions of dimers 2,
3 and 5 with weak donor ligands were also studied and were
found to follow the same scheme as the olefins.
Experimental Section
Table 3. Half-life time of complexes 2, 3 and 5 in selected donor solvents at
208C.
General aspects: All manipulations were carried out under an atmosphere
of purified nitrogen using standard Schlenk techniques. All solvents were
purified by standard procedures prior to use (hexane, THF and DME were
distilled from sodium/benzophenone). Compound 1 was prepared accord-
ing to the literature;[7] compound 1a was synthesised from 1 and 1,1-
diphenyl-1,3-butadiene[26] by a modified literature procedure.[7] CF3CO2Ag
(Merck) and C2F5CO2Ag (Aldrich) were used as received; C6F5CO2Ag[27]
and CCl3CO2Ag[28] were prepared from the corresponding acid and AgNO3
according to the literature. Dimer 2 was prepared as described earlier.[23]
Alkenes (Fluka) and diethyl diallylmalonate (Aldrich) were purified by
passing through activated alumina and distillation. NMR spectra were
acquired using a Bruker AMX-300 spectrometer at room temperature.
1
Complex
Solvent
Half-life time [h]
Concentration [mmolL
]
2
2
2
3
3
3
3
3
5
5
Py
CH2Cl2
THF
< 1
7
120
< 1
< 1
36
216
100
9
1.5
1.5
2.3
3.4
1.9
3.1
0.8
0.06
1.3
1.2
Py
CHCl3
MeOH
Et2O
THF
CH2Cl2
DME
9
Mass spectra were measured with
spectrometer.
a JEOL JMS SX/SX102A mass
ˆ
[Ru2( CHPh)2(C2F5CO2)2(m-C2F5CO2)2(PCy3)2(m-H2O)] (3): A solution of
C2F5CO2Ag (231.4 mg, 0.854 mmol) in THF (7 mL) was added to a solution
of 1 (346.8 mg, 0.412 mmol) in hexane (180 mL) at 308C in 20 min.
Formation of a white precipitate and a change of colour from purple to
light-green followed. The mixture was stirred for another 60 min at 208C
and then filtered. The filtrate was evaporated to dryness to yield a green
solid. This solid was extracted with hexane (3 Â 5 mL) at 788C to give a
green solution and an insoluble residue. This solution was reduced in
volume to 5 mL and placed at 808C overnight. Green crystals of 3 were
formed which were separated from the mother liquor at 788C and dried
protic solvent such as methanol and has a half-life time of 36 h
at 208C. Pyridine reacted as well with complex 3 to form a
neutral species with the phosphine and the carboxylate
coordinated to the ruthenium centre. The carbene ligand
was substituted by pyridine and a yellow crystalline product
was isolated by slow diffusion of hexane into the toluene
solution. A bidentate organic molecule (1,2-dimethoxyethane,
DME) also substitutes the water molecule in complex 5. The
1H NMR spectrum of the resulting material showed that the
carbene and the water ligands were removed from the
ruthenium centre. Nonequivalent phosphorous atoms were
found in the corresponding 31P NMR spectrum; a small
1
under vacuum for several hours (202.9 mg, 57%). H NMR (CD2Cl2): d ˆ
3
20.61 (d, 3JPH ˆ 5.1 Hz, Ru CH), 11.84 (s, H2O), 8.08 (d, JHH ˆ 8.1 Hz, o-H
ˆ
of Ph), 7.75 (t, 3JHH ˆ 7.3 Hz, p-H of Ph), 7.41 (t, 3JHH ˆ 7.7 Hz, m-H of Ph),
2.02 ± 0.86 (m, PCy3 and C6H14); 31P NMR (C6D6): d ˆ43.52 (s); 19F NMR
(CD2Cl2): d ˆ 80.67 (s), 81.64 (s), 116.49 (s), 116.54 (s), 118.30 (s);
IR (KBr): nÄ ˆ 3047 vw (CH), 3007 vw (CH), 2932 w (CH2), 2854 w (CH2),
1690 vs (CO2)a, 1448 m (CH2), 1266 m, 1202 s (CO2)s, 1147 s, 726 m (CF3),
515 cm w; FD-MS: m/z (%): 1390 (60), 668 (100), 280 (5) [PCy3] ;
elemental analysis calcd (%) for C62H80F20O9P2Ru2 Â C6H14 (1698.5): C
48.1, H 5.57; found: C 48.9, H 5.79.[29]
2
coupling constant JPP ˆ 46 Hz suggests a cis geometry at the
1
‡
ruthenium atom. Complex 3 was stable for days in a mixture
of hexane/THF (26:1) or hexane/Et2O (25:1). Fast decom-
position of the carbene ligand was observed in CHCl3 (see
Table 3).
ˆ
ˆ
[Ru2( CH-CH CPh2)2(CF3CO2)2(m-CF3CO2)2(PCy3)2(m-H2O)] (4): Com-
pound 4 was obtained in a similar way as described for 3 from 1a (132.5 mg,
0.143 mmol) and CF3CO2Ag (63.3 mg, 0.287 mmol) at 08C. Filtration and
removal of the volatiles yielded a yellow solid (125 mg, 54%). Micro-
crystalline 4 was obtained from hexane at 788C. 1H NMR (CD2Cl2): d ˆ
The substitution of the water and the carbene ligand by
bases or weak donor solvents may follow a similar route as
shown for the alkene metathesis in Scheme 2: the weakest
ruthenium ± ligand bond is broken with formation of a vacant
site, which then becomes occupied by an electron rich atom.
3
3
ˆ
ˆ
19.75 (dd, JPH ˆ 5.7 Hz, JHH ˆ 12.3 Hz, Ru CH-CH CPh2), 11.79 (s,
3
3
ˆ
ˆ
H2O), 8.45 (d, JHH ˆ 13.2 Hz, Ru CH-CH CPh2), 7.70 (d, JHH ˆ 7.5 Hz),
7.55 ± 7.45 (m), 7.37 ± 7.27 (m), all Ph, 2.0 ± 0.80 (m, PCy3, C6H14); 13C NMR
2
2
ˆ
ˆ
(C6D6): d ˆ 318.0 (d, JPC ˆ 14 Hz, Ru CH-CH CPh2), 170.6 (q, JCF
ˆ
2
3
38 Hz, CO2CF3), 167.2 (q, JCF ˆ 38 Hz, CO2CF3), 142.5 (d, JPC ˆ 2.2 Hz,
1
1
ˆ
ˆ
Ru CH-CH CPh2), 114.9 (q, JCF ˆ 289 Hz, CO2CF3), 114.6 (q, JCF
ˆ
1
289 Hz, CO2CF3), 35.60 (d, JCP ˆ 21 Hz), 31.53 (s), 28.48 (t, JCP ˆ 10 Hz),
26.84 (d, JCP ˆ 5.1 Hz); 31P NMR (C6D6): d ˆ 45.72 (s); 19F NMR (CD2Cl2):
d ˆ 74.00 (s), 74.35 (s); IR (KBr): nÄ ˆ 3053 w (CH), 3007 vw (CH), 2930
Conclusion
ˆ
ˆ
New dimeric ruthenium carbene complexes of the general
s (CH2), 2852 ms (CH2), 1689 vs (CO2)a, 1512 m (C C), 1489 mw (C C),
1446 m (CH2), 1262 s (CO2)s, 1202 s, 1175 ms, 1147 ms, 1105 ms, 1025 w, 849
ˆ
formula [Ru2( CHR)2(R'CO2)2(m-R'CO2)2(PCy3)2(m-H2O)]
1
w, 801 ms (CF3), 726 m, 700 m, 515 cm w; FD-MS: m/z (%): 1617 (30)
[M] , 1373 (10) [Ru2( CH-CH CPh2)2(CF3CO2)2(PCy3)2] , 1231 (10),
1092 (11), 670 (100), 384 (17), 280 (5) [PCy3] ; MALDI-TOF MS: m/z (%):
670 (100), 281 (10) [HPCy3] ; elemental analysis calcd (%) for
have been obtained in high yields by reacting
‡
‡
ˆ
ˆ
ˆ
[Ru( CHR)Cl2(PCy3)2] with silver salts of carboxylic acids.
‡
‡
The synthetically useful scope of this reaction has been
established, showing that the carbene ligand is stable only
with strongly electron-withdrawing carboxylates. The same
procedure can be used to prepare immobilised ruthenium
carbenes.
C74H92F12O9P2Ru2 Â 0.5C6H14 (1660.6): C 55.6, H 5.96; found: C 55.6, H
5.87.
ˆ
[Ru2( CHPh)2(C6F5CO2)2(m-C6F5CO2)2(PCy3)2(m-H2O)] (5): Compound 5
was obtained in a similar way as described for 3 from 1 (155.2 mg,
0.189 mmol) and C6F5CO2Ag (129.5 mg, 0.406 mmol) at
208C. The
The new compounds were tested for their catalytic activity
for the metathesis of alkenes. With R' ˆ CF3, C2F5 or CCl3
stirring at this temperature was maintained for additional 4 h. The green
solid obtained after filtration and solvents removal was washed with hexane
Chem. Eur. J. 2001, 7, No. 13
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2845

J. C. Mol et al.
FULL PAPER
at 788C (3 Â 2 mL) and dried under vacuum for several hours (145.2 mg,
solvents were evaporated and the residue was dissolved in CD2Cl2. 31P
NMR (CD2Cl2): d ˆ 51.87 s, 48.30 (d, JPP ˆ 46 Hz), 42.91 (d, JPP ˆ 46 Hz);
1H NMR (CD2Cl2): d ˆ 7.53 (m, 1H), 7.33 (m, 2H), 7.2 (m, 2H), 2.09 ± 1.08
(m, 43H, 1PCy3/1DME).
3
85%). 1H NMR (CD2Cl2): d ˆ 21.06 (d, JPH ˆ 7.2 Hz, Ru CH), 12.96 (s,
ˆ
3
3
H2O), 8.35 (d, JHH ˆ 8.4 Hz, o-H of Ph), 7.78 (t, JHH ˆ 7.5 Hz, p-H of Ph),
3
7.52 (t, JHH ˆ 7.3 Hz, m-H of Ph), 2.0 ± 1.0 (m, PCy3), 0.8 ± 0.6 (m, C6H14);
31P NMR (C6D6): d ˆ 43.20 (s); 19F NMR (C6D6): d ˆ 141.6 (m), 144.3
(m), 155.9 (dd, 3JFF ˆ 22 Hz), 156.1 (dd, 3JFF ˆ 22 Hz), 162.7 ± 162.9
(m); IR (KBr): nÄ ˆ 3049 vw (CH), 3003 vw (CH), 2931 s (CH2),
Reaction of 3 with THF: Complex 3 (0.50 mg, 2.8 Â 10 5 mmol) was
dissolved in C6D6 (0.5 mL) and THF (1 Â 10 3 mL) was added at room
temperature. The reaction was followed by 31P NMR and 1H NMR. The
half-life of complex 3 was 100 h.
ˆ
ˆ
2854 m (CH2), 1654 vs (CO2)a, 1521 m (C C), 1496 ms (C C), 1449 mw
1
(CH2), 1383 s (CO2)s, 1264 w, 1107 m, 994 m, 933 w, 747 m, 514 cm w;
FD-MS: m/z (%): 1787 (16) [Ru2( CHPh)2(C6F5CO2)4(PCy3)2] , 1762
(24) [Ru2( CHPh)(C6F5CO2)4(PCy3)2] , 1697 (35), 1608 (30)
[Ru2(C6F5CO2)4(PCy3)2] , 1579 (29), 1350 (33), 894 (100), 667 (35), 280
‡
Reaction of 3 with Et2O: Complex 3 (7 mg, 3.9 Â 10 4 mmol) was dissolved
in C6D6 (0.5 mL) and Et2O (1 Â 10 3 mL) was added at room temperature.
After stirring this solution for nine days, the 31P NMR and 1H NMR spectra
of the reaction mixture were identical to those of the starting material, that
is no reaction took place.
ˆ
‡
ˆ
‡
‡
(92) [PCy3] ; elemental analysis calcd (%) for C78H80F20O9P2Ru2 Â
0.5C6H14 (1848.63): C 52.63, H 4.74; found: C 52.13, H 4.89.
ˆ
ˆ
[Ru2( CH-CH CPh2)2(C6F5CO2)2(m-C6F5CO2)2(PCy3)2(m-H2O)]
(6):
X-ray crystal structure of 3: Crystals of 3 suitable for an X-ray diffraction
experiment were grown by cooling a concentrated solution in n-hexane to
228C. A green crystal of 0.45 Â 0.15 Â 0.06 mm3 was mounted on a glass
capillary on a Nonius KappaCCD diffractometer at a temperature of 150 K
(rotating anode, MoKa radiation, l ˆ 0.71073 Š). The unit cell determina-
tion was performed with the program DIRAX[31] and lead to a triclinic cell
with a ˆ 13.6727(10), b ˆ 13.8344(10), c ˆ 21.3117(10) Š, a ˆ 94.061(10),
b ˆ 91.494(10), g ˆ 110.258(10)8, Vˆ 3766.8(4) Š3. It turned out that the
crystal was non-merohedrically twinned with a twofold rotation around
hkl ˆ (001) as twin operation. The intensities were evaluated separately for
the two twin domains using the program EVAL14.[32] The structure was
solved with automated Patterson methods[33] based on the non-overlapping
reflections of the first twin domain. The structure was refined against F2
with a HKLF5 twin refinement[34] based on the non-merged reflections of
Compound 6 was obtained in a similar way as described for 3 from 1a
(123.2 mg, 0.133 mmol) and C6F5CO2Ag (85.5 mg, 0.268 mmol) at 208C.
Compound 6 (84.4 mg, 63%) was isolated as yellow, micro-crystalline solid
from hexane at 808C. 1H NMR (CD2Cl2): d ˆ 20.22 (dd, JPH ˆ 7.8 Hz,
3
3
3
ˆ
ˆ
JHH ˆ 12.6 Hz, Ru CH-CH CPh2), 12.61 (s, H2O), 8.63 (d, JHH ˆ 12.6 Hz,
3
ˆ
ˆ
Ru CH-CH CPh2), 7.63 (d, JHH ˆ 6.9 Hz, Ph), 7.46 ± 7.15 (m, Ph), 1.86 ±
1.04 (m, PCy3), 0.85 ± 0.60 (m, C6H14); 13C NMR (C6D6): d ˆ 317.9 (d, 2JPC
ˆ
ˆ
ˆ
16 Hz, Ru CH-CH CPh2), 171.8 (m, CO2CF3), 167.5 (m, CO2CF3), 141.4
3
1
ˆ
ˆ
(d, JPC ˆ 2.0 Hz, Ru CH-CH CPh2), 36.03 (d, JCP ˆ 20 Hz), 31.53 (s),
28.48 (m), 26.84 (s); 31P NMR (C6D6): d ˆ 43.85 (s); 19F NMR (CD2Cl2):
d ˆ 139.5 (m), 141.5 (m), 155.0 (t, JFF ˆ 21 Hz), 155.3 (t, JFF
ˆ
19 Hz), 161.6 (m), 162.0 (m); IR (KBr): nÄ ˆ 3033 vw (CH), 3007 vw
ˆ
(CH), 2928 s (CH2), 2853 mw (CH2), 1651 vs (CO2)a, 1520 ms (C C), 1496 s
1
ˆ
both domains using the program SHELXL97[35] up to a resolution of
(C C), 1446 w (CH2), 1381 (CO2)s s, 1263 w, 1106 m, 993 s, 746 m, 533 cm
w; FD-MS: m/z (%): 1992 (37) [Ru2( CH-CH CPh2)2 (C6F5CO2)4
(PCy3)2] , 1624 (55), 996 (100), 667 (65), 280 (28) [PCy3] ; elemental
analysis calcd (%) for C94H92F20O9P2Ru2 Â C6H14 (2096.0): C 57.3, H 5.10;
found: C 57.6, H 5.19.
ˆ
ˆ
1
(sin ql)max ˆ 0.59Š
.
Formula: C62H80F20O9P2Ru2 Â 0.8C6H14
,
Fw ˆ
‡
‡
1682.28, space group P1 (No. 2), Z ˆ 2, 1 ˆ 1.483 gcm 3, m ˆ 0.54mm
.
1
Å
Non hydrogen atoms were refined freely with anisotropic displacement
parameters, hydrogen atoms were refined as rigid groups. The partially
occupied hexane solvent molecule was refined with isotropic displacement
parameters. One of the pentafluoropropanate ligands was refined with a
disorder model. The drawing, structure calculations, and checking for
higher symmetry were performed with the program PLATON.[36] The final
R values were obtained as R1 (I > 2s(I)) ˆ 0.0709 and wR2 (I > 2s(I)) ˆ
0.1482; R1 (all refl.) ˆ 0.0960 and wR2 (all refl.) ˆ 0.1654. GoF ˆ 1.138.
Crystallographic data (excluding structure factors) for structure 3 in this
paper have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-151150. Copies of the data
can be obtained, free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: ‡44 1223 336033 or e-mail: deposit@ccdc.
cam.ac.uk).
ˆ
ˆ
[Ru2( CH-CH CPh2)2(CCl3CO2)2(m-CCl3CO2)2(PCy3)2(m-H2O)]
(7):
Compound 7 was prepared in a similar way as described for 3 from 1a
(81.5 mg, 0.088 mmol) and about two equivalents of CCl3CO2Ag (50 mg,
0.18 mmol) at 308C. Stirring was continued for 2 h while the temperature
was slowly raised to 108C. Filtration and solvents removal under vacuum
yielded a yellow solid (14 mg, 40%). 1H NMR (CD2Cl2): d ˆ 20.11 (dd,
3
3
3
ˆ
ˆ
JPH ˆ 6.0 Hz, JHH ˆ 12.6 Hz, Ru CH-CH CPh2), 12.06 (s, H2O), 8.48 (d,
3
3
ˆ
ˆ
JHH ˆ 12.6 Hz, Ru CH-CH CPh2), 7.68 (d, JHH ˆ 7.8 Hz), 7.59 (d, JHH
ˆ
7.5 Hz), 7.51 (t, 3JHH ˆ 7.1 Hz), 7.42 (q, 3JHH ˆ 6.6 Hz), 7.31 ± 7.21 (m), all Ph,
2.09 ± 1.08 (m), PCy3; 31P NMR (CD2Cl2): d ˆ 46.65 (s); IR (KBr): nÄ ˆ 3039
vw (CH), 3011 vw (CH), 2928 s (CH2), 2851 m (CH2), 1683 s (CO2)a,
ˆ
ˆ
1512 mw (C C), 1489 m (C C) 1445 m (CH2), 1338 ms (CO2)s, 1262 m,
1089 m, 1028 m, 846 m, 804 m, 740 m, 679 m, 515 cm 1 w; FD-MS: m/z (%):
384 (100), 296 (25), 208 (15); elemental analysis calcd (%) for
C74H92Cl12O9P2Ru2 Â C6H14 (1887.1): C 50.54, H 5.62; found: C 51.05, H
5.75.
Metathesis experiments: The glassware used in these experiments was
dried for several hours at 1208C and cooled down to the reaction
temperature under nitrogen. In a typical experiment, trans-4-decene
(0.62 mL, 3.27 mmol) was added to a solution of complex 3 (9.5 mg,
5.94 Â 10 3 mmol) in CH2Cl2 (2.0 mL). The resulting solution was vigo-
rously stirred. The progress of the metathesis reaction was monitored by
sampling through a septum at suitable time intervals. The catalyst in these
samples was immediately quenched with an excess of ethyl vinyl ether. The
samples were analysed by GC (Carlo Erba 8000Top) on a DB-5 (J&W
Scientific) column.
Oleon (pentatriaconta-9,26-dien-18-one) (10): Ketone 10 (oleon) was
obtained from methyl oleate (methyl cis-9-octadecenoate) as described by
McMurry et al.[30]
Reactions of 3 and 5 with donor solvents
Reaction of 3 with MeOH: Complex 3 (5 mg, 3.1 Â 10 3 mmol) was
dissolved in 1 mL of a 1:1 mixture of solvents CD3OD/C6D6 at room
temperature. A dark purple colour was formed over a period of 72 h. 31P
NMR (CD3OD/C6D6): d ˆ55.03 (s); 1H NMR (CD3OD/C6D6): d ˆ 2.09 ±
1.08 (m), PCy3.
For the ring-closing metathesis of diethyl diallylmalonate (9), neat diethyl
diallylmalonate (35 mg, 0.15 mmol) was added at room temperature to a
stirred solution of dimer 3 (12 mg, 7.2 Â 10 3 mmol) in CH2Cl2 (1.5 mL).
The colour of the reaction mixture turned yellow, the mixture was kept
under a nitrogen pressure of 1.015 bar. The progress of the reaction was
followed in the same way as described above.
Reaction of 3 with NC5H5: Complex 3 (20 mg, 1.2 Â 10 2 mmol) was
dissolved in hexane (5 mL) at room temperature. The green colour turned
slowly to yellow after pyridine (25 Â 10 3 mL) was added. Yellow crystals
were obtained by slow diffusion of hexane into toluene. 31P NMR (NC5D5):
d ˆ26.10 (s); 1H NMR (NC5D5): d ˆ 8.34 (m, 2H, ortho-RuNC5H5), 7.58
For the ring-closing metathesis of oleon (10), a solution of 10 (780 mg,
1.52 mmol) in CH2Cl2 (100 mL) and a solution of catalyst 3 (134 mg,
0.0788 mmol, 5 mol%) in hexane (100 mL) were added simultaneously to
CH2Cl2 (100 mL). The resulting mixture was vigorously stirred at room
temperature. The progress of the reaction was followed in the same way as
described above. The formation of the macrocyclic product 11 [see Eq. (6)]
was confirmed by GC/MS. The trans/cis ratio was measured on a CP-Sil 88
column.
(m, 2H, meta-RuNC5H5), 7.2 (m, 1H, para-RuNC5H5), 2.09 ± 1.08 (m),
PCy3; molar conductimetry: LM < 2 cm 2 Ohm 1mmol
.
1
Reaction of 5 with DME: Complex 5 (25 mg, 1.4 Â 10 3 mmol) was
dissolved in hexane (10 mL) at room temperature. The addition of DME
(50 Â 10 3 mL) was monitored by 31P NMR. The dimer carbene complex
decomposed when new phosphorus absorption appeared. This process
needed 18 h to be completed. The half-life of complex 5 was 9 h. The
2846
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Chem. Eur. J. 2001, 7, No. 13

Alkene Metathesis
2842±2847
[20] E. L. Dias, S. T. Nguyen, R. H. Grubbs, J. Am. Chem. Soc. 1997, 119,
3887.
Acknowledgements
[21] S. Chang, L. Jones II, C. Wang, L. M. Henling, R. H. Grubbs,
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This work was supported in part (M.L., A.L.S.) by the Council for Chemical
Sciences of The Netherlands Organization for Scientific Research (CW-
NWO). Technical support by R. Barendregt and the help of A. M. M.
Schreurs with the X-ray data handling are kindly acknowledged.
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Received: November 2, 2000 [F2845]
Chem. Eur. J. 2001, 7, No. 13
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0947-6539/01/0713-2847 $ 17.50+.50/0
2847