Ruthenium hydride complex supported on multi-wall carbon nanotubes for catalytic C-C bond formation via transfer hydrogenation

Article abstract of DOI:10.1016/j.jorganchem.2012.10.028

In this work, the preparation, characterization and investigation of catalytic activity ruthenium hydride catalyst, [RuHCl(CO)(PPh₃) ₃], supported on MWCNT in the synthesis of β,γ-unsaturated ketones via carbon-carbon bond formation are reported. In the first reaction step, the MWCNTs were modified with 1,2-ethanedithiol, and in a second reaction step, the catalyst was attached to MWCNTs via this linker. The catalyst was characterized by diffuse reflectance UV-vis and FT-IR spectroscopic techniques, SEM, ICP and elemental analysis methods. The catalyst was reused several times without significant loss of its catalytic activity.

Full text of DOI:10.1016/j.jorganchem.2012.10.028

Journal of Organometallic Chemistry 724 (2013) 32e39
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Ruthenium hydride complex supported on multi-wall carbon nanotubes
for catalytic CeC bond formation via transfer hydrogenation
*
**
Behjat Barati, Majid Moghadam , Abbas Rahmati , Valiollah Mirkhani, Shahram Tangestaninejad,
Iraj Mohammadpoor-Baltork
Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
In this work, the preparation, characterization and investigation of catalytic activity ruthenium hydride
Received 15 August 2012
Received in revised form
27 September 2012
catalyst, [RuHCl(CO)(PPh3)3], supported on MWCNT in the synthesis of
b,g-unsaturated ketones via
carbonecarbon bond formation are reported. In the first reaction step, the MWCNTs were modified with
1,2-ethanedithiol, and in a second reaction step, the catalyst was attached to MWCNTs via this linker. The
catalyst was characterized by diffuse reflectance UVevis and FT-IR spectroscopic techniques, SEM, ICP
and elemental analysis methods. The catalyst was reused several times without significant loss of its
catalytic activity.
Accepted 15 October 2012
Keywords:
Multi-wall carbon nanotube
CeC bond formation
Ruthenium hydride
Heterogeneous catalyst
Unsaturated ketones
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
nanotube/polysiloxane composite films for methanol electro-
oxidation [31], palladium supported on single-wall carbon nano-
The formation of carbonecarbon bond has received much
attention in chemical transformation specially for construction of
molecular frameworks with increasing complexity [1e7]. Many
tubes for Heck and Suzuki couplings, aerobic oxidation of alcohol
and selective hydrogenation [32], Pd-CNT for Suzuki coupling [33],
CNT supported cobalt for CO oxidation [34], Pd-CNT for hydro-
dehalogenation of aryl halides [35], Pt nanoparticles supported on
CNTs have been used for methanol oxidation [36], palladium
nanoparticles supported on CNTs for semihydrogenation of phe-
nylacetylene [37], chiral vanadylsalen complex supported on
single-wall CNTs for enantioselective cyanosilylation of aldehydes
[38,39], manganese(III) porphyrin and manganese(III) salophen
supported on MWCNTs for epoxidation of alkenes with NaIO4
[40,41] and molybdenum and tungsten hexacarbonyl supported on
MWCNTs for alkenes epoxidation with tert-BuOOH [42,43].
On the other hand, immobilization of catalysts on MWCNT can
improve specific properties such as selectivity and conversion,
catalytic activity, reduce the reaction time, stability, corrosion
resistance in electrocatalysts, easier separation and satisfactory
reusability, which shows the use of CNTs as support is a suitable
selection [44e48].
reports have been focused on the direct coupling of diverse
p-
unsaturated compounds such as allenes [8e10], alkynes [3,11],
enones [12e14], dienes [15e19] and enynes [2] with conventional
electrophiles, particularly carbonyl compounds, catalyzed by
homogenous metal catalysts. Ruthenium based complexes are
generally considered to be reactive toward these reactions. Despite
the high reactivity of ruthenium complexes in organic synthesis,
the difficulty of their reusability and stability limits their practical
applications. To overcome these problems, ruthenium catalysts
have been immobilized on different types of supports [20e27].
Carbon nanotubes (CNTs) have attracted much attention in the
synthesis, characterization, and applications because of their
unique structural, mechanical, thermal and electronical properties.
Due to the above-mentioned properties, and also high surface area
of CNTs and their insolubility in the most solvents, these materials
can be used as catalysts support [28e30]. For example, PtNi alloy
nanoparticles supported on functionalized multi-wall carbon
Recently, homogeneous ruthenium hydride catalyst has been
used for transfer hydrogenation of dienes with alcohols and alde-
hydes [17,18]. To develop this investigation, here, we report the
application of [RuHCl(CO)(PPh3)3] supported on MWCNT for cata-
lytic CeC bond formationvia transfer hydrogenation (Scheme 1). The
catalyst was characterized by elemental analysis, FT-IR and diffuse
reflectance UVevis spectroscopic methods and SEM technique.
* Corresponding author. Tel.: þ98 311 7932712; fax: þ98 311 6689732.
** Corresponding author.
E-mail addresses: moghadamm@sci.ui.ac.ir, majidmoghadamz@yahoo.com
(M. Moghadam), a.rahmati@sci.ui.ac.ir (A. Rahmati).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.10.028

B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
33
[50]. The carboxylated MWCNTs and 1,2-ethanedithiol (EDT) as
linker were mixed in THF and the mixture was stirred at 50 ꢁC for
12 h. Then the reaction mixture was cooled to room temperature
and filtered. The solid EDT-MWCNT was washed with THF and
dried.
Scheme 1. Synthesis of unsaturated ketones catalyzed by [RuHCl(CO)(PPh3)3] sup-
ported on MWNT.
2.1.2. Preparation of the MWCNT modified with different amines,
MWCNT-amine
For attachment of the amines to MWCNTs, the MWCNT-COOH
was converted to MWCNT-COCl [43]. In a 50 ml round-bottom
flask equipped with a magnetic stirring bar, MWCNT-COCl (1 g)
and Et3N (1 mL) were added to a solution of amine (0.5 g) in
dimethyl formamide (DMF) (20 mL) and heated at 80 ꢁC for 24 h.
Then, the reaction mixture was filtered, washed with CH3CN and
dried at 60 ꢁC.
Table 1
The specification of MWCNT-COOH used in this study.
MWCNT-COOH
Outside
diameter (nm)
Inside
diameter (nm)
Length
m)
COOH
content (%)
Specific surface
(
m
area (m2/g)
20e30
5e10
30
1.5
>110
2.2. Preparation of the catalyst [Ru-H@EDT-MWCNT]
2. Experimental
For attachment of catalyst to support, the EDT-MWCNT (1 g) was
dispersed in anhydrous toluene (50 mL) by vigorous stirring, and
a solution of [RuHCl(CO)(PPh3)3] (0.2 g) in anhydrous toluene
(10 mL) was added to this mixture. The mixture was refluxed for
24 h, the [Ru-H@EDT-MWCNT] was filtered, washed with toluene
to remove the excess reactants and dried under vacuum for 24 h.
A similar procedure was applied for attachment of [RuHCl(-
CO)(PPh3)3] to amine modified MWCNT.
All materials were commercial reagent grade and obtained from
Merck and Fluka chemical companies. Elemental analysis was
performed on a PerkineElmer 2400 instrument. Atomic absorption
analyses were carried out on a Shimadzu 120 spectrophotometer.
Diffuse reflectance spectra were recorded on a Shimadzu UV-265
instrument using optical grade BaSO4 as reference. FT-IR spectra
were obtained as potassium bromide pellets in the range 500e
4000 cmꢀ1 with a BomeneHartmann instrument. Scanning elec-
tron micrographs of the support and catalyst were taken on
a SEM EM 3200 instrument. 1H NMR spectra were recorded on
a Bruker-Avance AQS 400 MHz. The ICP analyses were performed
on an ICP-Spectrociros CCD instrument. Mass spectra were recor-
ded on a Platform II spectrometer from Micromass, EI mode at
70 eV. Solvents and aldehydes were distilled prior to use. The
products were purified by silica gel chromatography (Merck KGaA,
Silica Gel 60). The MWCNTs containing carboxylic acid groups
were purchased from Shenzen NTP Factory (China). Table 1 shows
the characteristics of these MWCNTs. The [RuHCl(CO)(PPh3)3]
complex was prepared according to the method reported in the
literature [49].
2.3. Synthesis of 2,3-dimethyl-1-phenylbut-3-en-1-one catalyzed
by [Ru-H@EDT-MWCNT]
Freshly distilled benzaldehyde (1a, 108 mg, 1 mmol), isoprene
(2a, 340.7 mg, 4 mmol), [Ru-H@EDT-MWCNT] (8 mol%, 400 mg,)
and toluene (6 mL) were placed in a screw capped test tube. The
test tube was purged with argon and sealed. The mixture was
stirred at 100 ꢁC for 16 h. After the reaction was completed, the
catalyst was filtered and washed with EtOH (10 ml). The solvent
was evaporated under reduced pressure and the residue was
purified by chromatography on a silica gel plate (petroleum ether/
ethyl acetate ¼ 50/1) to give 2,3-dimethyl-1-phenylbut-3-en-1-one
(3a, 161 mg, 90%).
2.1. Preparation of the supports
2.4. General procedure for the synthesis of
unsaturated ketones
a,b- and b,g-
2.1.1. Preparation of the MWCNT modified with 1,2-ethanedithiol,
EDT-MWCNT
First, carboxylic acid groups were converted to thiol groups
[eCOS(CH2)2SH], according to a previously reported method
In a screw capped test tube, freshly distilled aldehyde (1,1 mmol),
diene (2, 4 mmol), [Ru-H@EDT-MWCNT] (8 mol%, 400 mg,) were
SH
O
C
HS
COOH
THF, 50 oC
S
SH
[RuHCl(CO)(PPh3)3]
Toluene, Reflux
O
PPh3
C
H
S
S
Ru
Cl
OC
PPh3
Scheme 2. The preparation route for catalyst.

34
B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
added toluene (6 mL). The test tube was purged with argon and
sealed. The reaction mixture was allowed to stir at 100 ꢁC for 16 h.
After the reaction was completed, the catalyst was filtered and
washed with EtOH (10 ml). The solvent was evaporated under
reduced pressure and the residue was purified by chromatography
on a silica gel plate (petroleum ether/ethyl acetate ¼ 50/1) to give
desired product.
3. Results and discussion
3.1. Catalyst preparation and characterization
Scheme 2 shows the preparation route for catalyst. The modified
MWCNT, EDT-MWCNT, was prepared by the reaction of 1,2-
ethanedithiol with MWCNT-COOH via a thioester linkage. The
[Ru-H@EDT-MWCNT] catalyst was prepared by the reaction of EDT-
MWCNT with a solution of [RuHCl(CO)(PPh3)3]. The [Ru-H@EDT-
MWCNT] catalyst was characterized by elemental analysis, spec-
troscopic methods and SEM. The sulfur content of the support was
9.43%. According to this value, the amount of S which is available for
attachment of [RuHCl(CO)(PPh3)3] is about 1.47 mmol/g. The
amount of Ru in the supported catalyst, determined by ICP, was
about 2.1% (0.2 mmol/g). The FT-IR spectra of [RuHCl(CO)(PPh3)3]
showed characteristic bands at 2013 cmꢀ1(RueH) and 1925 cmꢀ1
Fig. 2. DR UVevis spectrum of: (A) [RuHCl(CO)(PPh3)3], (B) MWNT-SH, (C) [Ru-
H@EDT-MWNT] and (D) [RuHCl(CO)(PPh3)3] þ MWCNTs.
Fig. 1. FT-IR spectrum of: (A) [RuHCl(CO)(PPh3)3], (B) MWNT-SH and (C) [Ru-H@EDT-
MWNT].

B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
35
Fig. 3. SEM image of: (A) MWNT-SH and (B) [Ru-H@EDT-MWNT].
(C]O) which shifted to 2035 and 1944 cmꢀ1, respectively, upon
immobilization (Fig. 1), while MWCNTs show no band in this
region. These absorption peaks indicate that ruthenium complex
has been successfully supported on the MWNTs surface.
of Ru catalyst to MWCNTs in which the highest yield was observed
in the reaction of isoprene (1a) with benzaldehyde (2a) as model
reaction (Table 2). To check whether the reaction is catalyzed by
covalent attached or adsorbed RuHCl(CO)(PPh3)3, a mixture of
MWCNTs with RuHCl(CO)(PPh3)3 was refluxed in toluene for 24 h
and filtered. This catalyst was used in the model reaction. The
results showed that only 8% of the 2,3-dimethyl-1-phenylbut-3-en-
1-one was produced. This shows that the amount of adsorbed
catalyst is too low to catalyze the reaction.
Then, the reaction parameters such as catalyst amount, kind of
solvent and temperature were optimized in the model reaction.
Initial studies were focused on the coupling of isoprene (1a) with
benzaldehyde (2a) for the optimization of reaction conditions
(Table 3). The results showed that 8 mol% of [Ru-H@EDT-MWCNT]
efficiently catalyzed the model reaction at 100 ꢁC in toluene to
give the 2,3-dimethyl-1-phenylbut-3-en-1-one (3a) (Table 3, entry
3). The effect of different solvents was also investigated in the model
reaction. As can be seen, the highest yield was obtained using
toluene as reaction media. The effect of temperature was also
checked on the model reaction. The results showed that increasing
the temperature higher than 100 ꢁC did not affect the yield (entry 8).
The applicability and generality of this method were examined
using a variety of dienes and aldehydes (Table 4). The reaction of
isoprene (1a) with benzaldehyde and substituted benzaldehydes 2
bearing electron-donating substituents (methyl and methoxy) and
electron-withdrawing groups (bromo, fluoro, cyano and nitro)
The UVevis spectra of RuHCl(CO)(PPh3)3, EDT-MWNT and [Ru-
H@EDT-MWCNT] in the diffuse reflectance mode are shown in
Fig. 2. The homogeneous ruthenium hydride complex has a char-
acteristic absorption peak at 329 nm (Fig. 2A). The EDT-MWNT
exhibits an absorption peak at 237 nm (Fig. 2B), whereas the [Ru-
H@EDT-MWCNT] showed two peaks at 240 nm (corresponds to
the support) and 341 nm (Fig. 2C). The latter is attributed to the Ru
complex with a bathochromic shift in comparison with the non-
supported complex. The diffuse UVevis spectrum of a mixture of
RuHCl(CO)(PPh3)3 and MWCNTs was also recorded. As can be seen
in Fig. 2D, this spectrum is as same as homogeneous RuHCl(-
CO)(PPh3)3 spectrum. While the spectrum of [Ru-H@EDT-MWCNT]
shows that the coordination sphere may be different.
The SEM images of the [Ru-H@EDT-MWCNT] showed that the
nanotubes are aggregated and has retained their nanotube nature
upon functionalization with EDT and support of catalyst on them
(Fig. 3).
3.2. Synthesis of b,g-unsaturated ketones
First, we examined the effect of different linkers and it was
observed that 1,2-ethanedithiol was the best linker for attachment
Table 2
Effect of different linkers in the reaction of isoprene with benzaldehyde.a
Table 3
Optimization of conditions in the reaction of 1a with 2a.a
O
O
O
[Ru-H@linker-MWNT]
H
O
+
[Ru-H@EDT-MWNT]
Toluene
Toluene
H
+
1a
2a
3a
1a
2a
3a
Entry
1
Linker
Yield (%)b
50
Entry Catalyst amount (mol%) Solvent
Temperature Yield (%)b
H2N(CH2)2SH
1
2
3
4
5
6
7
8
4
6
8
10
8
8
Toluene
Toluene
Toluene
Toluene
1,2-Dichloroethane 80
THF
100
100
100
100
60
78
90
90
53
30
80
90
2
10
3
4
5
6
H2N(CH2)2OH
H2N(CH2)2NH2
HS(CH2)2SH
No linker
20
35
90
8
90
90
110
8
8
Toluene
Toluene
a
a
All reactions were performed using 1a (4 mmol), 2a (1 mmol), supported
All reactions were performed using 1a (4 mmol), 2a (1 mmol), supported
catalyst (8 mol%), and toluene (6 mL) in a screw test tube at 100 ꢁC for 16 h.
catalyst, and solvent (6 mL) in a screw test tube for 16 h.
b
b
Isolated yield.
Isolated yield.

36
B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
Table 4
Synthesis of unsaturated ketones catalyzed by [Ru-H@EDT-MWCNT].a
Entry
Diene1
Aldehyde 2
Unsaturated ketones 3
Yield (%)b
[Ru-H@EDT-MWCNT]
[RuHCl(CO)(PPh3)3] [18]
TON
TOF (hꢀ1
)
TON
TOF (hꢀ1
)
1
l
90
11.25
0.70
16.2
0.67
1a
2a
3a
2
1a
80
10.00
0.62
15.6
0.65
2b
2c
2d
3b
3c
3d
3
4
1a
1a
92
70
11.50
8.75
0.72
0.55
18.8
0.78
0.58
14
5
1a
68
8.50
0.53
e
e
3e
2e
6
7
8
1a
1a
1a
73
92
95
9.10
11.50
11.87
0.57
0.72
0.74
12.4
0.52
3f
2f
e
e
2g
2h
3g
3h
e
e
9
1a
87
10.87
0.68
e
e
2i
2i
3i
10c
1a
82
5.12
0.32
e
e
3j

B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
37
Table 4 (continued )
Entry Diene1
Aldehyde 2
Unsaturated ketones 3
Yield (%)b
[Ru-H@EDT-MWCNT]
[RuHCl(CO)(PPh3)3] [18]
TON
TOF (hꢀ1
)
TON
TOF (hꢀ1
)
11
1a
85
10.62
0.66
e
e
2j
3k
3l
12
13
81
83
10.12
10.37
0.63
0.65
e
e
1b
2g
1b
1b
e
e
3m
2h
14
79
84
9.87
0.62
e
e
e
e
2k
3n (E/Z = 48/52)
10.50
15
0.66
1c
2d
3o (E/Z = 49/51)
a
All reactions were performed using 1 (4 mmol), 2 (1 mmol), supported catalyst (8 mol%) and toluene (6 mL) in a screw test tube for 16 h.
Isolated yield.
Reaction was performed using 1a (8 mmol), 2i (1 mmol), supported catalyst (16 mol%) and toluene (10 mL) in a screw test tube for 16 h (See Scheme 2).
b
c
produced the corresponding
b
,
g
-unsaturated ketones 3 with good
reaction of 4-cyanobenzaldehyde (2g) and 4-nitrobenzaldehyde
(2h) with 1,5-hexadiene (1b) and in the presence of [Ru-H@EDT-
MWCNT], only the Z isomers (3l and 3m) were obtained (entries
12 and 13). But in the reaction of thiophene-3-carbaldehyde (2k)
to excellent yields at 100 ꢁC in toluene and in the presence of
0.08 mmol of [Ru-H@EDT-MWCNT] (entries 1e8). An excellent
selectivity was observed in the reaction of terephthalaldehyde (2i)
with isoprene (1a). When 1 mmol of terephthalaldehyde (2i) was
reacted with 4 mmol of isoprene (1a) (entry 9) in the presence of
0.08 mmol of catalyst, only one aldehydic group was reacted and
the other was remained intact, and the 4-(2,3-dimethyl-but-3-
enoyl)-benzaldehyde (3i) was obtained in 87% yield. On the other
hand, when the same reaction was carried out with 12 mmol of
isoprene (1a) and in the presence of 16 mol% of catalyst, both
aldehydic groups were reacted and 1,4-bis(2,3-dimethyl-but-3-
enoyl)benzene (3j) was produced in 82% yield (Scheme 3). The
reaction of indol-3-carbaldehyde (2j), as a heteroaromatic alde-
hyde, with isoprene (1a) was also investigated and the corre-
sponding unsaturated ketone (3k) was produced in 85% yield
(entry 11). Since the ruthenium hydride catalyst has been employed
for double bond isomerization [51], we tested the reactivity of 1,5-
hexadiene (1b) in cross-coupling reaction. Interestingly, in the
with 1,5-hexadiene (1b), the a,b-unsaturated ketone (3n) was ob-
tained as a 48/52 mixture of E/Z isomers (entry 14). When 1,3-
cyclooctadiene (1c) was used as diene, a 49/51 mixture of E/Z
isomers (3o) was produced (entry 15).
The study of the reactivity of aldehydes in Table 4 showed that
aldehydes constitute electron-withdrawing substituents was more
Scheme 3. Synthesis of1,4-bis(2,3-dimethyl-but-3-enoyl)benzene.

38
B. Barati et al. / Journal of Organometallic Chemistry 724 (2013) 32e39
Table 5
Table 6
Effect of different supported catalyst in the reaction of isoprene with benzaldehyde.a
The results of [Ru-H@EDT-MWCNT] catalyst recovery and the amount of Ru leached
in the reaction of benzaldehyde (2a) with isoprene (1a).
Row
Yield (%)a
Ru leached (%)b
1
2
3
4
90
86
83
76
1.1
0.8
0
0
a
Isolated yield.
Determined by atomic absorption spectroscopy.
b
Entry
Supported Catalyst
Yield (%)b
1
2
3
[Ru-H@EDT-MWCNT]
[Ru-H@EDT-AuNP]
[Ru-H@Nano-silica]
90
32
8
aldehyde 2 to this
turns produces the unsaturated ketone compound 3 and releases
the catalyst for the next catalytic cycle (Scheme 4).
p-complex gives the intermediate II, which in
a
Both reactions were performed using 1a (4 mmol), 2a (1 mmol), supported
catalyst (8 mol%), and toluene (6 mL) in a screw test tube at 100 ꢁC for 16 h.
b
Isolated yield.
3.3. Catalyst reuse
reactive than aldehydes bearing electron-donating groups and gave
the desired products in higher yields. It seems that electron-
donating groups stabilize the parent aldehydes via resonance and
therefore, the reaction rate and the yields reduce.
The reusability of the [Ru-H@EDT-MWCNT] was checked using
multiple sequential reaction of benzaldehyde (2a) with isoprene
(1a). For each of the repeated reactions, the catalyst was recovered,
washed exhaustively with diethyl ether, and dried before being
used with fresh benzaldehyde 2a with isoprene 1a. The results
showed that the catalyst was consecutively reused four times
without a significant loss in its activity (Table 6).
On the other hand, the reaction was stopped at half conversion
and the half of the volume with the material was filtered at 100 ꢁC
(reaction temperature). Execution of the reaction under the same
reaction conditions, as with catalyst, showed no significant
conversion and only 5% of 2,3-dimethyl-1-phenylbut-3-en-1-one
was produced. These observations show the strong attachment of
RuHCl(CO)(PPh3)3 to MWCNT via 1,2-ethanedithiol.
The catalytic activity of RuHCl(CO)(PPh3)3 supported on gold
nanoparticles (AuNP) and nano-silica was also investigated in the
reaction of isoprene (1a ) with benzaldehyde (2a) (Table 5). As can
be seen, these heterogeneous catalysts are less efficient than [Ru-
H@EDT-MWCNT]. During the reaction, the [Ru-H@EDT-MWCNT]
particles are suspended in the solvent. This is due to the bundled
agglomerates of MWCNT that aggregate slowly and make the
catalyst suspend in the reaction mixture for a long period of time.
While, other heterogeneous catalysts were aggregated more
rapidly in comparison with CNTs.
For comparison of catalytic activity of this catalyst with homo-
geneous counterpart, the TONs and TOFs were calculated (Table 5).
As can be seen, despite higher TONs for homogeneous catalyst, the
TOFs for heterogeneous catalyst are comparable to homogeneous
catalyst.
4. Conclusion
In conclusion, [Ru-H@EDT-MWCNT] was successfully supported
on 1,2-ethanedithiol functionalized MWCNTs and characterized.
This heterogeneous catalyst was used for preparation of unsatu-
rated ketones by the reaction of dienes with aldehydes. The catalyst
was reused several times without significant loss of its catalytic
activity.
Since the identification of intermediates was not possible;
therefore, a mechanism is reported on the basis of homogeneous
conditions [18]. As mentioned previously, the supported Ru catalyst
reacts with diene 1ato produce the
p-allyl complex I. Addition of
Acknowledgment
The financial support of this work by Research Council of the
1a
University of Isfahan is acknowledged.
Appendix A. Supplementary data
PPh3
PPh3
Cl
Cl
Supplementary data related to this article can be found at
http://dx.doi.org/10.1016/j.jorganchem.2012.10.028.
MWCNT
S
Ru
MWCNT
S
Ru
PPh3
CO
OC
H
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Scheme 4. The reaction pathway.

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