The reactivity of (μ-H)2Ru3(CO)9(μ3-η2-C8H12) and (μ-H)Ru3 (Co)9 (μ3-η3-C12 H19)

Article abstract of DOI:10.1016/S1381-1169(97)00311-7

The reactivity of (μ-H)₂Ru₃(CO)₉(μ₃-η²-C₈H₁₂) (1) and (μ-H)Ru₃(CO)₉(μ₃-η³-C₁₂H₁₉) (2) with hydrogen and carbon monoxide was studied at elevated temperatures. Also the catalytic activity of 1 in homogeneous hydrogenation of 1-hexene was studied. At the lower carbon monoxide pressures compounds 1 and 2 converted to Ru₃(CO)₁₂ while at higher pressures they tend to fragmentate to the other ruthenium carbonyl compounds. Under a hydrogen atmosphere 1 and 2 converted to H₄Ru₄(CO)₁₂ and at higher pressures tend to fragmentate to insoluble black precipitate. Complex 1 has a moderate activity in homogeneous hydrogenation of 1-hexene. Its activity is dependent on the temperature: activity increases when the temperature goes up.

Full text of DOI:10.1016/S1381-1169(97)00311-7

Ž
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Journal of Molecular Catalysis A: Chemical 135 1998 233–239
2
ž
/
ž / ž
/
The reactivity of m-H 2Ru3 CO 9 m3-h -C8H12 and
3
ž
/
ž / ž
/
m-H Ru3 CO 9 m3-h -C12 H19
)
K.O. Kallinen , T.T. Pakkanen, T.A. Pakkanen
UniÕersity of Joensuu, Department of Chemistry, P.O. Box 111, FIN-80101 Joensuu, Finland
Received 30 September 1997; accepted 1 December 1997
Abstract
2
3
Ž
.
Ž
. Ž
. Ž .
Ž
.
Ž
. Ž . Ž .
The reactivity of m-H 2Ru3 CO m3-h -C8H12
1
and m-H Ru3 CO m3-h -C12H19 2
with hydrogen and
9
9
carbon monoxide was studied at elevated temperatures. Also the catalytic activity of 1 in homogeneous hydrogenation of
Ž
.
12
1-hexene was studied. At the lower carbon monoxide pressures compounds 1 and 2 converted to Ru3 CO while at higher
pressures they tend to fragmentate to the other ruthenium carbonyl compounds. Under a hydrogen atmosphere 1 and 2
Ž
.
converted to H4Ru4 CO
and at higher pressures tend to fragmentate to insoluble black precipitate. Complex 1 has a
12
moderate activity in homogeneous hydrogenation of 1-hexene. Its activity is dependent on the temperature: activity increases
when the temperature goes up. q 1998 Elsevier Science B.V. All rights reserved.
Keywords: Cluster; Ruthenium; Olefin; Reactivity; Hydrogenation; Homogeneous
1. Introduction
metal particles while under hydrogen atmo-
sphere the behaviour is more complicated in-
cluding both fragmentation reactions and forma-
tions of new hydride derivatives of metal car-
bonyl complexes.
Ruthenium cluster compounds have been used
as catalyst precursors in several catalytic reac-
tions for example carbonylation of alcohols 1,2 ,
w
x
w
isomerization and hydrogenation of olefins 3–
We have now studied reactivity of cyclic
x
w x
6 , water gas shift reaction 7 and hydroformy-
Ž
.
Ž
2
.
9 ,
olefin derivatives of Ru3 CO 12, H2Ru3 CO -
9
w x
lation 8 , especially in homogeneous catalysis.
Ž
. Ž .
Ž
. Ž
. Ž . w x
C8H12 1 and HRu3 CO C12 H19
9
Reactivity tests under conditions where cluster
compounds might be expected to display cat-
alytic activity give useful information of their
shape during and after the catalytic reactions.
Usually under carbon monoxide the simple metal
carbonyl clusters tend to fragmentate to lower
nuclearity carbonyl compounds or insoluble
under carbon monoxide and hydrogen atmo-
sphere and the catalytic activity of 1 in the
hydrogenation of 1-hexene reaction. Earlier we
Ž
.
have studied the reactivity of HRu3 CO 12-1,3-
w
x
dithiacyclohexane 10 towards CO and H2 and
found that it has a moderate activity in the
w x
hydrogenation of 1-hexene 5 .
One aim of the work was the stabilization of
Ž
.
)
the Ru3 CO
cluster with suitable ligand for
12
Corresponding author. Tel.: q358-13-2513374; fax: q358-
catalytic reaction conditions. On the other hand
13-2513344; e-mail: kauko.kallinen@joyx.joensuu.fi
1381-1169r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved.
Ž
.
PII: S1381-1169 97 00311-7

(
)
234
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
the substitution of the carbonyl ligands by lightly
stabilizing ligands does not necessarily stabilize
the cluster framework. The replacement of CO
by weakly bound ligands can indeed increase
with an oil bath to the appropriate temperature.
Hydrogen or carbon monoxide was bubbled
trough the solution via a thin needle. Tempera-
ture was raised with 108C steps for H2 reactions
w
x
Ž
the reactivity of the new cluster complexes. 11
and 208C steps for CO reactions reaction condi-
tions of the experiments are introduced in Table
.
1 . Reactions were carried out at each tempera-
ture for one hour. After each step the mixture
2. Experimental
was analyzed with IR.
The reactions with CO or H2 at higher pres-
sures were carried out in a 100 ml autoclave
2.1. General comments
Ž
.
w
x Ž . w x
12 , H2Ru3 CO C8H12 9 and
9
Ru3 CO
Ž
Berghof with teflon liner, containing a Berghof
12
Ž
.
w x
HRu3 CO C12 H19 9 were prepared with the
.
Bar 845 temperature control unit . The exam-
ined complex was weighed ;20–30 mg and
packed into the autoclave and dissolved in
9
literature procedures. All manipulations were
carried out under nitrogen atmosphere and sol-
vents were deoxygenated with nitrogen gas for
fifteen minutes before use. All solvents were
p.a. grade and they were stored over molecular
sieves. IR-spectra were recorded on a Nicolet
Ž
.
Ž
.
toluene 5–14 ml . The autoclave was closed
and charged with carbon monoxide or hydrogen
Ž
.
gas 50 bar . After the reaction the pressure was
released and the autoclave was opened and the
reaction mixture was analyzed with IR and
NMR-spectrometers.
750 FT-IR-spectrometer and H and 13C NMR
1
spectra on a Bruker AMX-400 or a Bruker
AM-250 spectrometer in d6-acetone with TMS
as an internal reference.
2.3. Hydrogenation of 1-hexene catalyzed with
1
2.2. Reactions of 1 and 2 with carbon monoxide
Ž
.
Ž
.
H2Ru3 CO C8H12 was weighed 8 mg and
and hydrogen
9
Ž
.
Ž
packed with toluene as solvent 4 ml and 1-
hexene 10 ml into an autoclave Berghof,
containing a Berghof Bar 845 temperature con-
Ž
.
The reactions with a H2 or CO gas were
done in a 100 ml round bottom reaction vessel.
Ž
.
trol unit in a N2-filled glove box. The autoclave
The examined complex was weighed ;20–30
.
Ž
was charged with H2 50 bar, purity of hydro-
mg into the reaction vessel and the flask was
. Ž
min after the temperature was risen to the set
charged with nitrogen. The solvent was added
with a double-ended needle and the reaction
vessel was stirred magnetically and warmed
gen )99.99% and heated for one hour 15
.
Ž
.
value 72–1708C . After the reaction the auto-
Table 1
Reaction conditions
Ž
.
Ž
.
Experiment
Compound
Solvent
Reaction gas
Temperature 8C
Pressure atm
1
2
3
4
5
6
7
8
9
1
1
1
1
1
2
2
2
2
2
Toluene
Octane
Toluene
Octane
Toluene
Toluene
Octane
Toluene
Octane
Toluene
H2
H2
H2
CO
CO
H2
H2
H2
CO
CO
50–110
110–130
117
60–130
146
50–110
110–120
146
60–130
148
1
1
50
1
50
1
1
50
1
50
10

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)
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
235
clave was cooled down to room temperature
with liquid nitrogen, the pressure was released,
and the reaction mixture was analyzed.
Analysis was carried out with a gas chro-
Ž
matograph Hewlett Packard Series II 5890 us-
ing Chrompack OV 1-column: 50 m, Ø 0.53
.
mm, phase thickness 5 mm . Quantitative analy-
sis was carried out with GC by computing the
amounts of 1-hexene, trans-2-hexene, cis-2-
hexene and the total amounts of trans-3-hexene
Ž
and hexane the last two were not separated
.
using GC . Separated amounts of trans-3-hexene
and hexane were obtained with 13C NMR spec-
troscopy in deuterocloroform as solvent and
TMS as reference. The final results were com-
Ž
.
puted using both procedures NMR and GC .
Scheme 1. Reactions of 1 with H2 and CO in toluene or octane.
3. Results and discussion
Ž
.
12
3.1. The reactions of 1 and 2 with carbon
monoxide
At 1008C the carbonyl frequencies of Ru3 CO
1
at 2060.7, 2030.8 and 2011.7 cmy appeared in
Ž
.
IR and the proportion of Ru3 CO
increases
12
Under bubbling of CO compound 1 stayed
unchanged up to 808C according to IR, Fig. 1.
when the temperature goes up. After refluxing
the mixture in octane overnight 1308C only
Ž
.
Ž
.
the CO-bands due to Ru3 CO were observed
12
in IR. At higher CO pressures 1 changes to
Ž
.
Ž
.
Ru3 CO and other unidentified Ru CO -com-
12
plexes, Scheme 1. After the reaction IR-spectra
from the reaction mixture contains five signals:
2060.7 m, 2039.8 sh, 1990.3 m, 1956.5 vs and
1701.4 m. The plate cromatographic separation
of the reaction mixture gave only the yellow
Ž
.
band of Ru3 CO 12, the rest was not eluated
with common organic solvents.
Under bubbling of CO compound 2 also re-
Ž
.
mained unchanged up to 1208C Fig. 2 . In
Ž
.
Ž
.
refluxing octane 1308C it forms Ru3 CO in
an overnight reaction 21 h like 1. Unlike for 1
there are no signals of Ru3 CO present in IR
12
Ž
.
Ž
.
12
after the reaction made at higher temperatures
and pressures. Compound 2 obviously decom-
Ž
.
poses to the mixture of Ru CO -complexes,
Scheme 2, since after the reaction IR-spectra
from the reaction mixture contains six new
unidentified metal–carbonyl bands at 2097.4 w,
Ž
.
Fig. 1. IR of 1 at different temperatures 8C in octane bubbled
Ž
.
.
12
with CO, AsRu3 CO

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)
236
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
results are similar to that found for H2Ru3-
Ž
. Ž
.
Ž
CO NPh , which under CO atmosphere 10
9
.
Ž
.
w x
bar, 308C, 2 h converts to Ru3 CO
13 . At
12
higher CO pressures both compounds, 1 and 2,
start to decompose to other ruthenium carbonyl
compounds.
3.2. The reactions of 1 and 2 with hydrogen
In the reaction of 1 with H2 the IR-spectra in
the carbonyl stretching region stayed unchanged
up to 708C. At 808C a new band appeared at
2098 cmy1. Its intensity increased when the
temperature of the reaction was increased to
908C. At 1108C this new unidentified signal at
2098 cmy was clearly visible, Fig. 3, also the
1
Ž
.
Fig. 2. IR of 2 at different temperatures 8C in octane bubbled
Ž
.
Ž
2081, 2052 and 2031
12
signals of H4Ru4 CO
Ž
.
.
12
with CO, AsRu3 CO
cmy started to appear. At 1208C the signal at
1
.
1
2098 cmy disappeared and at 1308C only the
Ž
.
signals of H4Ru4 CO
were observed in IR.
2038.9 vs, 1997.8 m, 1960.2 s, 1937.8 sh and
1708 m. With both compounds there was also
some insoluble black precipitate formed in reac-
tion vessel indicating the decomposition of the
cluster frameworks.
Thus, both compounds, 1 and 2, are stable at
elevated temperatures, 1 up to 808C and 2 up to
1208C, under CO atmosphere. At higher temper-
atures CO can replace the olefin ligand, thus
12
Thus under hydrogen atmosphere compound 1
forms first a mixture of the starting cluster,
some unidentified compound and H4Ru4 CO
and then at the higher temperatures converts to
H4Ru4 CO 12, Fig. 3 and Scheme 1. Moreover,
in the reactions above 908C some insoluble
Ž
.
12
Ž
.
Ž
.
forming the parent cluster Ru3 CO 12. These
Ž
.
Fig. 3. IR of 1 at different temperatures 8C in toluene or octane
Ž
.
.
12
Scheme 2. Reactions of 2 with H2 and CO in toluene and octane.
bubbled with H2 , AsH4Ru4 CO

(
)
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
237
black precipitate appeared indicating the decom-
position of the cluster complexes. Under 50 bar
pressure of H2 the reaction of 1 with H2 pro-
fragmentation of the cluster core before the
reorganization, which includes the addition of
hydride ligands and building up the H4Ru4-
Ž
.
Ž
.
duces H4Ru4 CO
and some insoluble black
CO
cluster. The dissociation of the olefin
12
12
precipitate.
ligands rather than carbonyl groups at elevated
For complex 2 under H2 atmosphere the
IR-spectra stayed unchanged up to 708C. At
temperatures was due to the weaker bond be-
Ž
.
Ž
.
tween Ru–C olefin than Ru–C car-bonyl .
The transformation of both starting clusters 1
and 2 under CO atmosphere at elevated temper-
atures under rigorous reaction conditions to
Ž
.
808C the signals of H4Ru4 CO
appeared in
12
IR. Above this temperature a mixture of 2 and
Ž
.
H4Ru4 CO is present up to 1008C. At 1108C
12
Ž
.
Ž
.
Ž .
only H4Ru4 CO is left in solution according
Ru3 CO
and other Ru CO -compounds was
12
12
Ž
.
9
to the IR, Fig. 4 and Scheme 2. During the
reaction of 2 with H2 there also appeared some
unidentified insoluble black precipitate.
expected. These results show that H2Ru3 CO -
C8H12 and HRu3 CO C12H19 clusters are not
Ž
.
9
very highly stabilized with olefin ligands under
hydrogen or carbon monoxide atmosphere. They
seem to be converted under H2 and CO atmo-
spheres at elevated temperatures quite easily to
Under H2 atmosphere both Ru3-olefin clus-
Ž
.
ters, 1 and 2, change to H4Ru4 CO 12. These
results are similar to those found for HRu3-
Ž
. Ž
.
Ž
.
Ž
.
CO C12H15 , which under H2 atmosphere
H4Ru4 CO
and Ru3 CO 12, respectively.
9
12
Ž
.
Ž
.
1008Cr100 atmr24 h forms H4Ru4 CO and
Steric effects of the olefin ligand influence the
stability of the Ru3 CO olefin clusters. Com-
12
w
Ž
x
Ž
.
12
cyclododecane 14 . Also under H2 atmosphere
complexes Ru4 CO 12C8H10, Ru4 CO 11C8H10
and Ru4 CO 12C8H12 were converted to H4Ru4-
Ž
In addition in the reaction of Ru4 CO 11C8H10
and Ru4 CO 12C8H12 compound 1 was formed.
.
Ž
.
pound 2 seemed to be more stable under CO
atmosphere than compound 1. This is obviously
due to the different bonding mode: the bonding
via m3-h3-CCHC-linkage in 2 stabilizes better
the cluster framework than the m3-h2-bonding
mode in 1 under CO atmosphere. Under H2
atmosphere both compounds begin to convert to
Ž
.
.
CO
in toluene or cyclohexane at 80–908C.
12
Ž
.
Ž
.
w
x
15 A temperature high enough is needed for
the reorganization of compounds 1 and 2 to take
Ž
.
Ž
.
place )708C . The reaction presumably in-
H4Ru4 CO at the same temperature.
12
cludes dissociation of the olefin ligand and the
3.3. Hydrogenation of 1-hexene catalyzed
with 1
Ž
.
The catalytic activity of H2Ru3 CO C8H12
9
in the hydrogenation of 1-hexene was studied in
the temperature range of 72–1708C. Under
1008C the conversion of 1-hexene to hexane
was low and the isomerization of 1-hexene to
trans-2-hexene, cis-2-hexene and trans-3-
hexene was the principal reaction, Table 2 and
Fig. 5. The total conversion including the iso-
merization and hydrogenation increased when
the temperature went up. The total conversion
was 99.9% at 1108C. Above 1008C the catalytic
activity of 1 in hydrogenation of 1-hexene in-
Ž
.
Fig. 4. IR of 2 at different temperatures 8C in toluene or octane
Ž
Ž
.
creased sharply, Fig. 6, being 2600 mol mol Ru
bubbled with H2 , AsH4Ru4 CO
.
12

(
)
238
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
Table 2
a
Ž
.
The contents mol% of the liquid products and 1-hexene after the hydrogenation reaction of 1-hexene at different temperatures
Hydrogenation activityb
Ž
.
T
8C
1-hexene
t-2-hexene
t-3-hexene
c-2-hexene
Hexane
Conversion
72
79
88
101
107
117
128
138
167
170
91.3
87.4
79.5
24.8
2.74
1.76
1.99
1.96
1.16
2.39
3.81
5.96
10.7
43.4
42.3
33.7
36.3
31.4
20.2
30.3
0.73
0.31
0.68
1.10
16.2
13.2
13.5
11.8
13.2
10.8
1.99
3.34
6.06
22.5
13.3
10.5
12.2
10.5
7.36
10.8
2.17
3.00
3.05
8.18
25.4
40.9
35.9
44.5
58.1
45.8
8.69
12.6
20.5
75.2
97.8
98.2
98.0
98.0
98.8
97.6
48.0
67.0
68.0
139
564
907
1590
1970)
2580)
3870c
a
Ž
.
Ž
.
Ž
.
Ž .
Ž
.
Reaction conditions: P H2 s50 bar, solventstoluene 4 ml , 1-hexene 10 ml )20 ml , catalysts 1 8 mg 0.012 mmol , reaction time
ts1 h.
b
y1
ŽŽ
.
Mol hexane mol Ru
hy1
.
.
c ts0.25 h.
y
1
.
h
at 1678C. The reaction at 1708C with a
the decomposition and the reorganization of the
catalyst have not started at these temperatures.
The increasing temperature affects the reorgani-
zation of the catalyst precursor to active inter-
mediate, but the structure of the real active form
is not known. The activity tested for H4Ru4
reaction time of 15 min leads to a even higher
activity of 3900 mol mol Ru h
The rate of the hydrogenation increases at the
same time when the starting compound begins
to transform to H4Ru4 CO
temperature in which there is only H4Ru4 CO
left in solution the hydrogenation rate increases
sharply. At the lower temperatures the isomer-
ization and the hydrogenation are slow, since
y
1
Ž
.
.
Ž
.
12
and at the same
Ž
.
Ž
.
CO
12
in the hydrogenation of 1-hexene at
12
y
1248C was 593 mol mol Ru h 1. At the same
Ž
.
temperature the activity of 1 was twice as high,
y
1
Ž
.
namely 1370 mol mol Ru h
.
Ž
.
Ž
Fig. 5. The composition of the reaction mixture mol% at different temperatures in the hydrogenation of 1-hexene catalyzed by 1 at 1708C
.
reaction time 15 min, otherwise 1 h .

(
)
K.O. Kallinen et al.rJournal of Molecular Catalysis A: Chemical 135 1998 233–239
239
ment of the olefin ligand and formation of the
Ž
.
ruthenium clusters, Ru3 CO
and H4Ru4-
CO 12, respectively. The even higher pressures
and temperatures cause the formation of the
12
Ž
.
Ž
.
other Ru CO -complexes and insoluble precipi-
tates. Compound 1 has a moderate activity in
the hydrogenation of 1-hexene. The highest ac-
tivity was achieved at 1708C being 3900 mol
y
1
hy1
.
Ž
.
hexane formed mol Ru
y1
References
Ž
.
of 1 at
Fig. 6. The hydrogenation activity of molrmol Ru h
different temperatures in the hydrogenation of 1-hexene.
w x
Ž .
S.J. Choi, J.S. Lee, Y.G. Kim, J. Mol. Catal. 85 1993 L109.
G. Jenner, G. Bitsi, J. Mol. Catal. 45 1988 235.
M. Valle, D. Osella, G.A. Vaglio, Inorg. Chim. Acta 20
1
w x
2
Ž
.
w x
3
Compound 1 shows a moderate activity in
the hydrogenation and isomerization of 1-
hexene. It has been known for long time that
and its derivatives are active in
isomerization reactions of pentenes, cyclohex-
Ž
.
1976 213.
w x
Ž
.
4
w x
5
G.A. Vaglio, M. Valle, Inorg. Chim. Acta 30 1978 161.
K.O. Kallinen, T.T. Pakkanen, T.A. Pakkanen, J. Mol. Catal.
Ž
.
99 1995 29.
Ž
.
H4Ru4 CO
12
w x
6
D.F. Shriver, H.D. Kaesz, R.D. Adams, The Chemistry of
Metal Cluster Complexes, VCH Publishers, New York, 1990,
p. 329.
w
x
ene and other unsaturated compounds 3,4,16 .
The catalytic isomerization reactions with tran-
sition metal complexes are usually considered to
proceed by a hydrogen addition–elimination in-
volving s-alkyl intermediates or by a hydrogen
abstraction–addition mechanism involving p-al-
w x
7
A.D. King Jr., R.B. King, D.B. Yang, J. Am. Chem. Soc.
Ž
.
102 1980 1028.
w x
8
J.R. Fox, W.L. Gladfelter, G.L. Geoffroy, Inorg. Chem. 19
Ž
.
1980 2574.
w x
9
K.O. Kallinen, M. Ahlgren, T.T. Pakkanen, T.A. Pakkanen,
´
J. Organomet. Chem. 510 1996 37.
Ž
.
w
w
x
10 S. Rossi, K. Kallinen, J. Pursiainen, T.T. Pakkanen, T.A.
w x
lylic species 3 and with the migratory insertion
of a double bond, which can occur at the metal
Ž
.
Pakkanen, J. Organomet. Chem. 440 1992 367.
x
11 D.F. Shriver, H.D. Kaesz, R.D. Adams, The Chemistry of
Metal Cluster Complexes, VCH Publishers, New York, 1990,
p. 212.
w x
center 4 .
w
x
12 M.R. Churchill, F.J. Hollander, J.P. Hutckinson, Inorg. Chem.
Ž
.
16 1977 2655.
w
x
13 S. Bhaduri, K.S. Gopalkrishnan, W. Clegg, P.G. Jones, G.M.
Sheldrick, D. Stalke, J. Chem. Soc. Dalton Trans., 1984, p.
1765.
4. Conclusions
Ž
.
Cyclic olefin derivatives of Ru3 CO 12, 1 and
2, are stable up to 708C under hydrogen and up
w
w
w
x
14 M.I. Bruce, M.A. Cairns, M. Green, J. Chem. Soc. Dalton
Trans., 1972, p. 1293.
x
15 A.J. Canty, A.J.P. Domingos, B.F.G. Johnson, J. Lewis, J.
Ž .
Ž .
to 808C 1 and 1208C 2 under carbon monox-
ide atmosphere. The CO or H2 atmosphere at
the elevated temperature leads to the replace-
Chem. Soc. Dalton Trans., 1973, p. 2056.
x
16 G.A. Vaglio, D. Osella, M. Valle, Transition Met. Chem. 2
Ž
.
1977 94.