Catalytic hydrogenation of aromatics under biphasic conditions: Isolation and structural characterisation of the cluster intermediate [(η6-C6Me6)2(η 6-C6H6)Ru3(μ2-H) 2(μ2-OH)(μ3-O)]+

Article abstract of DOI:10.1016/S0022-328X(00)00773-7

The water-soluble cluster cation [(η⁶-C₆Me₆)₂(η ⁶-C₆H₆)Ru₃(μ₂-H) ₃(μ₃-O)]⁺ (2) catalyses the hydrogenation of benzene and benzene derivatives to give the corresponding cyclohexanes under biphasic conditions. The catalytic activity of 2 depends markedly on the substrate, an extremely high activity being observed for ethylbenzene. The cationic species present in the catalytic mixture of the ethylbenzene hydrogenation could be isolated as the tetrafluoroborate salt and characterised as the cation [(η⁶-C₆Me₆)₂(η ⁶-C₆H₆)Ru₃(μ₂-H) ₂(μ₂-OH)(μ₃-O)]⁺ (3). With 3 as the catalyst, the catalytic activity is also much higher for other benzene derivatives.

Full text of DOI:10.1016/S0022-328X(00)00773-7

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 621 (2001) 103–108
Catalytic hydrogenation of aromatics under biphasic conditions:
isolation and structural characterisation of the cluster intermediate
[(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)2(m2-OH)(m3-O)]+
Matthieu Faure, Ana Tesouro Vallina, Helen Stoeckli-Evans, Georg Su¨ss-Fink *
Institut de Chimie, Uni6ersite´ de Neuchaˆtel, Case postale 2, CH-2007 Neuchaˆtel, Switzerland
Received 3 July 2000; received in revised form 24 August 2000
Abstract
The water-soluble cluster cation [(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)3(m3-O)]+ (2) catalyses the hydrogenation of benzene and
benzene derivatives to give the corresponding cyclohexanes under biphasic conditions. The catalytic activity of 2 depends
markedly on the substrate, an extremely high activity being observed for ethylbenzene. The cationic species present in the catalytic
mixture of the ethylbenzene hydrogenation could be isolated as the tetrafluoroborate salt and characterised as the cation
[(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)2(m2-OH)(m3-O)]+ (3). With 3 as the catalyst, the catalytic activity is also much higher for other
benzene derivatives. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Arene ligand; Aromatic hydrogenation; Cluster; Oxo ligand; Ruthenium; Trinuclear; Water-soluble catalyst
C6H6)4Ru4H6]Cl2 [4], dissolved in water. In all cases, we
were able to detect the trinuclear oxo-capped cation
[(h6-C6H6)3Ru3(m2-H)2(m2-Cl)(m3-O)]+ (1) in the reac-
tion mixture [3]. This cation, which we had isolated and
characterised as the perchlorate salt [5], is considered to
be the catalytically active species, since the isolated
perchlorate salt of 1 is much more active in aqueous
solution than any other benzene ruthenium precursor
[3]. Unfortunately, under the catalytic conditions (hy-
drogen pressure), the trinuclear cluster cation 1 is not
stable: it is converted into a mixture of the tetranuclear
cluster cations [(h6-arene)4Ru4H4]2+ and [(h6-arene)4-
1. Introduction
Water has become an attractive solvent for catalytic
reactions, since the first industrial implementation of a
biphasic propylene hydroformylation process catalysed
by water-soluble rhodium phosphine complexes in a
100 000 t per year oxo plant (Ruhrchemie/Rhoˆne–Pou-
lenc) in 1984 proved to be successful [1]. As a conse-
quence, aqueous-phase organometallic catalysis became
a major issue of both applied and fundamental research
[2]. Water is not only a cheap and environmentally
friendly solvent, it also allows, in biphasic systems, the
facile separation of the catalyst, remaining in the
aqueous phase, from the products and the substrate
being in the organic phase, thus overcoming the cardi-
nal problem of homogeneous catalysis.
Ru4H6]2+
.
Since the corresponding tetranuclear hydrido clusters
are not accessible with the sterically hindered hexa-
methylbenzene ligand [6], we intended to design a
cationic trinuclear oxo-capped cluster which is an active
hydrogenation catalyst in aqueous solution, while being
stable under hydrogen pressure (catalytic conditions).
This aim was achieved by the synthesis of the mixed-lig-
and cluster cation [(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)3(m3-
O)]+ (2), accessible from [(h6-C6H6)2Ru3(H2O)3]2+ with
[(h6-C6Me6)2Ru3(m2-H)3]+ in aqueous solution [7].
Cation 2 is indeed catalytically active for the hydro-
genation of aromatic compounds under biphasic condi-
We have recently found that benzene and benzene
derivatives are efficiently hydrogenated to the corre-
sponding cyclohexanes under biphasic conditions,
catalysed by benzene ruthenium complexes such as
(h6-C6H6)2Ru2Cl4 [3], [(h6-C6H6)4Ru4H4]Cl2 or [(h6-
* Corresponding author. Tel.: +41-32-7182405; fax: +41-32-
7182511.
E-mail address: georg.suess-fink@unine.ch (G. Su¨ss-Fink).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00773-7

104
M. Faure et al. / Journal of Organometallic Chemistry 621 (2001) 103–108
Table 1
tions and does not convert into a tetranuclear cluster; it
is found intact at the end of the catalytic reaction [7].
To our surprise, we observed an unusually high
catalytic activity of 2 for the hydrogenation of ethyl-
benzene to give ethylcyclohexane under biphasic condi-
tions (110°C, 60 bar): A catalytic turnover of 850 cycles
is achieved after just 15 min, whereas several hours are
required for a similar turnover number of benzene,
toluene, n- and i-propylbenzene. Only in the case of
ethylbenzene could the cluster cation 2 not be recovered
at the end of the catalytic reaction; it had changed into
a more active species. We therefore decided to study in
detail the reaction of 2 with ethylbenzene and hydrogen
in water and to characterise the species formed.
,
Selected bond lengths (A) and angles (°) for 3
Interatomic distances
Ru(1)ꢀRu(2)
Ru(2)ꢀRu(1a)
Ru(1)···Ru(1a)
Ru(1)ꢀO(1)
Ru(1)ꢀO(2)
Ru(1a)ꢀO(1)
Ru(1a)ꢀO2(1)
Ru(1)ꢀH(1)
Ru(2)ꢀH(1)
O(2)ꢀH
Ru(1)ꢀC(1)
Ru(1)ꢀC(2)
Ru(1)ꢀC(3)
Ru(1)ꢀC(4)
Ru(1)ꢀC(5)
Ru(1)ꢀC(6)
Ru(2)ꢀC(13)
Ru(2)ꢀC(14)
Ru(2)ꢀC(15)
Ru(2)ꢀC(16)
2.780(1)
2.780(1)
3.196(1)
2.041(4)
2.086(5)
2.041(4)
2.086(5)
1.78(8)
1.72(8)
0.77(9)
2.215(6)
2.194(6)
2.204(6)
2.192(6)
2.196(6)
2.206(6)
2.227(10)
2.223(7)
2.190(6)
2.223(9)
2. Results and discussion
The reaction of [(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)3(m3-
O)]+ (2) with ethylbenzene under hydrogen pressure in
aqueous solution results in the formation of the tri-
nuclear cluster [(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)2(m2-
OH)(m3-O)]+ (3) according to Scheme 1. The reaction is
carried out at room temperature in neutral solution
(pH 6–7) over a period of 2 h. Cation 3 crystallises
from acetone as the tetrafluoroborate salt.
Hydrogen bond
O(1)···O(1W)
2.71(1)
Bond angles
Ru(1a)ꢀRu(2)ꢀRu(1)
Ru(1a)ꢀO(1)ꢀRu(1)
Ru(1a)ꢀO2(1)ꢀRu(1)
Ru(1)ꢀO(1)ꢀRu(2)
Ru(1a)ꢀO(1)ꢀRu(2)
70.17(3)
103.1(3)
100.0(3)
86.6(2)
86.6(2)
The product is characterised by NMR and IR spec-
troscopy, mass spectroscopy, micro-analysis, and by a
1
single-crystal X-ray structure analysis. In the H-NMR
spectrum in D2O, 3 gives rise to a singlet (l=
5.83 ppm) for the hydroxo ligand, a singlet (l=
Scheme 1.
5.37 ppm) for the benzene ligand and
a singlet
(l=2.03 ppm) for the two equivalent hexamethylben-
zene ligands; the two equivalent hydrido ligands appear
as a singlet (l= −13.56 ppm) in the high-field region.
In the electrospray mass spectrum, the molecular peak
is observed at m/z 744 with the expected Ru3 isotope
pattern (calculated for 102Ru: 743). The w(OꢀH) absorp-
tion is observed in the infrared spectrum at 3413 cm−1
(KBr).
Suitable crystals of the tetrafluoroborate salt of 3
were obtained from acetone upon slow evaporation of
the solvent. A single-crystal X-ray structure analysis
was performed with one of the orange block-shaped
crystals. The tetragonal crystal contains eight formula
units and eight water molecules per unit cell; half of the
cation, half of the anion and half of the water molecule
per asymmetric unit. The tetrafluoroborate anion is
strongly disordered. The structure of 3 is depicted in
Fig. 1; selected bond lengths and angle are given in
Table 1.
Fig. 1. Molecular structure of cation 3.

M. Faure et al. / Journal of Organometallic Chemistry 621 (2001) 103–108
105
biphasic system (Scheme 3). Cation 3 can be recovered
unchanged as the tetrafluoroborate salt after a catalytic
run from the aqueous phase.
With benzene, the reaction is almost complete within
15 min, corresponding to a catalytic turnover fre-
quency of 5466 h−1. The activity is much higher than
that reported for the other catalysts in the homoge-
neous phase, viz. [(h6-C6Me6)Ru2(m2-H)(m2-Cl)2]Cl2:
241 h−1 [8], (h5-C5H5)2Rh2Cl4: 23 h−1 [9], (h3-
C3H5)Co[(P(OMe)3)3]3: 0.7 h−1 [10]. The catalytic acti-
vity of 3 decreases in the case of substituted benzene
derivatives (Table 2). Toluene is hydrogenated more
slowly than benzene, presumably due to the steric hin-
drance of the alkyl substituent, which, however, is
counterbalanced by the increased electronic density of
the aromatic cycle. Unfortunately, the hydrogenation
of functionalised benzene derivatives is not very selec-
tive: Cyclohexylbenzene and biphenyl give the same
product, the catalytic turnover frequency being
Scheme 2.
Scheme 3.
The cluster cation 3 consists of an isosceles triangle
of three ruthenium atoms being capped by a m3-oxo
ligand. The two hydrido ligands bridging the two ruthe-
nium–ruthenium bonds could be localised and fully
refined. The third ruthenium–ruthenium distance
,
Ru(1)ꢀRu(1a) is too long [3.196(1) A] for a metal–
1000 h−1
.
metal bond, but this open edge is bridged by a m2-hy-
droxo ligand. The molecular arrangement of 3 shows
an almost perfect Cs symmetry. The oxo ligand is
mirror-symmetrically coordinated to the Ru3 triangle,
two ruthenium–oxygen distances being longer
Table 3 shows the influence of methyl substitution in
the aromatic cycle on the hydrogenation capacity. Sur-
prisingly, the more sterically hindered ortho-xylene is
more easily hydrogenated than the less hindered meta-
and para-xylenes. 1,2,4,5-Tetramethylbenzene is not hy-
drogenated all. Table 4 shows the catalytic activities of
cation 3 and cation 2. Cation 3 is up to 50 times faster
than cation 2. We suppose 3 to be the catalyst precur-
sor, although we could detect 3 only in the case of
ethylbenzene hydrogenation.
,
[Ru(1)ꢀO(1), Ru(1a)ꢀO(1): 2.041(4) A] in comparison
with the third ruthenium–oxygen bond in the mirror
,
plane [Ru(2)ꢀO(1): 2.014(6) A]. The water molecule is
hydrogen-bonded to the m3-oxo ligand [O···O distance
,
2.757(9) A] and cannot be removed in vacuo. Cluster 3
is an analogue of the chloro derivative 1 [5] found in
the catalytic arene hydrogenation by Ru2(h6-
C6Me4)3Cl4 in water [3] (Scheme 2).
Cluster 3 was indeed found to be a very active
catalyst: it catalyses the hydrogenation of benzene and
various benzene derivatives in aqueous solution to give
the corresponding cyclohexane derivatives with higher
turnover numbers than the other arene ruthenium
derivatives. The reaction proceeds under hydrogen
pressure (60 bar) at 110°C with vigorous stirring of the
The precise role of the cluster cation [(h6-
C6Me6)2(h6-C6H6)Ru3(m2-H)2(m2-OH)(m3-O)]+ (3) in the
catalytic hydrogenation of benzene and benzene deriva-
tives is not clear. In the case of the hydrogenation of
ethylbenzene, no substitution of a benzene or a hexa-
methylbenzene ligand by the ethylbenzene substrate is
observed; 3 is recovered unchanged. This means that
the aromatic substrate is not coordinated (by substitu-
tion) to one of the ruthenium atoms during the catalytic
Table 2
Hydrogenation of benzene and monosubstituted derivatives under biphasic conditionsa
Substrate
Product
Yield (%)b
Time (h)
TONc
TOF (h−1 d
)
Benzene
Toluene
Cyclohexane
91.1
92.3
85.3
0.25
0.33
0.25
0.33
0.33
1.0
911
923
853
5466
2769
3413
2913
3000
1000
1000
Methylcyclohexane
Ethylcyclohexane
Propylcyclohexane
Isopropylcyclohexane
Bicyclohexyl
Ethylbenzene
Propylbenzene
Isopropylbenzene
Cyclohexylbenzene
Biphenyle
97.1
971
100.0
100.0
100.0
1000
1000
1000
Bicyclohexyl
1.0
a Conditions: catalyst [(h6-C6H6)(h6-C6Me6)2Ru3(m2-H)2(m2-OH)(m3-O)][BF4] (cation 3) (0.01 mmol), 5 ml H2O, catalyst/substrate ratio 1/1000,
temperature 110°C, hydrogen pressure 60 bar, stirred at 900 min−1
b Measured by GC.
.
c Catalytic turnover number: moles of substrate transformed per mole of catalyst.
d Catalytic turnover frequency: moles of substrate transformed per mole of catalyst per hour.
e Substrate dissolved in cyclohexane (10 ml).

106
M. Faure et al. / Journal of Organometallic Chemistry 621 (2001) 103–108
Table 3
Hydrogenation of di-,tri- and tetra-substituted derivatives under biphasic conditionsa
Substrate
Product
Yield (%)b
Time (h)
0.25
TONc TOF (h−1 d
)
o-Xylene
trans-1,2-Dimethylcyclohexane
cis-1,2-Dimethylcyclohexane
10.0
77.5
875
974
880
760
0
3736
2922
2640
1520
0
m-Xylene
trans-1,3-Dimethylcyclohexane
cis-1,3-Dimethylcyclohexane
78.1
18.1
0.33
0.33
0.5
3
p-Xylene
trans-1,4-Dimethylcyclohexane
cis-1,4-Dimethylcyclohexane
26.5
69.5
1,3,5-Trimethylbenzene
1,2,4,5-Tetramethylbenzenee
trans,trans-1,3,5-Trimethylcyclohexane
cis,cis-1,3,5-Trimethylcyclohexane
60.6
13.5
trans,trans,trans-1,2,4,5-Tetramethylcyclohexane
cis,cis,cis-1,2,4,5-Tetramethylcyclohexane
0.0
0.0
a Conditions: catalyst [(h6-C6H6)(h6-C6Me6)2Ru3(m2-H)2(m2-OH)(m3-O)][BF4] (cation 3) (0.01 mmol), 5 ml H2O, catalyst/substrate ratio 1/1000,
temperature 110°C, hydrogen pressure 60 bar, stirred at 900 min−1
b Measured by GC.
.
c Catalytic turnover number: moles of substrate transformed per mole of catalyst.
d Catalytic turnover frequency: moles of substrate transformed per mole of catalyst per hour.
e Substrate dissolved in cyclohexane (10 ml).
Table 4
Comparison of catalytic turnover frequencies of cations 2a and 3a
Substrate
Product
2
3
TOF(3)/TOF(2)
Time (h)
TOF (h−1 b
)
Time (h)
TOF (h−1 b
)
Benzene
Toluene
Cyclohexane
Methylcyclohexane
Ethylcyclohexane
Propylcyclohexane
Isopropylcyclohexane
Bicyclohexyl
Bicyclohexyl
trans-1,2-Dimethylcyclohexane
cis-1,2-Dimethylcyclohexane
trans-1,3-Dimethylcyclohexane
cis-1,3-Dimethylcyclohexane
trans-1,4-Dimethylcyclohexane
cis-1,4-Dimethylcyclohexane
3.5
2.2
289
440
0.25
0.33
0.25
0.33
0.33
1.0
5466
2769
3413
2913
3000
1000
1000
3736
18.9
6.3
Ethylbenzene
Propylbenzene
Isopropylbenzene
Cyclohexylbenzene
Biphenylc
8.0
14.0
2.0
14.5
14.0
117
71
500
74
24.9
42.3
2.0
13.5
52.6
1.0
0.25
o-Xylene
71
m-Xylene
p-Xylene
3.0
2.0
232
396
71
0.33
0.33
0.5
2922
2640
1520
12.6
6.7
1,3,5-Trimethylbenzene trans,trans-1,3,5-Trimethylcyclohexane
cis,cis-1,3,5-Trimethylcyclohexane
14.0
21.4
a Catalyst (cation 2 or 3) as tetrafluoroborate salt (0.01 mmol), catalyst/substrate ratio 1/1000, temperature 110°C, hydrogen pressure 60 bar,
stirred at 900 min−1
.
b Catalytic turnover frequency: moles of substrate transformed per mole of catalyst per hour.
c Substrate dissolved in cyclohexane (10 ml).
3. Experimental
process; it seems that it is only loosely bound to the
open triangular face of the triruthenium framework,
opposite to the oxo cap, a phenomenon that may be
explained by interactions between the aromatic lig-
ands and the aromatic substrate in aqueous solution.
Similar phenomena are observed in inclusion com-
plexes of benzene–ruthenium units and cyclodextrines
[11].
3.1. General
All manipulations were carried out by routine under
nitrogen atmosphere, using Standard Schlenk tech-
niques, although the compounds are not air-sensitive.
The twice-distilled water was degassed and saturated

M. Faure et al. / Journal of Organometallic Chemistry 621 (2001) 103–108
107
with nitrogen prior to use. The NMR spectra were
recorded on a Varian Gemini 200 BB instrument; the
treatment of the spectra was performed using a SUN
Varian station. The IR spectra were recorded on a
Perkin–Elmer FT-IR 1720 X spectrometer (4000–
400 cm−1) as KBr pellets. Micro-analytical data were
obtained from the Service de Microchimie, Universite´
de Gene`ve. Electron mass spectra were obtained in
positive-ion mode with an LCQ Finnigan mass spec-
trometer using acetone as the mobile phase. The organic
phase containing products and substrate was analysed
by gas chromatography (GC) on a DANI 86.10 HT gas
chromatograph using a CHROMPACK Carbowax
WCOT fused silica column. The starting cation [(h6-
C6Me6)2(h6-C6H6)Ru3(m2-H)3(m3-O)]+ (2) [7] was syn-
twice-distilled water. To this solution, placed in a 100 ml
stainless steel autoclave, 1.225 ml of ethylbenzene were
added. After purging four times with hydrogen, the
autoclave was pressurised with hydrogen (60 bar) and
held at room temperature under vigorous stirring of the
reaction mixture (900 rpm). After 2 h the pressure was
released. The two-phase system was separated by
decanting. The yellow aqueous phase was evaporated
to dryness; the residue was dissolved in acetone, and
crystallisation at −20°C gave [(h6-C6Me6)2(h6-
C6H6)Ru3(m2-H)2(m2-OH)(m3-O)][BF4] (cation 3). Yield
7 mg (8.27×10−3 mmol, 43%). Anal. Found: C, 42.86;
H, 5.70. Calc. for C30H45B1F4O2Ru3·H2O: C, 42.61; H,
5.60%. IR(cm−1): 3413 (w), w(OꢀH); 3011 (w),
w(CꢀHar); 2930 (s), 2853 (m), w(CꢀH); 1438 (m), 1385
(m), w(C=C); 1084 (br, vs), w(BF4).
thesised
from
(h6-C6Me6)2Ru2Cl4
[12]
and
(h6-C6H6)2Ru2Cl4 [13] according to published methods.
3.3. X-ray structure determination of complex 3
3.2. Synthesis of
An orange crystal of [(h6-C6Me6)2(h6-C6H6)Ru3(m2-
H)2(m2-OH)(m3-O)][BF4] (cation 3) was mounted on a
Stoe imaging plate diffractometer system (Stoe & Cie,
1995) equipped with a one-circle € goniometer and a
graphite monochromator. Data collection was per-
formed at −120°C using Mo–Ka radiation (u=
[(p6-C6Me6)2(p6-C6H6)Ru3(v2-H)2(v2-OH)(v3-O)]+ (3)
[(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)3(m3-O)][BF4] (cation
2) (16 mg, 1.93×10−2 mmol) was dissolved in 5 ml of
,
0.710 73 A). 200 exposures (3 min per exposure) were
obtained at an image plate distance of 70 mm with
0B€B200° and with the crystal oscillating through 1°
in €. The resolution range was Dmin–Dmax 12.45–
Table 5
Crystallographic and selected experimental data for 3
Compound
[(h6-C6H6)(h6-C6Me6)2Ru3(m2-H)2-
,
0.81 A. The structure was solved by Patterson methods
(m2-OH)(m3-O)][BF4]·H2O
using SHELXS-97 [14]. Refinement was done by full-ma-
trix least squares on F2 with SHELXL-97 [15]. The
compound crystallises in the tetragonal system (cen-
trosymmetric space group I4/m) with half a molecule of
3 as well as half a water molecule and half of an
extremely disordered BF−4 anion per asymmetric unit.
The BꢀF distances in the distorted BF−4 anion were
constrained to their theoretical values [16]. The hydro-
gen atoms attached to the water molecule were derived
from Fourier difference maps and constrained to their
theoretical values [16]. The positions of the hydride
H1ꢀRu and the hydroxide H atom were also found as
electron density peaks and refined while the remaining
hydrogen atoms of the organic ligand were included in
calculated positions and treated as riding atoms using
SHELXL-97 default parameters. All non-hydrogen atoms
(except F3, F3a, F4, F4a and F4b atoms, which were
isotropically refined) were refined with anisotropic dis-
placement parameters. Selected bond lengths and bond
angles are listed in Table 1. Crystallographic details for
compound 3 are summarised in Table 5. The figure was
Empirical formula
Crystal colour
C30H47B1F4O3Ru3 (cation 3)
Orange
Block
Crystal shape
Crystal size (mm3)
0.30×0.20×0.15
845.70
Tetragonal
I4/m
18.2490(9)
18.2490(9)
20.2191(10)
90
90
90
6733.6(6)
8
1.668
1.379
3392
1.65–26.05
153(2)
26 603
3355
Mr (g mol−1
)
Crystal system
Space group
,
a (A)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
Dc (g cm−3
)
v (Mo–Ka) (mm−1
F(000)
)
q scan-range (°)
T (K)
Reflections measured
Independent reflections
Reflections observed [I\2|(I)] 2580
Final R indices [I\2|(I)]a
R indices (all data)a
Goodness of fit
R1=0.0501, wR2=0.1467
R1= 0.0643, wR2=0.1551
1.030
drawn with PLATON/PLUTON [17].
Maximum D/|
0.001
+1.539, −2.789
3.4. Catalytic runs
Residual density: maximum,
minimum Dz (e−
A
)
−3
,
In a typical experiment, a solution of 0.01 mmol of
a R1=S ꢀꢀFoꢀ−ꢀFcꢀꢀ/S ꢀFoꢀ, wR2=[S w(Fo2−F2c)2/S (wFo4)]1/2
.
[(h6-C6Me6)2(h6-C6H6)Ru3(m2-H)2(m2-OH)(m3-O)][BF4]

108
M. Faure et al. / Journal of Organometallic Chemistry 621 (2001) 103–108
(cation 3) in 5 ml of twice-distilled water was placed in
a 100 ml stainless steel autoclave, and 10 mmol of the
organic substrate was added. After purging four times
with hydrogen, the autoclave was pressurised with hy-
drogen (60 bar) and heated to 110°C in an oil bath
under vigorous stirring of the reaction mixture
(900 rpm). After the reaction time indicated in Tables 3
and 4, the autoclave was cooled with ice water to room
temperature, and the pressure was released. The two-
phase system was separated by decanting; the aqueous
phase was evaporated to dryness, the residue dissolved
in D2O and analysed by NMR spectroscopy. The or-
ganic phase containing the products and substrate was
analysed by GC and NMR spectroscopy.
References
[1] (a) E. Wiebus, B. Cornils, Chem. Ing. Tech. 66 (1994) 916. (b) B.
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Full tables of atomic parameters, bond lengths and
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Financial support of this work by the Swiss National
Science Foundation and a generous loan of rutheni-
um(III) chloride hydrate from the Johnson Matthey
Research Centre are gratefully acknowledged.
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.