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G
(2 mL). NaBH4 (3.6 mg, 9.510À5 mol, 2.5 equivs.) dissolved
in water (2 drops) was quickly added to the mixture under
vigorous stirring. Immediately, 2,2’-bipyridine (2.9 mg, 1.9
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quickly added under vigorous stirring to mixture. Then,
THF was eliminated under reduced pressure and the colloi-
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duction occurs instantaneously and is characterized by a
colour change from red to black. The obtained suspensions
are stable for several weeks. A similar reduction procedure
has been carried out with molecular hydrogen as reducing
agent. Nanoparticle synthesis was performed under 40 bar
H2 during 40 mn, followed by a stabilization step with addi-
tion of 2,2’-bipyridine.
General Procedure for Hydrogenation under
Hydrogen Pressure
The stainless steel autoclave was charged with 2 mL of bi-
pyridine-stabilized Rh(0) colloidal suspension in [BMI][PF6]
G
and a magnetic stirrer. The appropriate substrate (3.810À5
mol, 100 equivs.) was added into the autoclave and dihydro-
gen was admitted to the system at constant pressure up to
40 atm. The mixture was heated to 808C and stirred during
15 h. After cooling to ambient temperature, the mixture was
dispersed into 10 mL of CH3CN and centrifuged (g=
20152 msÀ2) during 10 min for the precipitation of nanopar-
ticles. The sample was analyzed by gas chromatography.
For the recycling procedure, after 15 h of reaction and
after cooling back to ambient temperature, the products
were extracted by liquid-liquid extraction and decantation
with diethyl ether until complete elimination of organic
products from the ionic liquid phase. After drying, the col-
loidal suspension was reused in a second hydrogenation in
the cleaned autoclave.
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Acknowledgements
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