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d
n
9
r
4
n
g
|
7
Figure 4.7 Proposed mechanism of selective oxidation of styrene catalyzed by a
Au
25
(SR)
18
cluster. For clarity, the thiolate ligands are not shown. (Dark
gray: Au atoms of the core, light gray: Au atoms of the shell).
(Reproduced with permission from ref. 37, Copyright Wiley-VCH Verlag
GmbH & Co. KGaA, 2010).
.
interconverted by using O
2
/peroxide as an oxidant. This process could be
responsible for the O
2
or tert-butyl hydroperoxide (TBHP) activation prior
to styrene oxidation during the catalytic process. Jin and co-workers have
also proposed a mechanism for the selective oxidation of styrene catalyzed
with Au
25
(SR)
18
nanoclusters (Figure 4.7).
37
Recently Liu et al.
39
have investigated styrene oxidation reaction using two
different Au
25
clusters capped with different ligands. They made an attempt
to correlate fundamental clectronic structure with styrene oxidation catalysis
by atomically precise mixed-ligand (thiol and phosphine) biicosahedral
structure [Au
25
(PPh
3
)
10
(SC
12
H
25
)
5
Cl
2
]
21
and thiol-stabilized icosahedral
core-shell structure [Au
25
(SCH
2
CH
2
Ph)
18
]
clusters by using a combination
of X-ray absorption spectroscopy (XAS) and ultraviolet photoemission spec-
troscopy (UPS).
4.2.2.3 Selective Hydrogenation of a,b-Unsaturated Ketones/
Aldehydes
Selective hydrogenation of a,b-unsaturated ketones/aldehydes to the cor-
responding alcohols is a well investigated chemical reaction catalyzed by a
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