Chemistry Reference
In-Depth Information
Table 5 Gas-phase IR spectroscopy of ligated neutral and anionic gold clusters. Experimentally
observed absorption bands and structures are listed
Absorption wave
number(s) (cm
1
)
Gold cluster
Ligand Structure
References
Au
4
0
1,502
O
2
2D distorted Y-shaped
[
226
]
Au
7
0
1,063
O
2
2D centred hexagone
[
226
]
Au
9
0
1,064
O
2
3D bicapped trigonal prism
[
226
]
Au
11
0
1,058
O
2
-
[
226
]
Au
21
0
1,069
O
2
-
[
226
]
Au
2
0
ca. 57
Kr
-
[
224
]
Au
3
0
ca. 95
Kr
Obtuse-angled isosceles triangle
[
224
]
Au
4
0
ca. 150
Kr
2D rhombus and Y-shaped
[
224
]
Au
7
0
165, 186, 201
Kr
2D structure
[
224
]
Au
19
0
149, 167
Kr
Truncated pyramid
[
225
]
Au
20
0
148
Kr
Tetrahedral
[
225
]
Au
4
ca. 1,060
O
2
2D distorted Y-shape
[
232
]
Au
6
ca. 1,060
O
2
2D D
3h
[
232
]
Au
8
1,043, 1,059, 1,102 O
2
Planar edge-capped hexagon
[
232
]
Au
10
ca. 1,060
O
2
Planar - contains a 7 Au
hexagonal motif
[
232
]
Au
x
(
x
¼ 12-20)
ca. 1,060
O
2
-
[
232
]
Several gas-phase IR spectroscopic studies aimed at understanding the structures
of small gold cluster anions, cations and neutrals were reported [
224
-
232
] and are
the subject of another chapter in this topic by A. Fielicke et al. Table
5
above is a
summary of the absorption wave numbers observed for selected neutral and anionic
gold clusters.
3.4 UV-Vis Spectroscopy
Gas-phase UV-Vis spectroscopic studies of gold clusters have been rarely reported.
The first report on neutral and cationic clusters of the form Au
n
(
n
¼
7, 9, 11, 13)
and Au
n
+
(
n
6-13) appeared around 20 years ago [
233
]. The authors highlighted
the odd-even alterations in the UV-Vis spectra; however, they concluded that little
structural information could be extracted from these spectra. Thus, only Au
13
was
reported to be consistent with an icosahedral structure. Recently, the UV-Vis
spectrum of the glutathione-protected gold cluster [Au
25
(SG)
18
-6H]
7
was
reported [
234
]. Although no structural information was extracted, the authors
have shown that the UV-Vis spectrum for this AuNC is similar in both the gas
and solution phases.
¼
