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and [Au
2
L
1
2
-H
+
]
+
(Table
2
,
a
00
¼
0,
b
00
¼
2,
c
00
¼
2,
d
00
¼
0,
n
00
¼
1) and a ligand
loss to generate [Au
5
L
1
3
-H
+
]
2+
.
2.6 Formation of Carbides, Hydroxides, Phosphides
and Tellurides from Miscellaneous Top-Down
Approaches
Top-down approaches that utilise particle or photon-surface interactions have been
used to 'synthesise' a range of clusters in which gold is combined with other
elements. Most of these studies have only used MS to determine the cluster ion
stoichiometries, and thus their structures remain unknown. Exceptions are Wang's
photoelectron spectroscopy studies on gold cluster anions containing other
elements, which are discussed further in Sect.
3.6
.
Gold carbide clusters, Au
x
C
y
+
, have been formed in several ways, including the
reactions of 'hot' laser-desorbed gold cluster cations with ethene and alkanes [
65
],
laser vaporisation of gold-coated carbon rods [
161
] and via impact of the C
60
anion at keV energies onto gold surfaces [
162
]. The latter approach produces both
gold carbide cluster cations and anions. The structures of these gold carbide cluster
ions have intrigued scientists and theoretical modelling has been employed to
examine potential isomers [
161
-
164
]. Many of the isomers found consist of
gold atoms coordinated to the end of carbon chains, and thus these do not possess
gold-gold bonds.
Caesium ion bombardment at keV energies of gold surfaces prepared by vapour
deposition of gold onto silver or glass substrates produces a wide range of anions
containing a combination of different numbers of gold, oxygen or hydrogen
[
165
]. The source of oxygen and hydrogen was assumed to be due to a surface
layer of adsorbed H
2
O and O
2
or their derived products. Anions with both even and
odd electron counts were observed with nearly similar abundances for the oligo-
meric series Au
x
O
2
x
H
y
and Au
x
O
2
x
+1
H
z
(where
x
¼ 2 or 3). Although the
structures of these clusters were not determined, the authors made analogies to
the known structures of neutral gold fluorides.
Finally laser ablation of nanogold mixtures with either red phosphorus or
tellurium has been used to produce a range of gold phosphide [
166
] and gold
telluride [
167
] cluster ions. A rich set of gold phosphide cations and anions were
identified including AuP
n
+
1, 2-88 (even numbers)); Au
2
P
n
+
(
n
¼
(
n
¼
1-7,
14-16, 21-51 (odd numbers)); Au
3
P
n
+
1-6, 8, 9, 14); Au
4
P
n
+
(
n
¼
(
n
¼
1-9,
14-16); Au
5
P
n
+
(
n
1-6, 14, 16); Au
6
P
n
+
(
n
1-6); Au
7
P
n
+
(
n
1-7); Au
8
P
n
+
¼
¼
¼
1-6, 8); Au
9
P
n
+
(
n
1-10); Au
10
P
n
+
(
n
1-8, 15), Au
11
P
n
+
(
n
(
n
¼
¼
¼
¼
1-6) and
Au
12
P
n
+
(
n
1, 2, 4); AuP
n
(
n
4-6, 8-26, 30-36 (even numbers), 48); Au
2
P
n
¼
¼
2-5, 8, 11, 13, 15, 17); Au
3
P
n
(
n
6-11, 32); Au
4
P
n
(
n
(
n
¼
¼
¼
1, 2, 4, 6, 10);
