Chemistry Reference
In-Depth Information
Table 2 The general formula [Au
(0)
a
Au
(+1)
b
L
c
A
(
1)
d
n
H
+
]
z
(Eq. (
5
)) can be tabulated and
used to account for the fragmentation channels of a mass-selected gold cluster ion
abcdnz
Mass-selected precursor ion [Au
(0)
a
Au
(+1)
b
L
c
A
(
1)
d
n
H
+
]
z
abcdnz
Product ion [Au
(0)
a
Au
(+1)
b
L
c
A
(
1)
d
n
H
+
]
z
a
0
b
0
c
0
d
0
n
0
z
0
Loss from precursor to form product [Au
(0)
a
Au
(+1)
b
L
c
A
(
1)
d
n
H
+
]
z
a
00
b
00
c
00
d
00
n
00
z
00
Fig. 18 Linear ion trap low-energy collision-induced dissociation of [Au
5
L
4
-H
+
]
2+
. The most
intense peak in the cluster is represented by the
m/z
value.
Asterisk
refers to the mass-selected
precursor ion peak [Au
5
L
4
-H
+
]
2+
. Figure adapted from [
113
]
1.
Ligand loss
occurs where no dissociation of the gold cluster core remains inert.
2.
Core fission
occurs when the cluster core undergoes fragmentation. As a subset
of core fission, the precursor ion can also split into complimentary ion pairs.
3.
Ligand activation
occurs when the protecting ligand fragments undergo frag-
mentation via loss of functional groups or rearrangement.
Table
2
summarises how precursor ion fragmentation can be accounted for using
the general formula [Au
(0)
a
Au
(+1)
b
L
c
A
(
1)
d
-
n
H
+
]
z
, (Eq. (
5
)), for gold cluster ions.
For instance, the fragmentation of [Au
5
L
1
4
-H
+
]
2+
, where L
dppm, has been
studied [
113
] via collision-induced dissociation (CID) in a LTQ FT hybrid linear
ion-trap mass spectrometer. Mass selection of [Au
5
L
1
4
-H
+
]
2+
and subsequent ion
activation, Fig.
18
, results in the mass-selected precursor, [Au
5
L
1
4
-H
+
]
2+
having
two main fragmentation channels. A charge separation fragmenting into the com-
plimentary ion pairs [Au
3
L
1
2
]
+
(Table
2
,
a
0
¼
¼
2,
b
0
¼
1,
c
0
¼
2,
d
0
¼
0,
n
0
¼
0)
