Chemistry Reference
In-Depth Information
Fig. 11 Molecular orbital interaction diagram for [Au
6
C(PPh
3
)
6
]
2+
. Similar analyses may be
constructed for trigonal bipyramidal [Au
5
N(PPh
3
)
5
]
2+
and tetrahedral [Au
4
O(PPh
3
)
4
]
2+
For gold clusters with 8 metal atoms or more metals the central cavity can
accommodate a metal atom with a comparable radius. Therefore, a wide range of
gold clusters with interstitial gold, rhodium, palladium and platinum interstitial
atoms have been synthesised and characterised crystallographically. The introduc-
tion of an interstitial metal with nd, (
n
+ 1)s and (
n
+ 1)p valence orbitals for
spherical clusters is represented schematically in Fig.
12
for an icosahedral cluster.
The interstitial metal atom has d, s and p valence orbitals and the s and p valence
orbitals symmetry match the skeletal molecular orbitals [S
σ
] and [P
σ
] in much the
same way as that described above for carbon. The d orbitals of the gold atom are
stabilised somewhat by a weaker interaction with the D
σ
antibonding skeletal
molecular orbitals, and therefore a spherical cluster is characterised by the
