Peripheral gold atoms

The theoretical treatment of bonding and structure of gold clusters has met with considerable success. For the higher gold dusters, the best predictions are that, for a cluster [AutL, 1]"+ in which the peripheral gold atoms define a closed spherical polyhedron, there will be a closed shell electron configuration when 12x + 6 electrons are present. The structures of complexes... 

On the other hand, if the peripheral gold atoms have a ring or torus structure for [AujeLje i]B+, the number of valence electrons for a filled shell should be 12 + 4. The complexes [Au8L7]2+ (100 valence electrons) and [Au9L8]3+ (112 valence electrons) fall into this class.663,685... 

In general, the theoretical predictions are upheld although the energy differences between structures are small as a result of the bonding between peripheral gold atoms being weak.685... 

In contrast, those cluster compounds with an 18-electron environment at the central heterometal do not undergo nucleophilic addition reactions. Ligand substitution reactions at both the central heterometal and the peripheral gold atoms are observed to occur for both 16- and 18-electron cluster compounds, as in the reactions shown below ... 

The structures of the large Au clusters with 8-13 gold atoms may be described to be derived from a centered icosahedral Ann cluster by removal of peripheral gold atoms. The structure of [Au9(Ptol3)8] + can be derived from a centered icosahedron, but it is more simply pictured as a bicapped centered chair as shown in (25). The cluster [Au9(Ptol3)9](N03)3 has been prepared by NaBH4 reduction of [Au(Ptol)3(N03)]. The structure of the related ion,... 

For the heteronudear gold clusters M(CO)v(AuPPh3),.]-+ with a central heteroatom M and three to seven peripheral gold atoms, as described in the previous... 

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