Condensed Non-octahedral Clusters

Numerous metal rich compounds which are composed of transition metals and p elements adopt structures that can be described in terms of condensed [M Xg] and [MgXn] type clusters, espedally if distortions of such clusters are accepted. However, care must be taken for these distortions can actually introduce significant changes in the chemical bonding when compared with the discrete units. In an early analysis it was demonstrated [102] that other cluster types also play an important role within the concept of cluster condensation. These may be dosely related to the octahedral clusters or may be of a completely different nature. It is not the intention here to deal with these structures in any detail, however, a short summary will be presented so as to draw attention to the breadth of the duster condensation concept. Of particular interest are those clusters which represent fractions of the octahedral clusters, for example, the [M6Xg] type. 

Figore 5-43. Projections of the crystal structures of a) Hf3 2 and b) RhsGes along the short axes. Metal atoms are connected by lines to indicate duster fragments. 

5 Discrete and Condensed Transition Metal Clusters in Solids 

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