Electron-Rich Hyperelectronic Polyhedral Boranes

Electron-rich or hyperelectronic polyhedral systems are those containing more than the 2k + 2 skeletal electrons required for globally delocalized K-vertex deltahedra 

Nido polyhedra can be classified into two fundamental types the pyramids with only one interior vertex (the apex) and the nonpyramids with more than one interior vertex. If n is the total number of vertices and v is the number of interior vertices in a nonpyramidal nido polyhedron, the interactions between the internal orbitals which generate bonding orbitals are of the following three different types  

The 2( - v) twin internal orbitals of the border atoms and the 2v twin internal orbitals of the interior atoms interact along the polyhedral surface to form n bonding orbitals and n antibonding orbitals. 

The V unique internal orbitals of the interior vertex atoms all interact with each other at the core of the structure in a way that may be represented by the complete graph to give a single bonding orbital and v - 1 antibonding orbitals. 

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A. Electron-Rich (Hyperelectronic) Polyhedral Boranes Nido and Arachno Structures... 

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