Wade electron counting rules borane-like cluster nomenclature

3 Wade electron counting rules borane-like cluster nomenclature. On initially studying compounds such as boranes (boron hydrides) and carboranes (or carbaboranes boron—carbon hydrides), Wade (1976) proposed a number of rules which have then been extended to several compounds and which relate the number of skeletal electrons with the structure of deltahedral clusters. A polyhedron which has only A-shaped, that is triangular, faces is also called a deltahedron. 

Closo-cluster (a cage) a complete deltahedral group. 

Nido-cluster (a nest) a deltahedral structure with one missing vertex. Arachno-cluster (a spider-web) a deltahedral structure with two missing vertices. Hypho-cluster (a net) a deltahedral structure with three missing vertices. 

The following optimum electron numbers have been defined on the basis of the so-called Polyhedral Skeletal Electron-Pair Theory (PSEPT) . 

arachno, hypho deltahedral clusters based on n main group vertex atoms are characterized by An + 2, An + 4, An + 6 and An + 8 total valence electrons respectively. The corresponding optimum VEC for closo and nido deltahedra 

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