Carboranes classification

Carboranes may be classified by structural type using the same method described previously for boranes. Because a carbon atom has the same number of valence electrons as a boron atom plus a hydrogen atom, formally each C should be converted to BH in the classification scheme. For example, for a carborane having the formula C2B8H)q,... 

TABLE 3.1. closo, nido, and arachno Classification of Carboranes, Carbocations, and Carbanions Containing Hypcrcarbon Atoms... 

TABLE 4.1. Classification of Metal-Hydrocarbon 7t Complexes, Aromatic Systems, and Varions Hydrocarbons as Carborane-Type Mixed Metal-Carbon Clnsters ... 

For a carborane system with the general formula [(CH)a (BH) Hq] , we can readily deduce its structural classification-c/oso, nido, or arachno, using Wades 2 + 2 rules. These rules are easily derived in the following manner. 

---