Bond Length Alternation - Preferred Additions to -Double Bonds

Bond Length Alternation - Preferred Additions to [6, -Double Bonds 

The bond length alternation in is due to symmetry and the occupation of its Jt-orbitals [36, 48, 105-108], In a first approximation the Tt-electron system of an 

Angular momentum quanmm number for a spherical shell of K electrons. 

What are the consequences of filling the 1=5 (h) shell on the geometry of Cg0 The complete filling of the I = 5 state would lead to an accumulation of 72 7t electrons, assuming that all the I = 5 states are filled, before any I = 6 level is occupied. In icosahedral symmetry the I = 5 states split into the + (2  

Comparable alternations between the [6,6]- and [5,6]- bond lengths are observed in many fullerene adducts and higher fullerenes. Moreover, from the evaluation of many exohedral transformation of fullerenes, in particular Cjq, an important principle of fullerene chemistry can be deduced, namely minimization of[5,6]-douhle bonds in the lowest energy Kekule structure. Minimization of [5,6]-double bonds is 

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