Graphical linking of MO multicenter bond index and VB structures. II-5-c rings and 6-c heterocyclic rings

Through the graphical method proposed, it is possible to create a link betw een an MO multicenter bond index and VB structures. The value of the index depends on the order of the atoms involved, if there are more than three. F or 5-c rings, three basic structures are required; the eventually different values are 12. Unlike the 6-c case, it may happen that different pairs of basic structures are used to build the same polygon. For the 6-c rings, inc luding heteroatoms, the original degeneracy of benzene splits, leading even tually to 60 different I-ring values.