Coulson Graphical Construction of Ch x

C4 = number of pairs of disjoint bonds -2x number of disjoint squares -6x number of disjoint tetrahedra or in equivalent form  

FIGURE 4.2 Graphical expressions for the leading coefficients of the characteristic polynomial due to Coulson. 

FIGURE 4.3 The graphical expression due to Coulson for the coefficients Cg of the characteristic polynomial of alternant systems (i.e., systems having no odd rings). 

According to Coulson, The calculation of in this manner is too involved, so he has only illustrated for alternant (even cycle) hydrocarbons, which are given by 

Ce = - 1 X total number of sets of three disjointed bonds - 2 X number of benzene rings (hexagon) 

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