Quantitative Aromatic Sextet Theory

Regularities in RBO Values in the Phenanthrene (C,4H,o)-Benzanthracene Family as the Number of Rings Increases 

Ring C14H10 QsBn C22H14 26 16 Difference in Numerator 

Find regularities in RBO analogous to those in phenathrene-benzanthracene in 

Pauling bond orders, which have been generally accepted, just as have been accepted their counterpart in MO theory, should have some tangible connection with quantum chemistry. This may be indicative that Clar s aromatic % electron sextet theory might also have tangible connection with quantum mechanics and be one of its reflections when considering benzenoid hydrocarbons. So we dare to propose 

Find the hidden connection of the Clar sextet theory with quantum mechanics or prove that there is no such. 

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Ring bond orders (RBO)—quantitative representation of Clar s aromatic sextet theory (Randid) [22]... 

In practice, the valence bond picture has probably exerted more influence on how chemists actually think than the HMO picture. However most early applications were primarily qualitative in nature. This qualitative VB picture can be summarized under die name of resonance theory [10]. The basic concept is that in general the more ways one has of arranging the spin pairing in the VB wave function, the more stable the molecule is likely to be. Thus, VB theory predicts that phenanthrene with 14 carbon atoms and 5 Kekule structures should be more stable than anthracene with 14 carbon atoms but just 4 Kekule structures, in complete accord with the experimental evidence. It also predicts that benzenoid hydrocarbons with no Kekule structures should be unstable and highly reactive, and in fact no such compounds are knowa Extensions of this qualitative picture appear, for example, in Clar s ideas of resonant sextets [11], which seem to be very powerful in rationalizing much of the chemistry of benzenoid aromatic hydrocarbons. The early ascendancy of HMO theory was thus largely based on the ease with which it could be used for quantitative computations rather than on any inherent superiority of its fundamental assumptions. 

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