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Some topological properties of two types of S,T-isomers. (English) Zbl 0655.05065

Summary: Two types of S,T-isomers are considered. All of these which are called \(S_ 3\), \(T_ 3\), \(S_ 4\), \(T_ 4\)-isomers are benzenoid systems formed from two identical subunits A and A’. It is proved that if the number of vertices of A is odd then the number of Kekulé structures of the \(S_ 3(S_ 4)\)-isomer is equal to zero. Furthermore, the \(S_ 3(S_ 4)\)-isomer does not have more aromatic \(\pi\) sextets than its corresponding \(T_ 3(T_ 4)\)-isomer. Analogous results for Kekulé structures are also obtained.

MSC:

05C99 Graph theory
92Exx Chemistry
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