A simple treatment to design NBMO degenerate systems in alternant and non-alternant hydrocarbons

A simple treatment for systems with many degenerate non-bonding molecular orbitals (NBMO's) in alternant and non-alternant hydrocarbons without performing computer calculations is presented at the Hückel level. Using Hückel theory, we have proven that the linkage between carbon atoms with coefficients of zero in an NBMO does not present any substantial action to the original NBMO. By using this simple rule, many polycyclic conjugated hydrocarbons possessing high spin multiplicity are hypothesized. We term these NBMO degenerate systems "NBMO network systems". This treatment can be expected to provide information for designing novel organic high-spin molecules including possible ferromagnetic substances in particular those consisting of non-alternant polycyclic conjugated hydrocarbons.