Structure–property relationships in phosphole oligomers: a theoretical insight

The influence of cyclic π-conjugation and interannular rotation on the vertical ionization energies and energy gaps of phosphole oligomers has theoretically been investigated which provided some useful structure–property relationships. While vertical ionization energies were obtained from negative HOMO-energies using the Hartree–Fock method, energy gaps were calculated using a DFT/hybrid method (B3LYP). Combination of geometric (JULG and dCα) and magnetic (NICS) criteria gives a qualitative indication about the competition between the cyclic- and the carbon backbone π-conjugation. Results of this preliminary theoretical study suggest that phosphole oligomers have interesting tunable electronic properties.