Prediction of the ground state for indenofluorene-type systems with Clar's π-sextet model

21 May 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


This study introduces the Ground State Stability (GSS) rule that allows predicting the nature of the ground state of indenofluorene (IF)-type systems from the simple counting of the Clar pi-sextets in the closed- and open-shell configurations. The IF-type system exhibits a triplet ground state when acquiring double or more the number of Clar pi-sextet in the open-shell form relative to the closed-shell form; otherwise, it assumes an open-shell singlet ground state. Performed state-of-the-art DFT calculations and analysis of aromaticity for the systems of interest validate the effectiveness of the proposed rule. We demonstrate that aromaticity plays the most crucial role in determining the ground electronic state for such polycyclic hydrocarbons. The simplicity of the GSS rule makes it a robust strategy for identifying promising systems in the development of indenofluorene-type materials.


Clar pi-sextets
diradical character
electronic ground state

Supplementary materials

Supporting Information
Computational details, Calculated relative energies of isomers of FF, Calculated relative energies of isomers of DIAn, Graph between NFOD and y0 values of all the isomers of IF, FF and DIAn, FOD plots for IF-1a and IF-2a isomers, pi-EDDB plots and NICS(1)zz values for CS and OS states of IF-1a, IF-1b, IF-2a, FF-1a and DIAn-1a.


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