Perylene Bisimide Radicals and Biradicals: Synthesis and Molecular Properties

Unprecedented neutral perylene‐3,4:9,10‐tetracarboxylic acid bisimide (PBI) radicals and biradicals were synthesized by facile chemical oxidation of 4‐hydroxyaryl‐substituted PBIs. Subsequent characterization by optical and magnetic spectroscopic techniques, as well as quantum chemical calculations, revealed an open‐shell singlet biradical ground state for the PBI biradical OS‐2.. (〈s2〉=1.2191) with a relatively small singlet–triplet energy gap of 0.041 eV and a large singlet biradical character of y=0.72. Stable biradicals: A singlet open‐shell perylene bisimide (PBI) biradical was generated by facile chemical oxidation of a 4‐hydroxyaryl‐substituted PBI. The remarkable stability of OS‐2.. facilitates its unambiguous characterization, revealing a large singlet biradical character of y=0.72.