Fluoreno[2,1-a]fluorene: an ortho-naphthoquinodimethane-based system with partial diradical character.
Allison S HackerMauricio PavanoJames E WoodHannah HashimotoKyle M D'AmbrosioConerd K FredericksonJosé L ZafraCarlos J Gómez-GarcíaVerònica PostilsAshley Ringer McDonaldDavid CasanovaDerik K FrantzJuan CasadoPublished in: Chemical communications (Cambridge, England) (2019)
Fluoreno[2,1-a]fluorene, a molecule comprising fused ortho-quinodimethane units in a 1,5-napthoquinodimethane core, has been prepared and investigated with spectroscopy (UV-Vis-NIR, 1H-NMR and Raman), SQUID magnetometry, spectroelectrochemistry and quantum chemistry. While para-quinodimethanes with a 2,6-substitution pattern exist as closed-shell species and meta-quinodimethanes with 2,7-substitution favour a ground electronic state with very large diradical character, our 1,5-substituted ortho-naphthoquinodimethane-based system exhibits an intermediate degree of diradical character.