abstract
The Clar Goblet, the first radical bowtie nanographene proposed by Erich Clar nearly 50 years ago, was recently synthesized. Bowtie nanographenes present quasi-degenerate magnetic ground states, which make them so elusive as unique. A thorough analysis is presented of the spin-state energetics of Clar Goblet and bowtie nanographenes by a battery of existing and novel ab initio procedures ranging from density functional theory to complete active space Hamiltonians. With this, it was proven that pi radicals of bowtie nanographenes sit on BP (Benzo[cd]Pyrene) moieties driven by their local aromaticity, a purely chemical concept, which confers global stability to the whole structure. Besides, a novel Pauli energy densities analysis provided a visual intuitive explanation for this preference. These findings allow envisioning that analogous bowtie nanographenes with arbitrary polyradical character are not only feasible at the molecular scale but will share Clar Goblet's peculiar properties.
keywords
MULTICENTER BOND INDEXES; TOPOLOGICAL FRUSTRATION; DELOCALIZATION INDEXES; DENSITY FUNCTIONALS; GRAPHENE; MAGNETISM
subject category
Chemistry
authors
Gil-Guerrero, S; Melle-Franco, M; Pena-Gallego, A; Mandado, M
our authors
Manuel Melle-Franco
Principal Researcheracknowledgements
S.G., A.P., and M.M. thank Xunta de Galicia for financial support through the project GRC2019/24. In addition, support through the project IF/00894/2015 and within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES is gratefully acknowledged. S.G. also acknowledges support by the University of Vigo through a PhD mobility grant.