title: Is C50 a superaromat? Evidence from electronic structure and ring current calculations.
abstract: The fullerene-50 is a 'magic number' cage according to the 2(N + 1)(2) rule. For the three lowest isomers of C50 with trigonal and pentagonal symmetries, we calculate the sphericity index, the spherical parentage of the occupied π-orbitals, and the current density in an applied magnetic field. The minimal energy isomer, with D3 symmetry, comes closest to a spherical aromat or a superaromat. In the D5h bond-stretch isomers the electronic structure shows larger deviations from the ideal spherical shells, with hybridisation or even reversal of spherical parentages. It is shown that relative stabilities of fullerene cages do not correlate well with aromaticity, unlike the magnetic properties which are very sensitive indicators of spherical aromaticity. Superaromatic diamagnetism in the D3 cage is characterized by global diatropic currents, which encircle the whole cage. The breakdown of sphericity in the D5h cages gives rise to local paratropic countercurrents.
authors.affiliation: Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium. ana.sanzmatias@chem.kuleuven.be arnout.ceulemans@chem.kuleuven.be.
authors.forename: Ana Sanz
authors.initials: AS
authors.lastname: Matías
authors.affiliation: Theoretical Chemistry, Zernike Institute for Advanced Materials and Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. r.w.a.havenith@rug.nl and Ghent Quantum Chemistry Group, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), B-9000 Gent, Belgium.
authors.forename: Remco W A
authors.initials: RW
authors.lastname: Havenith
authors.affiliation: Departamento de Química, Módulo-13, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. manuel.alcami@uam.es and Instituto Madrileño de Estudios Avanzados en Nanociencias (IMDEA-Nanociencia), Cantoblanco 28049 Madrid, Spain. manuel.alcami@imdea.org.
authors.forename: Manuel
authors.initials: M
authors.lastname: Alcamí
authors.affiliation: Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium. ana.sanzmatias@chem.kuleuven.be arnout.ceulemans@chem.kuleuven.be.
authors.forename: Arnout
authors.initials: A
authors.lastname: Ceulemans