title: Triplet fluoranthenes: aromaticity versus unpaired electrons.
abstract: Three fluoranthenes and one substituted fluoranthene, 2,2-dimethyl-2H-dibenzo[cd,k]fluoranthene, were investigated using the unrestricted symmetry-broken and complete active space methods. It was shown that four Kekuléan hydrocarbons are diradicals, implying that their ground state is a triplet. In the energetically less favorable singlet state these hydrocarbons exhibit pronounced diradical character. This occurance is explained with the tendency of the investigated molecules to delocalize their π-electrons. This leads to aromatic stabilization which is stronger than destabilization due to unpaired electrons. Our results for 2,2-dimethyl-2H-dibenzo[cd,k]fluoranthene are in excellent accord with experimental findings of McMaster et al. concerning this compound.
authors.affiliation: Faculty of Science, University of Kragujevac, 12 Radoja Domanovića, 34000 Kragujevac, Serbia. mark@kg.ac.rs
authors.forename: Svetlana
authors.initials: S
authors.lastname: Marković
authors.forename: Jelena
authors.initials: J
authors.lastname: Đurđević
authors.forename: Svetlana
authors.initials: S
authors.lastname: Jeremić
authors.forename: Ivan
authors.initials: I
authors.lastname: Gutman
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D005449:Fluorenes / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure
chemical_list: D005449:Fluorenes; C007738:fluoranthene