title: Didehydrophenanthrenes: structure, singlet-triplet splitting, and aromaticity.
abstract: In this work, we explore the geometries, relative stabilities, singlet-triplet (S-T) splittings, and local aromaticities of the 25 possible didehydrophenanthrenes (DDPs) at the BLYP/6-31G(d) level. The main aim is to understand their molecular structure and stability in terms of the electronic structure. To this end, we analyze the changes induced by didehydrogenation in molecular structure and local aromaticity and we investigate the coupling strength between radical centers in DDPs through the evaluation of S-T splittings. Further evidence for the repulsive character of the H-H interactions in phenanthrene's bay region is gained from the relative energies of the triplet states of the different DDPs.
authors.affiliation: Afdeling Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands.
authors.forename: Jordi
authors.initials: J
authors.lastname: Poater
authors.forename: F Matthias
authors.initials: FM
authors.lastname: Bickelhaupt
authors.forename: Miquel
authors.initials: M
authors.lastname: Solà