Predicting an unconventional facile route to metallaanthracenes

Metallaaromatics have attracted considerable interest from both experimentalists and theoreticians since the first prediction of metallabenzenes, in which a CH group is replaced by a transition metal fragment. In comparison with monocyclic metallabenzenes and bicyclic metallanaphthalenes, tricyclic metallaanthracenes are quite less developed. Thus, it is urgent to explore synthetic methods for this rare system. Here we report a thorough investigation on the formation of metallaanthracenes from transition metal fluorenyl complexes via density functional theory calculations. We systematically investigate how metal centres, ligands, and substituents affect such a rearrangement. Our results indicate that formation of metallaanthracenes could become thermodynamically and kinetically favourable from transition metal fluorenyl complexes by tuning suitable metal centres, ligands, and substituents, suggesting an unconventional facile way to prepare such rare tricyclic metallaaromatics for experimentalists, which is in sharp contrast to the traditional isomerisation of metallabenzenes to cyclopentadienyl complexes.