Theoretical analysis of the fluxional behaviour of cyclooctatetraene Ru and Ni complexes

Cyclooctatetraene's (COT) behaviour in some of its Ni and Ru complexes is studied by means of DFT methods (B3LYP and BLYP). The experimentally observed COT fragment conformational changes (tub-shaped or planar) are analysed, together with the different locations of metal-carbon bonds in the complexes. These phenomena are studied using both static and molecular dynamics calculations. The results allow us to predict changes in the COT fragment, which goes from aromatic to totally antiaromatic, depending on its environment. This situation favours the electronic flow through the metal atoms into the organometallic molecules, giving place to different geometries that generate the dynamic fluxional behaviour.