Mechanism of thermal reactions of dimerization and trimerization of hexafluoro-1,3-butadiene: A quantum-chemical study

The mechanism of thermal oligomerization of hexafluoro-l,3-butadiene was examined using RHF, ROHF, and GVB/DH, and by B3LYP/6-31G* and /6-311G* quantum-chemical methods. The energies of highly reactive excited states of the monomer and of intermediate biradical species were estimated. Isomeric biradicals (excited monomers and dimers) with the free valences localized on two carbon atoms were shown to coexist in the reaction mixture. Recombination of such biradicals and their reactions with neutral stable molecules give rise to diverse products, depending on the reaction temperature.