The electronic structure of p-xylylene and its reactivity with vinyl molecules

► Three electronic states (closed-shell singlet, open shell singlet and triplet states) of p-xylylene molecule were described using theoretical chemistry methods. ► The quinoidal closed-shell singlet state molecule is the most stable whereas the energy of the triplet benzoidal state of p-xylylene was found to be 38 kcal/mol higher. ► The singlet open-shell structure was predicted to be very unstable in comparison to the ground closed-shell state (by ca. 100 kcal/mol). ► The barriers for the p-xylylene reactions with alkenes substituted with electronegative groups do not exceed the barrier for initialization of parylene polymerization (15 kcal/mol). ► The reactivity of parylene monomers with vinyl molecules should be considered as competitive reaction to the reaction initializing parylene polymerization.