The trimerization of acetylenes involves a cascade of biradical and pericyclic processes

Thorough computational studies were performed on mechanisms and energies for the thermal trimerizations of neutral or electron-rich acetylenes used as cross-linkers in organic hard-masks for lithography applications. These studies indicate that the operative mechanism proceeds through initial cyclobutadiene formation via a biradical mechanism. Cyclobutadienes form Dewar benzenes via Diels-Alder cycloadditions, or biradical processes, or both, before producing benzenes by electrocyclic ring-opening reactions. These pathways are preferred to alternatives involving concerted trimerizations or mechanisms involving carbene intermediates. Thorough computational studies were performed on mechanisms and energies for the thermal trimerizations of neutral or electron-rich acetylenes used as cross-linkers in organic hard-masks for lithography applications.