Reaction Dynamics Study of the Molecular Hydrogen Loss Channel in the Elementary Reactions of Ground-State Silicon Atoms (Si(3P)) With 1-and 2-Methyl-1,3-Butadiene (C5H8)

The bimolecular gas-phase reactions involving ground-state atomic silicon (Si; P-3) and 1- and 2-methyl-1,3-butadiene were studied via crossed molecular beam experiments. Our data revealed indirect scattering dynamics through long-lived SiC5H8 collision complex(es) along with molecular hydrogen loss pathways, leading to facile formation of SiC5H6 isomer(s). We propose that the reactions of silicon with 1- and 2-methyl-1,3-butadiene possess reaction dynamics in an analogy to the silicon-1,3-butadiene system. This leads to cyclic methyl-substituted 2-methylene-1-silacyclobutene isomers via nonadiabatic reaction dynamics through intersystem crossing (ISC) from the triplet to the singlet surface in overall exoergic reactions through tight exit transition states and molecular hydrogen loss. Our study also suggests that the methyl group.although a spectator from the chemical viewpoint.can influence the disposal of the angular momentum into the rotational excitation of the final product.

Automated summary

This study investigates the bimolecular gas-phase reactions of silicon with 1- and 2-methyl-1,3-butadiene, revealing the formation of SiC5H6 isomers through long-lived collision complexes and molecular hydrogen loss pathways. The presence of methyl groups in the reactants can influence the rotational excitation of the final product, showcasing the impact of spectator groups in chemical reactions.