Unconventional S2 retention pathways induced by complex formation: High-level dynamics investigation of the NH + CHI polyatomic reaction.

Investigations on the dynamics of chemical reactions have been a hot topic for experimental and theoretical studies over the last few decades. Here, we carry out the first high-level dynamical characterization for the polyatom-polyatom reaction between NH and CHI. A global analytical potential energy surface is developed to describe the possible pathways with the quasi-classical trajectory method at several collision energies. In addition to S2 and proton abstraction, a significant iodine abstraction is identified, leading to the CH + [NH⋯I] products. For S2, our computations reveal an indirect character as well, promoting the formation of [CH⋯NH] complexes. Two novel dominant S2 retention pathways are uncovered induced by the rotation of the CH fragment in these latter [CH⋯NH] complexes. Moreover, these uncommon routes turn out to be the most dominant retention paths for the NH + CHI S2 reaction.