Low-Temperature Gas-Phase Formation of Methanimine (CH₂NH; X¹A′)─the Simplest Imine─under Single-Collision Conditions

Abstract

The D1-methanimine molecule (CHDNH; X 1 A′)�the simplest (deuterated) imine�has been prepared through the elementary reaction of the D1-methylidyne (CD; X 2 Π) with ammonia (NH 3 ; X 1 A 1 ) under single collision conditions. As a highly reactive species with a carbon−nitrogen double bond and a key building block of biomolecules such as amino acids and nucleobases, methanimine is of particular significance in coupling the nitrogen and carbon chemistries in the interstellar medium and in hydrocarbon-rich atmospheres of planets and their moons. However, the underlying formation mechanisms of methanimine in these extreme environments are still elusive. The directed, low-temperature gas-phase formation of D1methanimine will deepen our fundamental understanding of low-temperature molecular growth processes via carbon−nitrogen bond coupling. Considering the recent detection of the interstellar D1-methylidyne radical, the investigation of the CD−NH 3 system also suggests a promising pathway for future astronomical observations of D1-methanimine as a molecular tracer of gas phase deuterium enrichment in deep space.

Carbon Atom Condensation on NH3–H2O Ices. An Alternative Pathway to Interstellar Methanimine and Methylamine

“…In astronomical environments, recent observations and chemical modeling of H 3 CNH 2 toward different cold and hot cores support that HCN hydrogenation must be an important source of H 3 CNH 2 . Although this rationalization is useful to visualize the most abundant final product of the network, it is also simplistic because under ISM conditions there is an interplay between gas and grain processes, e.g., gas phase synthesis , feeds molecules onto icy dust. We also note that the H accretion rate (e.g., H fluxes) on interstellar dust are lower under ISM conditions than in experiments.…”