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

The D1-methanimine molecule (CHDNH; X¹A′)─the simplest (deuterated) imine─has been prepared through the elementary reaction of the D1-methylidyne (CD; X²Π) with ammonia (NH₃; X¹A₁) 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 D1-methanimine 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-NH₃ 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.