Generation and UV-photolysis of <i>N</i> -methyleneformamide

Simple imines have been detected in space and are considered as building blocks to larger heteroaromatic, cyclic and biologically relevant compounds. Herein, we revisited the formation of the simplest acylimine, namely <i>N</i>-methyleneformamide, by high-vacuum flash pyrolysis (HVFP) as well as its spectroscopic characterization by cryogenic matrix isolation infrared (IR) and UV/Vis spectroscopy. <i>N</i>-Methyleneformamide prefers a <i>gauche</i> over an s-<i>trans</i> conformation in contrast to the parent 1,3-butadiene. In UV-photolysis experiments we identified formaldehyde:HCN and formaldimine:CO complexes as the major decomposition products. As further photolysis products we observed HCN:CO and HNC:CO complexes. All experimental findings are supported by deuterium labeling experiments and high-level <i>ab initio</i> coupled cluster calculations. <i>N</i>-Methyleneformamide should be considered as a candidate for an interstellar search. The sequence R₂C[double bond, length as m-dash]N-RC[double bond, length as m-dash]O also occurs in cytosine making the title compound highly relevant for prebiotic chemistry and the search for the molecular origins of life.