A chemical link between methylamine and methylene imine and implications for interstellar glycine formation.

Methylamine CHNH is considered to be an important precursor of interstellar amino acid because hydrogen abstraction might lead to the aminomethyl radical •CHNH that can react with •HOCO to form glycine, but direct evidence of the formation and spectral identification of •CHNH remains unreported. We performed the reaction H + CHNH in solid p-H at 3.2 K and observed IR spectra of •CHNH and CHNH upon irradiation and when the matrix was maintained in darkness. Previously unidentified IR spectrum of •CHNH clearly indicates that •CHNH can be formed from the reaction H + CHNH in dark interstellar clouds. The observed dual-cycle mechanism containing two consecutive H-abstraction and two H-addition steps chemically connects CHNH and CHNH in interstellar media and explains their quasi-equilibrium. Experiments on CDNH produced CDHNH, in addition to •CDNH and CDNH, confirming the occurrence of H addition to •CDNH.