Photoinduced dehydrogenation reaction of CH 3NH 2 by NO 2 in a cryogenic Ar matrix. Identification of the CH 2 = NH · H 2O complex

Abstract

The visible light-induced reaction of NO 2 with methylamine (CH 3NH 2) in a cryogenic argon matrix has been investigated using an FTIR spectrometer. The photochemical products were identified as methyleneimine (CH 2 = NH), water and nitric oxide. This photoinduced dehydrogenation reaction, CH 3NH 2 + NO 2 + hν → CH 2 = NH + H 2O + NO, is interpreted by the following reaction sequence: (1) photoexcitation of NO 2, (2) oxygen atom transfer from excited NO 2 to methylamine and (3) isomerization from the methylamine N-oxide to methylhydroxylamine (intramolecular hydrogen atom migration), followed by (4) dissociation into methyleneimine and water. it was confirmed by the infrared spectrum that two of the dissociation products interact with each other in the matrix cage (CH 2 = NH · H 2O). This reaction mechanism is also supported by the formation of CD 2 = NH · HDO in the CD 3NH 2/NO 2 system.