Phototransformations of 2,3-Diamino-2-Butenedinitrile (DAMN) Monomers Isolated in Low-Temperature Argon Matrix

Abstract

UV-induced transformations were studied for monomers of 2,3-diamino-2-butenedinitrile (DAMN) isolated in argon matrices. Photoinduced hydrogen-atom transfer was found to be the major process occurring upon UV (λ > 320 nm or λ > 295 nm) excitation of matrix-isolated DAMN monomers. As a result of the transfer of a hydrogen atom from an amino group to a nitrile fragment, a tautomer of DAMN involving a ketenimine group was generated. Identification of this photo-produced species was based on comparison of its experimental IR spectrum with the spectrum theoretically predicted for the ketenimine form. Another product photogenerated upon UV (λ > 320 nm, λ > 295 nm, or λ > 270 nm) irradiation of DAMN isolated in Ar matrices was identified as 4-amino-1H-imidazole-5-carbonitrile (AICN). The structure of this photoproduct was unambiguously assigned on the basis of an exact match of wavenumbers of the bands in the IR spectrum of this photogenerated species and the wavenumbers of IR bands of AICN trapped (in a separate experiment) from the gas phase into an Ar matrix.