title: Infrared spectra of a species of astrochemical interest: aminoacrylonitrile (3-amino-2-propenenitrile).
abstract: Ammonia easily reacts on cyanoacetylene in the gas phase or in a solvent to form the Z- and E-isomers of aminoacrylonitrile (3-amino-2-propenenitrile, 2). This kinetically stable enamine presents interest for its possible presence in the interstellar medium, the comets, the atmospheres of Planets including the Primitive Earth, and from a theoretical point of view. B3LYP/6-311+G(3df,2p) and G2 calculations indicate that the imine isomer is significantly less stable than the enamine 2. DFT and G2 calculations indicate that the Z-isomer of compound 2 lies ca. 8.0 kJ mol(-1) lower in energy than the E-isomer. The infrared spectra of the aminoacrylonitrile, in both the gas and condensed phases were recorded in the range 500-4000 cm(-1). Consistent with the theoretical calculations, the imine and the E-isomer of the enamine have never been detected in the infrared spectrum of a gaseous sample and only the Z-isomer has been observed. With a neat sample in the condensed phase, IR spectra of a 1:1 and 20:1/Z:E mixtures were recorded. The comparison of these data with the spectrum of the Z-isomer in the gas phase allowed us to deduce the IR spectrum of the E-isomer. The E-Z isomerization takes place through a torsion around the C=C bond. A possible mechanism involving a previous enamine-imine tautomerism must be discarded because it implies a much larger barrier than the direct isomerization process. Consistently, the presence of a deuterium atom has not been observed on the sp2 carbon of the products of distillation of a 1:1/E:Z mixture of the NCCH=CHND2.
authors.affiliation: PALMS, UMR CNRS 6627, Université de Rennes 1, 35042 Rennes, France, Laboratoire de Synthèse et Activation de Biomolécules, UMR CNRS 6052, ENSCR, Institut de Chimie de Rennes, 35700 Rennes, France.
authors.forename: Abdessamad
authors.initials: A
authors.lastname: Benidar
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Guillemin
authors.forename: Otilia
authors.initials: O
authors.lastname: Mó
authors.forename: Manuel
authors.initials: M
authors.lastname: Yañez
mesh_terms: D005118:Extraterrestrial Environment / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D014732:Vibration
chemical_list: C516496:3-amino-2-propenenitrile; D009570:Nitriles; C520231:aminoacrylonitrile(3-amino-2-propenenitrile)