Isomerization of cyanopropyne in solid argon

Abstract : Cyanopropyne, CH3-C=C-CN, is a simple molecule whose photochemistry is still unexplored. Here we investigate the UV photolysis of this astrophysically significant nitrile trapped in solid argon. The FTIR study was assisted with N-15-isotopic substitution data and with DFT-level computations including the analyses of ground- and excited-state potential energy surfaces. Cyanopropyne was found to decay mainly via a two-step isomerization process. Infrared absorption spectra evolved to show signals from allenyl cyanide, CH2=C=CH-CN, which then further convert into propargyl cyanide, H-C=C-CH2-CN. Some evidence for the presence of allenyl isocyanide, propargyl isocyanide, 3-cyanocyclopropene, and 1,2,3-butatrien-1-imine under particular experimental conditions was also observed. Although cyano/isocyano interconversion has been observed during photolysis of other closely related species in solid argon matrices, including H-C=C-CN, no evidence could be found for production of 1-isocyano-1-propyne, CH3-C=C-NC for these experiments.
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Thomas Custer, Urszula Szczepaniak, Marcin Gronowski, Nathalie Piétri, Isabelle Couturier-Tamburelli, et al.. Isomerization of cyanopropyne in solid argon. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2019, 21 (25), pp.13668-13678. ⟨10.1039/c8cp06739b⟩. ⟨hal-02278409⟩



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