Matrix Infrared Spectra and DFT Computations of CH2CNH and CH2NCH Produced from CH3CN by Laser-Ablation Plume Radiation

The smallest ketenimine and hydrogen cyanide N-methylide (CH2CNH and CH2NCH) are provided from the argon/acetonitrile matrix samples exposed to radiation from laser ablation of transition-metals. New infrared bands are observed in addition to better determination of the vibrational characteristics for the previously reported bands, and the C-13 substituted isotopomers ((CH2CNH)-C-13-C-13 and (CH2NCH)-C-13-C-13) are also generated. Density functional frequency calculations and the D and C-13 isotopic shifts substantiate the vibrational assignments. CH2CNH is probably produced through single-step conversion of CH3CN, whereas CH2NCH through two-step conversion via 2H-azirine. Inter-conversions between these two products evidently do not occur during photolysis and annealing.