Molecular Structure of the Nitrile Ylide Derived from 3-Phenyl-2H-azirine in a Nitrogen Matrix

Article abstract of DOI:10.1021/j100281a018

Nitrile ylides derived from 3-phenyl-2H-azirine and five of its isotope-labeled counterparts were generated photochemically in 12 K nitrogen matrices and examined by FTIR.A prominent 1926 cm^-1 feature in the unlabeled ylide's spectrum undergoes a 66 cm^-1 shift with 15N substitution, and this effect is interpreted as being consistent only with the asymmetric stretching fundamental of a linear (-)C=(+)N=C skeleton.The spectra of the 13C- and D-labeled nitrile ylides corroborate this conclusion and clarify spectral regions where Fermi multiplets and overlapping absorptions complicate the interpretation.The allene-like nitrile ylide C_s geometry is retained over the temperature range 12-82 K, which suggests that this geometry is also adopted in solution where nitrile ylides have been implicated as 1,3-dipolar reactive intermediates from the photolysis of 2H-azirines.