HCN dimers: Iminoacetonitrile and N-cyanomethanimine

Article abstract of DOI:10.1021/ja00019a026

Iminoacetonitrile (1) has been prepared by two methods: (i) thermal decomposition of the tosylhydrazone salts 13 at 200 °C and (ii) Ar matrix photolysis of azidoacetonitrile (15). Ab initio calculations indicate that 1Z is of slightly lower energy than IE, and this is confirmed by the 1R spectra with use of the thermal methods. 1E/1Z undergo photochemical interconversion, giving a ca. 3:1 photostationary E:Z ratio. 1E and 1Z are fully characterized by their gas-phase, matrix, and thin-film IR spectra, which are in excellent agreement with ab initio calculations, by ¹H and ¹³C NMR spectroscopy in solution, and by mass spectrometry. 1 polymerizes in solution above -40 °C; pyrolysis produces HCN, and matrix photolysis produces HNC and van der Waals complexes containing HNC. N-tert-Butyliminoacetonitrile thermally fragments to tert-butyl isocyanide and HCN. N-Cyanomethanimine (3) has also been prepared by two methods: (i) pyrolysis of trimethylenetetrazole (20) at 500-800 °C and (ii) pyrolysis of ditetrazolopyrazine 22 at 600-850 °C. Both methods are extremely clean. 3 is fully characterized by its IR spectrum in agreement with ab initio calculations and, in conjunction with other work, by its mass and millimeter-wave spectra. 3 is thermodynamically stable in the gas phase up to ca. 800 °C at low pressure and short contact times but polymerizes in the solid state above -100 °C.