was characterised by a broad singlet at δC = 22.1 ppm (FWHM = 51 Hz) assigned to the CHCN resonance broadened due to the adjacent quadrupolar S = 5/2 27 Al nucleus. The CHCN resonance appeared as a doublet due to coupling to the S=1/2 C ( 1 JH-C = 127.4 Hz). IR spectroscopy of 2b revealed a strong band at 2038 cm -1 assigned as the C=N vibration. This is at a markedly lower wavenumber than the CºN vibration in CH3CN (2251 cm ). The experimental spectroscopic data is well reproduced by DFT calculations (Table ).