The 14N Nuclear Quadrupole Coupling in E- and Z-C-Cyanomethanimine; its Prediction from Restricted Hartree-Fock Wave Functions and its Experimental Determination by High Resolution Microwave Spectroscopy

Abstract

Abstract The 14N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH - C ≡ N, produced by flash pyrolysis from (CH3)2N -C ≡ N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane): The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14N hyperfine multiplets of the related pyruvonitriles, H - N = C(CH3) - C ≡ N, are predicted.