The microwave spectrum and molecular structure of ethylisocyanate

Abstract

We have remeasured the spectrum of the isotopically most abundant species of ethylisocyanate (12CH3 12CH2 14N12C16O), and assigned for the first time the spectra of all 13C-, 15N-, and 18O-monosubstituted isotopomers in their respective natural abundances employing pulsed molecular beam microwave Fourier transform spectroscopy. We used these data to determine the heavy atom r s and r o structure where the most interesting structural parameters, the C-N-C and N-C-O angles, were found to be 138·5° and 176°, with the oxygen atom trans to the ethyl group. Additionally we obtained improved values of the 14N quadrupole coupling constants (in MHz) χ aa = 2·5488(6), χ bb = -1·1717(8), and χ cc = -1·3771(8) of the 12CH3 12CH2 14N12C16O species. From the variation of the coupling constants with isotopic substitution, we also determined the angular position of the coupling tensor in the inertial axis system.