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.