Rotational spectrum of 3-butynenitrile in the microwave and radiofrequency range using one- and two-dimensional Fourier transform techniques

Abstract

Microwave and radiofrequency Fourier transform spectra have been measured for 3-butynenitrile (propargyl cyanide), HCCCH 2CN, as its normal isotopomer in the ground vibrational state. Single- and double-resonance pulse-type experiments have been performed to yield spectra in one- and two-frequency dimensions. The 14N quadrupole hyperfine structure has been resolved and the quadrupole coupling constants χ + = 2.256 MHz and χ − = −1.835 MHz have been obtained. Ab initio calculations (GAUSSIAN 86) have been undertaken to confirm the assumption of a nearly cylindrically symmetric 14N quadrupole coupling tensor. The additional information has been exploited to show that the CN group is bent away from the HCC group through an angle in the CH 2CN chain of 0.9°.