(2018). The energy ordering of its conformations (out-ap, in-ap, out-sp, and in-sp) and their associated spectroscopic parameters, including rotational constants and dipole moments, demonstrate strong agreement with prior computational studies. Similarly, the spectroscopic properties of 3-methyl-2-butenenitrile (molecule 16), such as rotational constants and dipole moments, match experimental data with deviations of less than 1% . This level of agreement highlights the accuracy and reliability of the methods used here.