Torsional barrier and equilibrium structure of ethyl cyanide

Why it is sometimes difficult to determine the accurate position of a hydrogen atom by the semiexperimental method: Structure of molecules containing the OH or the CH3 group

“…It is also useful to remember that these causes of error are often encountered. For propionitrile, large residuals were observed for the CH 2 Da species …”

A benchmark study of molecular structure by experimental and theoretical methods: Equilibrium structure of thymine from microwave rotational constants and coupled-cluster computations

“…When the CC bond is closer to a single bond, the increase is more significant. For instance, going from CH 3 CN to CH 3 CH 2 CN, the C1AC2 bond length increases from 1.459 Å [46] to 1.464 Å [47]. A similar effect is observed when going from CH 3 CHO to (CH 3 ) 2 CO where the CAC bond length increases from 1.499 Å [CCSD(T)(AE)/wCVQZ value] to 1.508 Å [48].…”

First High Resolution Spectroscopic Studies and Ab Initio Calculations of Ethanetellurol

“…First CH 3 functional group torsion has been excluded from consideration since the calculated value of the torsional barrier (15 kJ/mol) is too high to provide large splittings. For example, for a similar molecule such as ethyl cyanide, the barrier height is estimated to be 12.9 kJ/mol and no torsional splittings have been observed in millimeter-wave spectra. , Second, we have found that the separation between the components of a doublet depends on the J quantum number, and does not depend on the position within a band, that is, the K a quantum number. According to the theoretical estimations, such splittings can be caused by Te−H functional group tunneling motion.…”