Chiral and Steric Effects in Ethane: A Next Generation QTAIM Interpretation

TL;DR

This paper develops a new quantum theory approach to analyze ethane's chirality and steric effects, revealing a novel isomer and suggesting steric effects dominate ethane's geometry over hyper-conjugation.

Contribution

It introduces NG-QTAIM for chirality analysis, discovering a new 'null-isomer' and highlighting steric effects as key to ethane's staggered structure.

Findings

Discovery of a Q_sigma isomer with near-zero chirality-helicity function

Steric effects explain ethane's staggered geometry more than hyper-conjugation

Electric field reduces steric effects by half in the NG-QTAIM framework

Abstract

We introduce a development of next generation quantum theory of atoms in molecules (NG-QTAIM) for an investigation of the chirality of ethane and discover a $Q_{\sigma}$ isomer in addition to $S_{\sigma}$ and $R_{\sigma}$ stereoisomers in the stress tensor trajectory $U_{\sigma}$-space. The $Q_{\sigma}$ isomer is defined to be a 'null-isomer' since the value of the chirality-helicity function $\approx 0$. The presence of chiral contributions suggests that steric effects, rather than hyper-conjugation, explain the staggered geometry of ethane. The steric effects, within the NG-QTAIM interpretation, are reduced by a factor of two using an applied electric-field directed down a C-H bond.