The Cis-Effect Explained Using Next-Generation QTAIM

We used next-generation QTAIM (NG-QTAIM) to explain the cis-effect for two families of molecules: C2X2 (X = H, F, Cl) and N2X2 (X = H, F, Cl). We explained why the cis-effect is the exception rather than the rule. This was undertaken by tracking the motion of the bond critical point (BCP) of the stress tensor trajectories T-sigma(s) used to sample the U-sigma-space cis- and trans-characteristics. The T-sigma(s) were constructed by subjecting the C1-C2 BCP and N1-N2 BCP to torsions +/- theta and summing all possible T-sigma(s) from the bonding environment. During this process, care was taken to fully account for multi-reference effects. We associated bond-bending and bond-twisting components of the T-sigma(s) with cis- and trans-characteristics, respectively, based on the relative ease of motion of the electronic charge density rho(r(b)). Qualitative agreement is found with existing experimental data and predictions are made where experimental data is not available.

Automated summary

In this study, we used next-generation QTAIM to explain the cis-effect for two families of molecules by tracking the motion of bond critical points in stress tensor trajectories. By associating bond-bending and bond-twisting components with cis- and trans-characteristics, qualitative agreement with existing experimental data was found, and predictions were made in the absence of experimental data.