Exploring the versatility of the gCH topological electronegativity estimator

The topological analysis of functions endowed with chemical meaning has provided deep insights into the nature of the chemical bond for over thirty years. Actually, the combination of Bader’s quantum atoms with an electron density partitioning scheme capable of distinguishing bonding regions can be used to measure the atomic distribution of the bond electron density. The analysis of these atomic contributions allowed us to define the g AB index for a given A–B bond, which indeed is related to the effective electronegativity difference of the atoms involved in the bond. In this work, we check some qualitative statements regarding C effective electronegativity through the calculation of the g CH index in different prototypical systems. Thus, we confirm that g CH actually reproduces the expected trends for electronegativity evolution due to geometry variations and electronic effects caused by chemical functionalization. Moreover, the comparison of g CH values for different systems indicates that this index can also be used as an approximate transferability estimator.