The substituent effect in ethylenes and acetylenes – AIM analysis

The calculations on disubstituted ethylenes YCHCHX with Y = Li, H, F and X = H, F, Li, Na, OH, BeH, NH2, BH2, NO2 were performed at MP2/6-311++G(d,p) level of theory. The analysis of bond lengths and atoms in molecules based theory (AIM) topological parameters such as the characteristics of bond critical points (electron densities and their Laplacians) and atomic radii leads to the conclusion that the AIM parameters are much more sensitive to the action of intramolecular perturbations like substituents than traditional structural parameters such as bond lengths. A comparison of substituted ethylenes with the previously analyzed substituted acetylenes is also given.