For charged species, the effects of substituent orbital size in the more polarizable bonds to heavier elements show a particularly strong response to the charge introduction at the central atom. For bonds with the larger elements Y of the lower periods, trends in orbital hybridization depend strongly on both electronegativity and orbital size. The rehybridization effects are larger for fluorine- and oxygen-bonds than they are in the similar bonds to carbon. The results illustrate the scope and limitations of the Bent’s rule, the classic correlation between electronegativity and hybridization, commonly used in analyzing structural effects in carbon compounds.

This set of substrates probes the flexibility of the hybridization at five atoms X through variations in electronegativity, polarizability, and orbital size of Y.

Trends in hybridization were systematically analyzed through the combination of DFT calculations with NBO analysis for the five elements X (X = B, C, N, O, and F) in 75 H nX–YH m compounds, where Y spans the groups 13–17 of the periods 2–4.

Period 4 elements