A theoretical perspective on the bond length rule of Grochala, Albrecht, and Hoffmann

Grochala, Albrecht, and Hoffmann have recently observed that, for many orga nic and inorganic molecules, the bond lengths in the cation (R+), neutral s ystem (R-gs), first tripler excited state (R-es), and anion (R-) approximat ely satisfy R+ + R- - R-gs - R-es approximate to 0. This paper shows how th e Fukui function, a concept from the density functional theory of chemical reactivity, can be used to rationalize the Grochala-Albrecht-Hoffmann rule. The treatment also suggests which types of chemical systems will be best d escribed by the Grochala-Albrecht-Hoffmann rule.