Conceptual Density-Functional Theory for General Chemical Reactions, Including Those That Are Neither Charge- nor Frontier-Orbital-Controlled. 2. Application to Molecules Where Frontier Molecular Orbital Theory Fails

This paper examines cases where frontier molecular orbital theory is known to fail, specifically electrophilic aromatic substitution reactions on isoquinoline and borazarophenanthrenes. While we are able to explain the experimental regioselectivity preferences for isoquinoline without too much difficulty, describing the regioselectivity of the borazarophenanthrenes is much more challenging. This is attributed to the fact that these molecules lie between the electrostatic (or charge) control and electron-transfer (or frontier-orbital) control paradigms. These molecules can, however, be described using the general-purpose reactivity indicator introduced in the first paper of this series. The variation of the general-purpose reactivity indicator with respect to the parameters is readily summed up using what we term "reactivity transition tables", which provide a compact summary of which products form under different reaction conditions. For the otherwise problematic molecules considered here, the new reactivity indicator performs better than either the Fukui function or the electrostatic potential alone.