Nucleophilic Attack at the Pyridine Nitrogen Atom in a Bis(imino)pyridine System: The Local Hard and Soft Acids and Bases Principle Perspective

Abstract

Motivated by the unprecedented nucleophilic attack at the pyridine nitrogen atom in bis(imino)pyridines, observed by Gambarotta <em>et al.</em> and Gibson <em>et al.</em>, and the fact that normally pyridine undergoes reactions with electrophiles at its nitrogen atom, we applied the local hard and soft acids and bases principle to assert that nucleophilic attack at pyridine nitrogen atom depends fundamentally on stereoelectronic factors.

Electrophilic Modulation of the Superoxide Anion Radical Scavenging Ability of Copper(II) Complexes with 4-Methyl Imidazole

“…The condensed softness and philicity (intermolecular descriptors) values were calculated for nucleophilic ( s Ak + = Sf Ak + and ω Ak + = ω f Ak + ) and radical ( s Ak 0 = Sf Ak 0 and ω Ak 0 = ω f Ak 0 ) attacks using the condensed Fukui function values. Local properties calculation: the electron density ρ­( r ) values of the neutral (with N electrons), cationic (with N – 1 electrons), and anionic (with N + 1 electrons) species were calculated at the experimental geometry of the neutral compound to obtain the local Fukui functions for nucleophilic f + ( r ) = ρ N +1 ( r ) – ρ N ( r ) and radical f 0 ( r ) = ρ N +1 ( r ) – ρ N –1 ( r ) attacks. − ET calculations: the energy and the number of electrons involved in the interaction were calculated by and where and for nucleophilic (+) and radical (o) attacks, respectively. ,, …”