H-Bonding-assisted substituent effect

The impact of intramolecular noncovalent interaction, H-bonding and Li-bonding, on the properties of substituents communicating through the resonance effect in such molecular systems as salicylaldehyde, o-hydroxy Schiff base, o-nitrosophenol and their lithium analogues is examined. The studies have shown that the relation between intramolecular noncovalent interactions and the [pi]-electron delocalization in the sequence of [pi]-conjugated covalent bonds linking A and B is considered in terms of the Hammett-like substituent effect in which electron-donating and electron-withdrawing properties of substituents are affected by the noncovalent interaction.