NMR Study of the Ligand Interchange of Hexacyclen and Hexamethylhexacyclen Complexes with TI+ Ion in 70% Methanol Solution

Abstract

AbstractThe exchange kinetics of TI+ complexes with hexacyclen and hexamethylhexacyclen were studied in 70% methanol solution by proton NMR line‐shape analysis. In TI+‐hexacyclen system, a dissociative mechanism is found to be predominant at higher temperatures, while a bimolecular pathway may become more important at lower temperatures. In contrast, the TI+‐hexamethylhexacyclen system solely prefers a dissociative exchange mechanism in entire temperature range studied. The corresponding exchange rates and the activation parameters Ea, ΔH‡, ΔS‡ and ΔG‡ for the exchange have been determined, and the possible parameters controlling the exchange rates and mechanisms are discussed.