Bond Strength and Interaction Energies in Togni Reagents: Insights from Molecular Electrostatic Potential-Based Parameters

Togni reagents and their analogs, classified as hypervalent iodine(III) complexes, serve as potent trifluoromethylation agents. The interplay of <i>cis</i> and <i>trans</i> factors plays a pivotal role in shaping their performance, affecting aspects such as bond strength, interaction energies, stability, and subsequent nucleophilic reactions. In this context, we propose the utilization of the molecular electrostatic potential (MESP) at the carbon atom (<i>V</i>_C) of the I–CF₃ moiety as a sensitive parameter to quantify the <i>cis</i> and <i>trans</i> influences in Togni-type reagents. Our study has shown that <i>V</i>_C serves as a convenient probe for determining the heterolytic bond dissociation energy (BDE) and, consequently, assessing the reactivity of these reagents. Moreover, these parameters have been successfully applied to evaluate the strength of the σ-hole interactions with nucleophiles (Cl^– and NMe₃). Additionally, we provide insights into interactions of Togni reagents with Brønsted acids such as HCl and HSO₃F, elucidating them in terms of MESP topological parameters. These findings yield valuable information about the electronic properties of hypervalent iodine reagents, particularly Togni-type reagents, offering the potential for optimizing structurally modified reagents with enhanced activity and stability.