Asymmetric [N–I–N]+ halonium complexes in solution?

Abstract

Assessment of the solution equilibria of [bis(pyridine)iodine(I)]⁺ complexes by ESI-MS and NMR reveals the preference of iodine(I) to form complexes with a more basic pyridine. Mixtures of symmetric [bis(pyridine)iodine(I)]⁺ complexes undergo statistical ligand exchange, with a predominant entropic driving force favoring asymmetric systems. The influence of ligand basicity, concentration, temperature, and ligand composition is evaluated. Our findings are expected to facilitate the investigations, and the supramolecular and synthetic applications of halonium ions’ halogen bonds.