Isolable Radical Ions of Main‐Group Elements: Structures, Bonding and Properties

Abstract

Synthesis of stable main‐group element‐based radicals represents one of the most interesting topics in contemporary organometallic chemistry, because of their vital roles in organic, inorganic and biological chemistry as well as materials science. However, the access of stable main‐group element‐based radicals is highly challenging owing to the lack of energetically accessible orbitals in the main‐group elements. During the last decades, several synthetic strategies have been developed in obtaining these reactive species. Among them, utilizing the sterically demanding substituents and π‐conjugated ligands has proven to be an effective approach. Weakly coordinating ions (WCAs) have also been found to be exceptionally practical in synthesizing radical cations of main‐group elements. By introducing these stabilization methods, we have successfully prepared a variety of radical ions of p‐block elements in the crystalline forms, and investigated their properties by different experimental and quantum chemical calculation methods. According to the investigations, magnetic stability was observed, resulting from the intramolecular electron‐exchange interaction. Furthermore, we also found that the singlet‐triplet energy gaps of the bis(triarylamine) diradical dications can be tunable by varying the temperature. These investigations open new avenues of the main‐group element‐based radicals for a large variety of applications.