Probing the Dynamic Covalent Chemistry Behavior of Nitrogen-Centered Di- and Triurazole Radicals

Dynamic covalent chemistry (DCvC) describes systems in which readily reversible bond formation allows for control of product distributions by straightforward manipulation of reaction conditions (e.g., changes in temperature, solvent, concentration, etc). Nitrogen-centered 1-aryl urazole radicals reversibly form tetrazane dimers in solution via N-N bond formation. When two such urazole units are attached to a single, appropriately substituted benzene ring, the resulting diradical system engages in DCvC. At room temperature, a polymeric network of units is created that exhibits gel-like properties, while at higher temperatures, near quantitative dimerization to form a molecular cage is observed.However, attaching three such urazole units to a single appropriately substituted benzene ring inhibits DCvC behavior.