Pnictogen‐Rich Heterocycles Derived from a Phosphadiazonium Cation

Heterocycles that pair main group elements and nitrogen are extremely important within the π‐conjugated heterocycles research community. Compared to the vast number of boron‐nitrogen heterocycles, those that include phosphorus are less common. Furthermore, the use of phosphorus‐nitrogen triple bonds of any type to prepare such compounds is unprecedented. Here, we pair pyridyl hydrazonide ligands with phosphadiazonium cations and demonstrate that the chelated Mes*NP group is directly implicated in the photophysical and redox properties observed for the resulting heterocycles. In doing so, we introduce a novel building block for the production of phosphorus‐containing heterocycles that could find use in small molecule activation and catalysis or as the functional component of emerging organic electronics. For the first time, a phosphadiazonium cation has been used to create functional heterocycles. DFT calculations confirm that the Mes*NP group is directly implicated in the generation of the unique photophysical and redox properties observed opening the door for the further development of new families of pnictogen‐rich, π‐conjugated heterocycles.