Synthesis and Redox Properties of a Thermally Stable bis-N-Heterocyclic Carbene Adduct of Phosphorus Mononitride

Herein we report the synthesis and characterization of an unsymmetric thermally stable N-heterocyclic carbene adduct of phosphorus mononitride IPrMePNIPr (3). The asymmetry and thermal stability of 3 allowed for unambiguous characterization in both the solid-state and solution, including the dynamic motion and electrochemical properties, permitting the comparison to related compounds. 3 could be oxidized by one electron to form the corresponding radical cation salt [3][SbF6]. Further oxidation resulted degradation, either by fluoride abstraction from the counteranion or mechanisms unknown, depending on the nature of the oxidant. The Lewis acidity of the targeted dication [3]2+ was evaluated computationally, revealing a FIA in solution of 285 kJ mol−1, consistent with the observed reactivity.