Phosphazenes

Abstract

This chapter summarizes the chemistry of phosphazenes in the calendar year 2021. The topics covered are acyclic phosphazenes, cyclophosphazenes, polyphosphazenes and hybrid polymers. The synthesis, structure and reactivity of these systems are covered. The applications of these compounds in various fields ranging from catalysis to flame-retardant properties are also reviewed. Acyclic phosphazenes also known as iminophosphoranes have been studied because of their applications as strong bases and organocatalysts as well as their ability to function as ligands towards transition-, lanthanide- and main-group metal ions. Cyclophosphazenes are the archetypical inorganic heterocyclic rings which have been studied in terms of their reactivity as well as their use in preparing dendrimer-like molecules. In addition, cyclophosphazenes have also been used as ligands in coordination chemistry. These aspects are covered in this chapter. This chapter also discusses various aspects of phosphazene polymers including their preparation, characterization, and applications in multiple fields.