Phosphazenes as scaffolds for the construction of multi-site coordination ligands

Chlorocyclophosphazenes containing a reactive periphery and a robust framework offer an ideal platform for the construction of a large variety of multi-site coordination ligands. Various types of neutral or (multi)anionic multi-site coordinating ligands can be assembled containing different numbers, type and stereochemical orientations of coordination sites reflecting the ease of modulation of these ligand types. Also it is possible to construct new types of macrocyclic ligands using cyclophosphazenes as scaffolds. The interaction of these ligands with transition and main group metals leads to a number of different complex types showing the rich diversity that is present in this family of compounds. A study of these ligands in principle also allows the assembly of the corresponding polymeric ligands.