Cyclophosphazene-based multi-site coordination ligands

This review deals with the recent developments in the design, assembly and utility of cyclophosphazene-based ligands. The reactive periphery of the chlorocyclophosphazenes allows their ready elaboration into a variety of multi-site coordination ligands such as pyrazolylcyclophosphazenes, cyclophosphazene hydrazides, pyridyloxycyclophosphazenes, pyridylaminocyclophosphazenes, phosphine-containing cyclophosphazenes, etc. The versatile coordination behavior of these diverse ligand systems is described. The extension of the small-molecule chemistry to the more complex polymer systems, which has been done in a few systems, is described. The utility of aminocyclophosphazenes for preparing multi-metallic architectures is also discussed.