Stereochemical Aspects of Polyphosphazenes

Polyphosphazenes are the most important class of inorganic polymers having a backbone of alternating phosphorus and nitrogen atoms with phosphorus atoms bearing organic, inorganic or organometallic side groups. They are potentially optically active macromolecules because they may have a center of chirality anywhere in their structure. Although there have been a number of studies which deal with the polyphosphazenes having stereogenic P-moieties in the main chain, chiral groups in the side chain, optically active helical structure, and cyclolinear phosphazene polymers for over the last fifty years, there is little emphasis on the stereochemistry of phosphazene polymers to date. In this review the polyphosphazenes containing centers of chirality P- and/or C-moieties anywhere in their structure have been covered.