Cyclic trimer substitution-polymerization side groups

Third, metallocene units, such as ferrocene or ruthenocene, have been linked to phosphazene cyclic trimers or tetramers and these were polymerized and substituted to give polymers of the type mentioned previously (41). Polyphosphazenes with ferrocenyl groups can be doped with iodine to form weak semiconductors. Polymer chains that bear both ruthenocenyl and ferrocenyl side groups are prospective electrode mediator systems. 

Thus, the second approach to the synthesis of poly(organophosphazenes) involves the introduction of the organic (or organometallic) side groups at the cyclic trimer level, followed by ring-opening polymerization of the substituted cyclic trimer to the high polymer (reaction (ll)).23... 

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