Small-molecule cyclic models for the synthesis of new polyphosphazenes: Side-group construction via lithiophenoxy derivatives

Article abstract of DOI:10.1021/ic50206a047

Hexakis(p-lithiophen oxy)cyclotriphosphazene, [NP(OC₆H₄Li-p)₂]₃ (IV), has been synthesized as an intermediate for the covalent attachment of metallo, phosphino, carboxylato, alkyl, or tertiary alcohol units to the side-group structure. These reactions are models for the preparation of the corresponding phosphazene high polymers. Intermediate IV was prepared by the metal-halogen exchange reaction between [NP(OC₆H₄Br-p)₂]₃ (III) or [NP(OC₆H₄I-p)₂]₃ and n-butyllithium in tetrahydrofuran at -40 to -60°C. The subsequent interaction of IV with deuterium oxide, diphenylchlorophosphine, carbon dioxide, butyl bromide, benzophenone, triphenyltin chloride, or (triphenylphosphine)gold(I) chloride yielded the para-substituted derivatives [NP(OC₆H₄D)₂]₃ (VII), [NP(OC₆H₄P(C₆H₅)₂) ₂]₃ (VIII), [NP(OC₆H₄COOH)₂]₃ (IX), [NP(OC₆H₄C₄H₉)₂] ₃ (X), [NP(OC₆H₄C(OH)(C₆H₅) ₂)₂]₃ (XI), [NP(OC₆H₄Sn(C₆H₅)₃) ₂]₃ (XII), and [NP(OC₆H₄AuP(C₆H₅)₃) ₂]₃ (XIII), respectively. Compounds VII-XIII cannot be obtained readily by other synthetic routes. For example, the reaction of III with NaP(C₆H₅)₂ is a less efficient route to the preparation of VIII. Compound VIII is a model coordination carrier species for transition-metal catalysts. The possible extension of these reactions to linear phosphazene high polymers is discussed.