| Even though chlorophosphazene chemistry has been around since the 1800s, it was not until the 1950s when Allcock successfully synthesized the soluble chlorophosphazene polymer that the door to functionalized polyphosphazenes was opened. At present, polyphosphazenes constitute the largest group of inorganic backbone polymers, with their potential applications ranging from elastomers to biomaterials. Most functionalized polyphosphazenes are derived from polychlorophosphazenes. The problems surrounding the synthesis and storage of polychlorophosphazenes hinder the commercial development of functionalized polyphosphazenes. In the quest for a cost-effective synthetic route and for storage solutions, our group focuses on the fundamental chlorophosphazene chemistry.;This dissertation discusses our endeavors to understand fundamental chlorophosphazene chemistry, the majority of the work being on the chemistry of [PCl2N] 3. The dissertation is divided into six chapters; Introduction, Mechanistic Studies of the Fluxional Behavior of Group 13 Lewis Acid Adducts of [PCl 2N]3, Group 13 Super Acid Adducts of [PCl2N] 3, Crown ether complexes of HPCl6, Reactions of Group 15 Superacids with Chlorophosphazenes and Conclusion. Chapter I, the introduction, provides the overview of the previous studies of the acid-base chemistry of chlorophosphazenes. Chapter II describes a mechanistic study of the fluxional behavior of the Group 13 Lewis acid adducts of [PCl2N]3 and evaluates the likelihood that these adducts are directly involved as intermediates in the ROP process. The synthesis and characterization of Group 13 superacid adducts of [PCl2N]3 are discussed in Chapter III. The fragile acid HPCl6, which can potentially play an important role in chlorophosphazene chemistry, was isolated as complexes of crown ethers. Chapter IV describes the synthesis and characterization of these complexes. The reactivity of Group 15 acids, HPCl6 and HSbCl6 towards cyclic [PCl2N]n (n = 3, 4, 5, and 6) and polymeric [PCl 2N]n follows in Chapter V. This chapter also qualitatively compares the acid strengths of the relatively unknown HPCl6 and HSbCl6 acids to the strengths of more commonly known superacids, such as HAlCl4, HAlBr4, HGaCl4 and superacids with carborane anions. |
