Oxonium ions, secondary structure

Secondary Oxonium Ions [RR OH ]. 1H NMR and IR investigation75 of protonated ether salts (hexachloroantimonates) in dichloromethane solutions showed the formation of both (a) dialkyloxonium ions in which the proton is bound to only one oxygen (21) and (b) bidentate complexes in which the proton is shared between two ether molecules (22). Structural analysis of such a bidentate complex of diethyl ether with a complex anion shows a broad H+ resonance at 81 H 16.3 and unequal O—H bond distances (1.39 and 1.11 A).76... 

Macrocyclic structure/Ki, supposedly growing by ring-expansion, requires that a proton would exclusively constitute a component of the secondary oxonium ion both during propagation and after establMunent of the pofymer-monomer equilibrium ... 

Kubisa and Penczek measured the ratio of secondary and tertiary oxonium ions in the polymerization of dioxolane by CF3SO3H and found that it varied with both the concentration of reagents and with conversion. The use of the kinetic isotope effect to determine the structure of active centres in the polymerization of heterocycles was described. " Bucquoye and Goethals discuss the mechan- D. J. Sikkema and H. AngadOaur, Makmmol. Chern-, 1980,181,22S9. 

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