| Abstract
| - 119Sn NMR spectroscopy was employed for analysis of the interaction and reaction of SnCl4with the HCl−IBVE adduct [1; CH3CHCl(OiBu)] in the presence of nBu4NCl in CH2Cl2 solution at −78°C, which are model reactions for the living cationic polymerization of isobutyl vinyl ether (IBVE). Theaddition of 1 to an SnCl4 solution led to upfield shifts of the tin nucleus as the 1/SnCl4 mole ratio (<1)increases, which indicates the formation of SnCl5-, via the interaction between SnCl4 and the chlorineatom in 1. On further addition of 1, the pentacoordinated anion is converted into the hexacoordinatedSnCl6-. These tin species are in fast equilibrium among each other, and the 119Sn NMR analyses supportthe formation of a carbocation [2; CH3CH+(OiBu)] from 1 and the dynamic equilibrium between 1 and 2.More effective chloride-anion donors such as nBu4NCl and Ph3CCl can quantitatively convert SnCl4 intoSnCl5-, and then into SnCl62-. Thus under the conditions where living cationic IBVE polymerizationproceeds (1 < nBu4NCl/SnCl4< 2), SnCl4 is fully converted into a weaker Lewis acid, SnCl5-, with theaid of added nBu4NCl. The suppression of the carbocationic species in the living system has thus beenfound due to the interaction between the added salt and SnCl4.
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