Sulphur dioxide insertion into tin-carbon bonds: solvent effects and the nature of the transition state

摘要

Data describing the insertion of sulphur dioxide into the carbon-tin bond of a range of substituted phenyltrimethyltin compounds in methanol and benzene solvents have been reconsidered. The reaction in methanol is cleanly second order, but the reaction in benzene has both a second-order and third-order component, the latter ascribable to an initial equilibrium formation of a SO_2 complex with the phenyl ring followed by the insertion of a second SO_2 molecule into the carbon-tin bond. Molecular orbital calculations have identified the transition states (TS) and the favoured reaction pathways for the secondorder and third-order reaction pathways in benzene. The effects of solvents on TS and enthalpies of reaction have also been examined. New insights into the types of TS involved in electrophilic substitution reactions are revealed.