Reduction of 4-Styrylpyridine by SmI2: An Inner Sphere Electron Tranfer Case Where the Binding Site Differs from the Reaction Center

In the reduction of 4-styrylpyridine by SmI2, the binding site for SmI2 differs from the reaction center. MeOH and TFE exhibit an unprecedented behavior showing a sigmoidic effect on the reaction rate, which levels off around 0.5-1 M. The reactions display autocatalytic behavior and a U shape dependence of the reaction rate on the HMPA concentration. With high likelihood, the reactions involve a proton coupled electron transfer step.