Estimating the Limiting Reducing Power of SmI2/H2O/Amine and YbI2/H2O/Amine by Efficient Reduction of Unsaturated Hydrocarbons

The mixture of samarium diiodide, amine, and water (SmI2/H2O/Et3N) is known to be a particularly powerful reductant, but until now the limiting reducing power has not been determined. A series of unsaturated hydrocarbons with varying half-wave reduction potentials (E 1/2 = −1.6 to −3.4 V, vs SCE) have been treated with SmI2/H2O/Et3N and YbI2/H2O/Et3N, respectively. All hydrocarbons with potentials of −2.8 V or more positive were readily reduced with SmI2/H2O/Et3N, whereas all hydrocarbons with potentials of −2.3 V or more positive were readily reduced using YbI2/H2O/Et3N. This defines limiting values of the chemical reducing power of SmI2/H2O/Et3N to −2.8 V and of YbI2/H2O/Et3N to −2.3 V vs SCE.