Abstract
Samarium diiodide (SmI(2)) exhibits high selectivity for N(2)R catalyzed by molybdenum complexes; however, it has so far been employed only as a stoichiometric reagent (0.3 equiv of NH(3) per Sm) combined with coordinating proton sources (e.g., H(2)O, ROH). The latter inhibit catalytic turnover of Sm(III) owing to buildup of stable hydroxide/alkoxide sinks. Here, we report a tandem Sm/Mo-catalyzed eN(2)R system that achieves the lowest overpotential and highest Faradaic efficiency (82%) reported to date for nonaqueous eN(2)R at ambient pressure. Up to 8.4 equiv of NH(3) is produced per Sm, representing a 25-fold increase over N(2)R with stoichiometric SmI(2). A noncoordinating proton source enables electrochemical SmI(3)/SmI(2) cycling at the applied potential of -1.45 V vs Fc(+/0).