Reduction of K+ or Li+ in the Heterobimetallic Electride K+[LiN(SiMe3)2]e

Abstract

Given their very negative redox potential (e.g., Li⁺ → Li(0), -3.04 V; K⁺ → K(0), -2.93 V), chemical reduction of Group-1 metal cations is one of the biggest challenges in inorganic chemistry: they are widely accepted as irreducible in the synthetic chemistry regime. Their reduction usually requires harsh electrochemical conditions. Herein we suggest a new strategy: via a heterobimetallic electride intermediate and using the nonbinding "free" electron as reductant. Based on our previously reported K⁺[LiN(SiMe₃)₂]e^- heterobimetallic electride, we demonstrate the reducibility of both K⁺ and Li⁺ cations. Moreover, we find that external Lewis base ligands, namely tris[2-(dimethylamino)ethyl]amine (Me₆Tren) or 2,2,2-cryptand, can exert a level of reducing selectivity by preferably binding to Li⁺ (Me₆Tren) or K⁺ (2,2,2-cryptand), hence pushing the electron to the other cation.