New lithium borates with bistetrazolato2− and pyrazinediolato2− ligands – potentially interesting lithium electrolyte additives

Abstract

We present a convenient synthesis of the first silylated bistetrazole via a catalyzed twin [2 + 3] cycloaddition of TMS-azide at cyanogen and its application to access bistetrazolatoborates, structurally characterized by a unique unsaturated ten-membered B₂N₄C₄ heterocyclic system. Furthermore, new borate anions with two pyrazine-2,3-diolato ligands were synthesized from tetrafluoroborate salts and structurally characterized. Their organic cation can be exchanged for Li⁺via cation exchange. The conceptual relation of these new salts to lithium ion battery bisoxalalatoborate additive LiBOB, a prominent solid electrolyte interface (SEI) generator, is discussed.