A series of boroselenite-based open frameworks mediated by the cationic sizes of the alkali metals

Abstract

The first four metal boroselenites, namely, K₂Se₃B₂O₁₀, ASeB₃O₇ (A = Na, K), and Li₂SeB₈O₁₅, have been synthesized by high temperature solid state reactions. Interestingly, the different cationic sizes and their coordination geometries led to three different types of anionic boroselenite frameworks ranging from a one-dimensional (1D) chain, to two-dimensional (2D) layers to a three-dimensional (3D) network. K₂Se₂B₂O₁₀ features a novel 1D [Se₃B₂O₁₀]²⁻ chain based on isolated B₂O₇ and SeO₃ groups. ASeB₃O₇ (A = Na, K) feature a layered [SeB₃O₇]⁻ architecture built of 1D corner-sharing B₃O₇ clusters that are further bridged by Se atoms. Li₂SeB₈O₁₅ features an interesting 3D [SeB₈O₁₅]²⁻ anionic framework composed of B₃O₇ groups and SeO₃ units. Such 3D frameworks are further interpenetrated with each other into a 2-fold interpenetrating structure.