RbB3O4F2: a rubidium fluorooxoborate with an unprecedented [B3O5F2]3− functionalized unit and a large birefringence

Abstract

A new rubidium fluorooxoborate, RbB₃O₄F₂, was structurally designed and synthesized by using the strategy of fluorine-introduction into borates. Interestingly, RbB₃O₄F₂ presents the novel [B₃O₄F₂]⁻ chains formed by the unprecedented [B₃O₅F₂]³⁻ fundamental building block. More importantly, RbB₃O₄F₂ has a large birefringence and a deep-UV cutoff edge. The finding of novel [B₃O₅F₂]³⁻ FBB and [B₃O₄F₂]⁻ chains in RbB₃O₄F₂ greatly enriches the structural diversity of fluorooxoborates.