Designing Three Fluorooxoborates with a Wide Transmittance Window by Anionic Group Substitution.

Three fluorooxoborates, K0.42Rb2.58B3O3F6 and M3B2PO5F4 (M = K, Cs), were designed and synthesized under the open system. One of the common features is that the title compounds consist of six-membered oxofluoride anions. The oxofluoride anions [B3O3F6]3- and [B2PO5F4]3- display structures similar to the boroxine [B3O6]3-. Anionic group substitution using the [BO2F2]3- and [PO4]3- units can improve the optical property of the [B3O6]3- anion and help to generate a wide transmittance window.