A Fluorooxosilicophosphate with an Unprecedented SiO₂F₄ Species

The large number and structural beauty of silicates are largely due to the variety of connection mode of SiO₄ tetrahedra. SiO₆ and SiF₆ octahedra are also known and give rise for structural versatility of inorganic silicates. However, to date, the crystal structure of inorganic fluorooxosilicates with oxofluoride SiO_x F_4-x or SiO_x F_6-x species are unknown. Now, fluorine was successfully introduced into the silicophosphates, and the first fluorooxosilicophosphate K₄ Si₃ P₂ O₇ F₁₂ with an unprecedented SiO₂ F₄ species was synthesized. The existence of Si-F bonds was verified by comprehensively experimental and theoretical work. Using ab initio and bond valence calculations, the oxofluoride SiO_x F_6-x species is shown to be stable when oxygen atoms connect to other atoms with strong covalent interactions. This work will contribute to the structural diversity of silicate chemistry by the exploration of the new fluorooxosilicates.