A Fluorooxosilicophosphate with an Unprecedented SiO₂F₄ Species

Abstract

The large number and structural beauty of silicates are largely due to the variety of connection mode of SiO tetrahedra. SiO and SiF 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 F or SiO F species are unknown. Now, fluorine was successfully introduced into the silicophosphates, and the first fluorooxosilicophosphate K Si P O F with an unprecedented SiO F 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 F 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.

An Uncommon Hypervalent Fluorooxosilicophosphate

“…Recently,P an and coauthors obtained the first fluorooxosilicophosphate K 4 Si 3 P 2 O 7 F 12 which contains unprecedented hypervalent cis-SiO 2 F 4 specie. [20] This result discloses that hypervalentf luorooxosilicate speciec an maintain structurals tabilityi ni norganic compounds besides the reported organic compounds.…”

“…The O‐P‐O angles range from 104.7(4)° to 113.7(5)° in PO 4 , the O−Si−O bond angles in cis ‐SiO 2 F 4 is nearly 90°, and the distance the distance of two O atoms in cis ‐SiO 2 F 4 is nearly 2.61(7) Å. Close distance and small bond angle may result in the linkage of two PO 4 units forming polymeric P 2 O 7 units (such as in K 4 Si 3 P 2 O 7 F 12 , GeP 2 O 7 complexs). The O−Si−O angles in trans ‐SiO 2 F 4 are about 180° and the distance of two O atoms in trans ‐SiO 2 F 4 is 3.56 Å.…”

“…In phosphate system, constructed by PO 3 F units exhibits improved optical properties including a strong second harmonic generation, enhanced birefringence, wide band gap, and high damage threshold. Recently, Pan and coauthors obtained the first fluorooxosilicophosphate K 4 Si 3 P 2 O 7 F 12 which contains unprecedented hypervalent cis ‐SiO 2 F 4 specie . This result discloses that hypervalent fluorooxosilicate specie can maintain structural stability in inorganic compounds besides the reported organic compounds.…”

“…Hence, suppose the cis-SiO 2 F 4 units coordinate with two PO 4 by two Oa toms. The O-P-O anglesr ange from 104.7(4)8 to 113.7(5)8 in PO 4 ,t he OÀSiÀ Ob ond angles in cis-SiO 2 F 4 is nearly 908,a nd the distance the distance of two Oa toms in cis-SiO 2 F 4 is nearly 2.61 (7) .C lose distance and small bond angle may result in the linkage of two PO 4 units forming polymeric P 2 O 7 units (such as in K 4 Si 3 P 2 O 7 F 12 , [20] GeP 2 O 7 [28] complexs). The OÀSiÀOa ngles in trans-SiO 2 F 4 are about 1808 and the distance of two Oa toms in trans-SiO 2 F 4 is 3.56 .A saresult, two oxygen atoms in the trans-SiO 2 F 4 linearly link two PO 4 to form zigzag P-O-Si-O-P-Ochains which have ar egulara rrangement and furtherf ormed an ideal, fully ordered superstructure (Figure 1).…”

Ce(IO3)2F2⋅H2O: The First Rare‐Earth‐Metal Iodate Fluoride with Large Second Harmonic Generation Response

“…[1d-h] Moreover, iodates have wide transparent wavelengthr egions (from UV/Vis to mid-IR)a nd sizable crystals are easy to grow under mild reaction conditions. [5] Recently,f luorine-containing systemsf or designing optical materials, [6] such as iodates, [7] borates, [8] carbonates, [9] and phosphates, [10] have become attractive, because the introduction of Fa nionsi nto the mother systemsc an not only regulate the crystal structure, but also broaden the bandgapand generate ah igh laser-damage threshold. [5] Recently,f luorine-containing systemsf or designing optical materials, [6] such as iodates, [7] borates, [8] carbonates, [9] and phosphates, [10] have become attractive, because the introduction of Fa nionsi nto the mother systemsc an not only regulate the crystal structure, but also broaden the bandgapand generate ah igh laser-damage threshold.…”