Pressure-supported crystal growth and single-crystal structure determination of Li2SiF6

Abstract

High-pressure/high-temperature conditions of 5.5 GPa and 750°C applied to a powder of Li 2 SiF 6 led to a pressure-supported crystal growth of Li 2 SiF 6 maintaining single crystals of sufficient quality for a single-crystal structure determination. The compound crystallizes in the space group P321 (No. 150) with 3 formula units and the lattice parameters a = 8.219(2), c = 4.5580(9) Å, V = 266.65(8) Å 3 , R 1 = 0.0178, and wR 2 = 0.0391 (all data).This work verified the published powder diffraction data of Li 2 SiF 6 and the predicted space group. Additionally, powder-FT-IR and Raman-spectroscopic investigations on single-crystals of Li 2 SiF 6 were performed for the first time.

KLiSiF6 and CsLiSiF6 – A Structure Investigation

“…Within the second building unit [LiF 6 ] 5− , the Li−F bond lengths vary from 193.0(1) to 219.4(1) pm (Table S3). This corresponds with the values given in the literature for Li 2 SiF 6 ( d Li−F =195.5(2) to 216.6(4) pm) [2] . The bond angles are in accordance with a distorted octahedral coordination sphere (Table S4).…”

“…Salts of the hexafluoridosilicic acid are known since the beginning of the nineteen hundreds, with K 2 SiF 6 first mentioned in 1882 [1] . Recently, many of the ternary alkali metal hexafluoridosilicates A 2 SiF 6 ( A =Li, Na, K, Rb, Cs), [2–5] as well as the ternary alkaline earth metal hexafluoridosilicates A’ SiF 6 ( A’ =Ca, Ba, Sr, Eu) [6–8] were synthesized and are mentioned in the literature. Additionally, magnesium and strontium hexafluoridosilicates are known as hydrates (Mg(SiF 6 )(H 2 O) 6 and Sr(SiF 6 )(H 2 O) 2 ) [9–10] .…”

“…Additionally, magnesium and strontium hexafluoridosilicates are known as hydrates (Mg(SiF 6 )(H 2 O) 6 and Sr(SiF 6 )(H 2 O) 2 ) [9–10] . Nevertheless, a detailed structure description is limited to alkali metal hexafluoridosilicates and a few other hexafluoridosilicates A’ SiF 6 ( A’ =Ca, Ba, Sr, Eu) [2–8] . All of those described hexafluoridosilicates have a common building block, a [SiF 6 ] 2− unit.…”

HF-Free Synthesis of Li2SiF6:Mn4+: A Red-Emitting Phosphor

“…Powder X-ray analysis showed Li 2 SiF 6 as the main product with Cs 2 SiF 6 as side product (Figure , top). The use of high-pressure conditions for this step is crucial, because at ambient pressure Li 2 SiF 6 decomposes to LiF and SiF 4 at temperatures above 250 °C …”

Li2PbF6 and SrPbF6 Revisited

“…The crystal structures of the alkali metal hexafluoridosilicates(IV) and hexafluoridogermanates(IV) are also known for Li–Cs . The compounds M I 2 SnF 6 ( M I = Li–Cs) are structurally characterized as well , .…”