Infrared Absorption Spectra of Inorganic Solids. IV. Hexafluorosilicates. Raman Spectra of Aqueous SiF₆^2-

Abstract

Infrared absorption spectra of 11 solid hexafluorosilicates and the Raman spectra of aqueous solutions of some of these compounds have been investigated. Two intense bands observed in the infrared regions have been assigned as p4(Fiu) of SiFe2at 485 cm-1 and p3(Fm) of SiFe2-at 740 cm-1. The three Raman bands have been assigned as yi(Atg) at 656 cm-1, v"(F2e) at 395-400 cm-1, and vi{Eg) at 465 cm-1. By comparison with other ABe molecules and ions and observed combination bands, one estimates =325 cm-1.The infrared absorption spectra of 11 solid hexafluorosilicates have been examined in a continuation of studies of infrared absorption spectra of inorganic solids.

A novel route of synthesis of sodium hexafluorosilicate two component cluster crystals using BF4− containing ionic liquids

“…3. The intense lines at 738, 485 and 497 cm À 1 correspond to the Si-F stretching vibrations, which is the main character of Na 2 [SiF 6 ] [23]. Moreover, several signals at 1172 (C2-H, C4-H, N-Et, N-Me) and 1578 cm À 1 (CQC) [24] demonstrate the presence of imidazolium ring in the samples.…”

Large-scale synthesis of water-soluble Na2SiF6 nanotubes with polyacrylic acid as a surfactant

“…2f) was also employed to characterize the Na 2 SiF 6 nanotubes. It can be seen that the peaks located at 724, 498, and 477 cm À1 were all attributed to Si-F vibrations, which is a fingerprint character of Na 2 SiF 6 [18].…”

First X-ray structure of hexaamminecobalt(III) salt with complex fluoroanion: Synthesis and characterization of [Co(NH3)6]X·SiF6·nH2O, where X=Cl, Br, I and NO3 and crystal structure of [Co(NH3)6]Cl·SiF6·2H2O

“…The strong band in the range 740-760 cm À1 was assigned to the asymmetric stretching frequency (n as , Si-F), while the very strong band at 480 cm À1 corresponds to the asymmetric bending mode (d as , F-Si-F). The Infrared spectra of the anhydrous alkali metal salts like sodium or potassium hexafluorosilicate [15] which are not expected to show hydrogen bonding show strong sharp band in the range 740-760 cm À1 for Si-F bond and for ammonium hexafluorosilicate [16] the value is lower (at 730 cm À1 ) which may be attributed to the formation of SiÀF Á Á Á H type of hydrogen bonds. However, there is not much effect of SiÀF Á Á Á H hydrogen bonding in the case of trialkyl [17,18] and benzyl ammonium hexafluorosilicate [19] salts, which show the asymmetric Si-F stretch vibration at 740 cm À1 .…”