Structural Characterization of Hexafluorosilicate Compounds

The structural characterisation of hexafluorosilicate compounds centres on elucidating the arrangement and bonding of the SiF6 2– anion and its interplay with diverse counter-cations. Single-crystal X-ray diffraction has revealed that the hexafluorosilicate anion adopts a regular octahedral geometry, with Si–F bond lengths typically in the range 1.65–1.70 Å. Vibrational spectroscopy and multinuclear NMR provide complementary insights into local symmetry, dynamic behaviour and any deviation from ideal Oh symmetry. The nature of the organic or inorganic cation governs the formation of characteristic hydrogen-bonding motifs—ranging from sheet-like networks to rod-type assemblies and three-dimensional frameworks—through N–H···F and C–H···F contacts. Quantum-chemical calculations have further clarified the role of back-donation from fluorine lone pairs and the balance of electrostatic attractions that stabilise the anionic framework. These combined studies underpin advances in functional materials, including antimicrobial salts, ionic liquids with tailored conductivity, and host–guest architectures for selective sorption. The continued integration of experimental and computational approaches is deepening our understanding of assembly principles and guiding the rational design of hexafluorosilicate-based systems with targeted thermal stability, hydrolytic resistance and catalytic performance.

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Structural Characterization of Hexafluorosilicate Compounds publication trend

The graph below shows the total number of articles in structural characterization of hexafluorosilicate compounds across all publications each year (not limited to Nature Index journals).

Technical terms

Single-crystal X-ray diffraction: An experimental technique that determines precise atomic positions by analysing the diffraction pattern of X-rays passing through a single crystal.

Hydrogen bond: A non-covalent interaction involving a hydrogen atom covalently bonded to an electronegative donor (such as N or O) and an acceptor atom (often F in hexafluorosilicates), crucial for crystal packing.

Octahedral geometry: A coordination arrangement in which six ligands are symmetrically positioned at the corners of an octahedron around a central atom (Si in SiF6 2–).

Supramolecular architecture: The organised three-dimensional arrangement of molecular building blocks held together by non-covalent interactions, such as hydrogen bonds and π–π interactions.

References

1. Hexane-1,6-di­ammonium hexa­fluoro­silicate. Acta Crystallographica Section E: Crystallographic Communications (2013).
2. Hexafluorosilicates with antibacterial active guanidine containing cations. News of pharmacy (2014).
3. Synthesis and Structural Study of Some Pyrimidinium Hexafluoridosilicates. Acta Chimica Slovenica (2015).