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Updated: Jun 21, 2026

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Crystal structures and cation ordering in Cs2MgSi5O12, Rb2MgSi5O12 and Cs2ZnSi5O12 leucites
1Department of Photon Sciences, STFC Daresbury Laboratory, Warrington WA4 4AD, England. ynotlleb1@mac.com
Abstract:
The crystal structures of the leucite analogues Cs(2)MgSi(5)O(12), Cs(2)ZnSi(5)O(12) and Rb(2)MgSi(5)O(12) have been determined by synchrotron X-ray powder diffraction using Rietveld refinement in conjunction with (29)Si MAS NMR spectroscopy. These leucites are framework structures with distinct tetrahedral sites (T sites) occupied by Si and a divalent cation (either Mg or Zn in these samples); there is also a monovalent extra-framework cation (either Cs or Rb in these samples). The refined crystal structures were based on the Pbca leucite structure of Cs(2)CdSi(5)O(12), thus a framework with five ordered Si T sites and one ordered Cd T site was used as the starting model for refinement. (29)Si MAS NMR shows five distinct Si T sites for Cs(2)MgSi(5)O(12) and Rb(2)MgSi(5)O(12), but six Si T sites for Cs(2)ZnSi(5)O(12). The refined structures for Cs(2)MgSi(5)O(12) and Rb(2)MgSi(5)O(12) were determined with complete T-site ordering, but the refined structure for Cs(2)ZnSi(5)O(12) was determined with partial disorder of Mg and Si over two of the T sites.
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