The importance of London dispersion forces in crystalline magnesium nitrate hexahydrate

The role of London dispersion forces in crystalline magnesium nitrate hexahydrate [Mg(NO3)2·6H2O] has been investigated using terahertz spectroscopy and solid-state density functional theory modeling. The solid-state simulations were augmented with semi-empirical London dispersion corrections and revealed that such corrections are of negligible importance in this ionic solid. The comparison of the simulated and experimental crystal structures indicated a London force correction magnitude of less than 10% of that required in organic molecular solids of similar size and complexity. While London forces are certainly present in magnesium nitrate hexahydrate, electrostatic forces clearly dominate the intermolecular interactions governing its crystalline structure and dynamics.

Graphical abstractWeak London forces in magnesium nitrate hexahydrate have been investigated using terahertz spectroscopy and solid-state density functional theory with both revealing the magnitude and importance of such interactions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Terahertz spectroscopy of magnesium nitrate hexahydrate. ► Investigation of London forces in ionic compounds. ► Solid-state density functional theory used to model crystalline structure and dynamics.