Na3 SO4 H-The First Representative of the Material Class of Sulfate Hydrides

Abstract

The first representative of a novel class of mixed-anionic compounds, the sulfate hydride Na₃ SO₄ H, and the corresponding deuteride Na₃ SO₄ D were obtained from the solid-state reaction of NaH or NaD with dry Na₂ SO₄ . Precise reaction control is required, because too harsh conditions lead to the reduction of sulfate to sulfide. A combined X-ray and neutron diffraction study revealed that the compound crystallizes in the tetragonal space group P4/nmm with the lattice parameters a=7.0034(2) Å and c=4.8569(2) Å. The sole presence of hydride and absence of hydroxide ions is proven by vibrational spectroscopy and comparison with spectra predicted from quantum chemical calculations. ¹ H and ²³ Na MAS NMR spectra are consistent with the structure of Na₃ SO₄ H: a single ¹ H peak at 2.9 ppm is observed, while two peaks at 15.0 and 6.2 ppm for the inequivalent ²³ Na sites are observed. Elemental analysis and quantum chemical calculations further support these results.

Keywords: NMR spectroscopy; anions; density functional calculations; hydrides.