DOE OSTI2020
Na3(SO2)4As crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four arsenic molecules and one Na3(SO2)4 framework. In the Na3(SO2)4 framework, there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.44 Å) and two longer (2.52 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.35 Å) and two longer (2.39 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.26–2.48 Å. In the fourth Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.95 Å. There are four inequivalent S2+ sites. In the first S2+ site, S2+ is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.51 Å) and one longer (1.67 Å) S–O bond length. In the second S2+ site, S2+ is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.49 Å) and one longer (1.50 Å) S–O bond length. In the third S2+ site, S2+ is bonded in a single-bond geometry to one O2- atom. The S–O bond length is 1.55 Å. In the fourth S2+ site, S2+ is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.50 Å) and one longer (1.51 Å) S–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one S2+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one O2- atom. The O–O bond length is 1.46 Å. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and one S2+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Na1+ and one S2+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Na1+ and one S2+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to one Na1+ and one S2+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and one S2+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+, one S2+, and one O2- atom.