Materials Data on Na2Se2O7 by Materials Project
Na2Se2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six SeO4 tetrahedra and an edgeedge with one NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.45–2.48 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.46–3.06 Å. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with three equivalent NaO6 octahedra and a cornercorner with one SeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Se–O bond distances ranging from 1.64–1.81 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with three equivalent NaO6 octahedra and a cornercorner with one SeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Se–O bond distances ranging from 1.64–1.87 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Na1+ and one Se6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three Na1+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Na1+ and one Se6+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to two Se6+ atoms.