Materials Data on Na6W6Se2O25 by Materials Project
Na6W6Se2O25 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to seven O2- atoms to form NaO7 pentagonal bipyramids that share corners with two WO6 octahedra, an edgeedge with one NaO8 hexagonal bipyramid, and edges with two WO6 octahedra. The corner-sharing octahedra tilt angles range from 22–24°. There are a spread of Na–O bond distances ranging from 2.39–2.62 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 2.36–2.78 Å. In the third Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–2.90 Å. In the fourth Na1+ site, Na1+ is bonded to eight O2- atoms to form distorted NaO8 hexagonal bipyramids that share edges with six WO6 octahedra and an edgeedge with one NaO7 pentagonal bipyramid. There are a spread of Na–O bond distances ranging from 2.28–2.86 Å. In the fifth 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 2.31–2.78 Å. In the sixth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.58 Å. There are six inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with three WO6 octahedra, a cornercorner with one NaO7 pentagonal bipyramid, an edgeedge with one NaO8 hexagonal bipyramid, and an edgeedge with one NaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 24–50°. There are a spread of W–O bond distances ranging from 1.77–2.29 Å. In the second W6+ site, W6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 1.77–2.43 Å. In the third W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with three WO6 octahedra, a cornercorner with one NaO7 pentagonal bipyramid, an edgeedge with one NaO8 hexagonal bipyramid, and an edgeedge with one NaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 24–50°. There are a spread of W–O bond distances ranging from 1.78–2.28 Å. In the fourth W6+ site, W6+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of W–O bond distances ranging from 1.77–2.41 Å. In the fifth W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with four WO6 octahedra and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 30–37°. There are a spread of W–O bond distances ranging from 1.78–2.31 Å. In the sixth W6+ site, W6+ is bonded to six O2- atoms to form WO6 octahedra that share corners with four WO6 octahedra and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 30–37°. There are a spread of W–O bond distances ranging from 1.80–2.09 Å. There are two inequivalent Se4+ sites. In the first Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.72–1.78 Å. In the second Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.70–1.83 Å. There are twenty-five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and one W6+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+ and two W6+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two W6+ atoms. In the fourth O2- site, O2- is bonded to two Na1+ and two W6+ atoms to form a mixture of distorted edge and corner-sharing ONa2W2 tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two W6+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two W6+, and one Se4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two W6+ atoms. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one W6+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two W6+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and one W6+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two W6+, and one Se4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one W6+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and one W6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one W6+, and one Se4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+ and two W6+ atoms. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and one W6+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one W6+ atom. In the eighteenth O2- site, O2- is bonded to three Na1+ and one Se4+ atom to form a mixture of distorted edge and corner-sharing ONa3Se tetrahedra. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one W6+ atom. In the twentieth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two W6+ atoms. In the twenty-first O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two equivalent W6+ atoms. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two W6+ atoms. In the twenty-third O2- site, O2- is bonded to three Na1+ and one Se4+ atom to form distorted ONa3Se tetrahedra that share corners with two ONa2W2 tetrahedra and an edgeedge with one ONa3Se tetrahedra. In the twenty-fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two W6+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one W6+, and one Se4+ atom.