DOE OSTI2020
La5NSe6 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are twenty inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 2.92–3.37 Å. In the second La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 2.88–3.39 Å. In the third La3+ site, La3+ is bonded to one N3- and five Se2- atoms to form a mixture of distorted edge and corner-sharing LaSe5N octahedra. The corner-sharing octahedral tilt angles are 1°. The La–N bond length is 2.29 Å. There are a spread of La–Se bond distances ranging from 2.99–3.19 Å. In the fourth La3+ site, La3+ is bonded to one N3- and five Se2- atoms to form a mixture of distorted edge and corner-sharing LaSe5N octahedra. The corner-sharing octahedral tilt angles are 1°. The La–N bond length is 2.28 Å. There are a spread of La–Se bond distances ranging from 3.01–3.17 Å. In the fifth La3+ site, La3+ is bonded in a 2-coordinate geometry to two N3- and four Se2- atoms. There are one shorter (2.36 Å) and one longer (2.42 Å) La–N bond lengths. There are a spread of La–Se bond distances ranging from 3.14–3.37 Å. In the sixth La3+ site, La3+ is bonded in a 2-coordinate geometry to two N3- and four Se2- atoms. There are one shorter (2.39 Å) and one longer (2.42 Å) La–N bond lengths. There are a spread of La–Se bond distances ranging from 3.15–3.33 Å. In the seventh La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 2.97–3.36 Å. In the eighth La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 2.92–3.44 Å. In the ninth La3+ site, La3+ is bonded in a 1-coordinate geometry to one N3- and seven Se2- atoms. The La–N bond length is 2.41 Å. There are a spread of La–Se bond distances ranging from 3.04–3.27 Å. In the tenth La3+ site, La3+ is bonded in a 1-coordinate geometry to one N3- and seven Se2- atoms. The La–N bond length is 2.42 Å. There are a spread of La–Se bond distances ranging from 3.05–3.27 Å. In the eleventh La3+ site, La3+ is bonded in a 1-coordinate geometry to one N3- and five Se2- atoms. The La–N bond length is 2.33 Å. There are a spread of La–Se bond distances ranging from 2.96–3.20 Å. In the twelfth La3+ site, La3+ is bonded in a 1-coordinate geometry to one N3- and five Se2- atoms. The La–N bond length is 2.32 Å. There are a spread of La–Se bond distances ranging from 2.95–3.22 Å. In the thirteenth La3+ site, La3+ is bonded in a 7-coordinate geometry to two N3- and five Se2- atoms. There are one shorter (2.36 Å) and one longer (2.46 Å) La–N bond lengths. There are a spread of La–Se bond distances ranging from 2.99–3.27 Å. In the fourteenth La3+ site, La3+ is bonded in a 7-coordinate geometry to two N3- and five Se2- atoms. There are one shorter (2.36 Å) and one longer (2.50 Å) La–N bond lengths. There are a spread of La–Se bond distances ranging from 3.00–3.27 Å. In the fifteenth La3+ site, La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 3.00–3.59 Å. In the sixteenth La3+ site, La3+ is bonded in a 7-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 2.97–3.65 Å. In the seventeenth La3+ site, La3+ is bonded in a distorted single-bond geometry to one N3- and seven Se2- atoms. The La–N bond length is 2.34 Å. There are a spread of La–Se bond distances ranging from 3.06–3.42 Å. In the eighteenth La3+ site, La3+ is bonded in a distorted single-bond geometry to one N3- and six Se2- atoms. The La–N bond length is 2.30 Å. There are a spread of La–Se bond distances ranging from 3.08–3.44 Å. In the nineteenth La3+ site, La3+ is bonded to seven Se2- atoms to form a mixture of distorted edge and corner-sharing LaSe7 pentagonal bipyramids. There are a spread of La–Se bond distances ranging from 2.99–3.23 Å. In the twentieth La3+ site, La3+ is bonded to seven Se2- atoms to form a mixture of distorted edge and corner-sharing LaSe7 pentagonal bipyramids. There are a spread of La–Se bond distances ranging from 2.92–3.42 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded to four La3+ atoms to form NLa4 tetrahedra that share a cornercorner with one SeLa5 square pyramid, an edgeedge with one SeLa6 octahedra, an edgeedge with one SeLa5 square pyramid, and an edgeedge with one NLa4 tetrahedra. In the second N3- site, N3- is bonded to four La3+ atoms to form NLa4 tetrahedra that share an edgeedge with one SeLa6 octahedra, an edgeedge with one SeLa5 square pyramid, and an edgeedge with one NLa4 tetrahedra. In the third N3- site, N3- is bonded to four La3+ atoms to form NLa4 tetrahedra that share corners with two equivalent SeLa6 octahedra, a cornercorner with one SeLa5 square pyramid, a cornercorner with one SeLa5 trigonal bipyramid, an edgeedge with one SeLa6 octahedra, and an edgeedge with one NLa4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–71°. In the fourth N3- site, N3- is bonded to four La3+ atoms to form NLa4 tetrahedra that share corners with two equivalent SeLa6 octahedra, a cornercorner with one SeLa5 square pyramid, an edgeedge with one SeLa6 octahedra, and an edgeedge with one NLa4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–70°. There are twenty-four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to five La3+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to five La3+ atoms. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to five La3+ atoms. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to five La3+ atoms. In the fifth Se2- site, Se2- is bonded to five La3+ atoms to form distorted SeLa5 trigonal bipyramids that share corners with two equivalent SeLa5 square pyramids, a cornercorner with one NLa4 tetrahedra, corners with two equivalent SeLa5 trigonal bipyramids, an edgeedge with one SeLa6 octahedra, and an edgeedge with one SeLa5 square pyramid. In the sixth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the seventh Se2- site, Se2- is bonded in a 5-coordinate geometry to five La3+ atoms. In the eighth Se2- site, Se2- is bonded to five La3+ atoms to form distorted SeLa5 square pyramids that share a cornercorner with one SeLa6 octahedra, corners with two equivalent SeLa5 square pyramids, corners with three NLa4 tetrahedra, and edges with two NLa4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to six La3+ atoms. In the tenth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the eleventh Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four La3+ atoms. In the twelfth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to four La3+ atoms. In the thirteenth Se2- site, Se2- is bonded to five La3+ atoms to form a mixture of distorted edge and corner-sharing SeLa5 square pyramids. In the fourteenth Se2- site, Se2- is bonded to five La3+ atoms to form distorted SeLa5 trigonal bipyramids that share a cornercorner with one SeLa6 octahedra, a cornercorner with one SeLa5 square pyramid, and edges with three SeLa5 square pyramids. The corner-sharing octahedral tilt angles are 43°. In the fifteenth Se2- site, Se2- is bonded to five La3+ atoms to form distorted SeLa5 square pyramids that share a cornercorner with one SeLa6 octahedra, corners with two equivalent SeLa5 square pyramids, corners with two equivalent SeLa5 trigonal bipyramids, and edges with two SeLa5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 42°. In the sixteenth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the seventeenth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the eighteenth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the nineteenth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms. In the twentieth Se2- site, Se2- is bonded in a 4-coordinate geometry to four La3+ atoms. In the twenty-first Se2- site, Se2- is bonded to six La3+ atoms to form distorted SeLa6 octahedra that share corners with two equivalent SeLa6 octahedra, corners with two equivalent NLa4 tetrahedra, a cornercorner with one SeLa5 trigonal bipyramid, and edges with two NLa4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the twenty-second Se2- site, Se2- is bonded to six La3+ atoms to form distorted SeLa6 octahedra that share corners with two equivalent SeLa6 octahedra, corners with two SeLa5 square pyramids, corners with two equivalent NLa4 tetrahedra, edges with two NLa4 tetrahedra, and an edgeedge with one SeLa5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 51°. In the twenty-third Se2- site, Se2- is bonded in a 6-coordinate geometry to five La3+ atoms. In the twenty-fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to six La3+ atoms.