The material described by Na6Sn2O7 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Sn(1)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O6 octahedra, edges with two equivalent Sn(1)O4 tetrahedra, and  an edgeedge with one Na(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 21-62°. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Sn(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Sn(1)O4 tetrahedra, edges with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(4)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Sn(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(3)O6 octahedra. Sn(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SnO4 tetrahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Sn(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O6 octahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 26°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Sn(1) atom to form distorted ONa4Sn trigonal bipyramids that share  a cornercorner with one O(3)Na5Sn octahedra, corners with two equivalent O(1)Na4Sn trigonal bipyramids, corners with three equivalent O(2)Na4Sn trigonal bipyramids, edges with three equivalent O(3)Na5Sn octahedra, and edges with two equivalent O(2)Na4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 95°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Sn(1) atom to form distorted ONa4Sn trigonal bipyramids that share corners with five equivalent O(3)Na5Sn octahedra, corners with two equivalent O(2)Na4Sn trigonal bipyramids, corners with three equivalent O(1)Na4Sn trigonal bipyramids,  an edgeedge with one O(3)Na5Sn octahedra, and edges with two equivalent O(1)Na4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-78°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Sn(1) atom to form distorted ONa5Sn octahedra that share  a cornercorner with one O(3)Na5Sn octahedra,  a cornercorner with one O(1)Na4Sn trigonal bipyramid, corners with five equivalent O(2)Na4Sn trigonal bipyramids, edges with two equivalent O(3)Na5Sn octahedra,  an edgeedge with one O(2)Na4Sn trigonal bipyramid, and edges with three equivalent O(1)Na4Sn trigonal bipyramids. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Sn(1) atoms. is represented by the CIF file [CIF]
data_Na6Sn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.270
_cell_length_b   6.270
_cell_length_c   12.330
_cell_angle_alpha   77.953
_cell_angle_beta   77.953
_cell_angle_gamma   90.500
_symmetry_Int_Tables_number   1
_cell_volume   462.895
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na0  1  0.794  0.080  0.588  1.0
  Na  Na1  1  0.474  0.014  0.871  1.0
  Na  Na2  1  0.500  0.500  0.500  1.0
  Na  Na3  1  0.455  0.545  0.750  1.0
  Na  Na4  1  0.080  0.794  0.088  1.0
  Na  Na5  1  0.014  0.474  0.371  1.0
  Na  Na6  1  0.986  0.526  0.629  1.0
  Na  Na7  1  0.920  0.206  0.912  1.0
  Na  Na8  1  0.545  0.455  0.250  1.0
  Na  Na9  1  0.526  0.986  0.129  1.0
  Na  Na10  1  0.206  0.920  0.412  1.0
  Na  Na11  1  0.500  0.500  0.000  1.0
  Sn  Sn12  1  0.940  0.739  0.868  1.0
  Sn  Sn13  1  0.261  0.060  0.632  1.0
  Sn  Sn14  1  0.739  0.940  0.368  1.0
  Sn  Sn15  1  0.060  0.261  0.132  1.0
  O  O16  1  0.235  0.694  0.900  1.0
  O  O17  1  0.694  0.235  0.400  1.0
  O  O18  1  0.483  0.213  0.684  1.0
  O  O19  1  0.738  0.844  0.989  1.0
  O  O20  1  0.973  0.027  0.750  1.0
  O  O21  1  0.156  0.262  0.511  1.0
  O  O22  1  0.213  0.483  0.184  1.0
  O  O23  1  0.787  0.517  0.816  1.0
  O  O24  1  0.844  0.738  0.489  1.0
  O  O25  1  0.027  0.973  0.250  1.0
  O  O26  1  0.262  0.156  0.011  1.0
  O  O27  1  0.517  0.787  0.316  1.0
  O  O28  1  0.306  0.765  0.600  1.0
  O  O29  1  0.765  0.306  0.100  1.0
[/CIF]
.
The material described by Na6Sn2O7 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Sn(1)O4 tetrahedra,  a cornercorner with one Na(1)O5 trigonal bipyramid, corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O6 octahedra, edges with two equivalent Sn(1)O4 tetrahedra, and  an edgeedge with one Na(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 21-62°. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Sn(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Sn(1)O4 tetrahedra, edges with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(4)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Sn(1)O4 tetrahedra, corners with four equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(3)O6 octahedra. Sn(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SnO4 tetrahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Sn(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O6 octahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 26°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Sn(1) atom to form distorted ONa4Sn trigonal bipyramids that share  a cornercorner with one O(3)Na5Sn octahedra, corners with two equivalent O(1)Na4Sn trigonal bipyramids, corners with three equivalent O(2)Na4Sn trigonal bipyramids, edges with three equivalent O(3)Na5Sn octahedra, and edges with two equivalent O(2)Na4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 95°. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Sn(1) atom to form distorted ONa4Sn trigonal bipyramids that share corners with five equivalent O(3)Na5Sn octahedra, corners with two equivalent O(2)Na4Sn trigonal bipyramids, corners with three equivalent O(1)Na4Sn trigonal bipyramids,  an edgeedge with one O(3)Na5Sn octahedra, and edges with two equivalent O(1)Na4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-78°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Sn(1) atom to form distorted ONa5Sn octahedra that share  a cornercorner with one O(3)Na5Sn octahedra,  a cornercorner with one O(1)Na4Sn trigonal bipyramid, corners with five equivalent O(2)Na4Sn trigonal bipyramids, edges with two equivalent O(3)Na5Sn octahedra,  an edgeedge with one O(2)Na4Sn trigonal bipyramid, and edges with three equivalent O(1)Na4Sn trigonal bipyramids. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Sn(1) atoms. is represented by the CIF file [CIF]
data_Na6Sn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.270
_cell_length_b   6.270
_cell_length_c   12.330
_cell_angle_alpha   77.953
_cell_angle_beta   77.953
_cell_angle_gamma   90.500
_symmetry_Int_Tables_number   1
_cell_volume   462.895
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na0  1  0.794  0.080  0.588  1.0
  Na  Na1  1  0.474  0.014  0.871  1.0
  Na  Na2  1  0.500  0.500  0.500  1.0
  Na  Na3  1  0.455  0.545  0.750  1.0
  Na  Na4  1  0.080  0.794  0.088  1.0
  Na  Na5  1  0.014  0.474  0.371  1.0
  Na  Na6  1  0.986  0.526  0.629  1.0
  Na  Na7  1  0.920  0.206  0.912  1.0
  Na  Na8  1  0.545  0.455  0.250  1.0
  Na  Na9  1  0.526  0.986  0.129  1.0
  Na  Na10  1  0.206  0.920  0.412  1.0
  Na  Na11  1  0.500  0.500  0.000  1.0
  Sn  Sn12  1  0.940  0.739  0.868  1.0
  Sn  Sn13  1  0.261  0.060  0.632  1.0
  Sn  Sn14  1  0.739  0.940  0.368  1.0
  Sn  Sn15  1  0.060  0.261  0.132  1.0
  O  O16  1  0.235  0.694  0.900  1.0
  O  O17  1  0.694  0.235  0.400  1.0
  O  O18  1  0.483  0.213  0.684  1.0
  O  O19  1  0.738  0.844  0.989  1.0
  O  O20  1  0.973  0.027  0.750  1.0
  O  O21  1  0.156  0.262  0.511  1.0
  O  O22  1  0.213  0.483  0.184  1.0
  O  O23  1  0.787  0.517  0.816  1.0
  O  O24  1  0.844  0.738  0.489  1.0
  O  O25  1  0.027  0.973  0.250  1.0
  O  O26  1  0.262  0.156  0.011  1.0
  O  O27  1  0.517  0.787  0.316  1.0
  O  O28  1  0.306  0.765  0.600  1.0
  O  O29  1  0.765  0.306  0.100  1.0
[/CIF]
.