The compound described by Ca7Sn6 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one Sn(1), one Sn(4), two equivalent Sn(2), and two equivalent Sn(3) atoms. In the second Ca site, Ca(2) is bonded to one Sn(3), two equivalent Sn(1), two equivalent Sn(2), and two equivalent Sn(4) atoms to form distorted CaSn7 pentagonal bipyramids that share corners with two equivalent Ca(4)Sn6 octahedra, corners with two equivalent Ca(2)Sn7 pentagonal bipyramids, faces with two equivalent Ca(4)Sn6 octahedra, and faces with three equivalent Ca(2)Sn7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 45-48°. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to three equivalent Sn(2) and four equivalent Sn(1) atoms. In the fourth Ca site, Ca(4) is bonded to two equivalent Sn(2), two equivalent Sn(3), and two equivalent Sn(4) atoms to form distorted CaSn6 octahedra that share corners with four equivalent Ca(4)Sn6 octahedra, corners with four equivalent Ca(2)Sn7 pentagonal bipyramids, and faces with four equivalent Ca(2)Sn7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 52-54°. There are four inequivalent Sn sites. In the first Sn site, Sn(2) is bonded in a 9-coordinate geometry to one Ca(4), two equivalent Ca(1), two equivalent Ca(2), three equivalent Ca(3), and one Sn(1) atom. In the second Sn site, Sn(3) is bonded in a 9-coordinate geometry to two equivalent Ca(2), two equivalent Ca(4), four equivalent Ca(1), and one Sn(4) atom. In the third Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Ca(1), two equivalent Ca(4), four equivalent Ca(2), and one Sn(3) atom. In the fourth Sn site, Sn(1) is bonded in a 9-coordinate geometry to one Ca(1), two equivalent Ca(2), four equivalent Ca(3), one Sn(1), and one Sn(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca7Sn6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.937
_cell_length_b   8.507
_cell_length_c   23.907
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1614.098
_cell_formula_units_Z   4
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
  Ca  Ca0  1  0.997  0.675  0.664  1.0
  Ca  Ca1  1  0.497  0.825  0.836  1.0
  Ca  Ca2  1  0.503  0.175  0.336  1.0
  Ca  Ca3  1  0.003  0.325  0.164  1.0
  Ca  Ca4  1  0.003  0.325  0.336  1.0
  Ca  Ca5  1  0.503  0.175  0.164  1.0
  Ca  Ca6  1  0.497  0.825  0.664  1.0
  Ca  Ca7  1  0.997  0.675  0.836  1.0
  Ca  Ca8  1  0.829  0.180  0.647  1.0
  Ca  Ca9  1  0.329  0.320  0.853  1.0
  Ca  Ca10  1  0.671  0.680  0.353  1.0
  Ca  Ca11  1  0.171  0.820  0.147  1.0
  Ca  Ca12  1  0.171  0.820  0.353  1.0
  Ca  Ca13  1  0.671  0.680  0.147  1.0
  Ca  Ca14  1  0.329  0.320  0.647  1.0
  Ca  Ca15  1  0.829  0.180  0.853  1.0
  Ca  Ca16  1  0.670  0.326  0.022  1.0
  Ca  Ca17  1  0.170  0.174  0.478  1.0
  Ca  Ca18  1  0.830  0.826  0.978  1.0
  Ca  Ca19  1  0.330  0.674  0.522  1.0
  Ca  Ca20  1  0.330  0.674  0.978  1.0
  Ca  Ca21  1  0.830  0.826  0.522  1.0
  Ca  Ca22  1  0.170  0.174  0.022  1.0
  Ca  Ca23  1  0.670  0.326  0.478  1.0
  Ca  Ca24  1  0.666  0.494  0.750  1.0
  Ca  Ca25  1  0.166  0.006  0.750  1.0
  Ca  Ca26  1  0.834  0.994  0.250  1.0
  Ca  Ca27  1  0.334  0.506  0.250  1.0
  Sn  Sn28  1  0.000  0.445  0.558  1.0
  Sn  Sn29  1  0.500  0.055  0.942  1.0
  Sn  Sn30  1  0.500  0.945  0.442  1.0
  Sn  Sn31  1  1.000  0.555  0.058  1.0
  Sn  Sn32  1  1.000  0.555  0.442  1.0
  Sn  Sn33  1  0.500  0.945  0.058  1.0
  Sn  Sn34  1  0.500  0.055  0.558  1.0
  Sn  Sn35  1  0.000  0.445  0.942  1.0
  Sn  Sn36  1  0.841  0.025  0.099  1.0
  Sn  Sn37  1  0.341  0.475  0.401  1.0
  Sn  Sn38  1  0.659  0.525  0.901  1.0
  Sn  Sn39  1  0.159  0.975  0.599  1.0
  Sn  Sn40  1  0.159  0.975  0.901  1.0
  Sn  Sn41  1  0.659  0.525  0.599  1.0
  Sn  Sn42  1  0.341  0.475  0.099  1.0
  Sn  Sn43  1  0.841  0.025  0.401  1.0
  Sn  Sn44  1  0.793  0.887  0.750  1.0
  Sn  Sn45  1  0.293  0.613  0.750  1.0
  Sn  Sn46  1  0.707  0.387  0.250  1.0
  Sn  Sn47  1  0.207  0.113  0.250  1.0
  Sn  Sn48  1  0.542  0.135  0.750  1.0
  Sn  Sn49  1  0.042  0.365  0.750  1.0
  Sn  Sn50  1  0.958  0.635  0.250  1.0
  Sn  Sn51  1  0.458  0.865  0.250  1.0
[/CIF]
.
The compound described by Ca7Sn6 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one Sn(1), one Sn(4), two equivalent Sn(2), and two equivalent Sn(3) atoms. In the second Ca site, Ca(2) is bonded to one Sn(3), two equivalent Sn(1), two equivalent Sn(2), and two equivalent Sn(4) atoms to form distorted CaSn7 pentagonal bipyramids that share corners with two equivalent Ca(4)Sn6 octahedra, corners with two equivalent Ca(2)Sn7 pentagonal bipyramids, faces with two equivalent Ca(4)Sn6 octahedra, and faces with three equivalent Ca(2)Sn7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 45-48°. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to three equivalent Sn(2) and four equivalent Sn(1) atoms. In the fourth Ca site, Ca(4) is bonded to two equivalent Sn(2), two equivalent Sn(3), and two equivalent Sn(4) atoms to form distorted CaSn6 octahedra that share corners with four equivalent Ca(4)Sn6 octahedra, corners with four equivalent Ca(2)Sn7 pentagonal bipyramids, and faces with four equivalent Ca(2)Sn7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 52-54°. There are four inequivalent Sn sites. In the first Sn site, Sn(2) is bonded in a 9-coordinate geometry to one Ca(4), two equivalent Ca(1), two equivalent Ca(2), three equivalent Ca(3), and one Sn(1) atom. In the second Sn site, Sn(3) is bonded in a 9-coordinate geometry to two equivalent Ca(2), two equivalent Ca(4), four equivalent Ca(1), and one Sn(4) atom. In the third Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Ca(1), two equivalent Ca(4), four equivalent Ca(2), and one Sn(3) atom. In the fourth Sn site, Sn(1) is bonded in a 9-coordinate geometry to one Ca(1), two equivalent Ca(2), four equivalent Ca(3), one Sn(1), and one Sn(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca7Sn6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.937
_cell_length_b   8.507
_cell_length_c   23.907
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1614.098
_cell_formula_units_Z   4
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
  Ca  Ca0  1  0.997  0.675  0.664  1.0
  Ca  Ca1  1  0.497  0.825  0.836  1.0
  Ca  Ca2  1  0.503  0.175  0.336  1.0
  Ca  Ca3  1  0.003  0.325  0.164  1.0
  Ca  Ca4  1  0.003  0.325  0.336  1.0
  Ca  Ca5  1  0.503  0.175  0.164  1.0
  Ca  Ca6  1  0.497  0.825  0.664  1.0
  Ca  Ca7  1  0.997  0.675  0.836  1.0
  Ca  Ca8  1  0.829  0.180  0.647  1.0
  Ca  Ca9  1  0.329  0.320  0.853  1.0
  Ca  Ca10  1  0.671  0.680  0.353  1.0
  Ca  Ca11  1  0.171  0.820  0.147  1.0
  Ca  Ca12  1  0.171  0.820  0.353  1.0
  Ca  Ca13  1  0.671  0.680  0.147  1.0
  Ca  Ca14  1  0.329  0.320  0.647  1.0
  Ca  Ca15  1  0.829  0.180  0.853  1.0
  Ca  Ca16  1  0.670  0.326  0.022  1.0
  Ca  Ca17  1  0.170  0.174  0.478  1.0
  Ca  Ca18  1  0.830  0.826  0.978  1.0
  Ca  Ca19  1  0.330  0.674  0.522  1.0
  Ca  Ca20  1  0.330  0.674  0.978  1.0
  Ca  Ca21  1  0.830  0.826  0.522  1.0
  Ca  Ca22  1  0.170  0.174  0.022  1.0
  Ca  Ca23  1  0.670  0.326  0.478  1.0
  Ca  Ca24  1  0.666  0.494  0.750  1.0
  Ca  Ca25  1  0.166  0.006  0.750  1.0
  Ca  Ca26  1  0.834  0.994  0.250  1.0
  Ca  Ca27  1  0.334  0.506  0.250  1.0
  Sn  Sn28  1  0.000  0.445  0.558  1.0
  Sn  Sn29  1  0.500  0.055  0.942  1.0
  Sn  Sn30  1  0.500  0.945  0.442  1.0
  Sn  Sn31  1  1.000  0.555  0.058  1.0
  Sn  Sn32  1  1.000  0.555  0.442  1.0
  Sn  Sn33  1  0.500  0.945  0.058  1.0
  Sn  Sn34  1  0.500  0.055  0.558  1.0
  Sn  Sn35  1  0.000  0.445  0.942  1.0
  Sn  Sn36  1  0.841  0.025  0.099  1.0
  Sn  Sn37  1  0.341  0.475  0.401  1.0
  Sn  Sn38  1  0.659  0.525  0.901  1.0
  Sn  Sn39  1  0.159  0.975  0.599  1.0
  Sn  Sn40  1  0.159  0.975  0.901  1.0
  Sn  Sn41  1  0.659  0.525  0.599  1.0
  Sn  Sn42  1  0.341  0.475  0.099  1.0
  Sn  Sn43  1  0.841  0.025  0.401  1.0
  Sn  Sn44  1  0.793  0.887  0.750  1.0
  Sn  Sn45  1  0.293  0.613  0.750  1.0
  Sn  Sn46  1  0.707  0.387  0.250  1.0
  Sn  Sn47  1  0.207  0.113  0.250  1.0
  Sn  Sn48  1  0.542  0.135  0.750  1.0
  Sn  Sn49  1  0.042  0.365  0.750  1.0
  Sn  Sn50  1  0.958  0.635  0.250  1.0
  Sn  Sn51  1  0.458  0.865  0.250  1.0
[/CIF]
.