data_SrMgSn4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.32
_cell_length_b   6.32
_cell_length_c   6.32
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SrMgSn4
_chemical_formula_sum   'Sr1 Mg1 Sn4'
_cell_volume   178.29
_cell_formula_units_Z   1
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
  Sr  Sr5  1  0.7  0.7  0.7  1.0
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Sn  Sn1  1  0.58  0.58  0.35  1.0
  Sn  Sn2  1  0.58  0.35  0.58  1.0
  Sn  Sn3  1  0.35  0.58  0.58  1.0
  Sn  Sn4  1  0.35  0.35  0.35  1.0

data_SrMgSn4
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.32
_cell_length_b   6.32
_cell_length_c   15.47
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   SrMgSn4
_chemical_formula_sum   'Sr3 Mg3 Sn12'
_cell_volume   534.86
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Sr  Sr0  3  0.0  0.0  0.3  1.0
  Mg  Mg1  3  0.0  0.0  0.0  1.0
  Sn  Sn2  9  0.15  0.08  0.49  1.0
  Sn  Sn3  3  0.0  0.0  0.65  1.0

Sr Mg Sn Sn Sn Sn
Sr Mg Sn Sn Sn Sn 0 4 o o o 0 4 + o o 0 3 o o o 0 3 o + o 0 2 o o o 0 2 o o + 0 5 o o + 0 5 o + o 0 5 + o o 0 1 o + + 0 1 + o + 0 1 + + o 1 2 - - o 1 2 - o o 1 2 o - o 1 3 - o - 1 3 - o o 1 3 o o - 1 5 - o o 1 5 o - o 1 5 o o - 1 4 o - - 1 4 o - o 1 4 o o - 2 3 o o o 2 4 o o o 2 5 o o o 3 4 o o o 3 5 o o o 4 5 o o o 
SrMgSn4 crystallizes in the trigonal R3m space group. Sr(1) is bonded to three equivalent Mg(1), three equivalent Sn(2), and six equivalent Sn(1) atoms to form a mixture of distorted corner and edge-sharing SrMg3Sn9 cuboctahedra. All Sr(1)-Mg(1) bond lengths are 3.69 Å. All Sr(1)-Sn(2) bond lengths are 3.66 Å. There are three shorter (3.13 Å) and three longer (3.53 Å) Sr(1)-Sn(1) bond lengths. Mg(1) is bonded in a distorted trigonal planar geometry to three equivalent Sr(1) atoms. There are two inequivalent Sn sites. In the first Sn site, Sn(2) is bonded in a 6-coordinate geometry to three equivalent Sr(1) and three equivalent Sn(1) atoms. All Sn(2)-Sn(1) bond lengths are 2.53 Å. In the second Sn site, Sn(1) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Sn(2), and two equivalent Sn(1) atoms. Both Sn(1)-Sn(1) bond lengths are 1.46 Å.