data_Ca4MgBr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.01
_cell_length_b   7.01
_cell_length_c   7.01
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca4MgBr
_chemical_formula_sum   'Ca4 Mg1 Br1'
_cell_volume   244.07
_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
  Ca  Ca1  1  0.71  0.71  0.21  1.0
  Ca  Ca2  1  0.71  0.21  0.71  1.0
  Ca  Ca3  1  0.21  0.71  0.71  1.0
  Ca  Ca4  1  0.21  0.21  0.21  1.0
  Mg  Mg5  1  0.0  0.0  0.0  1.0
  Br  Br0  1  0.48  0.48  0.48  1.0

data_Ca4MgBr
_symmetry_space_group_name_H-M   R3m
_cell_length_a   7.01
_cell_length_b   7.01
_cell_length_c   17.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Ca4MgBr
_chemical_formula_sum   'Ca12 Mg3 Br3'
_cell_volume   732.21
_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
  Ca  Ca0  9  0.17  0.34  0.12  1.0
  Ca  Ca1  3  0.0  0.0  0.79  1.0
  Mg  Mg2  3  0.0  0.0  0.0  1.0
  Br  Br3  3  0.0  0.0  0.52  1.0

Ca Ca Ca Ca Mg Br
Ca Ca Ca Ca Mg Br 0 5 o o o 0 3 + o o 0 3 o + o 0 4 + + o 1 5 o o o 1 3 + o o 1 3 o o + 1 4 + o + 2 5 o o o 2 3 o + o 2 3 o o + 2 4 o + + 3 4 o o o 3 5 - o o 3 5 o - o 3 5 o o - 
Ca4MgBr crystallizes in the trigonal R3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted single-bond geometry to two equivalent Ca(2), one Mg(1), and one Br(1) atom. Both Ca(1)-Ca(2) bond lengths are 3.51 Å. The Ca(1)-Mg(1) bond length is 2.95 Å. The Ca(1)-Br(1) bond length is 2.28 Å. In the second Ca site, Ca(2) is bonded to six equivalent Ca(1) and one Mg(1) atom to form distorted corner-sharing CaCa6Mg hexagonal pyramids. The Ca(2)-Mg(1) bond length is 3.65 Å. Mg(1) is bonded in a 4-coordinate geometry to one Ca(2) and three equivalent Ca(1) atoms. Br(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ca(1) atoms.