data_MgBr4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.1
_cell_length_b   6.1
_cell_length_c   6.1
_cell_angle_alpha   117.7
_cell_angle_beta   117.7
_cell_angle_gamma   94.03
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgBr4
_chemical_formula_sum   'Mg1 Br4'
_cell_volume   165.99
_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
  Mg  Mg4  1  0.0  0.0  0.0  1.0
  Br  Br0  1  0.16  0.0  0.08  1.0
  Br  Br1  1  0.0  0.16  0.08  1.0
  Br  Br2  1  0.0  0.0  0.93  1.0
  Br  Br3  1  0.0  0.0  0.39  1.0

data_MgBr4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   8.32
_cell_length_b   8.93
_cell_length_c   6.1
_cell_angle_alpha   90.0
_cell_angle_beta   132.99
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgBr4
_chemical_formula_sum   'Mg2 Br8'
_cell_volume   331.99
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Mg  Mg0  2  0.0  0.0  0.0  1.0
  Br  Br1  4  0.42  0.42  0.92  1.0
  Br  Br2  2  0.0  0.0  0.07  1.0
  Br  Br3  2  0.0  0.0  0.61  1.0

Mg Br Br Br Br
MgBr4 is Copper structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two MgBr4 clusters. Mg(1) is bonded in a 3-coordinate geometry to one Br(2), one Br(3), and two equivalent Br(1) atoms. The Mg(1)-Br(2) bond length is 0.42 Å. The Mg(1)-Br(3) bond length is 2.40 Å. Both Mg(1)-Br(1) bond lengths are 0.85 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a single-bond geometry to one Mg(1) atom. In the second Br site, Br(2) is bonded in a single-bond geometry to one Mg(1) atom. In the third Br site, Br(3) is bonded in a distorted single-bond geometry to one Mg(1) atom.