data_MgTiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   5.21
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgTiBr2
_chemical_formula_sum   'Mg1 Ti1 Br2'
_cell_volume   99.99
_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  Mg2  1  0.0  0.0  0.0  1.0
  Ti  Ti3  1  0.84  0.84  0.84  1.0
  Br  Br0  1  0.68  0.68  0.68  1.0
  Br  Br1  1  0.53  0.53  0.53  1.0

data_MgTiBr2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   12.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgTiBr2
_chemical_formula_sum   'Mg3 Ti3 Br6'
_cell_volume   299.98
_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
  Mg  Mg0  3  0.0  0.0  0.0  1.0
  Ti  Ti1  3  0.0  0.0  0.16  1.0
  Br  Br2  3  0.0  0.0  0.32  1.0
  Br  Br3  3  0.0  0.0  0.47  1.0

Mg Ti Br Br
Mg Ti Br Br 0 1 - - - 1 2 o o o 2 3 o o o 
MgTiBr2 crystallizes in the trigonal R3m space group. Mg(1) is bonded to one Ti(1) and three equivalent Br(1) atoms to form MgTiBr3 trigonal pyramids that share corners with three equivalent Ti(1)MgBr4 trigonal bipyramids, corners with six equivalent Mg(1)TiBr3 trigonal pyramids, and edges with three equivalent Br(2)Ti3Br trigonal pyramids. The Mg(1)-Ti(1) bond length is 2.02 Å. All Mg(1)-Br(1) bond lengths are 3.02 Å. Ti(1) is bonded to one Mg(1), one Br(1), and three equivalent Br(2) atoms to form distorted TiMgBr4 trigonal bipyramids that share corners with six equivalent Ti(1)MgBr4 trigonal bipyramids,  a cornercorner with one Br(2)Ti3Br trigonal pyramid, and corners with three equivalent Mg(1)TiBr3 trigonal pyramids. The Ti(1)-Br(1) bond length is 2.02 Å. All Ti(1)-Br(2) bond lengths are 3.02 Å. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a distorted single-bond geometry to three equivalent Mg(1), one Ti(1), and one Br(2) atom. The Br(1)-Br(2) bond length is 2.02 Å. In the second Br site, Br(2) is bonded to three equivalent Ti(1) and one Br(1) atom to form BrTi3Br trigonal pyramids that share  a cornercorner with one Ti(1)MgBr4 trigonal bipyramid, corners with six equivalent Br(2)Ti3Br trigonal pyramids, and edges with three equivalent Mg(1)TiBr3 trigonal pyramids.