data_MgTaSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.59
_cell_length_b   4.59
_cell_length_c   4.59
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgTaSe
_chemical_formula_sum   'Mg1 Ta1 Se1'
_cell_volume   68.54
_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  Mg0  1  0.0  0.0  0.0  1.0
  Ta  Ta2  1  0.62  0.62  0.62  1.0
  Se  Se1  1  0.87  0.87  0.87  1.0

data_MgTaSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.59
_cell_length_b   4.59
_cell_length_c   11.25
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgTaSe
_chemical_formula_sum   'Mg3 Ta3 Se3'
_cell_volume   205.62
_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
  Ta  Ta1  3  0.0  0.0  0.38  1.0
  Se  Se2  3  0.0  0.0  0.13  1.0

Mg Ta Se
Mg Ta Se 0 2 - - - 0 1 o - - 0 1 - o - 0 1 - - o 1 2 o - o 1 2 - o o 1 2 o o - 1 2 o o o 
MgTaSe crystallizes in the trigonal R3m space group. Mg(1) is bonded in a single-bond geometry to three equivalent Ta(1) and one Se(1) atom. All Mg(1)-Ta(1) bond lengths are 2.70 Å. The Mg(1)-Se(1) bond length is 1.44 Å. Ta(1) is bonded in a 7-coordinate geometry to three equivalent Mg(1) and four equivalent Se(1) atoms. There is one shorter (2.79 Å) and three longer (2.82 Å) Ta(1)-Se(1) bond lengths. Se(1) is bonded in a single-bond geometry to one Mg(1) and four equivalent Ta(1) atoms.