data_MgNi4Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.83
_cell_length_b   4.83
_cell_length_c   4.83
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNi4Se
_chemical_formula_sum   'Mg1 Ni4 Se1'
_cell_volume   79.44
_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
  Ni  Ni1  1  0.56  0.27  0.56  1.0
  Ni  Ni2  1  0.27  0.56  0.56  1.0
  Ni  Ni3  1  0.27  0.27  0.27  1.0
  Ni  Ni4  1  0.56  0.56  0.27  1.0
  Se  Se5  1  0.71  0.71  0.71  1.0

data_MgNi4Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.83
_cell_length_b   4.83
_cell_length_c   11.82
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgNi4Se
_chemical_formula_sum   'Mg3 Ni12 Se3'
_cell_volume   238.33
_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
  Ni  Ni1  9  0.19  0.1  0.54  1.0
  Ni  Ni2  3  0.0  0.0  0.73  1.0
  Se  Se3  3  0.0  0.0  0.29  1.0

Mg Ni Ni Ni Ni Se
MgNi4Se crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 16-coordinate geometry to four equivalent Ni(2), nine equivalent Ni(1), and three equivalent Se(1) atoms. There are three shorter (2.90 Å) and one longer (3.15 Å) Mg(1)-Ni(2) bond length. There are six shorter (2.90 Å) and three longer (3.13 Å) Mg(1)-Ni(1) bond lengths. All Mg(1)-Se(1) bond lengths are 2.82 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1), two equivalent Ni(1), three equivalent Ni(2), and one Se(1) atom. Both Ni(1)-Ni(1) bond lengths are 1.41 Å. There is one shorter (2.44 Å) and two longer (2.98 Å) Ni(1)-Ni(2) bond lengths. The Ni(1)-Se(1) bond length is 2.23 Å. In the second Ni site, Ni(2) is bonded in a 16-coordinate geometry to four equivalent Mg(1), nine equivalent Ni(1), and three equivalent Se(1) atoms. All Ni(2)-Se(1) bond lengths are 3.06 Å. Se(1) is bonded in a 3-coordinate geometry to three equivalent Mg(1), three equivalent Ni(1), and three equivalent Ni(2) atoms.