data_MgMn2Ni
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.8
_cell_length_b   2.8
_cell_length_c   6.44
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgMn2Ni
_chemical_formula_sum   'Mg1 Mn2 Ni1'
_cell_volume   50.49
_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  0.8  1.0
  Mn  Mn1  1  0.4  0.4  0.33  1.0
  Mn  Mn2  1  0.0  0.0  0.47  1.0
  Ni  Ni3  1  0.4  0.4  0.06  1.0

data_MgMn2Ni
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.96
_cell_length_b   3.96
_cell_length_c   6.44
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgMn2Ni
_chemical_formula_sum   'Mg2 Mn4 Ni2'
_cell_volume   100.99
_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  0.8  1.0
  Mn  Mn1  2  0.0  0.0  0.47  1.0
  Mn  Mn2  2  0.4  0.0  0.33  1.0
  Ni  Ni3  2  0.4  0.0  0.06  1.0

Mg Mn Mn Ni
MgMn2Ni crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 9-coordinate geometry to four equivalent Mg(1), one Mn(2), and four equivalent Ni(1) atoms. All Mg(1)-Mg(1) bond lengths are 2.80 Å. The Mg(1)-Mn(2) bond length is 2.12 Å. There are a spread of Mg(1)-Ni(1) bond distances ranging from 2.32-2.92 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted single-bond geometry to one Mn(2) and one Ni(1) atom. The Mn(1)-Mn(2) bond length is 1.81 Å. The Mn(1)-Ni(1) bond length is 1.74 Å. In the second Mn site, Mn(2) is bonded in a 2-coordinate geometry to one Mg(1) and one Mn(1) atom. Ni(1) is bonded in a 2-coordinate geometry to four equivalent Mg(1) and one Mn(1) atom.