data_Ba2MnNb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.48
_cell_length_b   3.48
_cell_length_c   10.03
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba2MnNb
_chemical_formula_sum   'Ba2 Mn1 Nb1'
_cell_volume   121.4
_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
  Ba  Ba0  1  0.0  0.0  0.3  1.0
  Ba  Ba1  1  0.74  0.74  0.31  1.0
  Mn  Mn2  1  0.0  0.0  0.9  1.0
  Nb  Nb3  1  0.74  0.74  0.58  1.0

data_Ba2MnNb
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.92
_cell_length_b   4.92
_cell_length_c   10.03
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ba2MnNb
_chemical_formula_sum   'Ba4 Mn2 Nb2'
_cell_volume   242.8
_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
  Ba  Ba0  2  0.0  0.0  0.3  1.0
  Ba  Ba1  2  0.24  0.5  0.31  1.0
  Mn  Mn2  2  0.0  0.0  0.9  1.0
  Nb  Nb3  2  0.24  0.5  0.58  1.0

Ba Ba Mn Nb
Ba Ba Mn Nb 0 1 - - o 0 2 o o - 0 3 - - o 1 3 o o o 2 3 - - o 2 2 + o o 2 2 o + o 3 3 + o o 3 3 o + o 
Ba2NbMn crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted single-bond geometry to one Ba(2) and one Mn(1) atom. The Ba(1)-Ba(2) bond length is 1.28 Å. The Ba(1)-Mn(1) bond length is 4.10 Å. In the second Ba site, Ba(2) is bonded in a distorted L-shaped geometry to one Ba(1) and one Nb(1) atom. The Ba(2)-Nb(1) bond length is 2.68 Å. Nb(1) is bonded in a distorted single-bond geometry to one Ba(2) and one Mn(1) atom. The Nb(1)-Mn(1) bond length is 3.45 Å. Mn(1) is bonded to one Ba(1), one Nb(1), and four equivalent Mn(1) atoms to form a mixture of distorted corner and edge-sharing MnBaMn4Nb octahedra. The corner-sharing octahedra are not tilted. All Mn(1)-Mn(1) bond lengths are 3.48 Å.