data_Mg2NbCo
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.84
_cell_length_b   2.84
_cell_length_c   8.32
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2NbCo
_chemical_formula_sum   'Mg2 Nb1 Co1'
_cell_volume   66.99
_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  Mg1  1  0.42  0.42  0.8  1.0
  Mg  Mg2  1  0.42  0.42  0.52  1.0
  Nb  Nb3  1  0.0  0.0  0.16  1.0
  Co  Co0  1  0.0  0.0  0.0  1.0

data_Mg2NbCo
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.01
_cell_length_b   4.01
_cell_length_c   8.32
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2NbCo
_chemical_formula_sum   'Mg4 Nb2 Co2'
_cell_volume   133.97
_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  0.42  0.0  0.52  1.0
  Mg  Mg1  2  0.42  0.0  0.8  1.0
  Nb  Nb2  2  0.0  0.0  0.16  1.0
  Co  Co3  2  0.0  0.0  0.0  1.0

Mg Mg Nb Co
Mg Mg Nb Co 0 3 o o + 0 3 o + + 0 3 + o + 0 3 + + + 0 0 + o o 0 0 o + o 0 1 o o o 1 1 + o o 1 1 o + o 2 3 o o o 
Mg2NbCo crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 9-coordinate geometry to one Mg(2), four equivalent Mg(1), and four equivalent Co(1) atoms. The Mg(1)-Mg(2) bond length is 2.38 Å. All Mg(1)-Mg(1) bond lengths are 2.84 Å. There are a spread of Mg(1)-Co(1) bond distances ranging from 2.35-2.85 Å. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Mg(1), four equivalent Mg(2), and three equivalent Nb(1) atoms. All Mg(2)-Mg(2) bond lengths are 2.84 Å. There is one shorter (3.41 Å) and two longer (3.60 Å) Mg(2)-Nb(1) bond lengths. Nb(1) is bonded in a single-bond geometry to three equivalent Mg(2) and one Co(1) atom. The Nb(1)-Co(1) bond length is 1.33 Å. Co(1) is bonded in a distorted single-bond geometry to four equivalent Mg(1) and one Nb(1) atom.