data_MgNb2Cr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.95
_cell_length_b   4.95
_cell_length_c   5.35
_cell_angle_alpha   94.87
_cell_angle_beta   94.87
_cell_angle_gamma   31.11
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNb2Cr
_chemical_formula_sum   'Mg1 Nb2 Cr1'
_cell_volume   67.41
_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  0.99  0.0  0.99  1.0
  Nb  Nb2  1  0.04  0.0  0.3  1.0
  Nb  Nb3  1  0.07  0.0  0.4  1.0
  Cr  Cr0  1  0.56  0.0  0.63  1.0

data_MgNb2Cr
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.65
_cell_length_b   4.95
_cell_length_c   5.35
_cell_angle_alpha   94.87
_cell_angle_beta   90.0
_cell_angle_gamma   105.55
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgNb2Cr
_chemical_formula_sum   'Mg1 Nb2 Cr1'
_cell_volume   67.41
_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  0.01  0.01  1.0
  Nb  Nb1  1  0.0  0.93  0.6  1.0
  Nb  Nb2  1  0.0  0.96  0.7  1.0
  Cr  Cr3  1  0.0  0.44  0.37  1.0

Mg Nb Nb Cr
MgNb2Cr crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 1-coordinate geometry to one Nb(1) and one Cr(1) atom. The Mg(1)-Nb(1) bond length is 1.69 Å. The Mg(1)-Cr(1) bond length is 2.70 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a linear geometry to one Mg(1) and one Nb(2) atom. The Nb(1)-Nb(2) bond length is 0.53 Å. In the second Nb site, Nb(2) is bonded in a single-bond geometry to one Nb(1) and two equivalent Cr(1) atoms. There is one shorter (2.66 Å) and one longer (2.89 Å) Nb(2)-Cr(1) bond length. Cr(1) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Nb(2), and two equivalent Cr(1) atoms. Both Cr(1)-Cr(1) bond lengths are 2.65 Å.