data_MgCuNi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.34
_cell_length_b   4.34
_cell_length_c   2.72
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   105.07
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCuNi2
_chemical_formula_sum   'Mg1 Cu1 Ni2'
_cell_volume   49.5
_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  0.0  0.0  0.0  1.0
  Cu  Cu0  1  0.64  0.0  0.0  1.0
  Ni  Ni2  1  0.32  0.72  0.36  1.0
  Ni  Ni3  1  0.32  0.28  0.36  1.0

data_MgCuNi2
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.72
_cell_length_b   4.34
_cell_length_c   4.34
_cell_angle_alpha   105.07
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgCuNi2
_chemical_formula_sum   'Mg1 Cu1 Ni2'
_cell_volume   49.5
_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
  Cu  Cu1  1  0.0  0.64  0.0  1.0
  Ni  Ni2  1  0.36  0.32  0.28  1.0
  Ni  Ni3  1  0.36  0.32  0.72  1.0

Mg Cu Ni Ni
MgNi2Cu crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 2-coordinate geometry to one Ni(2), two equivalent Ni(1), and one Cu(1) atom. The Mg(1)-Ni(2) bond length is 1.86 Å. There is one shorter (2.28 Å) and one longer (2.70 Å) Mg(1)-Ni(1) bond length. The Mg(1)-Cu(1) bond length is 1.55 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Ni(2), and two equivalent Cu(1) atoms. The Ni(1)-Ni(2) bond length is 1.95 Å. There is one shorter (1.86 Å) and one longer (2.36 Å) Ni(1)-Cu(1) bond length. In the second Ni site, Ni(2) is bonded in a 1-coordinate geometry to one Mg(1) and one Ni(1) atom. Cu(1) is bonded in a distorted single-bond geometry to one Mg(1) and two equivalent Ni(1) atoms.