data_NaMg2Cu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.8
_cell_length_b   4.8
_cell_length_c   4.8
_cell_angle_alpha   122.11
_cell_angle_beta   122.11
_cell_angle_gamma   86.37
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaMg2Cu
_chemical_formula_sum   'Na1 Mg2 Cu1'
_cell_volume   75.56
_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
  Na  Na3  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.0  0.32  0.75  1.0
  Mg  Mg2  1  0.32  0.0  0.75  1.0
  Cu  Cu0  1  0.0  0.0  0.5  1.0

data_NaMg2Cu
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.57
_cell_length_b   6.57
_cell_length_c   4.8
_cell_angle_alpha   90.0
_cell_angle_beta   133.19
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaMg2Cu
_chemical_formula_sum   'Na2 Mg4 Cu2'
_cell_volume   151.13
_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
  Na  Na0  2  0.0  0.0  0.0  1.0
  Mg  Mg1  4  0.34  0.34  0.43  1.0
  Cu  Cu2  2  0.0  0.0  0.5  1.0

Na Mg Mg Cu
Na Mg Mg Cu 0 1 o o - 0 1 o - - 0 2 - o - 0 2 o o - 0 3 o o - 0 3 o o o 1 3 o o o 2 3 o o o 
NaMg2Cu crystallizes in the monoclinic Cm space group. Na(1) is bonded in a 6-coordinate geometry to four equivalent Mg(1) and two equivalent Cu(1) atoms. There are two shorter (2.41 Å) and two longer (2.80 Å) Na(1)-Mg(1) bond lengths. Both Na(1)-Cu(1) bond lengths are 2.40 Å. Mg(1) is bonded in a single-bond geometry to two equivalent Na(1) and one Cu(1) atom. The Mg(1)-Cu(1) bond length is 1.37 Å. Cu(1) is bonded in a distorted water-like geometry to two equivalent Na(1) and two equivalent Mg(1) atoms.