data_Na2YCu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.16
_cell_length_b   5.16
_cell_length_c   5.16
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2YCu
_chemical_formula_sum   'Na2 Y1 Cu1'
_cell_volume   97.1
_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  Na1  1  0.0  0.0  0.0  1.0
  Na  Na2  1  0.47  0.47  0.47  1.0
  Y  Y3  1  0.82  0.82  0.82  1.0
  Cu  Cu0  1  0.65  0.65  0.65  1.0

data_Na2YCu
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.16
_cell_length_b   5.16
_cell_length_c   12.64
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Na2YCu
_chemical_formula_sum   'Na6 Y3 Cu3'
_cell_volume   291.31
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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  3  0.0  0.0  0.0  1.0
  Na  Na1  3  0.0  0.0  0.53  1.0
  Y  Y2  3  0.0  0.0  0.18  1.0
  Cu  Cu3  3  0.0  0.0  0.35  1.0

Na Na Y Cu
Na2YCu crystallizes in the trigonal R3m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one Y(1) and three equivalent Cu(1) atoms to form distorted NaYCu3 trigonal pyramids that share  a cornercorner with one Cu(1)Na4Y trigonal bipyramid and corners with six equivalent Na(1)YCu3 trigonal pyramids. The Na(1)-Y(1) bond length is 2.22 Å. All Na(1)-Cu(1) bond lengths are 2.99 Å. In the second Na site, Na(2) is bonded in a distorted single-bond geometry to one Cu(1) atom. The Na(2)-Cu(1) bond length is 2.22 Å. Y(1) is bonded in a 2-coordinate geometry to one Na(1) and one Cu(1) atom. The Y(1)-Cu(1) bond length is 2.22 Å. Cu(1) is bonded to one Na(2), three equivalent Na(1), and one Y(1) atom to form distorted CuNa4Y trigonal bipyramids that share corners with six equivalent Cu(1)Na4Y trigonal bipyramids and  a cornercorner with one Na(1)YCu3 trigonal pyramid.