The structure described by MgCu2(NiO2)4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the second Ni site, Ni(2) is bonded to six equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ni(1) and one Cu(1) atom to form distorted OCuNi3 tetrahedra that share corners with nine equivalent O(2)MgCuNi3 square pyramids, corners with three equivalent O(1)CuNi3 tetrahedra, and edges with three equivalent O(2)MgCuNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(2), two equivalent Ni(1), and one Cu(1) atom to form OMgCuNi3 square pyramids that share corners with six equivalent O(2)MgCuNi3 square pyramids, corners with three equivalent O(1)CuNi3 tetrahedra, edges with six equivalent O(2)MgCuNi3 square pyramids, and  an edgeedge with one O(1)CuNi3 tetrahedra. is represented by the CIF file [CIF]
data_MgCu2(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.170
_cell_length_b   5.789
_cell_length_c   5.789
_cell_angle_alpha   60.002
_cell_angle_beta   90.000
_cell_angle_gamma   117.992
_symmetry_Int_Tables_number   1
_cell_volume   150.499
_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  0.625  0.750  0.125  1.0
  Cu  Cu1  1  0.087  0.059  0.971  1.0
  Cu  Cu2  1  0.163  0.441  0.279  1.0
  Ni  Ni3  1  0.625  0.250  0.125  1.0
  Ni  Ni4  1  0.625  0.250  0.625  1.0
  Ni  Ni5  1  0.625  0.750  0.625  1.0
  Ni  Ni6  1  0.125  0.750  0.625  1.0
  O  O7  1  0.810  0.207  0.396  1.0
  O  O8  1  0.389  0.256  0.372  1.0
  O  O9  1  0.861  0.244  0.878  1.0
  O  O10  1  0.860  0.739  0.383  1.0
  O  O11  1  0.440  0.293  0.854  1.0
  O  O12  1  0.860  0.739  0.878  1.0
  O  O13  1  0.390  0.761  0.372  1.0
  O  O14  1  0.390  0.761  0.867  1.0
[/CIF]
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The structure described by MgCu2(NiO2)4 crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Ni(2)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NiO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the second Ni site, Ni(2) is bonded to six equivalent O(2) atoms to form NiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 4°. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ni(1) and one Cu(1) atom to form distorted OCuNi3 tetrahedra that share corners with nine equivalent O(2)MgCuNi3 square pyramids, corners with three equivalent O(1)CuNi3 tetrahedra, and edges with three equivalent O(2)MgCuNi3 square pyramids. In the second O site, O(2) is bonded to one Mg(1), one Ni(2), two equivalent Ni(1), and one Cu(1) atom to form OMgCuNi3 square pyramids that share corners with six equivalent O(2)MgCuNi3 square pyramids, corners with three equivalent O(1)CuNi3 tetrahedra, edges with six equivalent O(2)MgCuNi3 square pyramids, and  an edgeedge with one O(1)CuNi3 tetrahedra. is represented by the CIF file [CIF]
data_MgCu2(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.170
_cell_length_b   5.789
_cell_length_c   5.789
_cell_angle_alpha   60.002
_cell_angle_beta   90.000
_cell_angle_gamma   117.992
_symmetry_Int_Tables_number   1
_cell_volume   150.499
_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  0.625  0.750  0.125  1.0
  Cu  Cu1  1  0.087  0.059  0.971  1.0
  Cu  Cu2  1  0.163  0.441  0.279  1.0
  Ni  Ni3  1  0.625  0.250  0.125  1.0
  Ni  Ni4  1  0.625  0.250  0.625  1.0
  Ni  Ni5  1  0.625  0.750  0.625  1.0
  Ni  Ni6  1  0.125  0.750  0.625  1.0
  O  O7  1  0.810  0.207  0.396  1.0
  O  O8  1  0.389  0.256  0.372  1.0
  O  O9  1  0.861  0.244  0.878  1.0
  O  O10  1  0.860  0.739  0.383  1.0
  O  O11  1  0.440  0.293  0.854  1.0
  O  O12  1  0.860  0.739  0.878  1.0
  O  O13  1  0.390  0.761  0.372  1.0
  O  O14  1  0.390  0.761  0.867  1.0
[/CIF]
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