The compound described by Mg(NiO2)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(4)O6 octahedra, corners with two equivalent Ni(3)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra,  a faceface with one Ni(1)O6 octahedra, and  a faceface with one Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-41°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form distorted NiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(3)O5 trigonal bipyramids, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-55°. In the second Ni site, Ni(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-55°. In the third Ni site, Ni(3) is bonded to one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-72°. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Ni(4) atoms. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted OMgNi3 tetrahedra that share corners with two equivalent O(2)MgNi3 tetrahedra,  a cornercorner with one O(3)MgNi3 trigonal pyramid, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(1), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(2)MgNi3 tetrahedra, corners with two equivalent O(3)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMg2Ni3 trigonal bipyramids that share edges with two equivalent O(2)MgNi3 tetrahedra, edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)MgNi3 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ni(4) and two equivalent Ni(1) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ni(3) and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ni(1) and two equivalent Ni(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Ni(2) and two equivalent Ni(3) atoms. is represented by the CIF card [CIF]
data_Mg(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.818
_cell_length_b   7.499
_cell_length_c   7.921
_cell_angle_alpha   92.030
_cell_angle_beta   79.750
_cell_angle_gamma   79.170
_symmetry_Int_Tables_number   1
_cell_volume   161.380
_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  0.453  0.550  0.549  1.0
  Ni  Ni1  1  0.650  0.196  0.509  1.0
  Ni  Ni2  1  0.158  0.479  0.211  1.0
  Ni  Ni3  1  0.824  0.465  0.892  1.0
  Ni  Ni4  1  0.353  0.861  0.438  1.0
  O  O5  1  0.844  0.752  0.566  1.0
  O  O6  1  0.436  0.390  0.743  1.0
  O  O7  1  0.539  0.624  0.303  1.0
  O  O8  1  0.106  0.358  0.435  1.0
  O  O9  1  0.176  0.059  0.594  1.0
  O  O10  1  0.775  0.337  0.119  1.0
  O  O11  1  0.853  0.970  0.329  1.0
  O  O12  1  0.202  0.592  0.010  1.0
[/CIF]
.
The compound described by Mg(NiO2)4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(4)O6 octahedra, corners with two equivalent Ni(3)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra,  a faceface with one Ni(1)O6 octahedra, and  a faceface with one Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-41°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form distorted NiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(3)O5 trigonal bipyramids, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-55°. In the second Ni site, Ni(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-55°. In the third Ni site, Ni(3) is bonded to one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-72°. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(7) atoms to form NiO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Ni(4) atoms. In the second O site, O(2) is bonded to one Mg(1), one Ni(1), and two equivalent Ni(3) atoms to form distorted OMgNi3 tetrahedra that share corners with two equivalent O(2)MgNi3 tetrahedra,  a cornercorner with one O(3)MgNi3 trigonal pyramid, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(1), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(2)MgNi3 tetrahedra, corners with two equivalent O(3)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMg2Ni3 trigonal bipyramids that share edges with two equivalent O(2)MgNi3 tetrahedra, edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)MgNi3 trigonal pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ni(4) and two equivalent Ni(1) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ni(3) and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ni(1) and two equivalent Ni(4) atoms. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Ni(2) and two equivalent Ni(3) atoms. is represented by the CIF card [CIF]
data_Mg(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.818
_cell_length_b   7.499
_cell_length_c   7.921
_cell_angle_alpha   92.030
_cell_angle_beta   79.750
_cell_angle_gamma   79.170
_symmetry_Int_Tables_number   1
_cell_volume   161.380
_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  0.453  0.550  0.549  1.0
  Ni  Ni1  1  0.650  0.196  0.509  1.0
  Ni  Ni2  1  0.158  0.479  0.211  1.0
  Ni  Ni3  1  0.824  0.465  0.892  1.0
  Ni  Ni4  1  0.353  0.861  0.438  1.0
  O  O5  1  0.844  0.752  0.566  1.0
  O  O6  1  0.436  0.390  0.743  1.0
  O  O7  1  0.539  0.624  0.303  1.0
  O  O8  1  0.106  0.358  0.435  1.0
  O  O9  1  0.176  0.059  0.594  1.0
  O  O10  1  0.775  0.337  0.119  1.0
  O  O11  1  0.853  0.970  0.329  1.0
  O  O12  1  0.202  0.592  0.010  1.0
[/CIF]
.