The material structure described by Mg(NiO2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Ni(1,1)O5 square pyramids;  an edgeedge with one Ni(1)O5 square pyramid; edges with two equivalent Mg(1)O5 square pyramids; and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-59°. In the second Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Ni(1,1)O5 square pyramids;  an edgeedge with one Ni(1)O5 square pyramid; edges with two equivalent Mg(1)O5 square pyramids; and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-59°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NiO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Mg(1,1)O5 square pyramids;  an edgeedge with one Mg(1)O5 square pyramid; and edges with two equivalent Ni(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 49-54°. In the second Ni site, Ni(2) is bonded to one O(1); two equivalent O(2); and three O(4,4) atoms to form NiO6 octahedra that share corners with four Mg(1,1)O5 square pyramids; corners with four Ni(1,1)O5 square pyramids; edges with four Ni(2,2)O6 octahedra; and  a faceface with one Mg(1)O5 square pyramid. In the third Ni site, Ni(2) is bonded to one O(1); two equivalent O(2); and three O(4,4) atoms to form NiO6 octahedra that share corners with four Mg(1,1)O5 square pyramids; corners with four Ni(1,1)O5 square pyramids; edges with four Ni(2,2)O6 octahedra; and  a faceface with one Mg(1)O5 square pyramid. In the fourth Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NiO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Mg(1,1)O5 square pyramids;  an edgeedge with one Mg(1)O5 square pyramid; and edges with two equivalent Ni(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 49-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(4)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(2) atoms. In the third O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(2) atoms. In the fourth O site, O(1) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(4)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the fifth O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Ni(1) atoms. In the sixth O site, O(4) is bonded to two equivalent Mg(1) and three Ni(2,2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(1)MgNi3 trigonal pyramid; edges with four O(4,4)Mg2Ni3 trigonal bipyramids; and edges with two equivalent O(1)MgNi3 trigonal pyramids. In the seventh O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Ni(1) atoms. In the eighth O site, O(4) is bonded to two equivalent Mg(1) and three Ni(2,2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(1)MgNi3 trigonal pyramid; edges with four O(4,4)Mg2Ni3 trigonal bipyramids; and edges with two equivalent O(1)MgNi3 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.869
_cell_length_b   7.549
_cell_length_c   7.403
_cell_angle_alpha   74.337
_cell_angle_beta   78.856
_cell_angle_gamma   78.930
_symmetry_Int_Tables_number   1
_cell_volume   149.791
_cell_formula_units_Z   2
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  0.319  0.146  0.215  1.0
  Mg  Mg1  1  0.676  0.831  0.815  1.0
  Ni  Ni2  1  0.610  0.189  0.588  1.0
  Ni  Ni3  1  0.154  0.501  0.192  1.0
  Ni  Ni4  1  0.843  0.476  0.837  1.0
  Ni  Ni5  1  0.386  0.787  0.441  1.0
  O  O6  1  0.860  0.677  0.605  1.0
  O  O7  1  0.442  0.332  0.783  1.0
  O  O8  1  0.555  0.644  0.246  1.0
  O  O9  1  0.137  0.300  0.424  1.0
  O  O10  1  0.135  0.014  0.714  1.0
  O  O11  1  0.775  0.342  0.106  1.0
  O  O12  1  0.861  0.962  0.315  1.0
  O  O13  1  0.220  0.635  0.923  1.0
[/CIF]
.
The material structure described by Mg(NiO2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Ni(1,1)O5 square pyramids;  an edgeedge with one Ni(1)O5 square pyramid; edges with two equivalent Mg(1)O5 square pyramids; and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-59°. In the second Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Ni(1,1)O5 square pyramids;  an edgeedge with one Ni(1)O5 square pyramid; edges with two equivalent Mg(1)O5 square pyramids; and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-59°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NiO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Mg(1,1)O5 square pyramids;  an edgeedge with one Mg(1)O5 square pyramid; and edges with two equivalent Ni(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 49-54°. In the second Ni site, Ni(2) is bonded to one O(1); two equivalent O(2); and three O(4,4) atoms to form NiO6 octahedra that share corners with four Mg(1,1)O5 square pyramids; corners with four Ni(1,1)O5 square pyramids; edges with four Ni(2,2)O6 octahedra; and  a faceface with one Mg(1)O5 square pyramid. In the third Ni site, Ni(2) is bonded to one O(1); two equivalent O(2); and three O(4,4) atoms to form NiO6 octahedra that share corners with four Mg(1,1)O5 square pyramids; corners with four Ni(1,1)O5 square pyramids; edges with four Ni(2,2)O6 octahedra; and  a faceface with one Mg(1)O5 square pyramid. In the fourth Ni site, Ni(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form NiO5 square pyramids that share corners with four Ni(2,2)O6 octahedra; corners with four Mg(1,1)O5 square pyramids;  an edgeedge with one Mg(1)O5 square pyramid; and edges with two equivalent Ni(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 49-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(4)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(2) atoms. In the third O site, O(2) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent Ni(2) atoms. In the fourth O site, O(1) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(4)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, and edges with two equivalent O(4)Mg2Ni3 trigonal bipyramids. In the fifth O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Ni(1) atoms. In the sixth O site, O(4) is bonded to two equivalent Mg(1) and three Ni(2,2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(1)MgNi3 trigonal pyramid; edges with four O(4,4)Mg2Ni3 trigonal bipyramids; and edges with two equivalent O(1)MgNi3 trigonal pyramids. In the seventh O site, O(3) is bonded in a square co-planar geometry to two equivalent Mg(1) and two equivalent Ni(1) atoms. In the eighth O site, O(4) is bonded to two equivalent Mg(1) and three Ni(2,2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(1)MgNi3 trigonal pyramid; edges with four O(4,4)Mg2Ni3 trigonal bipyramids; and edges with two equivalent O(1)MgNi3 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.869
_cell_length_b   7.549
_cell_length_c   7.403
_cell_angle_alpha   74.337
_cell_angle_beta   78.856
_cell_angle_gamma   78.930
_symmetry_Int_Tables_number   1
_cell_volume   149.791
_cell_formula_units_Z   2
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  0.319  0.146  0.215  1.0
  Mg  Mg1  1  0.676  0.831  0.815  1.0
  Ni  Ni2  1  0.610  0.189  0.588  1.0
  Ni  Ni3  1  0.154  0.501  0.192  1.0
  Ni  Ni4  1  0.843  0.476  0.837  1.0
  Ni  Ni5  1  0.386  0.787  0.441  1.0
  O  O6  1  0.860  0.677  0.605  1.0
  O  O7  1  0.442  0.332  0.783  1.0
  O  O8  1  0.555  0.644  0.246  1.0
  O  O9  1  0.137  0.300  0.424  1.0
  O  O10  1  0.135  0.014  0.714  1.0
  O  O11  1  0.775  0.342  0.106  1.0
  O  O12  1  0.861  0.962  0.315  1.0
  O  O13  1  0.220  0.635  0.923  1.0
[/CIF]
.