The compound described by Mg(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(13), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(8)O6 octahedra, corners with two equivalent Ni(3)O6 octahedra, corners with two equivalent Ni(6)O6 octahedra, corners with three equivalent Mg(5)O6 octahedra, and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the second Mg site, Mg(2) is bonded to one O(2), one O(9), and two equivalent O(4) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(7)O6 octahedra, corners with three equivalent Mg(3)O6 octahedra, and corners with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-61°. In the third Mg site, Mg(3) is bonded to one O(5), one O(9), two equivalent O(4), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with three equivalent Mg(2)O4 tetrahedra, corners with three equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(7)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(15), one O(6), and two equivalent O(10) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(7)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(8)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra, and corners with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the fifth Mg site, Mg(5) is bonded to one O(16), one O(3), two equivalent O(1), and two equivalent O(17) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(8)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. In the sixth Mg site, Mg(6) is bonded to one O(11), one O(18), and two equivalent O(12) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(8)O6 octahedra, corners with two equivalent Ni(6)O6 octahedra, corners with two equivalent Ni(7)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra, and corners with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-61°. There are nine inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form NiO6 octahedra that share  a cornercorner with one Mg(2)O4 tetrahedra,  a cornercorner with one Ni(9)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(5)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(11), one O(12), one O(14), one O(4), one O(6), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Mg(4)O4 tetrahedra,  a cornercorner with one Ni(5)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(7)O6 octahedra. In the third Ni site, Ni(3) is bonded to one O(2), one O(8), two equivalent O(1), and two equivalent O(7) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(2)O4 tetrahedra,  a cornercorner with one Ni(9)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(11), one O(15), two equivalent O(10), and two equivalent O(12) atoms to form NiO6 octahedra that share corners with three equivalent Mg(4)O4 tetrahedra, corners with three equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Ni(7)O6 octahedra,  an edgeedge with one Ni(8)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. In the fifth Ni site, Ni(5) is bonded to one O(14), one O(5), and two equivalent O(7) atoms to form NiO4 tetrahedra that share  a cornercorner with one Ni(7)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(3)O6 octahedra, corners with three equivalent Mg(3)O6 octahedra, and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the sixth Ni site, Ni(6) is bonded to one O(10), one O(13), one O(15), one O(16), one O(17), and one O(18) atom to form NiO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Mg(6)O4 tetrahedra, corners with two equivalent Mg(4)O4 tetrahedra, corners with two equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. In the seventh Ni site, Ni(7) is bonded to one O(14), one O(6), two equivalent O(12), and two equivalent O(4) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(4)O4 tetrahedra,  a cornercorner with one Ni(5)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. In the eighth Ni site, Ni(8) is bonded to one O(13), one O(18), two equivalent O(10), and two equivalent O(17) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Mg(6)O4 tetrahedra, corners with two equivalent Mg(4)O4 tetrahedra, corners with two equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. In the ninth Ni site, Ni(9) is bonded to one O(16), one O(8), and two equivalent O(17) atoms to form NiO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(8)O6 octahedra, corners with three equivalent Mg(5)O6 octahedra, and corners with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mg(5), one Ni(1), and one Ni(3) atom to form distorted OMg2Ni2 trigonal pyramids that share  a cornercorner with one O(1)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(3)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(5)MgNi3 trigonal pyramid, corners with three equivalent O(7)MgNi3 trigonal pyramids,  an edgeedge with one O(1)Mg2Ni2 trigonal pyramid, and  an edgeedge with one O(3)Mg2Ni2 trigonal pyramid. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Ni(3), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded to one Mg(1), one Mg(5), and two equivalent Ni(1) atoms to form distorted OMg2Ni2 trigonal pyramids that share corners with two equivalent O(1)Mg2Ni2 trigonal pyramids, corners with two equivalent O(5)MgNi3 trigonal pyramids, corners with two equivalent O(7)MgNi3 trigonal pyramids, and edges with two equivalent O(1)Mg2Ni2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Mg(3), one Ni(2), and one Ni(7) atom. In the fifth O site, O(5) is bonded to one Mg(3), one Ni(5), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid, corners with two equivalent O(1)Mg2Ni2 trigonal pyramids, corners with two equivalent O(3)Mg2Ni2 trigonal pyramids, corners with two equivalent O(7)MgNi3 trigonal pyramids, and edges with two equivalent O(7)MgNi3 trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(4), one Ni(7), and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded to one Mg(3), one Ni(1), one Ni(3), and one Ni(5) atom to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(3)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(5)MgNi3 trigonal pyramid,  a cornercorner with one O(7)MgNi3 trigonal pyramid, corners with three equivalent O(1)Mg2Ni2 trigonal pyramids,  an edgeedge with one O(5)MgNi3 trigonal pyramid, and  an edgeedge with one O(7)MgNi3 trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Ni(3), one Ni(9), and two equivalent Ni(1) atoms. In the ninth O site, O(9) is bonded to one Mg(2), one Mg(3), and two equivalent Ni(2) atoms to form distorted corner-sharing OMg2Ni2 trigonal pyramids. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(4), one Ni(4), one Ni(6), and one Ni(8) atom. In the eleventh O site, O(11) is bonded to one Mg(6), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(15)MgNi3 trigonal pyramid,  a cornercorner with one O(18)MgNi3 trigonal pyramid, corners with two equivalent O(9)Mg2Ni2 trigonal pyramids, corners with two equivalent O(12)MgNi3 trigonal pyramids, and edges with two equivalent O(12)MgNi3 trigonal pyramids. In the twelfth O site, O(12) is bonded to one Mg(6), one Ni(2), one Ni(4), and one Ni(7) atom to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(11)MgNi3 trigonal pyramid,  a cornercorner with one O(12)MgNi3 trigonal pyramid,  a cornercorner with one O(15)MgNi3 trigonal pyramid,  a cornercorner with one O(18)MgNi3 trigonal pyramid,  an edgeedge with one O(11)MgNi3 trigonal pyramid, and  an edgeedge with one O(12)MgNi3 trigonal pyramid. In the thirteenth O site, O(13) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(8), and two equivalent Ni(6) atoms. In the fourteenth O site, O(14) is bonded in a rectangular see-saw-like geometry to one Ni(5), one Ni(7), and two equivalent Ni(2) atoms. In the fifteenth O site, O(15) is bonded to one Mg(4), one Ni(4), and two equivalent Ni(6) atoms to form distorted corner-sharing OMgNi3 trigonal pyramids. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Mg(5), one Ni(9), and two equivalent Ni(6) atoms. In the seventeenth O site, O(17) is bonded in a rectangular see-saw-like geometry to one Mg(5), one Ni(6), one Ni(8), and one Ni(9) atom. In the eighteenth O site, O(18) is bonded to one Mg(6), one Ni(8), and two equivalent Ni(6) atoms to form distorted corner-sharing OMgNi3 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   5.907
_cell_length_b   5.907
_cell_length_c   14.456
_cell_angle_alpha   88.733
_cell_angle_beta   88.733
_cell_angle_gamma   59.309
_symmetry_Int_Tables_number   1
_cell_volume   433.677
_cell_formula_units_Z   6
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  0.333  0.333  0.050  1.0
  Mg  Mg1  1  0.998  0.998  0.382  1.0
  Mg  Mg2  1  0.665  0.665  0.334  1.0
  Mg  Mg3  1  0.670  0.670  0.712  1.0
  Mg  Mg4  1  0.001  0.001  0.000  1.0
  Mg  Mg5  1  0.999  0.999  0.623  1.0
  Ni  Ni6  1  0.330  0.834  0.166  1.0
  Ni  Ni7  1  0.834  0.330  0.166  1.0
  Ni  Ni8  1  0.998  0.497  0.500  1.0
  Ni  Ni9  1  0.835  0.835  0.166  1.0
  Ni  Ni10  1  0.497  0.998  0.500  1.0
  Ni  Ni11  1  0.335  0.335  0.665  1.0
  Ni  Ni12  1  0.332  0.332  0.283  1.0
  Ni  Ni13  1  0.663  0.171  0.833  1.0
  Ni  Ni14  1  0.499  0.499  0.501  1.0
  Ni  Ni15  1  0.171  0.663  0.833  1.0
  Ni  Ni16  1  0.170  0.170  0.833  1.0
  Ni  Ni17  1  0.666  0.666  0.954  1.0
  O  O18  1  0.699  0.153  0.095  1.0
  O  O19  1  0.999  0.999  0.246  1.0
  O  O20  1  0.153  0.699  0.095  1.0
  O  O21  1  0.150  0.150  0.094  1.0
  O  O22  1  0.361  0.812  0.428  1.0
  O  O23  1  0.514  0.514  0.238  1.0
  O  O24  1  0.665  0.665  0.575  1.0
  O  O25  1  0.512  0.970  0.237  1.0
  O  O26  1  0.668  0.668  0.083  1.0
  O  O27  1  0.812  0.361  0.428  1.0
  O  O28  1  0.816  0.816  0.429  1.0
  O  O29  1  0.970  0.512  0.237  1.0
  O  O30  1  0.042  0.482  0.749  1.0
  O  O31  1  0.182  0.182  0.573  1.0
  O  O32  1  0.186  0.627  0.579  1.0
  O  O33  1  0.332  0.332  0.909  1.0
  O  O34  1  0.333  0.333  0.424  1.0
  O  O35  1  0.482  0.042  0.749  1.0
  O  O36  1  0.486  0.486  0.756  1.0
  O  O37  1  0.627  0.186  0.579  1.0
  O  O38  1  0.842  0.842  0.910  1.0
  O  O39  1  0.841  0.322  0.911  1.0
  O  O40  1  0.003  0.003  0.761  1.0
  O  O41  1  0.322  0.841  0.911  1.0
[/CIF]
.
The compound described by Mg(NiO2)2 is Spinel-like structured and crystallizes in the monoclinic Cm space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(13), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(8)O6 octahedra, corners with two equivalent Ni(3)O6 octahedra, corners with two equivalent Ni(6)O6 octahedra, corners with three equivalent Mg(5)O6 octahedra, and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the second Mg site, Mg(2) is bonded to one O(2), one O(9), and two equivalent O(4) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(7)O6 octahedra, corners with three equivalent Mg(3)O6 octahedra, and corners with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-61°. In the third Mg site, Mg(3) is bonded to one O(5), one O(9), two equivalent O(4), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with three equivalent Mg(2)O4 tetrahedra, corners with three equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(7)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(15), one O(6), and two equivalent O(10) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(7)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(8)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra, and corners with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the fifth Mg site, Mg(5) is bonded to one O(16), one O(3), two equivalent O(1), and two equivalent O(17) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(8)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. In the sixth Mg site, Mg(6) is bonded to one O(11), one O(18), and two equivalent O(12) atoms to form MgO4 tetrahedra that share  a cornercorner with one Ni(8)O6 octahedra, corners with two equivalent Ni(6)O6 octahedra, corners with two equivalent Ni(7)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra, and corners with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-61°. There are nine inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form NiO6 octahedra that share  a cornercorner with one Mg(2)O4 tetrahedra,  a cornercorner with one Ni(9)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(5)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(11), one O(12), one O(14), one O(4), one O(6), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Mg(4)O4 tetrahedra,  a cornercorner with one Ni(5)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(7)O6 octahedra. In the third Ni site, Ni(3) is bonded to one O(2), one O(8), two equivalent O(1), and two equivalent O(7) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(2)O4 tetrahedra,  a cornercorner with one Ni(9)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Ni(5)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(11), one O(15), two equivalent O(10), and two equivalent O(12) atoms to form NiO6 octahedra that share corners with three equivalent Mg(4)O4 tetrahedra, corners with three equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Ni(7)O6 octahedra,  an edgeedge with one Ni(8)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. In the fifth Ni site, Ni(5) is bonded to one O(14), one O(5), and two equivalent O(7) atoms to form NiO4 tetrahedra that share  a cornercorner with one Ni(7)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(3)O6 octahedra, corners with three equivalent Mg(3)O6 octahedra, and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. In the sixth Ni site, Ni(6) is bonded to one O(10), one O(13), one O(15), one O(16), one O(17), and one O(18) atom to form NiO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Mg(6)O4 tetrahedra, corners with two equivalent Mg(4)O4 tetrahedra, corners with two equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. In the seventh Ni site, Ni(7) is bonded to one O(14), one O(6), two equivalent O(12), and two equivalent O(4) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(4)O4 tetrahedra,  a cornercorner with one Ni(5)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(6)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. In the eighth Ni site, Ni(8) is bonded to one O(13), one O(18), two equivalent O(10), and two equivalent O(17) atoms to form NiO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Mg(6)O4 tetrahedra, corners with two equivalent Mg(4)O4 tetrahedra, corners with two equivalent Ni(9)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. In the ninth Ni site, Ni(9) is bonded to one O(16), one O(8), and two equivalent O(17) atoms to form NiO4 tetrahedra that share  a cornercorner with one Ni(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Ni(8)O6 octahedra, corners with three equivalent Mg(5)O6 octahedra, and corners with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mg(5), one Ni(1), and one Ni(3) atom to form distorted OMg2Ni2 trigonal pyramids that share  a cornercorner with one O(1)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(3)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(5)MgNi3 trigonal pyramid, corners with three equivalent O(7)MgNi3 trigonal pyramids,  an edgeedge with one O(1)Mg2Ni2 trigonal pyramid, and  an edgeedge with one O(3)Mg2Ni2 trigonal pyramid. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Ni(3), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded to one Mg(1), one Mg(5), and two equivalent Ni(1) atoms to form distorted OMg2Ni2 trigonal pyramids that share corners with two equivalent O(1)Mg2Ni2 trigonal pyramids, corners with two equivalent O(5)MgNi3 trigonal pyramids, corners with two equivalent O(7)MgNi3 trigonal pyramids, and edges with two equivalent O(1)Mg2Ni2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Mg(3), one Ni(2), and one Ni(7) atom. In the fifth O site, O(5) is bonded to one Mg(3), one Ni(5), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid, corners with two equivalent O(1)Mg2Ni2 trigonal pyramids, corners with two equivalent O(3)Mg2Ni2 trigonal pyramids, corners with two equivalent O(7)MgNi3 trigonal pyramids, and edges with two equivalent O(7)MgNi3 trigonal pyramids. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(4), one Ni(7), and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded to one Mg(3), one Ni(1), one Ni(3), and one Ni(5) atom to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(3)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(5)MgNi3 trigonal pyramid,  a cornercorner with one O(7)MgNi3 trigonal pyramid, corners with three equivalent O(1)Mg2Ni2 trigonal pyramids,  an edgeedge with one O(5)MgNi3 trigonal pyramid, and  an edgeedge with one O(7)MgNi3 trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Ni(3), one Ni(9), and two equivalent Ni(1) atoms. In the ninth O site, O(9) is bonded to one Mg(2), one Mg(3), and two equivalent Ni(2) atoms to form distorted corner-sharing OMg2Ni2 trigonal pyramids. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(4), one Ni(4), one Ni(6), and one Ni(8) atom. In the eleventh O site, O(11) is bonded to one Mg(6), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(15)MgNi3 trigonal pyramid,  a cornercorner with one O(18)MgNi3 trigonal pyramid, corners with two equivalent O(9)Mg2Ni2 trigonal pyramids, corners with two equivalent O(12)MgNi3 trigonal pyramids, and edges with two equivalent O(12)MgNi3 trigonal pyramids. In the twelfth O site, O(12) is bonded to one Mg(6), one Ni(2), one Ni(4), and one Ni(7) atom to form distorted OMgNi3 trigonal pyramids that share  a cornercorner with one O(9)Mg2Ni2 trigonal pyramid,  a cornercorner with one O(11)MgNi3 trigonal pyramid,  a cornercorner with one O(12)MgNi3 trigonal pyramid,  a cornercorner with one O(15)MgNi3 trigonal pyramid,  a cornercorner with one O(18)MgNi3 trigonal pyramid,  an edgeedge with one O(11)MgNi3 trigonal pyramid, and  an edgeedge with one O(12)MgNi3 trigonal pyramid. In the thirteenth O site, O(13) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(8), and two equivalent Ni(6) atoms. In the fourteenth O site, O(14) is bonded in a rectangular see-saw-like geometry to one Ni(5), one Ni(7), and two equivalent Ni(2) atoms. In the fifteenth O site, O(15) is bonded to one Mg(4), one Ni(4), and two equivalent Ni(6) atoms to form distorted corner-sharing OMgNi3 trigonal pyramids. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Mg(5), one Ni(9), and two equivalent Ni(6) atoms. In the seventeenth O site, O(17) is bonded in a rectangular see-saw-like geometry to one Mg(5), one Ni(6), one Ni(8), and one Ni(9) atom. In the eighteenth O site, O(18) is bonded to one Mg(6), one Ni(8), and two equivalent Ni(6) atoms to form distorted corner-sharing OMgNi3 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   5.907
_cell_length_b   5.907
_cell_length_c   14.456
_cell_angle_alpha   88.733
_cell_angle_beta   88.733
_cell_angle_gamma   59.309
_symmetry_Int_Tables_number   1
_cell_volume   433.677
_cell_formula_units_Z   6
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  0.333  0.333  0.050  1.0
  Mg  Mg1  1  0.998  0.998  0.382  1.0
  Mg  Mg2  1  0.665  0.665  0.334  1.0
  Mg  Mg3  1  0.670  0.670  0.712  1.0
  Mg  Mg4  1  0.001  0.001  0.000  1.0
  Mg  Mg5  1  0.999  0.999  0.623  1.0
  Ni  Ni6  1  0.330  0.834  0.166  1.0
  Ni  Ni7  1  0.834  0.330  0.166  1.0
  Ni  Ni8  1  0.998  0.497  0.500  1.0
  Ni  Ni9  1  0.835  0.835  0.166  1.0
  Ni  Ni10  1  0.497  0.998  0.500  1.0
  Ni  Ni11  1  0.335  0.335  0.665  1.0
  Ni  Ni12  1  0.332  0.332  0.283  1.0
  Ni  Ni13  1  0.663  0.171  0.833  1.0
  Ni  Ni14  1  0.499  0.499  0.501  1.0
  Ni  Ni15  1  0.171  0.663  0.833  1.0
  Ni  Ni16  1  0.170  0.170  0.833  1.0
  Ni  Ni17  1  0.666  0.666  0.954  1.0
  O  O18  1  0.699  0.153  0.095  1.0
  O  O19  1  0.999  0.999  0.246  1.0
  O  O20  1  0.153  0.699  0.095  1.0
  O  O21  1  0.150  0.150  0.094  1.0
  O  O22  1  0.361  0.812  0.428  1.0
  O  O23  1  0.514  0.514  0.238  1.0
  O  O24  1  0.665  0.665  0.575  1.0
  O  O25  1  0.512  0.970  0.237  1.0
  O  O26  1  0.668  0.668  0.083  1.0
  O  O27  1  0.812  0.361  0.428  1.0
  O  O28  1  0.816  0.816  0.429  1.0
  O  O29  1  0.970  0.512  0.237  1.0
  O  O30  1  0.042  0.482  0.749  1.0
  O  O31  1  0.182  0.182  0.573  1.0
  O  O32  1  0.186  0.627  0.579  1.0
  O  O33  1  0.332  0.332  0.909  1.0
  O  O34  1  0.333  0.333  0.424  1.0
  O  O35  1  0.482  0.042  0.749  1.0
  O  O36  1  0.486  0.486  0.756  1.0
  O  O37  1  0.627  0.186  0.579  1.0
  O  O38  1  0.842  0.842  0.910  1.0
  O  O39  1  0.841  0.322  0.911  1.0
  O  O40  1  0.003  0.003  0.761  1.0
  O  O41  1  0.322  0.841  0.911  1.0
[/CIF]
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