The material structure described by MgNiO2 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(4), one O(6), and two equivalent O(7) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid,  a cornercorner with one Mg(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(1), one O(8), and two equivalent O(5) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Ni(3)O5 trigonal bipyramid,  a cornercorner with one Mg(3)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Ni(3)O5 trigonal bipyramid. In the third Mg site, Mg(3) is bonded to one O(7), one O(8), and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid,  a cornercorner with one Ni(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(3)O4 trigonal pyramids,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and  an edgeedge with one Ni(4)O4 trigonal pyramid. In the fourth Mg site, Mg(4) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(1)O4 trigonal pyramid,  a cornercorner with one Ni(1)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids,  an edgeedge with one Ni(3)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O4 trigonal pyramid. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form distorted NiO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, and  an edgeedge with one Mg(4)O4 trigonal pyramid. In the second Ni site, Ni(2) is bonded to one O(4), two equivalent O(3), and two equivalent O(6) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 trigonal pyramid, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, edges with two equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O4 trigonal pyramid, and  an edgeedge with one Mg(3)O4 trigonal pyramid. In the third Ni site, Ni(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(8) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Mg(2)O4 trigonal pyramid, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, edges with two equivalent Ni(3)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 trigonal pyramid, and  an edgeedge with one Mg(4)O4 trigonal pyramid. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(7), and two equivalent O(1) atoms to form distorted NiO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(3)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Mg(3)O4 trigonal pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), one Ni(3), and two equivalent Ni(4) atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(3)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(7)Mg3Ni trigonal pyramids, and corners with two equivalent O(1)MgNi3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Mg(4), one Ni(1), and two equivalent Ni(3) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(5)Mg3Ni trigonal pyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and  an edgeedge with one O(5)Mg3Ni trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Mg(3), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(7)Mg3Ni trigonal pyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ni3 trigonal bipyramids, and  an edgeedge with one O(7)Mg3Ni trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(3)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(7)Mg3Ni trigonal pyramids, and corners with two equivalent O(4)MgNi3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Mg(4), two equivalent Mg(2), and one Ni(1) atom to form distorted OMg3Ni trigonal pyramids that share  a cornercorner with one O(2)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, and  an edgeedge with one O(2)Mg2Ni3 trigonal bipyramid. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(4), and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded to one Mg(3), two equivalent Mg(1), and one Ni(4) atom to form distorted OMg3Ni trigonal pyramids that share  a cornercorner with one O(3)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(7)Mg3Ni trigonal pyramids, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, and  an edgeedge with one O(3)Mg2Ni3 trigonal bipyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(2), one Mg(3), and two equivalent Ni(3) atoms. is represented by the CIF card [CIF]
data_MgNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.983
_cell_length_b   8.013
_cell_length_c   8.325
_cell_angle_alpha   89.128
_cell_angle_beta   78.588
_cell_angle_gamma   90.223
_symmetry_Int_Tables_number   1
_cell_volume   194.997
_cell_formula_units_Z   4
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  0.381  0.072  0.279  1.0
  Mg  Mg1  1  0.617  0.908  0.750  1.0
  Mg  Mg2  1  0.146  0.722  0.134  1.0
  Mg  Mg3  1  0.850  0.257  0.894  1.0
  Ni  Ni4  1  0.462  0.243  0.592  1.0
  Ni  Ni5  1  0.082  0.391  0.231  1.0
  Ni  Ni6  1  0.913  0.589  0.797  1.0
  Ni  Ni7  1  0.534  0.737  0.437  1.0
  O  O8  1  0.962  0.738  0.594  1.0
  O  O9  1  0.410  0.396  0.787  1.0
  O  O10  1  0.586  0.584  0.241  1.0
  O  O11  1  0.033  0.242  0.435  1.0
  O  O12  1  0.115  0.070  0.758  1.0
  O  O13  1  0.638  0.255  0.127  1.0
  O  O14  1  0.883  0.910  0.271  1.0
  O  O15  1  0.357  0.725  0.901  1.0
[/CIF]
.
The material structure described by MgNiO2 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(4), one O(6), and two equivalent O(7) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid,  a cornercorner with one Mg(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Ni(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(1), one O(8), and two equivalent O(5) atoms to form distorted MgO4 trigonal pyramids that share  a cornercorner with one Ni(3)O5 trigonal bipyramid,  a cornercorner with one Mg(3)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Ni(3)O5 trigonal bipyramid. In the third Mg site, Mg(3) is bonded to one O(7), one O(8), and two equivalent O(3) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid,  a cornercorner with one Ni(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(3)O4 trigonal pyramids,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and  an edgeedge with one Ni(4)O4 trigonal pyramid. In the fourth Mg site, Mg(4) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form distorted MgO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(1)O4 trigonal pyramid,  a cornercorner with one Ni(1)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids,  an edgeedge with one Ni(3)O5 trigonal bipyramid, and  an edgeedge with one Ni(1)O4 trigonal pyramid. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form distorted NiO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(4)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, and  an edgeedge with one Mg(4)O4 trigonal pyramid. In the second Ni site, Ni(2) is bonded to one O(4), two equivalent O(3), and two equivalent O(6) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 trigonal pyramid, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, edges with two equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O4 trigonal pyramid, and  an edgeedge with one Mg(3)O4 trigonal pyramid. In the third Ni site, Ni(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(8) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Mg(2)O4 trigonal pyramid, corners with two equivalent Mg(3)O4 trigonal pyramids, corners with two equivalent Mg(4)O4 trigonal pyramids, corners with two equivalent Ni(1)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, edges with two equivalent Ni(3)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 trigonal pyramid, and  an edgeedge with one Mg(4)O4 trigonal pyramid. In the fourth Ni site, Ni(4) is bonded to one O(3), one O(7), and two equivalent O(1) atoms to form distorted NiO4 trigonal pyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with two equivalent Ni(3)O5 trigonal bipyramids,  a cornercorner with one Mg(3)O4 trigonal pyramid, corners with two equivalent Mg(1)O4 trigonal pyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Ni(4)O4 trigonal pyramids, and  an edgeedge with one Mg(3)O4 trigonal pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), one Ni(3), and two equivalent Ni(4) atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(3)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(7)Mg3Ni trigonal pyramids, and corners with two equivalent O(1)MgNi3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Mg(4), one Ni(1), and two equivalent Ni(3) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(5)Mg3Ni trigonal pyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and  an edgeedge with one O(5)Mg3Ni trigonal pyramid. In the third O site, O(3) is bonded to two equivalent Mg(3), one Ni(4), and two equivalent Ni(2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share  a cornercorner with one O(7)Mg3Ni trigonal pyramid, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, edges with two equivalent O(3)Mg2Ni3 trigonal bipyramids, and  an edgeedge with one O(7)Mg3Ni trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted OMgNi3 trigonal pyramids that share corners with two equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(3)Mg2Ni3 trigonal bipyramids, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(7)Mg3Ni trigonal pyramids, and corners with two equivalent O(4)MgNi3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Mg(4), two equivalent Mg(2), and one Ni(1) atom to form distorted OMg3Ni trigonal pyramids that share  a cornercorner with one O(2)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(5)Mg3Ni trigonal pyramids, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, and  an edgeedge with one O(2)Mg2Ni3 trigonal bipyramid. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(4), and two equivalent Ni(2) atoms. In the seventh O site, O(7) is bonded to one Mg(3), two equivalent Mg(1), and one Ni(4) atom to form distorted OMg3Ni trigonal pyramids that share  a cornercorner with one O(3)Mg2Ni3 trigonal bipyramid, corners with two equivalent O(7)Mg3Ni trigonal pyramids, corners with two equivalent O(1)MgNi3 trigonal pyramids, corners with two equivalent O(4)MgNi3 trigonal pyramids, and  an edgeedge with one O(3)Mg2Ni3 trigonal bipyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(2), one Mg(3), and two equivalent Ni(3) atoms. is represented by the CIF card [CIF]
data_MgNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.983
_cell_length_b   8.013
_cell_length_c   8.325
_cell_angle_alpha   89.128
_cell_angle_beta   78.588
_cell_angle_gamma   90.223
_symmetry_Int_Tables_number   1
_cell_volume   194.997
_cell_formula_units_Z   4
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  0.381  0.072  0.279  1.0
  Mg  Mg1  1  0.617  0.908  0.750  1.0
  Mg  Mg2  1  0.146  0.722  0.134  1.0
  Mg  Mg3  1  0.850  0.257  0.894  1.0
  Ni  Ni4  1  0.462  0.243  0.592  1.0
  Ni  Ni5  1  0.082  0.391  0.231  1.0
  Ni  Ni6  1  0.913  0.589  0.797  1.0
  Ni  Ni7  1  0.534  0.737  0.437  1.0
  O  O8  1  0.962  0.738  0.594  1.0
  O  O9  1  0.410  0.396  0.787  1.0
  O  O10  1  0.586  0.584  0.241  1.0
  O  O11  1  0.033  0.242  0.435  1.0
  O  O12  1  0.115  0.070  0.758  1.0
  O  O13  1  0.638  0.255  0.127  1.0
  O  O14  1  0.883  0.910  0.271  1.0
  O  O15  1  0.357  0.725  0.901  1.0
[/CIF]
.