The material described by MgNiO2 crystallizes in the triclinic P-1 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 distorted MgO5 trigonal bipyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with four equivalent Ni(1)O5 trigonal bipyramids,  an edgeedge with one Ni(1)O5 trigonal bipyramid, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Ni(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. There are two 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 distorted NiO5 trigonal bipyramids that share corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ni(2)O5 trigonal bipyramids, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four 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 OMgNi3 tetrahedra that share corners with two equivalent O(1)MgNi3 tetrahedra, corners with four equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with four equivalent O(3)Mg3Ni2 trigonal bipyramids, and  an edgeedge with one O(3)Mg3Ni2 trigonal bipyramid. In the second O site, O(2) is bonded to two equivalent Mg(2), one Ni(1), and two equivalent Ni(2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share corners with four equivalent O(1)MgNi3 tetrahedra, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)Mg3Ni2 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Ni(1) atoms to form distorted OMg3Ni2 trigonal bipyramids that share corners with four equivalent O(1)MgNi3 tetrahedra,  an edgeedge with one O(1)MgNi3 tetrahedra, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)Mg3Ni2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Ni(2) atoms. is represented by the CIF file [CIF]
data_MgNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.934
_cell_length_b   8.144
_cell_length_c   8.148
_cell_angle_alpha   86.894
_cell_angle_beta   79.667
_cell_angle_gamma   79.836
_symmetry_Int_Tables_number   1
_cell_volume   188.476
_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  0.573  0.593  0.254  1.0
  Mg  Mg1  1  0.427  0.407  0.746  1.0
  Mg  Mg2  1  0.195  0.229  0.391  1.0
  Mg  Mg3  1  0.805  0.771  0.609  1.0
  Ni  Ni4  1  0.181  0.725  0.914  1.0
  Ni  Ni5  1  0.412  0.913  0.264  1.0
  Ni  Ni6  1  0.588  0.087  0.736  1.0
  Ni  Ni7  1  0.819  0.275  0.086  1.0
  O  O8  1  0.425  0.233  0.932  1.0
  O  O9  1  0.199  0.902  0.714  1.0
  O  O10  1  0.801  0.098  0.286  1.0
  O  O11  1  0.575  0.767  0.068  1.0
  O  O12  1  0.830  0.582  0.770  1.0
  O  O13  1  0.942  0.745  0.370  1.0
  O  O14  1  0.170  0.418  0.230  1.0
  O  O15  1  0.058  0.255  0.630  1.0
[/CIF]
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The material described by MgNiO2 crystallizes in the triclinic P-1 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 distorted MgO5 trigonal bipyramids that share corners with two equivalent Ni(2)O5 trigonal bipyramids, corners with four equivalent Ni(1)O5 trigonal bipyramids,  an edgeedge with one Ni(1)O5 trigonal bipyramid, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Ni(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), and two equivalent O(2) atoms. There are two 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 distorted NiO5 trigonal bipyramids that share corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ni(2)O5 trigonal bipyramids, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four 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 OMgNi3 tetrahedra that share corners with two equivalent O(1)MgNi3 tetrahedra, corners with four equivalent O(2)Mg2Ni3 trigonal bipyramids, corners with four equivalent O(3)Mg3Ni2 trigonal bipyramids, and  an edgeedge with one O(3)Mg3Ni2 trigonal bipyramid. In the second O site, O(2) is bonded to two equivalent Mg(2), one Ni(1), and two equivalent Ni(2) atoms to form distorted OMg2Ni3 trigonal bipyramids that share corners with four equivalent O(1)MgNi3 tetrahedra, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)Mg3Ni2 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Ni(1) atoms to form distorted OMg3Ni2 trigonal bipyramids that share corners with four equivalent O(1)MgNi3 tetrahedra,  an edgeedge with one O(1)MgNi3 tetrahedra, edges with two equivalent O(2)Mg2Ni3 trigonal bipyramids, and edges with two equivalent O(3)Mg3Ni2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Ni(2) atoms. is represented by the CIF file [CIF]
data_MgNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.934
_cell_length_b   8.144
_cell_length_c   8.148
_cell_angle_alpha   86.894
_cell_angle_beta   79.667
_cell_angle_gamma   79.836
_symmetry_Int_Tables_number   1
_cell_volume   188.476
_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  0.573  0.593  0.254  1.0
  Mg  Mg1  1  0.427  0.407  0.746  1.0
  Mg  Mg2  1  0.195  0.229  0.391  1.0
  Mg  Mg3  1  0.805  0.771  0.609  1.0
  Ni  Ni4  1  0.181  0.725  0.914  1.0
  Ni  Ni5  1  0.412  0.913  0.264  1.0
  Ni  Ni6  1  0.588  0.087  0.736  1.0
  Ni  Ni7  1  0.819  0.275  0.086  1.0
  O  O8  1  0.425  0.233  0.932  1.0
  O  O9  1  0.199  0.902  0.714  1.0
  O  O10  1  0.801  0.098  0.286  1.0
  O  O11  1  0.575  0.767  0.068  1.0
  O  O12  1  0.830  0.582  0.770  1.0
  O  O13  1  0.942  0.745  0.370  1.0
  O  O14  1  0.170  0.418  0.230  1.0
  O  O15  1  0.058  0.255  0.630  1.0
[/CIF]
.