The crystal structure described by MgFe7(Ni3O8)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-18°. In the second Fe site, Fe(2) is bonded to one O(1), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-18°. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-18°. In the second Ni site, Ni(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with four equivalent Fe(3)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-5°. In the third Ni site, Ni(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with six equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(5) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Fe(3)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. There are six inequivalent O sites. In the first O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(2), one Fe(3), and one Ni(1) atom to form OMgFe3Ni square pyramids that share corners with three equivalent O(3)Fe2Ni4 octahedra, corners with two equivalent O(4)MgFe3Ni square pyramids,  an edgeedge with one O(2)Fe2Ni4 octahedra,  an edgeedge with one O(3)Fe2Ni4 octahedra,  an edgeedge with one O(5)Fe3Ni3 octahedra, and edges with three equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedral tilt angles range from 3-10°. In the second O site, O(5) is bonded to one Fe(2), two equivalent Fe(3), one Ni(4), and two equivalent Ni(3) atoms to form OFe3Ni3 octahedra that share corners with three equivalent O(5)Fe3Ni3 octahedra, edges with three equivalent O(2)Fe2Ni4 octahedra, edges with six equivalent O(3)Fe2Ni4 octahedra, and edges with two equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedra are not tilted. In the third O site, O(6) is bonded in a see-saw-like geometry to one Mg(1), two equivalent Fe(3), and one Ni(1) atom. In the fourth O site, O(1) is bonded in a see-saw-like geometry to one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. In the fifth O site, O(2) is bonded to two equivalent Fe(3), one Ni(1), one Ni(2), and two equivalent Ni(3) atoms to form OFe2Ni4 octahedra that share corners with three equivalent O(2)Fe2Ni4 octahedra, edges with three equivalent O(5)Fe3Ni3 octahedra, edges with six equivalent O(3)Fe2Ni4 octahedra, and edges with two equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(3) is bonded to one Fe(2), one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(3)Fe2Ni4 octahedra, corners with three equivalent O(4)MgFe3Ni square pyramids, edges with three equivalent O(2)Fe2Ni4 octahedra, edges with three equivalent O(3)Fe2Ni4 octahedra, edges with three equivalent O(5)Fe3Ni3 octahedra, and  an edgeedge with one O(4)MgFe3Ni square pyramid. The corner-sharing octahedra are not tilted. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe7(Ni3O8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.024
_cell_length_b   6.024
_cell_length_c   10.419
_cell_angle_alpha   105.275
_cell_angle_beta   74.725
_cell_angle_gamma   119.346
_symmetry_Int_Tables_number   1
_cell_volume   313.853
_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  0.812  0.188  0.062  1.0
  Fe  Fe1  1  0.312  0.688  0.062  1.0
  Fe  Fe2  1  0.063  0.937  0.823  1.0
  Fe  Fe3  1  0.563  0.939  0.313  1.0
  Fe  Fe4  1  0.061  0.437  0.313  1.0
  Fe  Fe5  1  0.562  0.438  0.302  1.0
  Fe  Fe6  1  0.564  0.938  0.812  1.0
  Fe  Fe7  1  0.062  0.436  0.812  1.0
  Ni  Ni8  1  0.063  0.937  0.299  1.0
  Ni  Ni9  1  0.312  0.688  0.562  1.0
  Ni  Ni10  1  0.812  0.688  0.562  1.0
  Ni  Ni11  1  0.312  0.188  0.562  1.0
  Ni  Ni12  1  0.812  0.188  0.562  1.0
  Ni  Ni13  1  0.562  0.438  0.826  1.0
  O  O14  1  0.415  0.585  0.212  1.0
  O  O15  1  0.184  0.816  0.441  1.0
  O  O16  1  0.685  0.821  0.442  1.0
  O  O17  1  0.179  0.315  0.442  1.0
  O  O18  1  0.942  0.558  0.198  1.0
  O  O19  1  0.442  0.058  0.198  1.0
  O  O20  1  0.683  0.317  0.440  1.0
  O  O21  1  0.914  0.086  0.210  1.0
  O  O22  1  0.210  0.790  0.913  1.0
  O  O23  1  0.441  0.559  0.684  1.0
  O  O24  1  0.683  0.817  0.927  1.0
  O  O25  1  0.183  0.317  0.927  1.0
  O  O26  1  0.940  0.554  0.683  1.0
  O  O27  1  0.446  0.060  0.683  1.0
  O  O28  1  0.942  0.058  0.685  1.0
  O  O29  1  0.711  0.289  0.915  1.0
[/CIF]
.
The crystal structure described by MgFe7(Ni3O8)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-18°. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-18°. In the second Fe site, Fe(2) is bonded to one O(1), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Ni(4)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-18°. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-18°. In the second Ni site, Ni(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with four equivalent Fe(3)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-5°. In the third Ni site, Ni(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with six equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(5) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Fe(3)O6 octahedra, and edges with four equivalent Ni(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. There are six inequivalent O sites. In the first O site, O(4) is bonded to one Mg(1), one Fe(1), one Fe(2), one Fe(3), and one Ni(1) atom to form OMgFe3Ni square pyramids that share corners with three equivalent O(3)Fe2Ni4 octahedra, corners with two equivalent O(4)MgFe3Ni square pyramids,  an edgeedge with one O(2)Fe2Ni4 octahedra,  an edgeedge with one O(3)Fe2Ni4 octahedra,  an edgeedge with one O(5)Fe3Ni3 octahedra, and edges with three equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedral tilt angles range from 3-10°. In the second O site, O(5) is bonded to one Fe(2), two equivalent Fe(3), one Ni(4), and two equivalent Ni(3) atoms to form OFe3Ni3 octahedra that share corners with three equivalent O(5)Fe3Ni3 octahedra, edges with three equivalent O(2)Fe2Ni4 octahedra, edges with six equivalent O(3)Fe2Ni4 octahedra, and edges with two equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedra are not tilted. In the third O site, O(6) is bonded in a see-saw-like geometry to one Mg(1), two equivalent Fe(3), and one Ni(1) atom. In the fourth O site, O(1) is bonded in a see-saw-like geometry to one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. In the fifth O site, O(2) is bonded to two equivalent Fe(3), one Ni(1), one Ni(2), and two equivalent Ni(3) atoms to form OFe2Ni4 octahedra that share corners with three equivalent O(2)Fe2Ni4 octahedra, edges with three equivalent O(5)Fe3Ni3 octahedra, edges with six equivalent O(3)Fe2Ni4 octahedra, and edges with two equivalent O(4)MgFe3Ni square pyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(3) is bonded to one Fe(2), one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(3)Fe2Ni4 octahedra, corners with three equivalent O(4)MgFe3Ni square pyramids, edges with three equivalent O(2)Fe2Ni4 octahedra, edges with three equivalent O(3)Fe2Ni4 octahedra, edges with three equivalent O(5)Fe3Ni3 octahedra, and  an edgeedge with one O(4)MgFe3Ni square pyramid. The corner-sharing octahedra are not tilted. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe7(Ni3O8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.024
_cell_length_b   6.024
_cell_length_c   10.419
_cell_angle_alpha   105.275
_cell_angle_beta   74.725
_cell_angle_gamma   119.346
_symmetry_Int_Tables_number   1
_cell_volume   313.853
_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  0.812  0.188  0.062  1.0
  Fe  Fe1  1  0.312  0.688  0.062  1.0
  Fe  Fe2  1  0.063  0.937  0.823  1.0
  Fe  Fe3  1  0.563  0.939  0.313  1.0
  Fe  Fe4  1  0.061  0.437  0.313  1.0
  Fe  Fe5  1  0.562  0.438  0.302  1.0
  Fe  Fe6  1  0.564  0.938  0.812  1.0
  Fe  Fe7  1  0.062  0.436  0.812  1.0
  Ni  Ni8  1  0.063  0.937  0.299  1.0
  Ni  Ni9  1  0.312  0.688  0.562  1.0
  Ni  Ni10  1  0.812  0.688  0.562  1.0
  Ni  Ni11  1  0.312  0.188  0.562  1.0
  Ni  Ni12  1  0.812  0.188  0.562  1.0
  Ni  Ni13  1  0.562  0.438  0.826  1.0
  O  O14  1  0.415  0.585  0.212  1.0
  O  O15  1  0.184  0.816  0.441  1.0
  O  O16  1  0.685  0.821  0.442  1.0
  O  O17  1  0.179  0.315  0.442  1.0
  O  O18  1  0.942  0.558  0.198  1.0
  O  O19  1  0.442  0.058  0.198  1.0
  O  O20  1  0.683  0.317  0.440  1.0
  O  O21  1  0.914  0.086  0.210  1.0
  O  O22  1  0.210  0.790  0.913  1.0
  O  O23  1  0.441  0.559  0.684  1.0
  O  O24  1  0.683  0.817  0.927  1.0
  O  O25  1  0.183  0.317  0.927  1.0
  O  O26  1  0.940  0.554  0.683  1.0
  O  O27  1  0.446  0.060  0.683  1.0
  O  O28  1  0.942  0.058  0.685  1.0
  O  O29  1  0.711  0.289  0.915  1.0
[/CIF]
.