The material structure described by MgNb2(FeO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(3), one O(7), and two equivalent O(8) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 19-26°. In the second Nb site, Nb(2) is bonded to one O(2), one O(5), one O(6), one O(8), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-19°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(7), and two equivalent O(2) atoms. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), one O(6), one O(8), and two equivalent O(1) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-34°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Nb(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgNbFe3 trigonal bipyramids that share corners with two equivalent O(1)MgNbFe3 trigonal bipyramids and edges with two equivalent O(2)NbFe3 tetrahedra. In the second O site, O(2) is bonded to one Nb(2), one Fe(2), and two equivalent Fe(1) atoms to form ONbFe3 tetrahedra that share corners with two equivalent O(2)NbFe3 tetrahedra and edges with two equivalent O(1)MgNbFe3 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Nb(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to two equivalent Nb(1) and one Fe(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Nb(1), one Nb(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(2), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Nb(1), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted square co-planar geometry to two equivalent Mg(1), one Nb(2), and one Fe(2) atom. is represented by the CIF card [CIF]
data_MgNb2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.957
_cell_length_b   6.853
_cell_length_c   7.143
_cell_angle_alpha   106.182
_cell_angle_beta   90.053
_cell_angle_gamma   106.654
_symmetry_Int_Tables_number   1
_cell_volume   177.534
_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  0.313  0.627  0.480  1.0
  Nb  Nb1  1  0.090  0.197  0.215  1.0
  Nb  Nb2  1  0.903  0.808  0.806  1.0
  Fe  Fe3  1  0.194  0.391  0.801  1.0
  Fe  Fe4  1  0.790  0.587  0.160  1.0
  O  O5  1  0.253  0.507  0.188  1.0
  O  O6  1  0.750  0.503  0.849  1.0
  O  O7  1  0.378  0.758  0.777  1.0
  O  O8  1  0.615  0.231  0.187  1.0
  O  O9  1  0.053  0.109  0.878  1.0
  O  O10  1  0.943  0.885  0.124  1.0
  O  O11  1  0.153  0.310  0.488  1.0
  O  O12  1  0.858  0.718  0.516  1.0
[/CIF]
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The material structure described by MgNb2(FeO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(3), one O(7), and two equivalent O(8) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 19-26°. In the second Nb site, Nb(2) is bonded to one O(2), one O(5), one O(6), one O(8), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-19°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(7), and two equivalent O(2) atoms. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), one O(6), one O(8), and two equivalent O(1) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-34°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Nb(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgNbFe3 trigonal bipyramids that share corners with two equivalent O(1)MgNbFe3 trigonal bipyramids and edges with two equivalent O(2)NbFe3 tetrahedra. In the second O site, O(2) is bonded to one Nb(2), one Fe(2), and two equivalent Fe(1) atoms to form ONbFe3 tetrahedra that share corners with two equivalent O(2)NbFe3 tetrahedra and edges with two equivalent O(1)MgNbFe3 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Nb(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to two equivalent Nb(1) and one Fe(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Nb(1), one Nb(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(2), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Nb(1), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted square co-planar geometry to two equivalent Mg(1), one Nb(2), and one Fe(2) atom. is represented by the CIF card [CIF]
data_MgNb2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.957
_cell_length_b   6.853
_cell_length_c   7.143
_cell_angle_alpha   106.182
_cell_angle_beta   90.053
_cell_angle_gamma   106.654
_symmetry_Int_Tables_number   1
_cell_volume   177.534
_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  0.313  0.627  0.480  1.0
  Nb  Nb1  1  0.090  0.197  0.215  1.0
  Nb  Nb2  1  0.903  0.808  0.806  1.0
  Fe  Fe3  1  0.194  0.391  0.801  1.0
  Fe  Fe4  1  0.790  0.587  0.160  1.0
  O  O5  1  0.253  0.507  0.188  1.0
  O  O6  1  0.750  0.503  0.849  1.0
  O  O7  1  0.378  0.758  0.777  1.0
  O  O8  1  0.615  0.231  0.187  1.0
  O  O9  1  0.053  0.109  0.878  1.0
  O  O10  1  0.943  0.885  0.124  1.0
  O  O11  1  0.153  0.310  0.488  1.0
  O  O12  1  0.858  0.718  0.516  1.0
[/CIF]
.