The compound described by MgNbCrO4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with four equivalent Nb(1)O6 octahedra, and edges with four equivalent Cr(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-21°. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent Cr(1)O5 trigonal bipyramids, edges with four equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. Cr(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form CrO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Cr(1)O5 trigonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-77°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a square co-planar geometry to one Mg(1), two equivalent Nb(1), and one Cr(1) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Nb(1), and two equivalent Cr(1) atoms to form a mixture of corner and edge-sharing OMg2NbCr2 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Nb(1), and two equivalent Cr(1) atoms to form a mixture of corner and edge-sharing OMg2NbCr2 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNbCrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.674
_cell_length_b   5.685
_cell_length_c   5.674
_cell_angle_alpha   138.162
_cell_angle_beta   137.059
_cell_angle_gamma   61.471
_symmetry_Int_Tables_number   1
_cell_volume   82.244
_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  0.281  0.814  0.533  1.0
  Nb  Nb1  1  0.019  0.055  0.036  1.0
  Cr  Cr2  1  0.745  0.278  0.534  1.0
  O  O3  1  0.500  0.034  0.534  1.0
  O  O4  1  0.243  0.276  0.033  1.0
  O  O5  1  0.037  0.572  0.535  1.0
  O  O6  1  0.794  0.828  0.033  1.0
[/CIF]
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The compound described by MgNbCrO4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with four equivalent Nb(1)O6 octahedra, and edges with four equivalent Cr(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-21°. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent Cr(1)O5 trigonal bipyramids, edges with four equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. Cr(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form CrO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Cr(1)O5 trigonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-77°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a square co-planar geometry to one Mg(1), two equivalent Nb(1), and one Cr(1) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Nb(1), and two equivalent Cr(1) atoms to form a mixture of corner and edge-sharing OMg2NbCr2 trigonal bipyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1), one Nb(1), and two equivalent Cr(1) atoms to form a mixture of corner and edge-sharing OMg2NbCr2 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNbCrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.674
_cell_length_b   5.685
_cell_length_c   5.674
_cell_angle_alpha   138.162
_cell_angle_beta   137.059
_cell_angle_gamma   61.471
_symmetry_Int_Tables_number   1
_cell_volume   82.244
_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  0.281  0.814  0.533  1.0
  Nb  Nb1  1  0.019  0.055  0.036  1.0
  Cr  Cr2  1  0.745  0.278  0.534  1.0
  O  O3  1  0.500  0.034  0.534  1.0
  O  O4  1  0.243  0.276  0.033  1.0
  O  O5  1  0.037  0.572  0.535  1.0
  O  O6  1  0.794  0.828  0.033  1.0
[/CIF]
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