The material structure described by MgCr4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), one O(6), and one O(7) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted CrO6 octahedra that share corners with four equivalent Cr(2)O6 octahedra, corners with three equivalent Cr(4)O5 trigonal bipyramids, and edges with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-65°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form CrO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra, corners with three equivalent Cr(3)O5 trigonal bipyramids, and edges with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-65°. In the third Cr site, Cr(3) is bonded to one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form CrO5 trigonal bipyramids that share corners with three equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(4)O5 trigonal bipyramids, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. In the fourth Cr site, Cr(4) is bonded to one O(1), one O(4), one O(5), one O(7), and one O(8) atom to form distorted CrO5 trigonal bipyramids that share corners with three equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(3)O5 trigonal bipyramids, and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(3) atom. In the third O site, O(3) is bonded to one Mg(1), one Cr(1), one Cr(2), and one Cr(3) atom to form a mixture of distorted corner and edge-sharing OMgCr3 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(1), one Cr(2), and one Cr(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(2), and one Cr(4) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Cr(1), and one Cr(3) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Cr(1), one Cr(3), and one Cr(4) atom to form a mixture of distorted corner and edge-sharing OMgCr3 tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Cr(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgCr4O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.064
_cell_length_b   5.204
_cell_length_c   5.919
_cell_angle_alpha   93.875
_cell_angle_beta   75.427
_cell_angle_gamma   95.332
_symmetry_Int_Tables_number   1
_cell_volume   150.141
_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  0.175  0.081  0.366  1.0
  Cr  Cr1  1  0.525  0.244  0.675  1.0
  Cr  Cr2  1  0.004  0.751  0.848  1.0
  Cr  Cr3  1  0.598  0.699  0.423  1.0
  Cr  Cr4  1  0.914  0.250  0.068  1.0
  O  O5  1  0.773  0.074  0.853  1.0
  O  O6  1  0.764  0.580  0.628  1.0
  O  O7  1  0.309  0.895  0.584  1.0
  O  O8  1  0.201  0.451  0.910  1.0
  O  O9  1  0.175  0.993  0.039  1.0
  O  O10  1  0.358  0.397  0.461  1.0
  O  O11  1  0.780  0.096  0.382  1.0
  O  O12  1  0.737  0.591  0.120  1.0
[/CIF]
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The material structure described by MgCr4O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), one O(6), and one O(7) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted CrO6 octahedra that share corners with four equivalent Cr(2)O6 octahedra, corners with three equivalent Cr(4)O5 trigonal bipyramids, and edges with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-65°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form CrO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra, corners with three equivalent Cr(3)O5 trigonal bipyramids, and edges with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-65°. In the third Cr site, Cr(3) is bonded to one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form CrO5 trigonal bipyramids that share corners with three equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(4)O5 trigonal bipyramids, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. In the fourth Cr site, Cr(4) is bonded to one O(1), one O(4), one O(5), one O(7), and one O(8) atom to form distorted CrO5 trigonal bipyramids that share corners with three equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(3)O5 trigonal bipyramids, and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(3) atom. In the third O site, O(3) is bonded to one Mg(1), one Cr(1), one Cr(2), and one Cr(3) atom to form a mixture of distorted corner and edge-sharing OMgCr3 tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(1), one Cr(2), and one Cr(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(2), and one Cr(4) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Cr(1), and one Cr(3) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Cr(1), one Cr(3), and one Cr(4) atom to form a mixture of distorted corner and edge-sharing OMgCr3 tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Cr(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgCr4O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.064
_cell_length_b   5.204
_cell_length_c   5.919
_cell_angle_alpha   93.875
_cell_angle_beta   75.427
_cell_angle_gamma   95.332
_symmetry_Int_Tables_number   1
_cell_volume   150.141
_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  0.175  0.081  0.366  1.0
  Cr  Cr1  1  0.525  0.244  0.675  1.0
  Cr  Cr2  1  0.004  0.751  0.848  1.0
  Cr  Cr3  1  0.598  0.699  0.423  1.0
  Cr  Cr4  1  0.914  0.250  0.068  1.0
  O  O5  1  0.773  0.074  0.853  1.0
  O  O6  1  0.764  0.580  0.628  1.0
  O  O7  1  0.309  0.895  0.584  1.0
  O  O8  1  0.201  0.451  0.910  1.0
  O  O9  1  0.175  0.993  0.039  1.0
  O  O10  1  0.358  0.397  0.461  1.0
  O  O11  1  0.780  0.096  0.382  1.0
  O  O12  1  0.737  0.591  0.120  1.0
[/CIF]
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