The crystal structure described by MgCr3CuO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, corners with two equivalent Cr(2)O4 tetrahedra, and  an edgeedge with one Cr(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 60-73°. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-59°. In the second Cr site, Cr(2) is bonded to one O(3), one O(6), and two equivalent O(1) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-54°. In the third Cr site, Cr(3) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Cu(1)O6 octahedra. Cu(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form CuO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Cr(3)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Cu(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Cr(1) and one Cu(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Cr(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Cr(3), and one Cu(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Cr(1) and one Cr(3) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Cu(1) atom. is represented by the CIF file [CIF]
data_MgCr3CuO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.107
_cell_length_b   5.107
_cell_length_c   6.407
_cell_angle_alpha   88.355
_cell_angle_beta   88.360
_cell_angle_gamma   67.651
_symmetry_Int_Tables_number   1
_cell_volume   154.465
_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  0.665  0.665  0.765  1.0
  Cr  Cr1  1  0.339  0.339  0.734  1.0
  Cr  Cr2  1  0.643  0.643  0.264  1.0
  Cr  Cr3  1  0.002  0.002  0.497  1.0
  Cu  Cu4  1  0.998  0.998  0.015  1.0
  O  O5  1  0.786  0.268  0.273  1.0
  O  O6  1  0.227  0.227  0.954  1.0
  O  O7  1  0.268  0.786  0.273  1.0
  O  O8  1  0.771  0.771  0.488  1.0
  O  O9  1  0.724  0.246  0.733  1.0
  O  O10  1  0.238  0.238  0.515  1.0
  O  O11  1  0.246  0.724  0.733  1.0
  O  O12  1  0.770  0.770  0.035  1.0
[/CIF]
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The crystal structure described by MgCr3CuO8 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form distorted MgO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, corners with two equivalent Cr(2)O4 tetrahedra, and  an edgeedge with one Cr(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 60-73°. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-59°. In the second Cr site, Cr(2) is bonded to one O(3), one O(6), and two equivalent O(1) atoms to form CrO4 tetrahedra that share corners with three equivalent Cr(3)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-54°. In the third Cr site, Cr(3) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Cu(1)O6 octahedra. Cu(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form CuO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Cr(3)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Cu(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Cr(1) and one Cu(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Cr(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Cr(3), and one Cu(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Cr(1) and one Cr(3) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Cu(1) atom. is represented by the CIF file [CIF]
data_MgCr3CuO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.107
_cell_length_b   5.107
_cell_length_c   6.407
_cell_angle_alpha   88.355
_cell_angle_beta   88.360
_cell_angle_gamma   67.651
_symmetry_Int_Tables_number   1
_cell_volume   154.465
_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  0.665  0.665  0.765  1.0
  Cr  Cr1  1  0.339  0.339  0.734  1.0
  Cr  Cr2  1  0.643  0.643  0.264  1.0
  Cr  Cr3  1  0.002  0.002  0.497  1.0
  Cu  Cu4  1  0.998  0.998  0.015  1.0
  O  O5  1  0.786  0.268  0.273  1.0
  O  O6  1  0.227  0.227  0.954  1.0
  O  O7  1  0.268  0.786  0.273  1.0
  O  O8  1  0.771  0.771  0.488  1.0
  O  O9  1  0.724  0.246  0.733  1.0
  O  O10  1  0.238  0.238  0.515  1.0
  O  O11  1  0.246  0.724  0.733  1.0
  O  O12  1  0.770  0.770  0.035  1.0
[/CIF]
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