The structure described by Mg(ScSe2)2 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form MgSe4 tetrahedra that share corners with two equivalent Sc(1)Se6 octahedra, corners with four equivalent Sc(2)Se6 octahedra,  an edgeedge with one Sc(2)Se6 octahedra, and edges with two equivalent Sc(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-70°. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form ScSe6 octahedra that share corners with four equivalent Sc(2)Se6 octahedra, corners with two equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sc(1)Se6 octahedra, edges with two equivalent Sc(2)Se6 octahedra, and edges with two equivalent Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-50°. In the second Sc site, Sc(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form ScSe6 octahedra that share corners with four equivalent Sc(1)Se6 octahedra, corners with four equivalent Sc(2)Se6 octahedra, corners with four equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sc(1)Se6 octahedra, and  an edgeedge with one Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-50°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sc(1), and two equivalent Sc(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sc(2), and two equivalent Sc(1) atoms. In the third Se site, Se(3) is bonded to one Mg(1), one Sc(2), and two equivalent Sc(1) atoms to form distorted corner-sharing SeMgSc3 trigonal pyramids. is represented by the CIF file [CIF]
data_Mg(ScSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.480
_cell_length_b   7.833
_cell_length_c   6.620
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   698.993
_cell_formula_units_Z   4
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  0.093  0.250  0.916  1.0
  Mg  Mg1  1  0.907  0.750  0.084  1.0
  Mg  Mg2  1  0.407  0.750  0.416  1.0
  Mg  Mg3  1  0.593  0.250  0.584  1.0
  Sc  Sc4  1  0.000  0.000  0.500  1.0
  Sc  Sc5  1  0.500  0.000  0.000  1.0
  Sc  Sc6  1  0.500  0.500  0.000  1.0
  Sc  Sc7  1  0.000  0.500  0.500  1.0
  Sc  Sc8  1  0.239  0.750  0.009  1.0
  Sc  Sc9  1  0.761  0.250  0.991  1.0
  Sc  Sc10  1  0.261  0.250  0.509  1.0
  Sc  Sc11  1  0.739  0.750  0.491  1.0
  Se  Se12  1  0.171  0.995  0.730  1.0
  Se  Se13  1  0.829  0.005  0.270  1.0
  Se  Se14  1  0.329  0.005  0.230  1.0
  Se  Se15  1  0.671  0.995  0.770  1.0
  Se  Se16  1  0.671  0.505  0.770  1.0
  Se  Se17  1  0.329  0.495  0.230  1.0
  Se  Se18  1  0.829  0.495  0.270  1.0
  Se  Se19  1  0.171  0.505  0.730  1.0
  Se  Se20  1  0.079  0.750  0.257  1.0
  Se  Se21  1  0.921  0.250  0.743  1.0
  Se  Se22  1  0.421  0.250  0.757  1.0
  Se  Se23  1  0.579  0.750  0.243  1.0
  Se  Se24  1  0.090  0.250  0.297  1.0
  Se  Se25  1  0.910  0.750  0.703  1.0
  Se  Se26  1  0.410  0.750  0.797  1.0
  Se  Se27  1  0.590  0.250  0.203  1.0
[/CIF]
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The structure described by Mg(ScSe2)2 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form MgSe4 tetrahedra that share corners with two equivalent Sc(1)Se6 octahedra, corners with four equivalent Sc(2)Se6 octahedra,  an edgeedge with one Sc(2)Se6 octahedra, and edges with two equivalent Sc(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-70°. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form ScSe6 octahedra that share corners with four equivalent Sc(2)Se6 octahedra, corners with two equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sc(1)Se6 octahedra, edges with two equivalent Sc(2)Se6 octahedra, and edges with two equivalent Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-50°. In the second Sc site, Sc(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form ScSe6 octahedra that share corners with four equivalent Sc(1)Se6 octahedra, corners with four equivalent Sc(2)Se6 octahedra, corners with four equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sc(1)Se6 octahedra, and  an edgeedge with one Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-50°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sc(1), and two equivalent Sc(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sc(2), and two equivalent Sc(1) atoms. In the third Se site, Se(3) is bonded to one Mg(1), one Sc(2), and two equivalent Sc(1) atoms to form distorted corner-sharing SeMgSc3 trigonal pyramids. is represented by the CIF file [CIF]
data_Mg(ScSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.480
_cell_length_b   7.833
_cell_length_c   6.620
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   698.993
_cell_formula_units_Z   4
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  0.093  0.250  0.916  1.0
  Mg  Mg1  1  0.907  0.750  0.084  1.0
  Mg  Mg2  1  0.407  0.750  0.416  1.0
  Mg  Mg3  1  0.593  0.250  0.584  1.0
  Sc  Sc4  1  0.000  0.000  0.500  1.0
  Sc  Sc5  1  0.500  0.000  0.000  1.0
  Sc  Sc6  1  0.500  0.500  0.000  1.0
  Sc  Sc7  1  0.000  0.500  0.500  1.0
  Sc  Sc8  1  0.239  0.750  0.009  1.0
  Sc  Sc9  1  0.761  0.250  0.991  1.0
  Sc  Sc10  1  0.261  0.250  0.509  1.0
  Sc  Sc11  1  0.739  0.750  0.491  1.0
  Se  Se12  1  0.171  0.995  0.730  1.0
  Se  Se13  1  0.829  0.005  0.270  1.0
  Se  Se14  1  0.329  0.005  0.230  1.0
  Se  Se15  1  0.671  0.995  0.770  1.0
  Se  Se16  1  0.671  0.505  0.770  1.0
  Se  Se17  1  0.329  0.495  0.230  1.0
  Se  Se18  1  0.829  0.495  0.270  1.0
  Se  Se19  1  0.171  0.505  0.730  1.0
  Se  Se20  1  0.079  0.750  0.257  1.0
  Se  Se21  1  0.921  0.250  0.743  1.0
  Se  Se22  1  0.421  0.250  0.757  1.0
  Se  Se23  1  0.579  0.750  0.243  1.0
  Se  Se24  1  0.090  0.250  0.297  1.0
  Se  Se25  1  0.910  0.750  0.703  1.0
  Se  Se26  1  0.410  0.750  0.797  1.0
  Se  Se27  1  0.590  0.250  0.203  1.0
[/CIF]
.