The compound described by MgU2(SiO8)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra. U(1) is bonded in a 7-coordinate geometry to one O(1), one O(4), one O(5), and four equivalent O(3) atoms. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent U(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one U(1) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one U(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Mg(1) atom. is represented by the CIF file [CIF]
data_MgU2(SiO8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.240
_cell_length_b   9.240
_cell_length_c   6.792
_cell_angle_alpha   74.966
_cell_angle_beta   74.966
_cell_angle_gamma   45.201
_symmetry_Int_Tables_number   1
_cell_volume   394.928
_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  0.000  0.000  0.500  1.0
  U  U1  1  0.742  0.742  0.148  1.0
  U  U2  1  0.258  0.258  0.852  1.0
  Si  Si3  1  0.784  0.784  0.649  1.0
  Si  Si4  1  0.216  0.216  0.351  1.0
  O  O5  1  0.736  0.736  0.473  1.0
  O  O6  1  0.264  0.264  0.527  1.0
  O  O7  1  0.882  0.882  0.536  1.0
  O  O8  1  0.118  0.118  0.464  1.0
  O  O9  1  0.582  0.938  0.810  1.0
  O  O10  1  0.062  0.418  0.190  1.0
  O  O11  1  0.418  0.062  0.190  1.0
  O  O12  1  0.938  0.582  0.810  1.0
  O  O13  1  0.852  0.852  0.081  1.0
  O  O14  1  0.148  0.148  0.919  1.0
  O  O15  1  0.633  0.633  0.180  1.0
  O  O16  1  0.367  0.367  0.820  1.0
  O  O17  1  0.774  0.181  0.726  1.0
  O  O18  1  0.819  0.226  0.274  1.0
  O  O19  1  0.226  0.819  0.274  1.0
  O  O20  1  0.181  0.774  0.726  1.0
[/CIF]
.
The compound described by MgU2(SiO8)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra. U(1) is bonded in a 7-coordinate geometry to one O(1), one O(4), one O(5), and four equivalent O(3) atoms. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent U(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one U(1) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one U(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Mg(1) atom. is represented by the CIF file [CIF]
data_MgU2(SiO8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.240
_cell_length_b   9.240
_cell_length_c   6.792
_cell_angle_alpha   74.966
_cell_angle_beta   74.966
_cell_angle_gamma   45.201
_symmetry_Int_Tables_number   1
_cell_volume   394.928
_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  0.000  0.000  0.500  1.0
  U  U1  1  0.742  0.742  0.148  1.0
  U  U2  1  0.258  0.258  0.852  1.0
  Si  Si3  1  0.784  0.784  0.649  1.0
  Si  Si4  1  0.216  0.216  0.351  1.0
  O  O5  1  0.736  0.736  0.473  1.0
  O  O6  1  0.264  0.264  0.527  1.0
  O  O7  1  0.882  0.882  0.536  1.0
  O  O8  1  0.118  0.118  0.464  1.0
  O  O9  1  0.582  0.938  0.810  1.0
  O  O10  1  0.062  0.418  0.190  1.0
  O  O11  1  0.418  0.062  0.190  1.0
  O  O12  1  0.938  0.582  0.810  1.0
  O  O13  1  0.852  0.852  0.081  1.0
  O  O14  1  0.148  0.148  0.919  1.0
  O  O15  1  0.633  0.633  0.180  1.0
  O  O16  1  0.367  0.367  0.820  1.0
  O  O17  1  0.774  0.181  0.726  1.0
  O  O18  1  0.819  0.226  0.274  1.0
  O  O19  1  0.226  0.819  0.274  1.0
  O  O20  1  0.181  0.774  0.726  1.0
[/CIF]
.