The compound described by USe2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 9-coordinate geometry to four equivalent Se(2) and five equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to four equivalent U(1) atoms to form SeU4 tetrahedra that share corners with eight equivalent Se(2)U4 tetrahedra, corners with eight equivalent Se(1)U5 trigonal bipyramids, edges with two equivalent Se(2)U4 tetrahedra, and edges with six equivalent Se(1)U5 trigonal bipyramids. In the second Se site, Se(1) is bonded to five equivalent U(1) atoms to form distorted SeU5 trigonal bipyramids that share corners with eight equivalent Se(2)U4 tetrahedra, corners with eight equivalent Se(1)U5 trigonal bipyramids, edges with six equivalent Se(2)U4 tetrahedra, and edges with six equivalent Se(1)U5 trigonal bipyramids. is represented by the CIF file [CIF]
data_USe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.207
_cell_length_b   7.530
_cell_length_c   9.082
_cell_angle_alpha   89.981
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   287.702
_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
  U  U0  1  0.250  0.256  0.628  1.0
  U  U1  1  0.750  0.744  0.372  1.0
  U  U2  1  0.250  0.756  0.872  1.0
  U  U3  1  0.750  0.244  0.128  1.0
  Se  Se4  1  0.250  0.535  0.162  1.0
  Se  Se5  1  0.750  0.465  0.837  1.0
  Se  Se6  1  0.250  0.035  0.338  1.0
  Se  Se7  1  0.750  0.965  0.662  1.0
  Se  Se8  1  0.250  0.138  0.929  1.0
  Se  Se9  1  0.750  0.862  0.071  1.0
  Se  Se10  1  0.250  0.639  0.571  1.0
  Se  Se11  1  0.750  0.362  0.429  1.0
[/CIF]
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The compound described by USe2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 9-coordinate geometry to four equivalent Se(2) and five equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to four equivalent U(1) atoms to form SeU4 tetrahedra that share corners with eight equivalent Se(2)U4 tetrahedra, corners with eight equivalent Se(1)U5 trigonal bipyramids, edges with two equivalent Se(2)U4 tetrahedra, and edges with six equivalent Se(1)U5 trigonal bipyramids. In the second Se site, Se(1) is bonded to five equivalent U(1) atoms to form distorted SeU5 trigonal bipyramids that share corners with eight equivalent Se(2)U4 tetrahedra, corners with eight equivalent Se(1)U5 trigonal bipyramids, edges with six equivalent Se(2)U4 tetrahedra, and edges with six equivalent Se(1)U5 trigonal bipyramids. is represented by the CIF file [CIF]
data_USe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.207
_cell_length_b   7.530
_cell_length_c   9.082
_cell_angle_alpha   89.981
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   287.702
_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
  U  U0  1  0.250  0.256  0.628  1.0
  U  U1  1  0.750  0.744  0.372  1.0
  U  U2  1  0.250  0.756  0.872  1.0
  U  U3  1  0.750  0.244  0.128  1.0
  Se  Se4  1  0.250  0.535  0.162  1.0
  Se  Se5  1  0.750  0.465  0.837  1.0
  Se  Se6  1  0.250  0.035  0.338  1.0
  Se  Se7  1  0.750  0.965  0.662  1.0
  Se  Se8  1  0.250  0.138  0.929  1.0
  Se  Se9  1  0.750  0.862  0.071  1.0
  Se  Se10  1  0.250  0.639  0.571  1.0
  Se  Se11  1  0.750  0.362  0.429  1.0
[/CIF]
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