The compound described by U2Ce8O21 is alpha bismuth trifluoride-derived structured and crystallizes in the orthorhombic Cmmm space group. U(1,2) is bonded in a distorted body-centered cubic geometry to two equivalent O(4) and eight equivalent O(3) atoms. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 9-coordinate geometry to one O(4), four equivalent O(1), and four equivalent O(3) atoms. In the second Ce site, Ce(2,3) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. In the third Ce site, Ce(4) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ce(1); one Ce(4); and two equivalent Ce(2,3) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce2U4 octahedra, corners with four equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(3)Ce2U2 tetrahedra, corners with six equivalent O(2)Ce4 tetrahedra,  an edgeedge with one O(3)Ce2U2 tetrahedra,  an edgeedge with one O(2)Ce4 tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. In the second O site, O(2) is bonded to four equivalent Ce(2,3) atoms to form a mixture of edge and corner-sharing OCe4 tetrahedra. In the third O site, O(3) is bonded to two equivalent U(1,2); one Ce(1); and one Ce(4) atom to form OCe2U2 tetrahedra that share corners with two equivalent O(4)Ce2U4 octahedra, corners with six equivalent O(1)Ce4 tetrahedra, corners with ten equivalent O(3)Ce2U2 tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra, edges with five equivalent O(3)Ce2U2 tetrahedra, and  a faceface with one O(4)Ce2U4 octahedra. The corner-sharing octahedral tilt angles are 57°. In the fourth O site, O(4) is bonded to four equivalent U(1,2) and two equivalent Ce(1) atoms to form OCe2U4 octahedra that share corners with four equivalent O(4)Ce2U4 octahedra, corners with eight equivalent O(1)Ce4 tetrahedra, corners with sixteen equivalent O(3)Ce2U2 tetrahedra, and faces with eight equivalent O(3)Ce2U2 tetrahedra. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Ce8U2O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.872
_cell_length_b   13.872
_cell_length_c   5.443
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   157.383
_symmetry_Int_Tables_number   1
_cell_volume   402.775
_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
  Ce  Ce0  1  0.403  0.597  0.000  1.0
  Ce  Ce1  1  0.300  0.700  0.500  1.0
  Ce  Ce2  1  0.200  0.800  0.000  1.0
  Ce  Ce3  1  0.897  0.103  0.500  1.0
  Ce  Ce4  1  0.103  0.897  0.500  1.0
  Ce  Ce5  1  0.800  0.200  0.000  1.0
  Ce  Ce6  1  0.700  0.300  0.500  1.0
  Ce  Ce7  1  0.597  0.403  0.000  1.0
  U  U8  1  0.000  0.000  0.000  1.0
  U  U9  1  0.500  0.500  0.500  1.0
  O  O10  1  0.103  0.402  0.248  1.0
  O  O11  1  0.000  0.500  0.750  1.0
  O  O12  1  0.598  0.897  0.752  1.0
  O  O13  1  0.500  0.000  0.250  1.0
  O  O14  1  0.285  0.187  0.736  1.0
  O  O15  1  0.402  0.103  0.752  1.0
  O  O16  1  0.187  0.285  0.264  1.0
  O  O17  1  0.285  0.187  0.264  1.0
  O  O18  1  0.897  0.598  0.248  1.0
  O  O19  1  0.813  0.715  0.264  1.0
  O  O20  1  0.500  0.500  0.000  1.0
  O  O21  1  0.103  0.402  0.752  1.0
  O  O22  1  0.187  0.285  0.736  1.0
  O  O23  1  0.813  0.715  0.736  1.0
  O  O24  1  0.715  0.813  0.736  1.0
  O  O25  1  0.715  0.813  0.264  1.0
  O  O26  1  0.598  0.897  0.248  1.0
  O  O27  1  0.500  0.000  0.750  1.0
  O  O28  1  0.402  0.103  0.248  1.0
  O  O29  1  0.000  0.500  0.250  1.0
  O  O30  1  0.897  0.598  0.752  1.0
[/CIF]
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The compound described by U2Ce8O21 is alpha bismuth trifluoride-derived structured and crystallizes in the orthorhombic Cmmm space group. U(1,2) is bonded in a distorted body-centered cubic geometry to two equivalent O(4) and eight equivalent O(3) atoms. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 9-coordinate geometry to one O(4), four equivalent O(1), and four equivalent O(3) atoms. In the second Ce site, Ce(2,3) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. In the third Ce site, Ce(4) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ce(1); one Ce(4); and two equivalent Ce(2,3) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce2U4 octahedra, corners with four equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(3)Ce2U2 tetrahedra, corners with six equivalent O(2)Ce4 tetrahedra,  an edgeedge with one O(3)Ce2U2 tetrahedra,  an edgeedge with one O(2)Ce4 tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. In the second O site, O(2) is bonded to four equivalent Ce(2,3) atoms to form a mixture of edge and corner-sharing OCe4 tetrahedra. In the third O site, O(3) is bonded to two equivalent U(1,2); one Ce(1); and one Ce(4) atom to form OCe2U2 tetrahedra that share corners with two equivalent O(4)Ce2U4 octahedra, corners with six equivalent O(1)Ce4 tetrahedra, corners with ten equivalent O(3)Ce2U2 tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra, edges with five equivalent O(3)Ce2U2 tetrahedra, and  a faceface with one O(4)Ce2U4 octahedra. The corner-sharing octahedral tilt angles are 57°. In the fourth O site, O(4) is bonded to four equivalent U(1,2) and two equivalent Ce(1) atoms to form OCe2U4 octahedra that share corners with four equivalent O(4)Ce2U4 octahedra, corners with eight equivalent O(1)Ce4 tetrahedra, corners with sixteen equivalent O(3)Ce2U2 tetrahedra, and faces with eight equivalent O(3)Ce2U2 tetrahedra. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Ce8U2O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.872
_cell_length_b   13.872
_cell_length_c   5.443
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   157.383
_symmetry_Int_Tables_number   1
_cell_volume   402.775
_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
  Ce  Ce0  1  0.403  0.597  0.000  1.0
  Ce  Ce1  1  0.300  0.700  0.500  1.0
  Ce  Ce2  1  0.200  0.800  0.000  1.0
  Ce  Ce3  1  0.897  0.103  0.500  1.0
  Ce  Ce4  1  0.103  0.897  0.500  1.0
  Ce  Ce5  1  0.800  0.200  0.000  1.0
  Ce  Ce6  1  0.700  0.300  0.500  1.0
  Ce  Ce7  1  0.597  0.403  0.000  1.0
  U  U8  1  0.000  0.000  0.000  1.0
  U  U9  1  0.500  0.500  0.500  1.0
  O  O10  1  0.103  0.402  0.248  1.0
  O  O11  1  0.000  0.500  0.750  1.0
  O  O12  1  0.598  0.897  0.752  1.0
  O  O13  1  0.500  0.000  0.250  1.0
  O  O14  1  0.285  0.187  0.736  1.0
  O  O15  1  0.402  0.103  0.752  1.0
  O  O16  1  0.187  0.285  0.264  1.0
  O  O17  1  0.285  0.187  0.264  1.0
  O  O18  1  0.897  0.598  0.248  1.0
  O  O19  1  0.813  0.715  0.264  1.0
  O  O20  1  0.500  0.500  0.000  1.0
  O  O21  1  0.103  0.402  0.752  1.0
  O  O22  1  0.187  0.285  0.736  1.0
  O  O23  1  0.813  0.715  0.736  1.0
  O  O24  1  0.715  0.813  0.736  1.0
  O  O25  1  0.715  0.813  0.264  1.0
  O  O26  1  0.598  0.897  0.248  1.0
  O  O27  1  0.500  0.000  0.750  1.0
  O  O28  1  0.402  0.103  0.248  1.0
  O  O29  1  0.000  0.500  0.250  1.0
  O  O30  1  0.897  0.598  0.752  1.0
[/CIF]
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