The compound described by U2CuSi2O17 crystallizes in the triclinic P-1 space group. U(1) is bonded to one O(1), one O(2), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form distorted UO7 pentagonal bipyramids that share  a cornercorner with one Cu(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent U(1)O7 pentagonal bipyramids, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. Cu(1) is bonded to two equivalent O(1), two equivalent O(7), and two equivalent O(8) atoms to form distorted CuO6 octahedra that share corners with two equivalent U(1)O7 pentagonal bipyramids. Si(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with three equivalent U(1)O7 pentagonal bipyramids and  an edgeedge with one U(1)O7 pentagonal bipyramid. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one U(1) and one Cu(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one U(1) and one O(9) 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 3-coordinate geometry to two equivalent U(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one O(8) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one Cu(1) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Cu(1) and one O(5) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent O(2) atoms. is represented by the CIF card [CIF]
data_U2CuSi2O17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.797
_cell_length_b   7.049
_cell_length_c   7.859
_cell_angle_alpha   73.035
_cell_angle_beta   71.554
_cell_angle_gamma   86.400
_symmetry_Int_Tables_number   1
_cell_volume   341.475
_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
  U  U0  1  0.637  0.241  0.000  1.0
  U  U1  1  0.363  0.759  1.000  1.0
  Cu  Cu2  1  0.000  0.500  0.500  1.0
  Si  Si3  1  0.851  0.749  0.939  1.0
  Si  Si4  1  0.149  0.251  0.061  1.0
  O  O5  1  0.692  0.335  0.748  1.0
  O  O6  1  0.308  0.665  0.252  1.0
  O  O7  1  0.431  0.863  0.736  1.0
  O  O8  1  0.569  0.137  0.264  1.0
  O  O9  1  0.682  0.568  0.998  1.0
  O  O10  1  0.318  0.432  0.002  1.0
  O  O11  1  0.698  0.935  0.947  1.0
  O  O12  1  0.302  0.065  0.053  1.0
  O  O13  1  0.017  0.748  0.717  1.0
  O  O14  1  0.983  0.252  0.283  1.0
  O  O15  1  0.030  0.742  0.033  1.0
  O  O16  1  0.970  0.258  0.967  1.0
  O  O17  1  0.178  0.403  0.622  1.0
  O  O18  1  0.822  0.597  0.378  1.0
  O  O19  1  0.070  0.268  0.412  1.0
  O  O20  1  0.930  0.732  0.588  1.0
  O  O21  1  0.500  0.000  0.500  1.0
[/CIF]
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The compound described by U2CuSi2O17 crystallizes in the triclinic P-1 space group. U(1) is bonded to one O(1), one O(2), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form distorted UO7 pentagonal bipyramids that share  a cornercorner with one Cu(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent U(1)O7 pentagonal bipyramids, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. Cu(1) is bonded to two equivalent O(1), two equivalent O(7), and two equivalent O(8) atoms to form distorted CuO6 octahedra that share corners with two equivalent U(1)O7 pentagonal bipyramids. Si(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with three equivalent U(1)O7 pentagonal bipyramids and  an edgeedge with one U(1)O7 pentagonal bipyramid. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one U(1) and one Cu(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one U(1) and one O(9) 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 3-coordinate geometry to two equivalent U(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one O(8) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one Cu(1) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Cu(1) and one O(5) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent O(2) atoms. is represented by the CIF card [CIF]
data_U2CuSi2O17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.797
_cell_length_b   7.049
_cell_length_c   7.859
_cell_angle_alpha   73.035
_cell_angle_beta   71.554
_cell_angle_gamma   86.400
_symmetry_Int_Tables_number   1
_cell_volume   341.475
_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
  U  U0  1  0.637  0.241  0.000  1.0
  U  U1  1  0.363  0.759  1.000  1.0
  Cu  Cu2  1  0.000  0.500  0.500  1.0
  Si  Si3  1  0.851  0.749  0.939  1.0
  Si  Si4  1  0.149  0.251  0.061  1.0
  O  O5  1  0.692  0.335  0.748  1.0
  O  O6  1  0.308  0.665  0.252  1.0
  O  O7  1  0.431  0.863  0.736  1.0
  O  O8  1  0.569  0.137  0.264  1.0
  O  O9  1  0.682  0.568  0.998  1.0
  O  O10  1  0.318  0.432  0.002  1.0
  O  O11  1  0.698  0.935  0.947  1.0
  O  O12  1  0.302  0.065  0.053  1.0
  O  O13  1  0.017  0.748  0.717  1.0
  O  O14  1  0.983  0.252  0.283  1.0
  O  O15  1  0.030  0.742  0.033  1.0
  O  O16  1  0.970  0.258  0.967  1.0
  O  O17  1  0.178  0.403  0.622  1.0
  O  O18  1  0.822  0.597  0.378  1.0
  O  O19  1  0.070  0.268  0.412  1.0
  O  O20  1  0.930  0.732  0.588  1.0
  O  O21  1  0.500  0.000  0.500  1.0
[/CIF]
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