The compound described by U2Ni2Si7 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to two equivalent Si(1), two equivalent Si(4), two equivalent Si(6), four equivalent Si(5), and four equivalent Si(7) atoms. In the second U site, U(2) is bonded in a 14-coordinate geometry to four equivalent Ni(2), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and four equivalent Si(6) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a body-centered cubic geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(2), one Si(6), two equivalent Si(2), and two equivalent Si(3) atoms. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(2), and two equivalent Si(7) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(3), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(7), and two equivalent Si(6) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Ni(2), and two equivalent Si(5) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(5), two equivalent Si(1), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U2Si7Ni2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.841
_cell_length_b   10.841
_cell_length_c   3.973
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   158.493
_symmetry_Int_Tables_number   1
_cell_volume   171.175
_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  0.166  0.834  0.000  1.0
  U  U1  1  0.829  0.171  0.000  1.0
  Si  Si2  1  0.057  0.943  0.500  1.0
  Si  Si3  1  0.938  0.062  0.500  1.0
  Si  Si4  1  0.438  0.562  0.000  1.0
  Si  Si5  1  0.556  0.444  0.000  1.0
  Si  Si6  1  0.727  0.273  0.500  1.0
  Si  Si7  1  0.281  0.719  0.500  1.0
  Si  Si8  1  0.620  0.380  0.500  1.0
  Ni  Ni9  1  0.003  0.997  0.000  1.0
  Ni  Ni10  1  0.387  0.613  0.500  1.0
[/CIF]
.
The compound described by U2Ni2Si7 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to two equivalent Si(1), two equivalent Si(4), two equivalent Si(6), four equivalent Si(5), and four equivalent Si(7) atoms. In the second U site, U(2) is bonded in a 14-coordinate geometry to four equivalent Ni(2), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and four equivalent Si(6) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a body-centered cubic geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(2), one Si(6), two equivalent Si(2), and two equivalent Si(3) atoms. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(2), and two equivalent Si(7) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(3), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(7), and two equivalent Si(6) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Ni(2), and two equivalent Si(5) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(5), two equivalent Si(1), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U2Si7Ni2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.841
_cell_length_b   10.841
_cell_length_c   3.973
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   158.493
_symmetry_Int_Tables_number   1
_cell_volume   171.175
_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  0.166  0.834  0.000  1.0
  U  U1  1  0.829  0.171  0.000  1.0
  Si  Si2  1  0.057  0.943  0.500  1.0
  Si  Si3  1  0.938  0.062  0.500  1.0
  Si  Si4  1  0.438  0.562  0.000  1.0
  Si  Si5  1  0.556  0.444  0.000  1.0
  Si  Si6  1  0.727  0.273  0.500  1.0
  Si  Si7  1  0.281  0.719  0.500  1.0
  Si  Si8  1  0.620  0.380  0.500  1.0
  Ni  Ni9  1  0.003  0.997  0.000  1.0
  Ni  Ni10  1  0.387  0.613  0.500  1.0
[/CIF]
.