The crystal structure described by Y3Si2O6Cl5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(2), one O(3), one Cl(2), one Cl(4), and three equivalent Cl(3) atoms to form distorted YCl5O2 pentagonal bipyramids that share corners with four equivalent Y(1)Cl5O2 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Y(2)Cl2O6 hexagonal bipyramid, and edges with two equivalent Y(1)Cl5O2 pentagonal bipyramids. In the second Y site, Y(2) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent Cl(1) atoms to form distorted YCl2O6 hexagonal bipyramids that share corners with four equivalent Y(2)Cl2O6 hexagonal bipyramids, edges with two equivalent Y(1)Cl5O2 pentagonal bipyramids, and edges with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)Cl5O2 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and edges with two equivalent Y(2)Cl2O6 hexagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Y(2) and two equivalent Si(1) atoms. There are four inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a bent 150 degrees geometry to two equivalent Y(2) atoms. In the second Cl site, Cl(2) is bonded in a bent 150 degrees geometry to two equivalent Y(1) atoms. In the third Cl site, Cl(3) is bonded in a trigonal planar geometry to three equivalent Y(1) atoms. In the fourth Cl site, Cl(4) is bonded in a bent 150 degrees geometry to two equivalent Y(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y3Si2Cl5O6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.475
_cell_length_b   7.475
_cell_length_c   11.733
_cell_angle_alpha   80.607
_cell_angle_beta   80.607
_cell_angle_gamma   88.661
_symmetry_Int_Tables_number   1
_cell_volume   638.112
_cell_formula_units_Z   2
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
  Y  Y0  1  0.417  0.918  0.330  1.0
  Y  Y1  1  0.583  0.082  0.670  1.0
  Y  Y2  1  0.000  0.500  0.000  1.0
  Y  Y3  1  0.918  0.417  0.330  1.0
  Y  Y4  1  0.082  0.583  0.670  1.0
  Y  Y5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.890  0.182  0.856  1.0
  Si  Si7  1  0.818  0.110  0.144  1.0
  Si  Si8  1  0.182  0.890  0.856  1.0
  Si  Si9  1  0.110  0.818  0.144  1.0
  Cl  Cl10  1  0.685  0.685  0.002  1.0
  Cl  Cl11  1  0.621  0.621  0.355  1.0
  Cl  Cl12  1  0.881  0.330  0.579  1.0
  Cl  Cl13  1  0.670  0.119  0.421  1.0
  Cl  Cl14  1  0.784  0.784  0.662  1.0
  Cl  Cl15  1  0.315  0.315  0.998  1.0
  Cl  Cl16  1  0.330  0.881  0.579  1.0
  Cl  Cl17  1  0.216  0.216  0.338  1.0
  Cl  Cl18  1  0.119  0.670  0.421  1.0
  Cl  Cl19  1  0.379  0.379  0.645  1.0
  O  O20  1  0.047  0.047  0.805  1.0
  O  O21  1  0.692  0.132  0.828  1.0
  O  O22  1  0.132  0.692  0.828  1.0
  O  O23  1  0.953  0.953  0.195  1.0
  O  O24  1  0.956  0.393  0.828  1.0
  O  O25  1  0.308  0.868  0.172  1.0
  O  O26  1  0.393  0.956  0.828  1.0
  O  O27  1  0.607  0.044  0.172  1.0
  O  O28  1  0.142  0.858  0.000  1.0
  O  O29  1  0.044  0.607  0.172  1.0
  O  O30  1  0.858  0.142  0.000  1.0
  O  O31  1  0.868  0.308  0.172  1.0
[/CIF]
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The crystal structure described by Y3Si2O6Cl5 crystallizes in the monoclinic C2/m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(2), one O(3), one Cl(2), one Cl(4), and three equivalent Cl(3) atoms to form distorted YCl5O2 pentagonal bipyramids that share corners with four equivalent Y(1)Cl5O2 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Y(2)Cl2O6 hexagonal bipyramid, and edges with two equivalent Y(1)Cl5O2 pentagonal bipyramids. In the second Y site, Y(2) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent Cl(1) atoms to form distorted YCl2O6 hexagonal bipyramids that share corners with four equivalent Y(2)Cl2O6 hexagonal bipyramids, edges with two equivalent Y(1)Cl5O2 pentagonal bipyramids, and edges with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)Cl5O2 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and edges with two equivalent Y(2)Cl2O6 hexagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent Y(2) and two equivalent Si(1) atoms. There are four inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a bent 150 degrees geometry to two equivalent Y(2) atoms. In the second Cl site, Cl(2) is bonded in a bent 150 degrees geometry to two equivalent Y(1) atoms. In the third Cl site, Cl(3) is bonded in a trigonal planar geometry to three equivalent Y(1) atoms. In the fourth Cl site, Cl(4) is bonded in a bent 150 degrees geometry to two equivalent Y(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y3Si2Cl5O6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.475
_cell_length_b   7.475
_cell_length_c   11.733
_cell_angle_alpha   80.607
_cell_angle_beta   80.607
_cell_angle_gamma   88.661
_symmetry_Int_Tables_number   1
_cell_volume   638.112
_cell_formula_units_Z   2
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
  Y  Y0  1  0.417  0.918  0.330  1.0
  Y  Y1  1  0.583  0.082  0.670  1.0
  Y  Y2  1  0.000  0.500  0.000  1.0
  Y  Y3  1  0.918  0.417  0.330  1.0
  Y  Y4  1  0.082  0.583  0.670  1.0
  Y  Y5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.890  0.182  0.856  1.0
  Si  Si7  1  0.818  0.110  0.144  1.0
  Si  Si8  1  0.182  0.890  0.856  1.0
  Si  Si9  1  0.110  0.818  0.144  1.0
  Cl  Cl10  1  0.685  0.685  0.002  1.0
  Cl  Cl11  1  0.621  0.621  0.355  1.0
  Cl  Cl12  1  0.881  0.330  0.579  1.0
  Cl  Cl13  1  0.670  0.119  0.421  1.0
  Cl  Cl14  1  0.784  0.784  0.662  1.0
  Cl  Cl15  1  0.315  0.315  0.998  1.0
  Cl  Cl16  1  0.330  0.881  0.579  1.0
  Cl  Cl17  1  0.216  0.216  0.338  1.0
  Cl  Cl18  1  0.119  0.670  0.421  1.0
  Cl  Cl19  1  0.379  0.379  0.645  1.0
  O  O20  1  0.047  0.047  0.805  1.0
  O  O21  1  0.692  0.132  0.828  1.0
  O  O22  1  0.132  0.692  0.828  1.0
  O  O23  1  0.953  0.953  0.195  1.0
  O  O24  1  0.956  0.393  0.828  1.0
  O  O25  1  0.308  0.868  0.172  1.0
  O  O26  1  0.393  0.956  0.828  1.0
  O  O27  1  0.607  0.044  0.172  1.0
  O  O28  1  0.142  0.858  0.000  1.0
  O  O29  1  0.044  0.607  0.172  1.0
  O  O30  1  0.858  0.142  0.000  1.0
  O  O31  1  0.868  0.308  0.172  1.0
[/CIF]
.