The compound described by Si5O(PO4)6 crystallizes in the trigonal R-3 space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent O(5) atoms to form SiO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form SiO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(3) and three equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Si(2)O6 octahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 29-47°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(3) and one P(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Si(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one P(1) atom. is represented by the CIF card [CIF]
data_Si5P6O25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.236
_cell_length_b   9.236
_cell_length_c   9.236
_cell_angle_alpha   50.406
_cell_angle_beta   50.406
_cell_angle_gamma   50.406
_symmetry_Int_Tables_number   1
_cell_volume   430.863
_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
  Si  Si0  1  0.000  0.000  0.000  1.0
  Si  Si1  1  0.180  0.180  0.180  1.0
  Si  Si2  1  0.820  0.820  0.820  1.0
  Si  Si3  1  0.434  0.434  0.434  1.0
  Si  Si4  1  0.566  0.566  0.566  1.0
  P  P5  1  0.073  0.378  0.826  1.0
  P  P6  1  0.378  0.826  0.073  1.0
  P  P7  1  0.826  0.073  0.378  1.0
  P  P8  1  0.927  0.622  0.174  1.0
  P  P9  1  0.622  0.174  0.927  1.0
  P  P10  1  0.174  0.927  0.622  1.0
  O  O11  1  0.143  0.095  0.428  1.0
  O  O12  1  0.428  0.143  0.095  1.0
  O  O13  1  0.095  0.428  0.143  1.0
  O  O14  1  0.857  0.905  0.572  1.0
  O  O15  1  0.572  0.857  0.905  1.0
  O  O16  1  0.905  0.572  0.857  1.0
  O  O17  1  0.408  0.791  0.572  1.0
  O  O18  1  0.572  0.408  0.791  1.0
  O  O19  1  0.791  0.572  0.408  1.0
  O  O20  1  0.592  0.209  0.428  1.0
  O  O21  1  0.428  0.592  0.209  1.0
  O  O22  1  0.500  0.500  0.500  1.0
  O  O23  1  0.219  0.268  0.925  1.0
  O  O24  1  0.268  0.925  0.219  1.0
  O  O25  1  0.925  0.219  0.268  1.0
  O  O26  1  0.781  0.732  0.075  1.0
  O  O27  1  0.732  0.075  0.781  1.0
  O  O28  1  0.075  0.781  0.732  1.0
  O  O29  1  0.975  0.250  0.897  1.0
  O  O30  1  0.250  0.897  0.975  1.0
  O  O31  1  0.897  0.975  0.250  1.0
  O  O32  1  0.025  0.750  0.103  1.0
  O  O33  1  0.750  0.103  0.025  1.0
  O  O34  1  0.103  0.025  0.750  1.0
  O  O35  1  0.209  0.428  0.592  1.0
[/CIF]
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The compound described by Si5O(PO4)6 crystallizes in the trigonal R-3 space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent O(5) atoms to form SiO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form SiO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(3) and three equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Si(2)O6 octahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 29-47°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(2) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(3) and one P(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Si(2) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one P(1) atom. is represented by the CIF card [CIF]
data_Si5P6O25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.236
_cell_length_b   9.236
_cell_length_c   9.236
_cell_angle_alpha   50.406
_cell_angle_beta   50.406
_cell_angle_gamma   50.406
_symmetry_Int_Tables_number   1
_cell_volume   430.863
_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
  Si  Si0  1  0.000  0.000  0.000  1.0
  Si  Si1  1  0.180  0.180  0.180  1.0
  Si  Si2  1  0.820  0.820  0.820  1.0
  Si  Si3  1  0.434  0.434  0.434  1.0
  Si  Si4  1  0.566  0.566  0.566  1.0
  P  P5  1  0.073  0.378  0.826  1.0
  P  P6  1  0.378  0.826  0.073  1.0
  P  P7  1  0.826  0.073  0.378  1.0
  P  P8  1  0.927  0.622  0.174  1.0
  P  P9  1  0.622  0.174  0.927  1.0
  P  P10  1  0.174  0.927  0.622  1.0
  O  O11  1  0.143  0.095  0.428  1.0
  O  O12  1  0.428  0.143  0.095  1.0
  O  O13  1  0.095  0.428  0.143  1.0
  O  O14  1  0.857  0.905  0.572  1.0
  O  O15  1  0.572  0.857  0.905  1.0
  O  O16  1  0.905  0.572  0.857  1.0
  O  O17  1  0.408  0.791  0.572  1.0
  O  O18  1  0.572  0.408  0.791  1.0
  O  O19  1  0.791  0.572  0.408  1.0
  O  O20  1  0.592  0.209  0.428  1.0
  O  O21  1  0.428  0.592  0.209  1.0
  O  O22  1  0.500  0.500  0.500  1.0
  O  O23  1  0.219  0.268  0.925  1.0
  O  O24  1  0.268  0.925  0.219  1.0
  O  O25  1  0.925  0.219  0.268  1.0
  O  O26  1  0.781  0.732  0.075  1.0
  O  O27  1  0.732  0.075  0.781  1.0
  O  O28  1  0.075  0.781  0.732  1.0
  O  O29  1  0.975  0.250  0.897  1.0
  O  O30  1  0.250  0.897  0.975  1.0
  O  O31  1  0.897  0.975  0.250  1.0
  O  O32  1  0.025  0.750  0.103  1.0
  O  O33  1  0.750  0.103  0.025  1.0
  O  O34  1  0.103  0.025  0.750  1.0
  O  O35  1  0.209  0.428  0.592  1.0
[/CIF]
.