The compound described by Rb2Ti(Si2O5)3 crystallizes in the monoclinic Cc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(13), one O(2), one O(3), one O(6), one O(7), and one O(8) atom. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(14), one O(15), one O(4), and one O(8) atom. Ti(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(6) atom to form TiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(4), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(15), one O(6), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. In the third Si site, Si(3) is bonded to one O(1), one O(14), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(15), and one O(2) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. In the fifth Si site, Si(5) is bonded to one O(10), one O(13), one O(14), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the sixth Si site, Si(6) is bonded to one O(11), one O(13), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Ti(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Ti(1), and one Si(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(1), one Ti(1), and one Si(6) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Rb(2), one Ti(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Rb(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Rb(1), one Si(2), and one Si(6) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Rb(2), one Si(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Rb(2), one Ti(1), and one Si(5) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Si(4), and one Si(6) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Rb(1), one Si(5), and one Si(6) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one Rb(2), one Si(3), and one Si(5) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Rb(2), one Si(2), and one Si(4) atom. is represented by the CIF card [CIF]
data_Rb2Ti(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.354
_cell_length_b   7.354
_cell_length_c   15.133
_cell_angle_alpha   76.945
_cell_angle_beta   76.945
_cell_angle_gamma   59.861
_symmetry_Int_Tables_number   1
_cell_volume   683.317
_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
  Rb  Rb0  1  0.410  0.144  0.691  1.0
  Rb  Rb1  1  0.144  0.410  0.191  1.0
  Rb  Rb2  1  0.637  0.883  0.023  1.0
  Rb  Rb3  1  0.883  0.637  0.523  1.0
  Ti  Ti4  1  0.784  0.303  0.095  1.0
  Ti  Ti5  1  0.303  0.784  0.595  1.0
  Si  Si6  1  0.550  0.415  0.461  1.0
  Si  Si7  1  0.415  0.550  0.961  1.0
  Si  Si8  1  0.637  0.998  0.255  1.0
  Si  Si9  1  0.998  0.637  0.755  1.0
  Si  Si10  1  0.357  0.156  0.445  1.0
  Si  Si11  1  0.156  0.357  0.945  1.0
  Si  Si12  1  0.532  0.636  0.256  1.0
  Si  Si13  1  0.636  0.532  0.756  1.0
  Si  Si14  1  0.075  0.017  0.932  1.0
  Si  Si15  1  0.017  0.075  0.432  1.0
  Si  Si16  1  0.069  0.921  0.245  1.0
  Si  Si17  1  0.921  0.069  0.745  1.0
  O  O18  1  0.959  0.435  0.024  1.0
  O  O19  1  0.435  0.959  0.524  1.0
  O  O20  1  0.714  0.479  0.189  1.0
  O  O21  1  0.479  0.714  0.689  1.0
  O  O22  1  0.039  0.077  0.151  1.0
  O  O23  1  0.077  0.039  0.651  1.0
  O  O24  1  0.537  0.524  0.041  1.0
  O  O25  1  0.524  0.537  0.541  1.0
  O  O26  1  0.765  0.186  0.468  1.0
  O  O27  1  0.186  0.765  0.968  1.0
  O  O28  1  0.617  0.172  0.168  1.0
  O  O29  1  0.172  0.617  0.668  1.0
  O  O30  1  0.885  0.844  0.273  1.0
  O  O31  1  0.844  0.885  0.773  1.0
  O  O32  1  0.355  0.360  0.472  1.0
  O  O33  1  0.360  0.355  0.972  1.0
  O  O34  1  0.502  0.108  0.346  1.0
  O  O35  1  0.108  0.502  0.846  1.0
  O  O36  1  0.857  0.137  0.996  1.0
  O  O37  1  0.137  0.857  0.496  1.0
  O  O38  1  0.698  0.292  0.743  1.0
  O  O39  1  0.292  0.698  0.243  1.0
  O  O40  1  0.545  0.570  0.862  1.0
  O  O41  1  0.570  0.545  0.362  1.0
  O  O42  1  0.042  0.054  0.826  1.0
  O  O43  1  0.054  0.042  0.326  1.0
  O  O44  1  0.110  0.238  0.431  1.0
  O  O45  1  0.238  0.110  0.931  1.0
  O  O46  1  0.859  0.542  0.734  1.0
  O  O47  1  0.542  0.859  0.234  1.0
[/CIF]
.
The compound described by Rb2Ti(Si2O5)3 crystallizes in the monoclinic Cc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(13), one O(2), one O(3), one O(6), one O(7), and one O(8) atom. In the second Rb site, Rb(2) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(14), one O(15), one O(4), and one O(8) atom. Ti(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(6) atom to form TiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(4), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(15), one O(6), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. In the third Si site, Si(3) is bonded to one O(1), one O(14), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(15), and one O(2) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. In the fifth Si site, Si(5) is bonded to one O(10), one O(13), one O(14), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the sixth Si site, Si(6) is bonded to one O(11), one O(13), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Ti(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Ti(1), and one Si(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(1), one Ti(1), and one Si(6) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Rb(2), one Ti(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Rb(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Rb(1), one Si(2), and one Si(6) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Rb(2), one Si(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Rb(2), one Ti(1), and one Si(5) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Si(4), and one Si(6) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Rb(1), one Si(5), and one Si(6) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one Rb(2), one Si(3), and one Si(5) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Rb(2), one Si(2), and one Si(4) atom. is represented by the CIF card [CIF]
data_Rb2Ti(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.354
_cell_length_b   7.354
_cell_length_c   15.133
_cell_angle_alpha   76.945
_cell_angle_beta   76.945
_cell_angle_gamma   59.861
_symmetry_Int_Tables_number   1
_cell_volume   683.317
_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
  Rb  Rb0  1  0.410  0.144  0.691  1.0
  Rb  Rb1  1  0.144  0.410  0.191  1.0
  Rb  Rb2  1  0.637  0.883  0.023  1.0
  Rb  Rb3  1  0.883  0.637  0.523  1.0
  Ti  Ti4  1  0.784  0.303  0.095  1.0
  Ti  Ti5  1  0.303  0.784  0.595  1.0
  Si  Si6  1  0.550  0.415  0.461  1.0
  Si  Si7  1  0.415  0.550  0.961  1.0
  Si  Si8  1  0.637  0.998  0.255  1.0
  Si  Si9  1  0.998  0.637  0.755  1.0
  Si  Si10  1  0.357  0.156  0.445  1.0
  Si  Si11  1  0.156  0.357  0.945  1.0
  Si  Si12  1  0.532  0.636  0.256  1.0
  Si  Si13  1  0.636  0.532  0.756  1.0
  Si  Si14  1  0.075  0.017  0.932  1.0
  Si  Si15  1  0.017  0.075  0.432  1.0
  Si  Si16  1  0.069  0.921  0.245  1.0
  Si  Si17  1  0.921  0.069  0.745  1.0
  O  O18  1  0.959  0.435  0.024  1.0
  O  O19  1  0.435  0.959  0.524  1.0
  O  O20  1  0.714  0.479  0.189  1.0
  O  O21  1  0.479  0.714  0.689  1.0
  O  O22  1  0.039  0.077  0.151  1.0
  O  O23  1  0.077  0.039  0.651  1.0
  O  O24  1  0.537  0.524  0.041  1.0
  O  O25  1  0.524  0.537  0.541  1.0
  O  O26  1  0.765  0.186  0.468  1.0
  O  O27  1  0.186  0.765  0.968  1.0
  O  O28  1  0.617  0.172  0.168  1.0
  O  O29  1  0.172  0.617  0.668  1.0
  O  O30  1  0.885  0.844  0.273  1.0
  O  O31  1  0.844  0.885  0.773  1.0
  O  O32  1  0.355  0.360  0.472  1.0
  O  O33  1  0.360  0.355  0.972  1.0
  O  O34  1  0.502  0.108  0.346  1.0
  O  O35  1  0.108  0.502  0.846  1.0
  O  O36  1  0.857  0.137  0.996  1.0
  O  O37  1  0.137  0.857  0.496  1.0
  O  O38  1  0.698  0.292  0.743  1.0
  O  O39  1  0.292  0.698  0.243  1.0
  O  O40  1  0.545  0.570  0.862  1.0
  O  O41  1  0.570  0.545  0.362  1.0
  O  O42  1  0.042  0.054  0.826  1.0
  O  O43  1  0.054  0.042  0.326  1.0
  O  O44  1  0.110  0.238  0.431  1.0
  O  O45  1  0.238  0.110  0.931  1.0
  O  O46  1  0.859  0.542  0.734  1.0
  O  O47  1  0.542  0.859  0.234  1.0
[/CIF]
.