The compound described by Rb2Ta15O32 crystallizes in the trigonal R-3 space group. Rb(1) is bonded to three equivalent O(1), three equivalent O(4), and six equivalent O(2) atoms to form distorted RbO12 cuboctahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, edges with three equivalent Rb(1)O12 cuboctahedra, edges with three equivalent Ta(2)O6 octahedra, edges with three equivalent Ta(3)O5 square pyramids, and faces with three equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-57°. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Rb(1)O12 cuboctahedra and corners with six equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles are 34°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form TaO6 octahedra that share  a cornercorner with one Rb(1)O12 cuboctahedra,  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, corners with three equivalent Ta(3)O5 square pyramids,  an edgeedge with one Rb(1)O12 cuboctahedra, edges with two equivalent Ta(2)O6 octahedra, and  a faceface with one Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 34-43°. In the third Ta site, Ta(3) is bonded to one O(6), two equivalent O(4), and two equivalent O(5) atoms to form TaO5 square pyramids that share  a cornercorner with one Ta(4)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, corners with four equivalent Ta(3)O5 square pyramids,  an edgeedge with one Rb(1)O12 cuboctahedra, and  an edgeedge with one Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-53°. In the fourth Ta site, Ta(4) is bonded to three equivalent O(5) and three equivalent O(6) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with three equivalent Ta(3)O5 square pyramids, and edges with three equivalent Ta(3)O5 square pyramids. The corner-sharing octahedral tilt angles are 43°. There are six inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Rb(1), one Ta(2), and two equivalent Ta(3) atoms. In the second O site, O(5) is bonded in a T-shaped geometry to one Ta(4) and two equivalent Ta(3) atoms. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to one Ta(2), one Ta(3), and one Ta(4) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one Rb(1), one Ta(1), and one Ta(2) atom. In the fifth O site, O(2) is bonded in a distorted water-like geometry to two equivalent Rb(1) and two equivalent Ta(2) atoms. In the sixth O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Ta(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2Ta15O32
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.801
_cell_length_b   12.801
_cell_length_c   12.801
_cell_angle_alpha   35.605
_cell_angle_beta   35.605
_cell_angle_gamma   35.605
_symmetry_Int_Tables_number   1
_cell_volume   635.485
_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
  Rb  Rb0  1  0.140  0.140  0.140  1.0
  Rb  Rb1  1  0.860  0.860  0.860  1.0
  Ta  Ta2  1  0.500  0.500  0.500  1.0
  Ta  Ta3  1  0.700  0.026  0.571  1.0
  Ta  Ta4  1  0.026  0.571  0.700  1.0
  Ta  Ta5  1  0.571  0.700  0.026  1.0
  Ta  Ta6  1  0.300  0.974  0.429  1.0
  Ta  Ta7  1  0.974  0.429  0.300  1.0
  Ta  Ta8  1  0.429  0.300  0.974  1.0
  Ta  Ta9  1  0.054  0.815  0.228  1.0
  Ta  Ta10  1  0.815  0.228  0.054  1.0
  Ta  Ta11  1  0.228  0.054  0.815  1.0
  Ta  Ta12  1  0.946  0.185  0.772  1.0
  Ta  Ta13  1  0.185  0.772  0.946  1.0
  Ta  Ta14  1  0.772  0.946  0.185  1.0
  Ta  Ta15  1  0.362  0.362  0.362  1.0
  Ta  Ta16  1  0.638  0.638  0.638  1.0
  O  O17  1  0.467  0.674  0.262  1.0
  O  O18  1  0.674  0.262  0.467  1.0
  O  O19  1  0.262  0.467  0.674  1.0
  O  O20  1  0.533  0.326  0.738  1.0
  O  O21  1  0.326  0.738  0.533  1.0
  O  O22  1  0.738  0.533  0.326  1.0
  O  O23  1  0.967  0.848  0.554  1.0
  O  O24  1  0.848  0.554  0.967  1.0
  O  O25  1  0.554  0.967  0.848  1.0
  O  O26  1  0.033  0.152  0.446  1.0
  O  O27  1  0.152  0.446  0.033  1.0
  O  O28  1  0.446  0.033  0.152  1.0
  O  O29  1  0.736  0.736  0.736  1.0
  O  O30  1  0.264  0.264  0.264  1.0
  O  O31  1  0.859  0.040  0.299  1.0
  O  O32  1  0.040  0.299  0.859  1.0
  O  O33  1  0.299  0.859  0.040  1.0
  O  O34  1  0.570  0.169  0.260  1.0
  O  O35  1  0.260  0.570  0.169  1.0
  O  O36  1  0.169  0.260  0.570  1.0
  O  O37  1  0.430  0.831  0.740  1.0
  O  O38  1  0.740  0.430  0.831  1.0
  O  O39  1  0.831  0.740  0.430  1.0
  O  O40  1  0.543  0.844  0.430  1.0
  O  O41  1  0.430  0.543  0.844  1.0
  O  O42  1  0.844  0.430  0.543  1.0
  O  O43  1  0.457  0.156  0.570  1.0
  O  O44  1  0.570  0.457  0.156  1.0
  O  O45  1  0.156  0.570  0.457  1.0
  O  O46  1  0.701  0.141  0.960  1.0
  O  O47  1  0.960  0.701  0.141  1.0
  O  O48  1  0.141  0.960  0.701  1.0
[/CIF]
.
The compound described by Rb2Ta15O32 crystallizes in the trigonal R-3 space group. Rb(1) is bonded to three equivalent O(1), three equivalent O(4), and six equivalent O(2) atoms to form distorted RbO12 cuboctahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, edges with three equivalent Rb(1)O12 cuboctahedra, edges with three equivalent Ta(2)O6 octahedra, edges with three equivalent Ta(3)O5 square pyramids, and faces with three equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-57°. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Rb(1)O12 cuboctahedra and corners with six equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles are 34°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form TaO6 octahedra that share  a cornercorner with one Rb(1)O12 cuboctahedra,  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, corners with three equivalent Ta(3)O5 square pyramids,  an edgeedge with one Rb(1)O12 cuboctahedra, edges with two equivalent Ta(2)O6 octahedra, and  a faceface with one Rb(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 34-43°. In the third Ta site, Ta(3) is bonded to one O(6), two equivalent O(4), and two equivalent O(5) atoms to form TaO5 square pyramids that share  a cornercorner with one Ta(4)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, corners with four equivalent Ta(3)O5 square pyramids,  an edgeedge with one Rb(1)O12 cuboctahedra, and  an edgeedge with one Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-53°. In the fourth Ta site, Ta(4) is bonded to three equivalent O(5) and three equivalent O(6) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with three equivalent Ta(3)O5 square pyramids, and edges with three equivalent Ta(3)O5 square pyramids. The corner-sharing octahedral tilt angles are 43°. There are six inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Rb(1), one Ta(2), and two equivalent Ta(3) atoms. In the second O site, O(5) is bonded in a T-shaped geometry to one Ta(4) and two equivalent Ta(3) atoms. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to one Ta(2), one Ta(3), and one Ta(4) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one Rb(1), one Ta(1), and one Ta(2) atom. In the fifth O site, O(2) is bonded in a distorted water-like geometry to two equivalent Rb(1) and two equivalent Ta(2) atoms. In the sixth O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Ta(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2Ta15O32
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.801
_cell_length_b   12.801
_cell_length_c   12.801
_cell_angle_alpha   35.605
_cell_angle_beta   35.605
_cell_angle_gamma   35.605
_symmetry_Int_Tables_number   1
_cell_volume   635.485
_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
  Rb  Rb0  1  0.140  0.140  0.140  1.0
  Rb  Rb1  1  0.860  0.860  0.860  1.0
  Ta  Ta2  1  0.500  0.500  0.500  1.0
  Ta  Ta3  1  0.700  0.026  0.571  1.0
  Ta  Ta4  1  0.026  0.571  0.700  1.0
  Ta  Ta5  1  0.571  0.700  0.026  1.0
  Ta  Ta6  1  0.300  0.974  0.429  1.0
  Ta  Ta7  1  0.974  0.429  0.300  1.0
  Ta  Ta8  1  0.429  0.300  0.974  1.0
  Ta  Ta9  1  0.054  0.815  0.228  1.0
  Ta  Ta10  1  0.815  0.228  0.054  1.0
  Ta  Ta11  1  0.228  0.054  0.815  1.0
  Ta  Ta12  1  0.946  0.185  0.772  1.0
  Ta  Ta13  1  0.185  0.772  0.946  1.0
  Ta  Ta14  1  0.772  0.946  0.185  1.0
  Ta  Ta15  1  0.362  0.362  0.362  1.0
  Ta  Ta16  1  0.638  0.638  0.638  1.0
  O  O17  1  0.467  0.674  0.262  1.0
  O  O18  1  0.674  0.262  0.467  1.0
  O  O19  1  0.262  0.467  0.674  1.0
  O  O20  1  0.533  0.326  0.738  1.0
  O  O21  1  0.326  0.738  0.533  1.0
  O  O22  1  0.738  0.533  0.326  1.0
  O  O23  1  0.967  0.848  0.554  1.0
  O  O24  1  0.848  0.554  0.967  1.0
  O  O25  1  0.554  0.967  0.848  1.0
  O  O26  1  0.033  0.152  0.446  1.0
  O  O27  1  0.152  0.446  0.033  1.0
  O  O28  1  0.446  0.033  0.152  1.0
  O  O29  1  0.736  0.736  0.736  1.0
  O  O30  1  0.264  0.264  0.264  1.0
  O  O31  1  0.859  0.040  0.299  1.0
  O  O32  1  0.040  0.299  0.859  1.0
  O  O33  1  0.299  0.859  0.040  1.0
  O  O34  1  0.570  0.169  0.260  1.0
  O  O35  1  0.260  0.570  0.169  1.0
  O  O36  1  0.169  0.260  0.570  1.0
  O  O37  1  0.430  0.831  0.740  1.0
  O  O38  1  0.740  0.430  0.831  1.0
  O  O39  1  0.831  0.740  0.430  1.0
  O  O40  1  0.543  0.844  0.430  1.0
  O  O41  1  0.430  0.543  0.844  1.0
  O  O42  1  0.844  0.430  0.543  1.0
  O  O43  1  0.457  0.156  0.570  1.0
  O  O44  1  0.570  0.457  0.156  1.0
  O  O45  1  0.156  0.570  0.457  1.0
  O  O46  1  0.701  0.141  0.960  1.0
  O  O47  1  0.960  0.701  0.141  1.0
  O  O48  1  0.141  0.960  0.701  1.0
[/CIF]
.