The material described by Ta2W2O11 crystallizes in the monoclinic C2 space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO5 trigonal bipyramids that share corners with two equivalent W(3)O6 octahedra,  a cornercorner with one Ta(2)O5 trigonal bipyramid, and corners with two equivalent Ta(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 29-42°. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(5), one O(7), and one O(8) atom to form TaO5 trigonal bipyramids that share  a cornercorner with one W(1)O6 octahedra,  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one Ta(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-44°. There are three inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms to form WO6 octahedra that share corners with four equivalent W(2)O6 octahedra and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the second W site, W(2) is bonded to one O(1), one O(10), one O(3), one O(5), and two equivalent O(9) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the third W site, W(3) is bonded to two equivalent O(11), two equivalent O(2), and two equivalent O(4) atoms to form WO6 octahedra that share corners with two equivalent Ta(2)O5 trigonal bipyramids and corners with four equivalent Ta(1)O5 trigonal bipyramids. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to two equivalent W(2) atoms. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta2W2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.343
_cell_length_b   7.343
_cell_length_c   13.935
_cell_angle_alpha   69.721
_cell_angle_beta   69.721
_cell_angle_gamma   59.728
_symmetry_Int_Tables_number   1
_cell_volume   594.924
_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
  Ta  Ta0  1  0.007  0.473  0.540  1.0
  Ta  Ta1  1  0.692  0.779  0.228  1.0
  Ta  Ta2  1  0.527  0.993  0.460  1.0
  Ta  Ta3  1  0.221  0.308  0.772  1.0
  W  W4  1  0.007  0.993  0.000  1.0
  W  W5  1  0.502  0.009  0.987  1.0
  W  W6  1  0.991  0.498  0.013  1.0
  W  W7  1  0.520  0.480  0.500  1.0
  O  O8  1  0.282  0.909  0.024  1.0
  O  O9  1  0.619  0.585  0.350  1.0
  O  O10  1  0.911  0.276  0.029  1.0
  O  O11  1  0.790  0.400  0.529  1.0
  O  O12  1  0.884  0.532  0.151  1.0
  O  O13  1  0.229  0.210  0.491  1.0
  O  O14  1  0.114  0.093  0.854  1.0
  O  O15  1  0.596  0.983  0.319  1.0
  O  O16  1  0.276  0.282  0.024  1.0
  O  O17  1  0.494  0.913  0.146  1.0
  O  O18  1  0.601  0.210  0.471  1.0
  O  O19  1  0.425  0.770  0.516  1.0
  O  O20  1  0.468  0.116  0.849  1.0
  O  O21  1  0.718  0.724  0.976  1.0
  O  O22  1  0.790  0.771  0.509  1.0
  O  O23  1  0.907  0.886  0.146  1.0
  O  O24  1  0.087  0.506  0.854  1.0
  O  O25  1  0.230  0.575  0.484  1.0
  O  O26  1  0.017  0.404  0.681  1.0
  O  O27  1  0.091  0.718  0.976  1.0
  O  O28  1  0.415  0.381  0.650  1.0
  O  O29  1  0.724  0.089  0.971  1.0
[/CIF]
.
The material described by Ta2W2O11 crystallizes in the monoclinic C2 space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO5 trigonal bipyramids that share corners with two equivalent W(3)O6 octahedra,  a cornercorner with one Ta(2)O5 trigonal bipyramid, and corners with two equivalent Ta(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 29-42°. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(5), one O(7), and one O(8) atom to form TaO5 trigonal bipyramids that share  a cornercorner with one W(1)O6 octahedra,  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one Ta(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-44°. There are three inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms to form WO6 octahedra that share corners with four equivalent W(2)O6 octahedra and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the second W site, W(2) is bonded to one O(1), one O(10), one O(3), one O(5), and two equivalent O(9) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the third W site, W(3) is bonded to two equivalent O(11), two equivalent O(2), and two equivalent O(4) atoms to form WO6 octahedra that share corners with two equivalent Ta(2)O5 trigonal bipyramids and corners with four equivalent Ta(1)O5 trigonal bipyramids. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to two equivalent W(2) atoms. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta2W2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.343
_cell_length_b   7.343
_cell_length_c   13.935
_cell_angle_alpha   69.721
_cell_angle_beta   69.721
_cell_angle_gamma   59.728
_symmetry_Int_Tables_number   1
_cell_volume   594.924
_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
  Ta  Ta0  1  0.007  0.473  0.540  1.0
  Ta  Ta1  1  0.692  0.779  0.228  1.0
  Ta  Ta2  1  0.527  0.993  0.460  1.0
  Ta  Ta3  1  0.221  0.308  0.772  1.0
  W  W4  1  0.007  0.993  0.000  1.0
  W  W5  1  0.502  0.009  0.987  1.0
  W  W6  1  0.991  0.498  0.013  1.0
  W  W7  1  0.520  0.480  0.500  1.0
  O  O8  1  0.282  0.909  0.024  1.0
  O  O9  1  0.619  0.585  0.350  1.0
  O  O10  1  0.911  0.276  0.029  1.0
  O  O11  1  0.790  0.400  0.529  1.0
  O  O12  1  0.884  0.532  0.151  1.0
  O  O13  1  0.229  0.210  0.491  1.0
  O  O14  1  0.114  0.093  0.854  1.0
  O  O15  1  0.596  0.983  0.319  1.0
  O  O16  1  0.276  0.282  0.024  1.0
  O  O17  1  0.494  0.913  0.146  1.0
  O  O18  1  0.601  0.210  0.471  1.0
  O  O19  1  0.425  0.770  0.516  1.0
  O  O20  1  0.468  0.116  0.849  1.0
  O  O21  1  0.718  0.724  0.976  1.0
  O  O22  1  0.790  0.771  0.509  1.0
  O  O23  1  0.907  0.886  0.146  1.0
  O  O24  1  0.087  0.506  0.854  1.0
  O  O25  1  0.230  0.575  0.484  1.0
  O  O26  1  0.017  0.404  0.681  1.0
  O  O27  1  0.091  0.718  0.976  1.0
  O  O28  1  0.415  0.381  0.650  1.0
  O  O29  1  0.724  0.089  0.971  1.0
[/CIF]
.