The structure described by Ag2Nb4O11 crystallizes in the trigonal R3 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(10), one O(3), one O(8), and three equivalent O(5) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Ag(1)O6 octahedra,  a cornercorner with one Ag(2)O6 octahedra, corners with two equivalent Nb(1)O7 pentagonal bipyramids, and edges with four equivalent Nb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), one O(7), one O(9), and three equivalent O(6) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Ag(1)O6 octahedra,  a cornercorner with one Ag(2)O6 octahedra, corners with two equivalent Nb(2)O7 pentagonal bipyramids, and edges with four equivalent Nb(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. In the third Nb site, Nb(3) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Ag(1)O6 octahedra. In the fourth Nb site, Nb(4) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Ag(2)O6 octahedra. There are four inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form distorted AgO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Nb(3)O6 octahedra. In the second Ag site, Ag(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form distorted AgO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Nb(4)O6 octahedra. In the third Ag site, Ag(3) is bonded in a 7-coordinate geometry to one O(9), three equivalent O(1), and three equivalent O(4) atoms. In the fourth Ag site, Ag(4) is bonded in a 7-coordinate geometry to one O(10), three equivalent O(2), and three equivalent O(3) atoms. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(4), one Ag(2), and one Ag(3) atom. In the second O site, O(9) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(2) and one Ag(3) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(3), one Ag(1), and one Ag(4) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(3), one Ag(1), and one Ag(4) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(4), one Ag(2), and one Ag(3) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to three equivalent Nb(1) atoms. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the eighth O site, O(7) is bonded in a trigonal planar geometry to three equivalent Nb(2) atoms. In the ninth O site, O(8) is bonded in a trigonal planar geometry to three equivalent Nb(1) atoms. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(1) and one Ag(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nb4Ag2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.189
_cell_length_b   13.189
_cell_length_c   13.189
_cell_angle_alpha   27.574
_cell_angle_beta   27.574
_cell_angle_gamma   27.574
_symmetry_Int_Tables_number   1
_cell_volume   433.919
_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
  Nb  Nb0  1  0.122  0.748  0.389  1.0
  Nb  Nb1  1  0.748  0.389  0.122  1.0
  Nb  Nb2  1  0.389  0.122  0.748  1.0
  Nb  Nb3  1  0.620  0.891  0.249  1.0
  Nb  Nb4  1  0.891  0.249  0.620  1.0
  Nb  Nb5  1  0.249  0.620  0.891  1.0
  Nb  Nb6  1  0.006  0.006  0.006  1.0
  Nb  Nb7  1  0.506  0.506  0.506  1.0
  Ag  Ag8  1  0.675  0.675  0.675  1.0
  Ag  Ag9  1  0.172  0.172  0.172  1.0
  Ag  Ag10  1  0.833  0.833  0.833  1.0
  Ag  Ag11  1  0.331  0.331  0.331  1.0
  O  O12  1  0.432  0.228  0.746  1.0
  O  O13  1  0.228  0.746  0.432  1.0
  O  O14  1  0.746  0.432  0.228  1.0
  O  O15  1  0.937  0.245  0.725  1.0
  O  O16  1  0.245  0.725  0.937  1.0
  O  O17  1  0.725  0.937  0.245  1.0
  O  O18  1  0.052  0.753  0.285  1.0
  O  O19  1  0.753  0.285  0.052  1.0
  O  O20  1  0.285  0.052  0.753  1.0
  O  O21  1  0.562  0.779  0.251  1.0
  O  O22  1  0.779  0.251  0.562  1.0
  O  O23  1  0.251  0.562  0.779  1.0
  O  O24  1  0.499  0.752  0.001  1.0
  O  O25  1  0.752  0.001  0.499  1.0
  O  O26  1  0.001  0.499  0.752  1.0
  O  O27  1  0.001  0.499  0.253  1.0
  O  O28  1  0.499  0.253  0.001  1.0
  O  O29  1  0.253  0.001  0.499  1.0
  O  O30  1  0.592  0.592  0.592  1.0
  O  O31  1  0.091  0.091  0.091  1.0
  O  O32  1  0.907  0.907  0.907  1.0
  O  O33  1  0.405  0.405  0.405  1.0
[/CIF]
.
The structure described by Ag2Nb4O11 crystallizes in the trigonal R3 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(10), one O(3), one O(8), and three equivalent O(5) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Ag(1)O6 octahedra,  a cornercorner with one Ag(2)O6 octahedra, corners with two equivalent Nb(1)O7 pentagonal bipyramids, and edges with four equivalent Nb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), one O(7), one O(9), and three equivalent O(6) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Ag(1)O6 octahedra,  a cornercorner with one Ag(2)O6 octahedra, corners with two equivalent Nb(2)O7 pentagonal bipyramids, and edges with four equivalent Nb(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. In the third Nb site, Nb(3) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Ag(1)O6 octahedra. In the fourth Nb site, Nb(4) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Ag(2)O6 octahedra. There are four inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form distorted AgO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Nb(3)O6 octahedra. In the second Ag site, Ag(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form distorted AgO6 octahedra that share corners with three equivalent Nb(1)O7 pentagonal bipyramids, corners with three equivalent Nb(2)O7 pentagonal bipyramids, and edges with three equivalent Nb(4)O6 octahedra. In the third Ag site, Ag(3) is bonded in a 7-coordinate geometry to one O(9), three equivalent O(1), and three equivalent O(4) atoms. In the fourth Ag site, Ag(4) is bonded in a 7-coordinate geometry to one O(10), three equivalent O(2), and three equivalent O(3) atoms. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(4), one Ag(2), and one Ag(3) atom. In the second O site, O(9) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(2) and one Ag(3) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(3), one Ag(1), and one Ag(4) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(3), one Ag(1), and one Ag(4) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(4), one Ag(2), and one Ag(3) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to three equivalent Nb(1) atoms. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the eighth O site, O(7) is bonded in a trigonal planar geometry to three equivalent Nb(2) atoms. In the ninth O site, O(8) is bonded in a trigonal planar geometry to three equivalent Nb(1) atoms. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(1) and one Ag(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nb4Ag2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.189
_cell_length_b   13.189
_cell_length_c   13.189
_cell_angle_alpha   27.574
_cell_angle_beta   27.574
_cell_angle_gamma   27.574
_symmetry_Int_Tables_number   1
_cell_volume   433.919
_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
  Nb  Nb0  1  0.122  0.748  0.389  1.0
  Nb  Nb1  1  0.748  0.389  0.122  1.0
  Nb  Nb2  1  0.389  0.122  0.748  1.0
  Nb  Nb3  1  0.620  0.891  0.249  1.0
  Nb  Nb4  1  0.891  0.249  0.620  1.0
  Nb  Nb5  1  0.249  0.620  0.891  1.0
  Nb  Nb6  1  0.006  0.006  0.006  1.0
  Nb  Nb7  1  0.506  0.506  0.506  1.0
  Ag  Ag8  1  0.675  0.675  0.675  1.0
  Ag  Ag9  1  0.172  0.172  0.172  1.0
  Ag  Ag10  1  0.833  0.833  0.833  1.0
  Ag  Ag11  1  0.331  0.331  0.331  1.0
  O  O12  1  0.432  0.228  0.746  1.0
  O  O13  1  0.228  0.746  0.432  1.0
  O  O14  1  0.746  0.432  0.228  1.0
  O  O15  1  0.937  0.245  0.725  1.0
  O  O16  1  0.245  0.725  0.937  1.0
  O  O17  1  0.725  0.937  0.245  1.0
  O  O18  1  0.052  0.753  0.285  1.0
  O  O19  1  0.753  0.285  0.052  1.0
  O  O20  1  0.285  0.052  0.753  1.0
  O  O21  1  0.562  0.779  0.251  1.0
  O  O22  1  0.779  0.251  0.562  1.0
  O  O23  1  0.251  0.562  0.779  1.0
  O  O24  1  0.499  0.752  0.001  1.0
  O  O25  1  0.752  0.001  0.499  1.0
  O  O26  1  0.001  0.499  0.752  1.0
  O  O27  1  0.001  0.499  0.253  1.0
  O  O28  1  0.499  0.253  0.001  1.0
  O  O29  1  0.253  0.001  0.499  1.0
  O  O30  1  0.592  0.592  0.592  1.0
  O  O31  1  0.091  0.091  0.091  1.0
  O  O32  1  0.907  0.907  0.907  1.0
  O  O33  1  0.405  0.405  0.405  1.0
[/CIF]
.