The compound described by Rb2MgNb2(TeO6)2 crystallizes in the triclinic P1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 3-coordinate geometry to one O(11), one O(7), and one O(9) atom. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(3), one O(5), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(5), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(6), one O(8), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-44°. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(11), one O(3), and one O(7) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in an L-shaped geometry to one Mg(1) and one Te(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(2), one Mg(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Mg(1) and one Nb(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Te(1), and one Te(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Rb(1) and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(1), and one Te(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Rb(2), one Mg(1), one Nb(2), and one Te(1) atom. is represented by the CIF file [CIF]
data_Rb2MgNb2(TeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.991
_cell_length_b   7.486
_cell_length_c   7.972
_cell_angle_alpha   88.297
_cell_angle_beta   55.705
_cell_angle_gamma   115.811
_symmetry_Int_Tables_number   1
_cell_volume   329.500
_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  0.704  0.357  0.394  1.0
  Rb  Rb1  1  0.120  0.543  0.595  1.0
  Mg  Mg2  1  0.480  0.784  0.746  1.0
  Nb  Nb3  1  0.487  0.495  0.998  1.0
  Nb  Nb4  1  0.542  0.023  0.048  1.0
  Te  Te5  1  0.995  0.004  0.517  1.0
  Te  Te6  1  0.016  0.927  0.957  1.0
  O  O7  1  0.803  0.890  0.431  1.0
  O  O8  1  0.571  0.283  0.939  1.0
  O  O9  1  0.233  0.835  0.819  1.0
  O  O10  1  0.207  0.298  0.317  1.0
  O  O11  1  0.353  0.469  0.866  1.0
  O  O12  1  0.236  0.941  0.331  1.0
  O  O13  1  0.131  0.093  0.670  1.0
  O  O14  1  0.405  0.724  0.077  1.0
  O  O15  1  0.750  0.099  0.100  1.0
  O  O16  1  0.814  0.718  0.722  1.0
  O  O17  1  0.725  0.657  0.099  1.0
  O  O18  1  0.749  0.068  0.717  1.0
[/CIF]
.
The compound described by Rb2MgNb2(TeO6)2 crystallizes in the triclinic P1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 3-coordinate geometry to one O(11), one O(7), and one O(9) atom. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(3), one O(5), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(5), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(6), one O(8), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-44°. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(11), one O(3), and one O(7) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in an L-shaped geometry to one Mg(1) and one Te(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(2), one Mg(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Mg(1) and one Nb(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Te(1), and one Te(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Rb(1) and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(1), and one Te(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Rb(2), one Mg(1), one Nb(2), and one Te(1) atom. is represented by the CIF file [CIF]
data_Rb2MgNb2(TeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.991
_cell_length_b   7.486
_cell_length_c   7.972
_cell_angle_alpha   88.297
_cell_angle_beta   55.705
_cell_angle_gamma   115.811
_symmetry_Int_Tables_number   1
_cell_volume   329.500
_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  0.704  0.357  0.394  1.0
  Rb  Rb1  1  0.120  0.543  0.595  1.0
  Mg  Mg2  1  0.480  0.784  0.746  1.0
  Nb  Nb3  1  0.487  0.495  0.998  1.0
  Nb  Nb4  1  0.542  0.023  0.048  1.0
  Te  Te5  1  0.995  0.004  0.517  1.0
  Te  Te6  1  0.016  0.927  0.957  1.0
  O  O7  1  0.803  0.890  0.431  1.0
  O  O8  1  0.571  0.283  0.939  1.0
  O  O9  1  0.233  0.835  0.819  1.0
  O  O10  1  0.207  0.298  0.317  1.0
  O  O11  1  0.353  0.469  0.866  1.0
  O  O12  1  0.236  0.941  0.331  1.0
  O  O13  1  0.131  0.093  0.670  1.0
  O  O14  1  0.405  0.724  0.077  1.0
  O  O15  1  0.750  0.099  0.100  1.0
  O  O16  1  0.814  0.718  0.722  1.0
  O  O17  1  0.725  0.657  0.099  1.0
  O  O18  1  0.749  0.068  0.717  1.0
[/CIF]
.