The compound described by Rb3Nb2Br9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent Br(1) and six equivalent Br(2) atoms to form RbBr12 cuboctahedra that share corners with six equivalent Rb(1)Br12 cuboctahedra, corners with six equivalent Rb(2)Br12 cuboctahedra, faces with six equivalent Rb(2)Br12 cuboctahedra, and faces with six equivalent Nb(1)Br6 octahedra. In the second Rb site, Rb(2) is bonded to three equivalent Br(2) and nine equivalent Br(1) atoms to form RbBr12 cuboctahedra that share corners with three equivalent Rb(1)Br12 cuboctahedra, corners with six equivalent Rb(2)Br12 cuboctahedra, corners with three equivalent Nb(1)Br6 octahedra, faces with three equivalent Rb(1)Br12 cuboctahedra, faces with four equivalent Rb(2)Br12 cuboctahedra, and faces with four equivalent Nb(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 27°. Nb(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form distorted NbBr6 octahedra that share corners with three equivalent Rb(2)Br12 cuboctahedra, faces with three equivalent Rb(1)Br12 cuboctahedra, faces with four equivalent Rb(2)Br12 cuboctahedra, and  a faceface with one Nb(1)Br6 octahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Rb(1), three equivalent Rb(2), and one Nb(1) atom to form a mixture of distorted face, edge, and corner-sharing BrRb4Nb square pyramids. In the second Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and two equivalent Nb(1) atoms. is represented by the CIF file [CIF]
data_Rb3Nb2Br9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.709
_cell_length_b   7.709
_cell_length_c   18.016
_cell_angle_alpha   90.001
_cell_angle_beta   89.998
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   927.175
_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  0.000  1.000  0.250  1.0
  Rb  Rb1  1  0.000  0.000  0.750  1.0
  Rb  Rb2  1  0.333  0.667  0.067  1.0
  Rb  Rb3  1  0.667  0.333  0.567  1.0
  Rb  Rb4  1  0.333  0.667  0.433  1.0
  Rb  Rb5  1  0.667  0.333  0.933  1.0
  Nb  Nb6  1  0.333  0.667  0.825  1.0
  Nb  Nb7  1  0.667  0.333  0.325  1.0
  Nb  Nb8  1  0.667  0.333  0.175  1.0
  Nb  Nb9  1  0.333  0.667  0.675  1.0
  Br  Br10  1  0.828  0.172  0.407  1.0
  Br  Br11  1  0.828  0.656  0.407  1.0
  Br  Br12  1  0.344  0.172  0.407  1.0
  Br  Br13  1  0.656  0.828  0.907  1.0
  Br  Br14  1  0.172  0.344  0.593  1.0
  Br  Br15  1  0.172  0.828  0.907  1.0
  Br  Br16  1  0.172  0.344  0.907  1.0
  Br  Br17  1  0.828  0.172  0.093  1.0
  Br  Br18  1  0.344  0.172  0.093  1.0
  Br  Br19  1  0.656  0.828  0.593  1.0
  Br  Br20  1  0.492  0.984  0.250  1.0
  Br  Br21  1  0.508  0.492  0.750  1.0
  Br  Br22  1  0.984  0.492  0.750  1.0
  Br  Br23  1  0.016  0.508  0.250  1.0
  Br  Br24  1  0.492  0.508  0.250  1.0
  Br  Br25  1  0.508  0.016  0.750  1.0
  Br  Br26  1  0.828  0.656  0.093  1.0
  Br  Br27  1  0.172  0.828  0.593  1.0
[/CIF]
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The compound described by Rb3Nb2Br9 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to six equivalent Br(1) and six equivalent Br(2) atoms to form RbBr12 cuboctahedra that share corners with six equivalent Rb(1)Br12 cuboctahedra, corners with six equivalent Rb(2)Br12 cuboctahedra, faces with six equivalent Rb(2)Br12 cuboctahedra, and faces with six equivalent Nb(1)Br6 octahedra. In the second Rb site, Rb(2) is bonded to three equivalent Br(2) and nine equivalent Br(1) atoms to form RbBr12 cuboctahedra that share corners with three equivalent Rb(1)Br12 cuboctahedra, corners with six equivalent Rb(2)Br12 cuboctahedra, corners with three equivalent Nb(1)Br6 octahedra, faces with three equivalent Rb(1)Br12 cuboctahedra, faces with four equivalent Rb(2)Br12 cuboctahedra, and faces with four equivalent Nb(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 27°. Nb(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form distorted NbBr6 octahedra that share corners with three equivalent Rb(2)Br12 cuboctahedra, faces with three equivalent Rb(1)Br12 cuboctahedra, faces with four equivalent Rb(2)Br12 cuboctahedra, and  a faceface with one Nb(1)Br6 octahedra. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to one Rb(1), three equivalent Rb(2), and one Nb(1) atom to form a mixture of distorted face, edge, and corner-sharing BrRb4Nb square pyramids. In the second Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), and two equivalent Nb(1) atoms. is represented by the CIF file [CIF]
data_Rb3Nb2Br9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.709
_cell_length_b   7.709
_cell_length_c   18.016
_cell_angle_alpha   90.001
_cell_angle_beta   89.998
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   927.175
_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  0.000  1.000  0.250  1.0
  Rb  Rb1  1  0.000  0.000  0.750  1.0
  Rb  Rb2  1  0.333  0.667  0.067  1.0
  Rb  Rb3  1  0.667  0.333  0.567  1.0
  Rb  Rb4  1  0.333  0.667  0.433  1.0
  Rb  Rb5  1  0.667  0.333  0.933  1.0
  Nb  Nb6  1  0.333  0.667  0.825  1.0
  Nb  Nb7  1  0.667  0.333  0.325  1.0
  Nb  Nb8  1  0.667  0.333  0.175  1.0
  Nb  Nb9  1  0.333  0.667  0.675  1.0
  Br  Br10  1  0.828  0.172  0.407  1.0
  Br  Br11  1  0.828  0.656  0.407  1.0
  Br  Br12  1  0.344  0.172  0.407  1.0
  Br  Br13  1  0.656  0.828  0.907  1.0
  Br  Br14  1  0.172  0.344  0.593  1.0
  Br  Br15  1  0.172  0.828  0.907  1.0
  Br  Br16  1  0.172  0.344  0.907  1.0
  Br  Br17  1  0.828  0.172  0.093  1.0
  Br  Br18  1  0.344  0.172  0.093  1.0
  Br  Br19  1  0.656  0.828  0.593  1.0
  Br  Br20  1  0.492  0.984  0.250  1.0
  Br  Br21  1  0.508  0.492  0.750  1.0
  Br  Br22  1  0.984  0.492  0.750  1.0
  Br  Br23  1  0.016  0.508  0.250  1.0
  Br  Br24  1  0.492  0.508  0.250  1.0
  Br  Br25  1  0.508  0.016  0.750  1.0
  Br  Br26  1  0.828  0.656  0.093  1.0
  Br  Br27  1  0.172  0.828  0.593  1.0
[/CIF]
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