The crystal structure described by Nb2Mn3O9 crystallizes in the trigonal P3c1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra, and corners with three equivalent Mn(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 33-44°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(3) atoms. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mn(2)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 33-45°. In the second Mn site, Mn(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MnO6 pentagonal pyramids that share corners with three equivalent Nb(1)O6 octahedra, edges with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the third Mn site, Mn(3) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, and edges with three equivalent Mn(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 44-45°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Nb(2), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of distorted edge and corner-sharing OMn3Nb trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(2), and one Mn(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn3Nb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.270
_cell_length_b   5.270
_cell_length_c   14.602
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   351.164
_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
  Mn  Mn0  1  0.667  0.333  0.683  1.0
  Mn  Mn1  1  0.667  0.333  0.978  1.0
  Mn  Mn2  1  0.667  0.333  0.478  1.0
  Mn  Mn3  1  0.333  0.667  0.506  1.0
  Mn  Mn4  1  0.333  0.667  0.006  1.0
  Mn  Mn5  1  0.667  0.333  0.183  1.0
  Nb  Nb6  1  0.000  0.000  0.858  1.0
  Nb  Nb7  1  0.000  0.000  0.145  1.0
  Nb  Nb8  1  0.000  0.000  0.645  1.0
  Nb  Nb9  1  0.000  0.000  0.358  1.0
  O  O10  1  0.361  0.326  0.091  1.0
  O  O11  1  0.679  0.698  0.921  1.0
  O  O12  1  0.930  0.243  0.244  1.0
  O  O13  1  0.313  0.070  0.244  1.0
  O  O14  1  0.964  0.639  0.091  1.0
  O  O15  1  0.674  0.639  0.591  1.0
  O  O16  1  0.757  0.070  0.744  1.0
  O  O17  1  0.019  0.321  0.921  1.0
  O  O18  1  0.019  0.698  0.421  1.0
  O  O19  1  0.361  0.036  0.591  1.0
  O  O20  1  0.313  0.243  0.744  1.0
  O  O21  1  0.964  0.326  0.591  1.0
  O  O22  1  0.757  0.687  0.244  1.0
  O  O23  1  0.302  0.981  0.921  1.0
  O  O24  1  0.674  0.036  0.091  1.0
  O  O25  1  0.679  0.981  0.421  1.0
  O  O26  1  0.302  0.321  0.421  1.0
  O  O27  1  0.930  0.687  0.744  1.0
[/CIF]
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The crystal structure described by Nb2Mn3O9 crystallizes in the trigonal P3c1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra, and corners with three equivalent Mn(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 33-44°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(3) atoms. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mn(2)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 33-45°. In the second Mn site, Mn(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MnO6 pentagonal pyramids that share corners with three equivalent Nb(1)O6 octahedra, edges with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the third Mn site, Mn(3) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, and edges with three equivalent Mn(2)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 44-45°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Nb(2), one Mn(1), one Mn(2), and one Mn(3) atom to form a mixture of distorted edge and corner-sharing OMn3Nb trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(2), and one Mn(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn3Nb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.270
_cell_length_b   5.270
_cell_length_c   14.602
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   351.164
_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
  Mn  Mn0  1  0.667  0.333  0.683  1.0
  Mn  Mn1  1  0.667  0.333  0.978  1.0
  Mn  Mn2  1  0.667  0.333  0.478  1.0
  Mn  Mn3  1  0.333  0.667  0.506  1.0
  Mn  Mn4  1  0.333  0.667  0.006  1.0
  Mn  Mn5  1  0.667  0.333  0.183  1.0
  Nb  Nb6  1  0.000  0.000  0.858  1.0
  Nb  Nb7  1  0.000  0.000  0.145  1.0
  Nb  Nb8  1  0.000  0.000  0.645  1.0
  Nb  Nb9  1  0.000  0.000  0.358  1.0
  O  O10  1  0.361  0.326  0.091  1.0
  O  O11  1  0.679  0.698  0.921  1.0
  O  O12  1  0.930  0.243  0.244  1.0
  O  O13  1  0.313  0.070  0.244  1.0
  O  O14  1  0.964  0.639  0.091  1.0
  O  O15  1  0.674  0.639  0.591  1.0
  O  O16  1  0.757  0.070  0.744  1.0
  O  O17  1  0.019  0.321  0.921  1.0
  O  O18  1  0.019  0.698  0.421  1.0
  O  O19  1  0.361  0.036  0.591  1.0
  O  O20  1  0.313  0.243  0.744  1.0
  O  O21  1  0.964  0.326  0.591  1.0
  O  O22  1  0.757  0.687  0.244  1.0
  O  O23  1  0.302  0.981  0.921  1.0
  O  O24  1  0.674  0.036  0.091  1.0
  O  O25  1  0.679  0.981  0.421  1.0
  O  O26  1  0.302  0.321  0.421  1.0
  O  O27  1  0.930  0.687  0.744  1.0
[/CIF]
.