The crystal structure described by Mn4Nb2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Nb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NbO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and edges with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nb(1) and two equivalent Mn(1) atoms to form distorted OMn2Nb2 trigonal pyramids that share corners with four equivalent O(1)Mn2Nb2 trigonal pyramids, corners with eight equivalent O(2)Mn3Nb trigonal pyramids, edges with two equivalent O(1)Mn2Nb2 trigonal pyramids, and edges with two equivalent O(2)Mn3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Nb(1), one Mn(1), and two equivalent Mn(2) atoms to form distorted OMn3Nb trigonal pyramids that share corners with four equivalent O(1)Mn2Nb2 trigonal pyramids, corners with eight equivalent O(2)Mn3Nb trigonal pyramids,  an edgeedge with one O(1)Mn2Nb2 trigonal pyramid, and edges with three equivalent O(2)Mn3Nb trigonal pyramids. is represented by the CIF card [CIF]
data_Mn4Nb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.297
_cell_length_b   14.356
_cell_length_c   5.297
_cell_angle_alpha   90.000
_cell_angle_beta   120.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   348.899
_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  0.333  0.697  0.667  1.0
  Mn  Mn1  1  0.333  0.197  0.667  1.0
  Mn  Mn2  1  0.333  0.984  0.667  1.0
  Mn  Mn3  1  0.333  0.484  0.667  1.0
  Mn  Mn4  1  0.667  0.803  0.333  1.0
  Mn  Mn5  1  0.667  0.303  0.333  1.0
  Mn  Mn6  1  0.667  0.516  0.333  1.0
  Mn  Mn7  1  0.667  0.016  0.333  1.0
  Nb  Nb8  1  1.000  0.858  1.000  1.0
  Nb  Nb9  1  1.000  0.642  0.000  1.0
  Nb  Nb10  1  0.000  0.142  0.000  1.0
  Nb  Nb11  1  0.000  0.358  0.000  1.0
  O  O12  1  0.283  0.750  0.283  1.0
  O  O13  1  0.717  0.750  1.000  1.0
  O  O14  1  0.000  0.750  0.717  1.0
  O  O15  1  0.717  0.250  0.717  1.0
  O  O16  1  0.283  0.250  1.000  1.0
  O  O17  1  0.000  0.250  0.283  1.0
  O  O18  1  0.659  0.585  0.684  1.0
  O  O19  1  0.025  0.585  0.341  1.0
  O  O20  1  0.316  0.585  0.975  1.0
  O  O21  1  0.341  0.915  0.025  1.0
  O  O22  1  0.975  0.915  0.316  1.0
  O  O23  1  0.684  0.915  0.659  1.0
  O  O24  1  0.316  0.085  0.341  1.0
  O  O25  1  0.025  0.085  0.684  1.0
  O  O26  1  0.659  0.085  0.975  1.0
  O  O27  1  0.684  0.415  0.025  1.0
  O  O28  1  0.975  0.415  0.659  1.0
  O  O29  1  0.341  0.415  0.316  1.0
[/CIF]
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The crystal structure described by Mn4Nb2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Nb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NbO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and edges with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nb(1) and two equivalent Mn(1) atoms to form distorted OMn2Nb2 trigonal pyramids that share corners with four equivalent O(1)Mn2Nb2 trigonal pyramids, corners with eight equivalent O(2)Mn3Nb trigonal pyramids, edges with two equivalent O(1)Mn2Nb2 trigonal pyramids, and edges with two equivalent O(2)Mn3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Nb(1), one Mn(1), and two equivalent Mn(2) atoms to form distorted OMn3Nb trigonal pyramids that share corners with four equivalent O(1)Mn2Nb2 trigonal pyramids, corners with eight equivalent O(2)Mn3Nb trigonal pyramids,  an edgeedge with one O(1)Mn2Nb2 trigonal pyramid, and edges with three equivalent O(2)Mn3Nb trigonal pyramids. is represented by the CIF card [CIF]
data_Mn4Nb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.297
_cell_length_b   14.356
_cell_length_c   5.297
_cell_angle_alpha   90.000
_cell_angle_beta   120.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   348.899
_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  0.333  0.697  0.667  1.0
  Mn  Mn1  1  0.333  0.197  0.667  1.0
  Mn  Mn2  1  0.333  0.984  0.667  1.0
  Mn  Mn3  1  0.333  0.484  0.667  1.0
  Mn  Mn4  1  0.667  0.803  0.333  1.0
  Mn  Mn5  1  0.667  0.303  0.333  1.0
  Mn  Mn6  1  0.667  0.516  0.333  1.0
  Mn  Mn7  1  0.667  0.016  0.333  1.0
  Nb  Nb8  1  1.000  0.858  1.000  1.0
  Nb  Nb9  1  1.000  0.642  0.000  1.0
  Nb  Nb10  1  0.000  0.142  0.000  1.0
  Nb  Nb11  1  0.000  0.358  0.000  1.0
  O  O12  1  0.283  0.750  0.283  1.0
  O  O13  1  0.717  0.750  1.000  1.0
  O  O14  1  0.000  0.750  0.717  1.0
  O  O15  1  0.717  0.250  0.717  1.0
  O  O16  1  0.283  0.250  1.000  1.0
  O  O17  1  0.000  0.250  0.283  1.0
  O  O18  1  0.659  0.585  0.684  1.0
  O  O19  1  0.025  0.585  0.341  1.0
  O  O20  1  0.316  0.585  0.975  1.0
  O  O21  1  0.341  0.915  0.025  1.0
  O  O22  1  0.975  0.915  0.316  1.0
  O  O23  1  0.684  0.915  0.659  1.0
  O  O24  1  0.316  0.085  0.341  1.0
  O  O25  1  0.025  0.085  0.684  1.0
  O  O26  1  0.659  0.085  0.975  1.0
  O  O27  1  0.684  0.415  0.025  1.0
  O  O28  1  0.975  0.415  0.659  1.0
  O  O29  1  0.341  0.415  0.316  1.0
[/CIF]
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