The structure described by MnFe2(PO9)2 crystallizes in the monoclinic P2_1/c space group. Mn(1) is bonded to two equivalent O(3), two equivalent O(7), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(6), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with three equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-49°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a bent 120 degrees geometry to one Mn(1) and one O(9) atom. In the second O site, O(8) is bonded in a single-bond geometry to one Mn(1) atom. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(9) is bonded in a single-bond geometry to one O(7) atom. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one Mn(1) and one P(1) atom. In the seventh O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the eighth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Fe(1) atoms. In the ninth O site, O(6) is bonded in a single-bond geometry to one Fe(1) atom. is represented by the CIF file [CIF]
data_MnFe2(PO9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.157
_cell_length_b   9.654
_cell_length_c   9.923
_cell_angle_alpha   78.807
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   672.584
_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  0.500  0.000  0.500  1.0
  Mn  Mn1  1  0.000  0.000  0.000  1.0
  Fe  Fe2  1  0.373  0.486  0.744  1.0
  Fe  Fe3  1  0.873  0.514  0.756  1.0
  Fe  Fe4  1  0.627  0.514  0.256  1.0
  Fe  Fe5  1  0.127  0.486  0.244  1.0
  P  P6  1  0.139  0.309  0.004  1.0
  P  P7  1  0.639  0.691  0.496  1.0
  P  P8  1  0.861  0.691  0.996  1.0
  P  P9  1  0.361  0.309  0.504  1.0
  O  O10  1  0.380  0.324  0.656  1.0
  O  O11  1  0.880  0.676  0.844  1.0
  O  O12  1  0.620  0.676  0.344  1.0
  O  O13  1  0.120  0.324  0.156  1.0
  O  O14  1  0.308  0.390  0.934  1.0
  O  O15  1  0.808  0.610  0.566  1.0
  O  O16  1  0.692  0.610  0.066  1.0
  O  O17  1  0.192  0.390  0.434  1.0
  O  O18  1  0.327  0.150  0.504  1.0
  O  O19  1  0.827  0.850  0.996  1.0
  O  O20  1  0.673  0.850  0.496  1.0
  O  O21  1  0.173  0.150  0.004  1.0
  O  O22  1  0.451  0.640  0.570  1.0
  O  O23  1  0.951  0.360  0.930  1.0
  O  O24  1  0.549  0.360  0.430  1.0
  O  O25  1  0.049  0.640  0.070  1.0
  O  O26  1  0.369  0.537  0.197  1.0
  O  O27  1  0.869  0.463  0.303  1.0
  O  O28  1  0.631  0.463  0.803  1.0
  O  O29  1  0.131  0.537  0.697  1.0
  O  O30  1  0.341  0.664  0.795  1.0
  O  O31  1  0.841  0.336  0.705  1.0
  O  O32  1  0.659  0.336  0.205  1.0
  O  O33  1  0.159  0.664  0.295  1.0
  O  O34  1  0.537  0.961  0.758  1.0
  O  O35  1  0.037  0.039  0.742  1.0
  O  O36  1  0.463  0.039  0.242  1.0
  O  O37  1  0.963  0.961  0.258  1.0
  O  O38  1  0.310  0.881  0.520  1.0
  O  O39  1  0.810  0.119  0.980  1.0
  O  O40  1  0.690  0.119  0.480  1.0
  O  O41  1  0.190  0.881  0.020  1.0
  O  O42  1  0.507  0.054  0.824  1.0
  O  O43  1  0.007  0.946  0.676  1.0
  O  O44  1  0.493  0.946  0.176  1.0
  O  O45  1  0.993  0.054  0.324  1.0
[/CIF]
.
The structure described by MnFe2(PO9)2 crystallizes in the monoclinic P2_1/c space group. Mn(1) is bonded to two equivalent O(3), two equivalent O(7), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(6), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with three equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-49°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a bent 120 degrees geometry to one Mn(1) and one O(9) atom. In the second O site, O(8) is bonded in a single-bond geometry to one Mn(1) atom. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(9) is bonded in a single-bond geometry to one O(7) atom. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the sixth O site, O(3) is bonded in a bent 120 degrees geometry to one Mn(1) and one P(1) atom. In the seventh O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the eighth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Fe(1) atoms. In the ninth O site, O(6) is bonded in a single-bond geometry to one Fe(1) atom. is represented by the CIF file [CIF]
data_MnFe2(PO9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.157
_cell_length_b   9.654
_cell_length_c   9.923
_cell_angle_alpha   78.807
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   672.584
_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  0.500  0.000  0.500  1.0
  Mn  Mn1  1  0.000  0.000  0.000  1.0
  Fe  Fe2  1  0.373  0.486  0.744  1.0
  Fe  Fe3  1  0.873  0.514  0.756  1.0
  Fe  Fe4  1  0.627  0.514  0.256  1.0
  Fe  Fe5  1  0.127  0.486  0.244  1.0
  P  P6  1  0.139  0.309  0.004  1.0
  P  P7  1  0.639  0.691  0.496  1.0
  P  P8  1  0.861  0.691  0.996  1.0
  P  P9  1  0.361  0.309  0.504  1.0
  O  O10  1  0.380  0.324  0.656  1.0
  O  O11  1  0.880  0.676  0.844  1.0
  O  O12  1  0.620  0.676  0.344  1.0
  O  O13  1  0.120  0.324  0.156  1.0
  O  O14  1  0.308  0.390  0.934  1.0
  O  O15  1  0.808  0.610  0.566  1.0
  O  O16  1  0.692  0.610  0.066  1.0
  O  O17  1  0.192  0.390  0.434  1.0
  O  O18  1  0.327  0.150  0.504  1.0
  O  O19  1  0.827  0.850  0.996  1.0
  O  O20  1  0.673  0.850  0.496  1.0
  O  O21  1  0.173  0.150  0.004  1.0
  O  O22  1  0.451  0.640  0.570  1.0
  O  O23  1  0.951  0.360  0.930  1.0
  O  O24  1  0.549  0.360  0.430  1.0
  O  O25  1  0.049  0.640  0.070  1.0
  O  O26  1  0.369  0.537  0.197  1.0
  O  O27  1  0.869  0.463  0.303  1.0
  O  O28  1  0.631  0.463  0.803  1.0
  O  O29  1  0.131  0.537  0.697  1.0
  O  O30  1  0.341  0.664  0.795  1.0
  O  O31  1  0.841  0.336  0.705  1.0
  O  O32  1  0.659  0.336  0.205  1.0
  O  O33  1  0.159  0.664  0.295  1.0
  O  O34  1  0.537  0.961  0.758  1.0
  O  O35  1  0.037  0.039  0.742  1.0
  O  O36  1  0.463  0.039  0.242  1.0
  O  O37  1  0.963  0.961  0.258  1.0
  O  O38  1  0.310  0.881  0.520  1.0
  O  O39  1  0.810  0.119  0.980  1.0
  O  O40  1  0.690  0.119  0.480  1.0
  O  O41  1  0.190  0.881  0.020  1.0
  O  O42  1  0.507  0.054  0.824  1.0
  O  O43  1  0.007  0.946  0.676  1.0
  O  O44  1  0.493  0.946  0.176  1.0
  O  O45  1  0.993  0.054  0.324  1.0
[/CIF]
.