The crystal structure described by MgFeP2O7 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. 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 corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 3-47°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Mg(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Fe(1) and one P(1) atom. is represented by the CIF card [CIF]
data_MgFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.378
_cell_length_b   5.375
_cell_length_c   4.965
_cell_angle_alpha   84.851
_cell_angle_beta   95.133
_cell_angle_gamma   78.765
_symmetry_Int_Tables_number   1
_cell_volume   139.360
_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
  Mg  Mg0  1  0.503  0.503  1.000  1.0
  Fe  Fe1  1  0.109  0.109  1.000  1.0
  P  P2  1  0.248  0.668  0.564  1.0
  P  P3  1  0.668  0.248  0.436  1.0
  O  O4  1  0.546  0.547  0.500  1.0
  O  O5  1  0.845  0.322  0.221  1.0
  O  O6  1  0.443  0.182  0.262  1.0
  O  O7  1  0.322  0.845  0.779  1.0
  O  O8  1  0.182  0.443  0.738  1.0
  O  O9  1  0.099  0.781  0.297  1.0
  O  O10  1  0.781  0.099  0.703  1.0
[/CIF]
.
The crystal structure described by MgFeP2O7 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. 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 corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 3-47°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Mg(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Fe(1) and one P(1) atom. is represented by the CIF card [CIF]
data_MgFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.378
_cell_length_b   5.375
_cell_length_c   4.965
_cell_angle_alpha   84.851
_cell_angle_beta   95.133
_cell_angle_gamma   78.765
_symmetry_Int_Tables_number   1
_cell_volume   139.360
_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
  Mg  Mg0  1  0.503  0.503  1.000  1.0
  Fe  Fe1  1  0.109  0.109  1.000  1.0
  P  P2  1  0.248  0.668  0.564  1.0
  P  P3  1  0.668  0.248  0.436  1.0
  O  O4  1  0.546  0.547  0.500  1.0
  O  O5  1  0.845  0.322  0.221  1.0
  O  O6  1  0.443  0.182  0.262  1.0
  O  O7  1  0.322  0.845  0.779  1.0
  O  O8  1  0.182  0.443  0.738  1.0
  O  O9  1  0.099  0.781  0.297  1.0
  O  O10  1  0.781  0.099  0.703  1.0
[/CIF]
.