The crystal structure described by Fe2P2O7 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and edges with three equivalent Fe(1)O6 octahedra. 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 six equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-60°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent P(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.498
_cell_length_b   5.447
_cell_length_c   9.877
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   97.327
_symmetry_Int_Tables_number   1
_cell_volume   240.047
_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
  Fe  Fe0  1  0.112  0.394  0.659  1.0
  Fe  Fe1  1  0.888  0.106  0.159  1.0
  Fe  Fe2  1  0.888  0.606  0.341  1.0
  Fe  Fe3  1  0.112  0.894  0.841  1.0
  P  P4  1  0.642  0.842  0.610  1.0
  P  P5  1  0.358  0.658  0.110  1.0
  P  P6  1  0.358  0.158  0.390  1.0
  P  P7  1  0.642  0.342  0.890  1.0
  O  O8  1  0.877  0.520  0.817  1.0
  O  O9  1  0.123  0.980  0.317  1.0
  O  O10  1  0.123  0.480  0.183  1.0
  O  O11  1  0.877  0.020  0.683  1.0
  O  O12  1  0.500  0.000  0.500  1.0
  O  O13  1  0.500  0.500  0.000  1.0
  O  O14  1  0.213  0.356  0.465  1.0
  O  O15  1  0.787  0.144  0.965  1.0
  O  O16  1  0.385  0.234  0.800  1.0
  O  O17  1  0.615  0.266  0.300  1.0
  O  O18  1  0.615  0.766  0.200  1.0
  O  O19  1  0.385  0.734  0.700  1.0
  O  O20  1  0.213  0.856  0.035  1.0
  O  O21  1  0.787  0.644  0.535  1.0
[/CIF]
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The crystal structure described by Fe2P2O7 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and edges with three equivalent Fe(1)O6 octahedra. 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 six equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-60°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent P(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.498
_cell_length_b   5.447
_cell_length_c   9.877
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   97.327
_symmetry_Int_Tables_number   1
_cell_volume   240.047
_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
  Fe  Fe0  1  0.112  0.394  0.659  1.0
  Fe  Fe1  1  0.888  0.106  0.159  1.0
  Fe  Fe2  1  0.888  0.606  0.341  1.0
  Fe  Fe3  1  0.112  0.894  0.841  1.0
  P  P4  1  0.642  0.842  0.610  1.0
  P  P5  1  0.358  0.658  0.110  1.0
  P  P6  1  0.358  0.158  0.390  1.0
  P  P7  1  0.642  0.342  0.890  1.0
  O  O8  1  0.877  0.520  0.817  1.0
  O  O9  1  0.123  0.980  0.317  1.0
  O  O10  1  0.123  0.480  0.183  1.0
  O  O11  1  0.877  0.020  0.683  1.0
  O  O12  1  0.500  0.000  0.500  1.0
  O  O13  1  0.500  0.500  0.000  1.0
  O  O14  1  0.213  0.356  0.465  1.0
  O  O15  1  0.787  0.144  0.965  1.0
  O  O16  1  0.385  0.234  0.800  1.0
  O  O17  1  0.615  0.266  0.300  1.0
  O  O18  1  0.615  0.766  0.200  1.0
  O  O19  1  0.385  0.734  0.700  1.0
  O  O20  1  0.213  0.856  0.035  1.0
  O  O21  1  0.787  0.644  0.535  1.0
[/CIF]
.