The compound described by FeP2O7 crystallizes in the monoclinic C2/c space group. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-47°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) 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 36-48°. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.427
_cell_length_b   6.427
_cell_length_c   13.518
_cell_angle_alpha   74.503
_cell_angle_beta   74.503
_cell_angle_gamma   80.822
_symmetry_Int_Tables_number   1
_cell_volume   516.207
_cell_formula_units_Z   4
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  0.591  0.122  0.147  1.0
  Fe  Fe1  1  0.122  0.591  0.647  1.0
  Fe  Fe2  1  0.878  0.409  0.353  1.0
  Fe  Fe3  1  0.409  0.878  0.853  1.0
  P  P4  1  0.588  0.667  0.069  1.0
  P  P5  1  0.333  0.412  0.431  1.0
  P  P6  1  0.252  0.086  0.634  1.0
  P  P7  1  0.914  0.748  0.866  1.0
  P  P8  1  0.086  0.252  0.134  1.0
  P  P9  1  0.748  0.914  0.366  1.0
  P  P10  1  0.667  0.588  0.569  1.0
  P  P11  1  0.412  0.333  0.931  1.0
  O  O12  1  0.638  0.819  0.126  1.0
  O  O13  1  0.554  0.466  0.358  1.0
  O  O14  1  0.577  0.016  0.303  1.0
  O  O15  1  0.087  0.872  0.877  1.0
  O  O16  1  0.385  0.194  0.517  1.0
  O  O17  1  0.534  0.446  0.142  1.0
  O  O18  1  0.128  0.913  0.623  1.0
  O  O19  1  0.228  0.591  0.490  1.0
  O  O20  1  0.016  0.577  0.803  1.0
  O  O21  1  0.409  0.772  0.010  1.0
  O  O22  1  0.103  0.268  0.677  1.0
  O  O23  1  0.806  0.615  0.983  1.0
  O  O24  1  0.181  0.362  0.374  1.0
  O  O25  1  0.268  0.103  0.177  1.0
  O  O26  1  0.732  0.897  0.823  1.0
  O  O27  1  0.819  0.638  0.626  1.0
  O  O28  1  0.194  0.385  0.017  1.0
  O  O29  1  0.897  0.732  0.323  1.0
  O  O30  1  0.591  0.228  0.990  1.0
  O  O31  1  0.984  0.423  0.197  1.0
  O  O32  1  0.772  0.409  0.510  1.0
  O  O33  1  0.872  0.087  0.377  1.0
  O  O34  1  0.466  0.554  0.858  1.0
  O  O35  1  0.615  0.806  0.483  1.0
  O  O36  1  0.913  0.128  0.123  1.0
  O  O37  1  0.423  0.984  0.697  1.0
  O  O38  1  0.446  0.534  0.642  1.0
  O  O39  1  0.362  0.181  0.874  1.0
[/CIF]
.
The compound described by FeP2O7 crystallizes in the monoclinic C2/c space group. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-47°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) 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 36-48°. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(5) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.427
_cell_length_b   6.427
_cell_length_c   13.518
_cell_angle_alpha   74.503
_cell_angle_beta   74.503
_cell_angle_gamma   80.822
_symmetry_Int_Tables_number   1
_cell_volume   516.207
_cell_formula_units_Z   4
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  0.591  0.122  0.147  1.0
  Fe  Fe1  1  0.122  0.591  0.647  1.0
  Fe  Fe2  1  0.878  0.409  0.353  1.0
  Fe  Fe3  1  0.409  0.878  0.853  1.0
  P  P4  1  0.588  0.667  0.069  1.0
  P  P5  1  0.333  0.412  0.431  1.0
  P  P6  1  0.252  0.086  0.634  1.0
  P  P7  1  0.914  0.748  0.866  1.0
  P  P8  1  0.086  0.252  0.134  1.0
  P  P9  1  0.748  0.914  0.366  1.0
  P  P10  1  0.667  0.588  0.569  1.0
  P  P11  1  0.412  0.333  0.931  1.0
  O  O12  1  0.638  0.819  0.126  1.0
  O  O13  1  0.554  0.466  0.358  1.0
  O  O14  1  0.577  0.016  0.303  1.0
  O  O15  1  0.087  0.872  0.877  1.0
  O  O16  1  0.385  0.194  0.517  1.0
  O  O17  1  0.534  0.446  0.142  1.0
  O  O18  1  0.128  0.913  0.623  1.0
  O  O19  1  0.228  0.591  0.490  1.0
  O  O20  1  0.016  0.577  0.803  1.0
  O  O21  1  0.409  0.772  0.010  1.0
  O  O22  1  0.103  0.268  0.677  1.0
  O  O23  1  0.806  0.615  0.983  1.0
  O  O24  1  0.181  0.362  0.374  1.0
  O  O25  1  0.268  0.103  0.177  1.0
  O  O26  1  0.732  0.897  0.823  1.0
  O  O27  1  0.819  0.638  0.626  1.0
  O  O28  1  0.194  0.385  0.017  1.0
  O  O29  1  0.897  0.732  0.323  1.0
  O  O30  1  0.591  0.228  0.990  1.0
  O  O31  1  0.984  0.423  0.197  1.0
  O  O32  1  0.772  0.409  0.510  1.0
  O  O33  1  0.872  0.087  0.377  1.0
  O  O34  1  0.466  0.554  0.858  1.0
  O  O35  1  0.615  0.806  0.483  1.0
  O  O36  1  0.913  0.128  0.123  1.0
  O  O37  1  0.423  0.984  0.697  1.0
  O  O38  1  0.446  0.534  0.642  1.0
  O  O39  1  0.362  0.181  0.874  1.0
[/CIF]
.