The compound described by SrFeP2O7 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(7) atoms. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Fe(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Sr(1), one Fe(1), and one P(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(1), 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 P(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.425
_cell_length_b   8.391
_cell_length_c   12.917
_cell_angle_alpha   90.000
_cell_angle_beta   90.214
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   588.017
_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
  Sr  Sr0  1  0.713  0.837  0.778  1.0
  Sr  Sr1  1  0.787  0.337  0.722  1.0
  Sr  Sr2  1  0.287  0.163  0.222  1.0
  Sr  Sr3  1  0.213  0.663  0.278  1.0
  Fe  Fe4  1  0.681  0.849  0.105  1.0
  Fe  Fe5  1  0.319  0.151  0.895  1.0
  Fe  Fe6  1  0.819  0.349  0.395  1.0
  Fe  Fe7  1  0.181  0.651  0.605  1.0
  P  P8  1  0.689  0.700  0.480  1.0
  P  P9  1  0.811  0.200  0.020  1.0
  P  P10  1  0.311  0.300  0.520  1.0
  P  P11  1  0.189  0.800  0.980  1.0
  P  P12  1  0.249  0.537  0.834  1.0
  P  P13  1  0.749  0.963  0.334  1.0
  P  P14  1  0.751  0.463  0.166  1.0
  P  P15  1  0.251  0.037  0.666  1.0
  O  O16  1  0.052  0.620  0.767  1.0
  O  O17  1  0.448  0.120  0.733  1.0
  O  O18  1  0.948  0.380  0.233  1.0
  O  O19  1  0.552  0.880  0.267  1.0
  O  O20  1  0.410  0.670  0.471  1.0
  O  O21  1  0.090  0.170  0.029  1.0
  O  O22  1  0.590  0.330  0.529  1.0
  O  O23  1  0.910  0.830  0.971  1.0
  O  O24  1  0.740  0.884  0.448  1.0
  O  O25  1  0.760  0.384  0.052  1.0
  O  O26  1  0.260  0.116  0.552  1.0
  O  O27  1  0.240  0.616  0.948  1.0
  O  O28  1  0.793  0.688  0.591  1.0
  O  O29  1  0.707  0.188  0.909  1.0
  O  O30  1  0.207  0.312  0.409  1.0
  O  O31  1  0.293  0.812  0.091  1.0
  O  O32  1  0.824  0.637  0.152  1.0
  O  O33  1  0.676  0.137  0.348  1.0
  O  O34  1  0.176  0.363  0.848  1.0
  O  O35  1  0.324  0.863  0.652  1.0
  O  O36  1  0.664  0.097  0.097  1.0
  O  O37  1  0.836  0.597  0.403  1.0
  O  O38  1  0.510  0.560  0.792  1.0
  O  O39  1  0.164  0.403  0.597  1.0
  O  O40  1  0.010  0.940  0.292  1.0
  O  O41  1  0.490  0.440  0.208  1.0
  O  O42  1  0.990  0.060  0.708  1.0
  O  O43  1  0.336  0.903  0.903  1.0
[/CIF]
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The compound described by SrFeP2O7 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(7) atoms. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with three equivalent Fe(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Fe(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the third O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Sr(1), one Fe(1), and one P(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(1), 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 P(1) and one P(2) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.425
_cell_length_b   8.391
_cell_length_c   12.917
_cell_angle_alpha   90.000
_cell_angle_beta   90.214
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   588.017
_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
  Sr  Sr0  1  0.713  0.837  0.778  1.0
  Sr  Sr1  1  0.787  0.337  0.722  1.0
  Sr  Sr2  1  0.287  0.163  0.222  1.0
  Sr  Sr3  1  0.213  0.663  0.278  1.0
  Fe  Fe4  1  0.681  0.849  0.105  1.0
  Fe  Fe5  1  0.319  0.151  0.895  1.0
  Fe  Fe6  1  0.819  0.349  0.395  1.0
  Fe  Fe7  1  0.181  0.651  0.605  1.0
  P  P8  1  0.689  0.700  0.480  1.0
  P  P9  1  0.811  0.200  0.020  1.0
  P  P10  1  0.311  0.300  0.520  1.0
  P  P11  1  0.189  0.800  0.980  1.0
  P  P12  1  0.249  0.537  0.834  1.0
  P  P13  1  0.749  0.963  0.334  1.0
  P  P14  1  0.751  0.463  0.166  1.0
  P  P15  1  0.251  0.037  0.666  1.0
  O  O16  1  0.052  0.620  0.767  1.0
  O  O17  1  0.448  0.120  0.733  1.0
  O  O18  1  0.948  0.380  0.233  1.0
  O  O19  1  0.552  0.880  0.267  1.0
  O  O20  1  0.410  0.670  0.471  1.0
  O  O21  1  0.090  0.170  0.029  1.0
  O  O22  1  0.590  0.330  0.529  1.0
  O  O23  1  0.910  0.830  0.971  1.0
  O  O24  1  0.740  0.884  0.448  1.0
  O  O25  1  0.760  0.384  0.052  1.0
  O  O26  1  0.260  0.116  0.552  1.0
  O  O27  1  0.240  0.616  0.948  1.0
  O  O28  1  0.793  0.688  0.591  1.0
  O  O29  1  0.707  0.188  0.909  1.0
  O  O30  1  0.207  0.312  0.409  1.0
  O  O31  1  0.293  0.812  0.091  1.0
  O  O32  1  0.824  0.637  0.152  1.0
  O  O33  1  0.676  0.137  0.348  1.0
  O  O34  1  0.176  0.363  0.848  1.0
  O  O35  1  0.324  0.863  0.652  1.0
  O  O36  1  0.664  0.097  0.097  1.0
  O  O37  1  0.836  0.597  0.403  1.0
  O  O38  1  0.510  0.560  0.792  1.0
  O  O39  1  0.164  0.403  0.597  1.0
  O  O40  1  0.010  0.940  0.292  1.0
  O  O41  1  0.490  0.440  0.208  1.0
  O  O42  1  0.990  0.060  0.708  1.0
  O  O43  1  0.336  0.903  0.903  1.0
[/CIF]
.