The material described by FeP2O7 crystallizes in the triclinic P1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(14), one O(17), one O(24), one O(27), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(10), one O(12), one O(20), one O(23), one O(4), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, corners with two equivalent P(7)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. In the third Fe site, Fe(3) is bonded to one O(10), one O(13), one O(21), one O(25), one O(5), and one O(6) atom to form distorted FeO6 trigonal bipyramids that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(11), one O(15), one O(2), one O(22), and one O(9) atom to form distorted FeO6 trigonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are eight inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(19), one O(22), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(7)O4 tetrahedra, and  an edgeedge with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 43-46°. In the second P site, P(2) is bonded to one O(16), one O(27), one O(28), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(8)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. In the third P site, P(3) is bonded to one O(14), one O(15), one O(24), and one O(3) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-49°. In the fourth P site, P(4) is bonded to one O(10), one O(17), one O(25), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and  an edgeedge with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 43-46°. In the fifth P site, P(5) is bonded to one O(11), one O(18), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one Fe(3)O6 trigonal bipyramid, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 38°. In the sixth P site, P(6) is bonded to one O(18), one O(20), one O(21), and one O(26) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. In the seventh P site, P(7) is bonded to one O(19), one O(23), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-49°. In the eighth P site, P(8) is bonded to one O(12), one O(13), one O(16), and one O(2) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Fe(3)O6 trigonal bipyramid, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 38°. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Fe(1), one Fe(4), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(4) and one P(8) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one P(3) and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one P(7) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(5) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(7) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(5) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(2), one Fe(3), and one P(4) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(5) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(8) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(8) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(3) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 120 degrees geometry to one P(2) and one P(8) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(4) atom. In the eighteenth O site, O(18) is bonded in a distorted bent 120 degrees geometry to one P(5) and one P(6) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one P(1) and one P(7) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(6) atom. In the twenty-first O site, O(21) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(6) atom. In the twenty-second O site, O(22) is bonded in a water-like geometry to one Fe(4) and one P(1) atom. In the twenty-third O site, O(23) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(7) atom. In the twenty-fourth O site, O(24) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the twenty-fifth O site, O(25) is bonded in a water-like geometry to one Fe(3) and one P(4) atom. In the twenty-sixth O site, O(26) is bonded in a single-bond geometry to one P(6) atom. In the twenty-seventh O site, O(27) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the twenty-eighth O site, O(28) is bonded in a single-bond geometry to one P(2) atom. is represented by the CIF card [CIF]
data_FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.451
_cell_length_b   9.675
_cell_length_c   10.647
_cell_angle_alpha   115.312
_cell_angle_beta   85.825
_cell_angle_gamma   107.123
_symmetry_Int_Tables_number   1
_cell_volume   572.987
_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  0.375  0.497  0.748  1.0
  Fe  Fe1  1  0.625  0.503  0.252  1.0
  Fe  Fe2  1  0.727  0.092  0.221  1.0
  Fe  Fe3  1  0.273  0.908  0.779  1.0
  P  P4  1  0.415  0.682  0.537  1.0
  P  P5  1  0.073  0.184  0.794  1.0
  P  P6  1  0.890  0.549  0.698  1.0
  P  P7  1  0.585  0.318  0.463  1.0
  P  P8  1  0.311  0.801  0.035  1.0
  P  P9  1  0.927  0.816  0.206  1.0
  P  P10  1  0.110  0.451  0.302  1.0
  P  P11  1  0.689  0.199  0.965  1.0
  O  O12  1  0.439  0.673  0.677  1.0
  O  O13  1  0.551  0.072  0.828  1.0
  O  O14  1  0.798  0.453  0.538  1.0
  O  O15  1  0.305  0.457  0.210  1.0
  O  O16  1  0.454  0.916  0.168  1.0
  O  O17  1  0.002  0.272  0.282  1.0
  O  O18  1  0.391  0.658  0.944  1.0
  O  O19  1  0.602  0.657  0.443  1.0
  O  O20  1  0.108  0.051  0.824  1.0
  O  O21  1  0.561  0.327  0.323  1.0
  O  O22  1  0.271  0.891  0.956  1.0
  O  O23  1  0.609  0.342  0.056  1.0
  O  O24  1  0.729  0.109  0.044  1.0
  O  O25  1  0.695  0.543  0.790  1.0
  O  O26  1  0.998  0.728  0.718  1.0
  O  O27  1  0.921  0.266  0.911  1.0
  O  O28  1  0.398  0.343  0.557  1.0
  O  O29  1  0.079  0.734  0.089  1.0
  O  O30  1  0.202  0.547  0.462  1.0
  O  O31  1  0.722  0.674  0.189  1.0
  O  O32  1  0.892  0.949  0.176  1.0
  O  O33  1  0.361  0.840  0.581  1.0
  O  O34  1  0.945  0.516  0.272  1.0
  O  O35  1  0.055  0.484  0.728  1.0
  O  O36  1  0.639  0.160  0.419  1.0
  O  O37  1  0.042  0.884  0.348  1.0
  O  O38  1  0.278  0.326  0.811  1.0
  O  O39  1  0.956  0.104  0.648  1.0
[/CIF]
.
The material described by FeP2O7 crystallizes in the triclinic P1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(14), one O(17), one O(24), one O(27), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(10), one O(12), one O(20), one O(23), one O(4), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, corners with two equivalent P(7)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. In the third Fe site, Fe(3) is bonded to one O(10), one O(13), one O(21), one O(25), one O(5), and one O(6) atom to form distorted FeO6 trigonal bipyramids that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one P(7)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(11), one O(15), one O(2), one O(22), and one O(9) atom to form distorted FeO6 trigonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(8)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are eight inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(19), one O(22), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(7)O4 tetrahedra, and  an edgeedge with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 43-46°. In the second P site, P(2) is bonded to one O(16), one O(27), one O(28), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(8)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. In the third P site, P(3) is bonded to one O(14), one O(15), one O(24), and one O(3) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-49°. In the fourth P site, P(4) is bonded to one O(10), one O(17), one O(25), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and  an edgeedge with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 43-46°. In the fifth P site, P(5) is bonded to one O(11), one O(18), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one P(6)O4 tetrahedra,  a cornercorner with one Fe(3)O6 trigonal bipyramid, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 38°. In the sixth P site, P(6) is bonded to one O(18), one O(20), one O(21), and one O(26) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(5)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. In the seventh P site, P(7) is bonded to one O(19), one O(23), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one Fe(3)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-49°. In the eighth P site, P(8) is bonded to one O(12), one O(13), one O(16), and one O(2) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Fe(3)O6 trigonal bipyramid, and  a cornercorner with one Fe(4)O6 trigonal bipyramid. The corner-sharing octahedral tilt angles are 38°. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Fe(1), one Fe(4), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(4) and one P(8) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one P(3) and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one P(7) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(5) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(7) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(5) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Fe(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(2), one Fe(3), and one P(4) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(5) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(8) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(8) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(3) atom. In the sixteenth O site, O(16) is bonded in a distorted bent 120 degrees geometry to one P(2) and one P(8) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(4) atom. In the eighteenth O site, O(18) is bonded in a distorted bent 120 degrees geometry to one P(5) and one P(6) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one P(1) and one P(7) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(6) atom. In the twenty-first O site, O(21) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(6) atom. In the twenty-second O site, O(22) is bonded in a water-like geometry to one Fe(4) and one P(1) atom. In the twenty-third O site, O(23) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(7) atom. In the twenty-fourth O site, O(24) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the twenty-fifth O site, O(25) is bonded in a water-like geometry to one Fe(3) and one P(4) atom. In the twenty-sixth O site, O(26) is bonded in a single-bond geometry to one P(6) atom. In the twenty-seventh O site, O(27) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the twenty-eighth O site, O(28) is bonded in a single-bond geometry to one P(2) atom. is represented by the CIF card [CIF]
data_FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.451
_cell_length_b   9.675
_cell_length_c   10.647
_cell_angle_alpha   115.312
_cell_angle_beta   85.825
_cell_angle_gamma   107.123
_symmetry_Int_Tables_number   1
_cell_volume   572.987
_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  0.375  0.497  0.748  1.0
  Fe  Fe1  1  0.625  0.503  0.252  1.0
  Fe  Fe2  1  0.727  0.092  0.221  1.0
  Fe  Fe3  1  0.273  0.908  0.779  1.0
  P  P4  1  0.415  0.682  0.537  1.0
  P  P5  1  0.073  0.184  0.794  1.0
  P  P6  1  0.890  0.549  0.698  1.0
  P  P7  1  0.585  0.318  0.463  1.0
  P  P8  1  0.311  0.801  0.035  1.0
  P  P9  1  0.927  0.816  0.206  1.0
  P  P10  1  0.110  0.451  0.302  1.0
  P  P11  1  0.689  0.199  0.965  1.0
  O  O12  1  0.439  0.673  0.677  1.0
  O  O13  1  0.551  0.072  0.828  1.0
  O  O14  1  0.798  0.453  0.538  1.0
  O  O15  1  0.305  0.457  0.210  1.0
  O  O16  1  0.454  0.916  0.168  1.0
  O  O17  1  0.002  0.272  0.282  1.0
  O  O18  1  0.391  0.658  0.944  1.0
  O  O19  1  0.602  0.657  0.443  1.0
  O  O20  1  0.108  0.051  0.824  1.0
  O  O21  1  0.561  0.327  0.323  1.0
  O  O22  1  0.271  0.891  0.956  1.0
  O  O23  1  0.609  0.342  0.056  1.0
  O  O24  1  0.729  0.109  0.044  1.0
  O  O25  1  0.695  0.543  0.790  1.0
  O  O26  1  0.998  0.728  0.718  1.0
  O  O27  1  0.921  0.266  0.911  1.0
  O  O28  1  0.398  0.343  0.557  1.0
  O  O29  1  0.079  0.734  0.089  1.0
  O  O30  1  0.202  0.547  0.462  1.0
  O  O31  1  0.722  0.674  0.189  1.0
  O  O32  1  0.892  0.949  0.176  1.0
  O  O33  1  0.361  0.840  0.581  1.0
  O  O34  1  0.945  0.516  0.272  1.0
  O  O35  1  0.055  0.484  0.728  1.0
  O  O36  1  0.639  0.160  0.419  1.0
  O  O37  1  0.042  0.884  0.348  1.0
  O  O38  1  0.278  0.326  0.811  1.0
  O  O39  1  0.956  0.104  0.648  1.0
[/CIF]
.