The compound described by Li2FeP2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(6), one O(8), and two equivalent O(10) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(5), one O(7), and two equivalent O(9) atoms. In the third Li site, Li(3) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(5), and one O(9) atom. In the fourth Li site, Li(4) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(2), and one O(6) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(11), one O(5), one O(7), and two equivalent O(3) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(12), one O(2), one O(6), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(12), one O(14), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-59°. In the second P site, P(2) is bonded to one O(11), one O(13), one O(2), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-59°. In the third P site, P(3) is bonded to one O(13), one O(5), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-55°. In the fourth P site, P(4) is bonded to one O(10), one O(14), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-55°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(3), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(4), one Fe(2), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar 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(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(2), one Li(3), one Fe(1), and one P(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), one Li(4), one Fe(2), and one P(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(4) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Li(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded to one Li(3), two equivalent Li(2), and one P(3) atom to form distorted edge-sharing OLi3P trigonal pyramids. In the tenth O site, O(10) is bonded to one Li(4), two equivalent Li(1), and one P(4) atom to form distorted edge-sharing OLi3P trigonal pyramids. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Li(4), one Fe(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Li(3), one Fe(2), and one P(1) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(4) atom. is represented by the CIF card [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.412
_cell_length_b   6.544
_cell_length_c   8.950
_cell_angle_alpha   108.195
_cell_angle_beta   99.430
_cell_angle_gamma   106.065
_symmetry_Int_Tables_number   1
_cell_volume   278.250
_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  0.105  0.605  0.366  1.0
  Fe  Fe1  1  0.895  0.395  0.635  1.0
  Li  Li2  1  0.205  0.794  0.960  1.0
  Li  Li3  1  0.795  0.206  0.041  1.0
  Li  Li4  1  0.317  0.218  0.760  1.0
  Li  Li5  1  0.683  0.782  0.240  1.0
  O  O6  1  0.062  0.898  0.345  1.0
  O  O7  1  0.938  0.102  0.655  1.0
  O  O8  1  0.062  0.305  0.414  1.0
  O  O9  1  0.937  0.695  0.586  1.0
  O  O10  1  0.324  0.543  0.816  1.0
  O  O11  1  0.676  0.457  0.184  1.0
  O  O12  1  0.178  0.418  0.139  1.0
  O  O13  1  0.823  0.582  0.861  1.0
  O  O14  1  0.327  0.117  0.955  1.0
  O  O15  1  0.673  0.883  0.045  1.0
  O  O16  1  0.531  0.767  0.451  1.0
  O  O17  1  0.469  0.234  0.549  1.0
  O  O18  1  0.647  0.853  0.758  1.0
  O  O19  1  0.353  0.147  0.242  1.0
  P  P20  1  0.235  0.150  0.398  1.0
  P  P21  1  0.765  0.850  0.602  1.0
  P  P22  1  0.617  0.703  0.874  1.0
  P  P23  1  0.383  0.297  0.126  1.0
[/CIF]
.
The compound described by Li2FeP2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(6), one O(8), and two equivalent O(10) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(5), one O(7), and two equivalent O(9) atoms. In the third Li site, Li(3) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(5), and one O(9) atom. In the fourth Li site, Li(4) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(2), and one O(6) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(11), one O(5), one O(7), and two equivalent O(3) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(12), one O(2), one O(6), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(12), one O(14), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-59°. In the second P site, P(2) is bonded to one O(11), one O(13), one O(2), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-59°. In the third P site, P(3) is bonded to one O(13), one O(5), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-55°. In the fourth P site, P(4) is bonded to one O(10), one O(14), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-55°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(3), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(4), one Fe(2), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar 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(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(2), one Li(3), one Fe(1), and one P(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), one Li(4), one Fe(2), and one P(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Fe(1), and one P(4) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Li(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded to one Li(3), two equivalent Li(2), and one P(3) atom to form distorted edge-sharing OLi3P trigonal pyramids. In the tenth O site, O(10) is bonded to one Li(4), two equivalent Li(1), and one P(4) atom to form distorted edge-sharing OLi3P trigonal pyramids. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Li(4), one Fe(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Li(3), one Fe(2), and one P(1) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(4) atom. is represented by the CIF card [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.412
_cell_length_b   6.544
_cell_length_c   8.950
_cell_angle_alpha   108.195
_cell_angle_beta   99.430
_cell_angle_gamma   106.065
_symmetry_Int_Tables_number   1
_cell_volume   278.250
_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  0.105  0.605  0.366  1.0
  Fe  Fe1  1  0.895  0.395  0.635  1.0
  Li  Li2  1  0.205  0.794  0.960  1.0
  Li  Li3  1  0.795  0.206  0.041  1.0
  Li  Li4  1  0.317  0.218  0.760  1.0
  Li  Li5  1  0.683  0.782  0.240  1.0
  O  O6  1  0.062  0.898  0.345  1.0
  O  O7  1  0.938  0.102  0.655  1.0
  O  O8  1  0.062  0.305  0.414  1.0
  O  O9  1  0.937  0.695  0.586  1.0
  O  O10  1  0.324  0.543  0.816  1.0
  O  O11  1  0.676  0.457  0.184  1.0
  O  O12  1  0.178  0.418  0.139  1.0
  O  O13  1  0.823  0.582  0.861  1.0
  O  O14  1  0.327  0.117  0.955  1.0
  O  O15  1  0.673  0.883  0.045  1.0
  O  O16  1  0.531  0.767  0.451  1.0
  O  O17  1  0.469  0.234  0.549  1.0
  O  O18  1  0.647  0.853  0.758  1.0
  O  O19  1  0.353  0.147  0.242  1.0
  P  P20  1  0.235  0.150  0.398  1.0
  P  P21  1  0.765  0.850  0.602  1.0
  P  P22  1  0.617  0.703  0.874  1.0
  P  P23  1  0.383  0.297  0.126  1.0
[/CIF]
.