The crystal structure described by Li2FeP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), one O(6), and one O(7) atom. In the second Li site, Li(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Fe(1)O5 trigonal bipyramids. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent Li(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(1), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(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(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  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(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Fe(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Fe(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Li(2), and one P(2) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.616
_cell_length_b   5.114
_cell_length_c   8.028
_cell_angle_alpha   87.600
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   558.577
_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
  Li  Li0  1  0.103  0.165  0.865  1.0
  Li  Li1  1  0.897  0.835  0.135  1.0
  Li  Li2  1  0.306  0.252  0.166  1.0
  Li  Li3  1  0.806  0.248  0.334  1.0
  Li  Li4  1  0.397  0.665  0.365  1.0
  Li  Li5  1  0.694  0.748  0.834  1.0
  Li  Li6  1  0.194  0.752  0.666  1.0
  Li  Li7  1  0.603  0.335  0.635  1.0
  Fe  Fe8  1  0.161  0.790  0.238  1.0
  Fe  Fe9  1  0.661  0.710  0.262  1.0
  Fe  Fe10  1  0.339  0.290  0.738  1.0
  Fe  Fe11  1  0.839  0.210  0.762  1.0
  P  P12  1  0.822  0.739  0.533  1.0
  P  P13  1  0.178  0.261  0.467  1.0
  P  P14  1  0.529  0.198  0.277  1.0
  P  P15  1  0.029  0.302  0.223  1.0
  P  P16  1  0.322  0.761  0.967  1.0
  P  P17  1  0.971  0.698  0.777  1.0
  P  P18  1  0.678  0.239  0.033  1.0
  P  P19  1  0.471  0.802  0.723  1.0
  O  O20  1  0.937  0.723  0.578  1.0
  O  O21  1  0.105  0.145  0.124  1.0
  O  O22  1  0.563  0.223  0.078  1.0
  O  O23  1  0.706  0.530  0.047  1.0
  O  O24  1  0.294  0.470  0.953  1.0
  O  O25  1  0.437  0.777  0.922  1.0
  O  O26  1  0.895  0.855  0.876  1.0
  O  O27  1  0.268  0.941  0.839  1.0
  O  O28  1  0.691  0.148  0.854  1.0
  O  O29  1  0.964  0.400  0.820  1.0
  O  O30  1  0.073  0.811  0.781  1.0
  O  O31  1  0.573  0.689  0.719  1.0
  O  O32  1  0.464  0.100  0.680  1.0
  O  O33  1  0.309  0.852  0.146  1.0
  O  O34  1  0.191  0.352  0.646  1.0
  O  O35  1  0.395  0.645  0.624  1.0
  O  O36  1  0.768  0.559  0.661  1.0
  O  O37  1  0.794  0.030  0.547  1.0
  O  O38  1  0.206  0.970  0.453  1.0
  O  O39  1  0.063  0.277  0.422  1.0
  O  O40  1  0.605  0.355  0.376  1.0
  O  O41  1  0.809  0.648  0.354  1.0
  O  O42  1  0.232  0.441  0.339  1.0
  O  O43  1  0.536  0.900  0.320  1.0
  O  O44  1  0.427  0.311  0.281  1.0
  O  O45  1  0.927  0.189  0.219  1.0
  O  O46  1  0.036  0.600  0.180  1.0
  O  O47  1  0.732  0.059  0.161  1.0
[/CIF]
.
The crystal structure described by Li2FeP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), one O(6), and one O(7) atom. In the second Li site, Li(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Fe(1)O5 trigonal bipyramids. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent Li(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(1), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(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(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  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(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Fe(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Fe(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Li(2), and one P(2) atom. is represented by the CIF file [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.616
_cell_length_b   5.114
_cell_length_c   8.028
_cell_angle_alpha   87.600
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   558.577
_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
  Li  Li0  1  0.103  0.165  0.865  1.0
  Li  Li1  1  0.897  0.835  0.135  1.0
  Li  Li2  1  0.306  0.252  0.166  1.0
  Li  Li3  1  0.806  0.248  0.334  1.0
  Li  Li4  1  0.397  0.665  0.365  1.0
  Li  Li5  1  0.694  0.748  0.834  1.0
  Li  Li6  1  0.194  0.752  0.666  1.0
  Li  Li7  1  0.603  0.335  0.635  1.0
  Fe  Fe8  1  0.161  0.790  0.238  1.0
  Fe  Fe9  1  0.661  0.710  0.262  1.0
  Fe  Fe10  1  0.339  0.290  0.738  1.0
  Fe  Fe11  1  0.839  0.210  0.762  1.0
  P  P12  1  0.822  0.739  0.533  1.0
  P  P13  1  0.178  0.261  0.467  1.0
  P  P14  1  0.529  0.198  0.277  1.0
  P  P15  1  0.029  0.302  0.223  1.0
  P  P16  1  0.322  0.761  0.967  1.0
  P  P17  1  0.971  0.698  0.777  1.0
  P  P18  1  0.678  0.239  0.033  1.0
  P  P19  1  0.471  0.802  0.723  1.0
  O  O20  1  0.937  0.723  0.578  1.0
  O  O21  1  0.105  0.145  0.124  1.0
  O  O22  1  0.563  0.223  0.078  1.0
  O  O23  1  0.706  0.530  0.047  1.0
  O  O24  1  0.294  0.470  0.953  1.0
  O  O25  1  0.437  0.777  0.922  1.0
  O  O26  1  0.895  0.855  0.876  1.0
  O  O27  1  0.268  0.941  0.839  1.0
  O  O28  1  0.691  0.148  0.854  1.0
  O  O29  1  0.964  0.400  0.820  1.0
  O  O30  1  0.073  0.811  0.781  1.0
  O  O31  1  0.573  0.689  0.719  1.0
  O  O32  1  0.464  0.100  0.680  1.0
  O  O33  1  0.309  0.852  0.146  1.0
  O  O34  1  0.191  0.352  0.646  1.0
  O  O35  1  0.395  0.645  0.624  1.0
  O  O36  1  0.768  0.559  0.661  1.0
  O  O37  1  0.794  0.030  0.547  1.0
  O  O38  1  0.206  0.970  0.453  1.0
  O  O39  1  0.063  0.277  0.422  1.0
  O  O40  1  0.605  0.355  0.376  1.0
  O  O41  1  0.809  0.648  0.354  1.0
  O  O42  1  0.232  0.441  0.339  1.0
  O  O43  1  0.536  0.900  0.320  1.0
  O  O44  1  0.427  0.311  0.281  1.0
  O  O45  1  0.927  0.189  0.219  1.0
  O  O46  1  0.036  0.600  0.180  1.0
  O  O47  1  0.732  0.059  0.161  1.0
[/CIF]
.