The material described by Li2FeP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra and  an edgeedge with one Li(1)O4 tetrahedra. Fe(1) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with four equivalent Li(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   8.170
_cell_length_c   8.934
_cell_angle_alpha   113.631
_cell_angle_beta   90.006
_cell_angle_gamma   107.955
_symmetry_Int_Tables_number   1
_cell_volume   317.424
_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  1.000  0.500  1.000  1.0
  Fe  Fe1  1  1.000  0.500  0.500  1.0
  Li  Li2  1  0.048  0.881  0.552  1.0
  Li  Li3  1  0.952  0.119  0.448  1.0
  Li  Li4  1  0.667  0.119  0.948  1.0
  Li  Li5  1  0.333  0.881  0.052  1.0
  O  O6  1  0.482  0.500  0.750  1.0
  O  O7  1  0.518  0.500  0.250  1.0
  O  O8  1  0.335  0.712  0.163  1.0
  O  O9  1  0.665  0.288  0.837  1.0
  O  O10  1  0.124  0.288  0.337  1.0
  O  O11  1  0.876  0.712  0.663  1.0
  O  O12  1  0.755  0.854  0.388  1.0
  O  O13  1  0.401  0.146  0.112  1.0
  O  O14  1  0.599  0.854  0.888  1.0
  O  O15  1  0.245  0.146  0.612  1.0
  O  O16  1  0.945  0.704  0.941  1.0
  O  O17  1  0.055  0.296  0.059  1.0
  O  O18  1  0.259  0.704  0.441  1.0
  O  O19  1  0.741  0.296  0.559  1.0
  P  P20  1  0.262  0.294  0.184  1.0
  P  P21  1  0.532  0.294  0.684  1.0
  P  P22  1  0.738  0.706  0.816  1.0
  P  P23  1  0.468  0.706  0.316  1.0
[/CIF]
.
The material described by Li2FeP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra and  an edgeedge with one Li(1)O4 tetrahedra. Fe(1) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with four equivalent Li(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Li(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   8.170
_cell_length_c   8.934
_cell_angle_alpha   113.631
_cell_angle_beta   90.006
_cell_angle_gamma   107.955
_symmetry_Int_Tables_number   1
_cell_volume   317.424
_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  1.000  0.500  1.000  1.0
  Fe  Fe1  1  1.000  0.500  0.500  1.0
  Li  Li2  1  0.048  0.881  0.552  1.0
  Li  Li3  1  0.952  0.119  0.448  1.0
  Li  Li4  1  0.667  0.119  0.948  1.0
  Li  Li5  1  0.333  0.881  0.052  1.0
  O  O6  1  0.482  0.500  0.750  1.0
  O  O7  1  0.518  0.500  0.250  1.0
  O  O8  1  0.335  0.712  0.163  1.0
  O  O9  1  0.665  0.288  0.837  1.0
  O  O10  1  0.124  0.288  0.337  1.0
  O  O11  1  0.876  0.712  0.663  1.0
  O  O12  1  0.755  0.854  0.388  1.0
  O  O13  1  0.401  0.146  0.112  1.0
  O  O14  1  0.599  0.854  0.888  1.0
  O  O15  1  0.245  0.146  0.612  1.0
  O  O16  1  0.945  0.704  0.941  1.0
  O  O17  1  0.055  0.296  0.059  1.0
  O  O18  1  0.259  0.704  0.441  1.0
  O  O19  1  0.741  0.296  0.559  1.0
  P  P20  1  0.262  0.294  0.184  1.0
  P  P21  1  0.532  0.294  0.684  1.0
  P  P22  1  0.738  0.706  0.816  1.0
  P  P23  1  0.468  0.706  0.316  1.0
[/CIF]
.