The compound described by Li2CrP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form distorted LiO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and corners with three equivalent Cr(1)O5 trigonal bipyramids. 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 two equivalent Li(1)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Cr(1)O5 trigonal bipyramids. Cr(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CrO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent Li(1)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 Li(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra, and corners with three equivalent Cr(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, corners with three equivalent Li(1)O4 tetrahedra, and corners with two equivalent Cr(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 trigonal planar geometry to one Li(1), one Cr(1), and one P(2) atom. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Li(2), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(2), one Cr(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Cr(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 Cr(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_Li2CrP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.709
_cell_length_b   5.104
_cell_length_c   7.965
_cell_angle_alpha   86.567
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   556.367
_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  0.101  0.192  0.859  1.0
  Li  Li1  1  0.899  0.808  0.141  1.0
  Li  Li2  1  0.302  0.260  0.171  1.0
  Li  Li3  1  0.802  0.240  0.329  1.0
  Li  Li4  1  0.399  0.692  0.359  1.0
  Li  Li5  1  0.698  0.740  0.829  1.0
  Li  Li6  1  0.198  0.760  0.671  1.0
  Li  Li7  1  0.601  0.308  0.641  1.0
  Cr  Cr8  1  0.153  0.787  0.241  1.0
  Cr  Cr9  1  0.653  0.713  0.259  1.0
  Cr  Cr10  1  0.347  0.287  0.741  1.0
  Cr  Cr11  1  0.847  0.213  0.759  1.0
  P  P12  1  0.827  0.731  0.530  1.0
  P  P13  1  0.173  0.269  0.470  1.0
  P  P14  1  0.525  0.212  0.276  1.0
  P  P15  1  0.025  0.288  0.224  1.0
  P  P16  1  0.327  0.769  0.970  1.0
  P  P17  1  0.975  0.712  0.776  1.0
  P  P18  1  0.673  0.231  0.030  1.0
  P  P19  1  0.475  0.788  0.724  1.0
  O  O20  1  0.942  0.736  0.577  1.0
  O  O21  1  0.102  0.130  0.128  1.0
  O  O22  1  0.558  0.236  0.077  1.0
  O  O23  1  0.711  0.513  0.047  1.0
  O  O24  1  0.289  0.487  0.953  1.0
  O  O25  1  0.442  0.764  0.923  1.0
  O  O26  1  0.898  0.870  0.872  1.0
  O  O27  1  0.279  0.961  0.837  1.0
  O  O28  1  0.683  0.135  0.853  1.0
  O  O29  1  0.969  0.415  0.827  1.0
  O  O30  1  0.076  0.831  0.781  1.0
  O  O31  1  0.576  0.669  0.719  1.0
  O  O32  1  0.779  0.539  0.663  1.0
  O  O33  1  0.317  0.865  0.147  1.0
  O  O34  1  0.183  0.365  0.647  1.0
  O  O35  1  0.398  0.630  0.628  1.0
  O  O36  1  0.469  0.085  0.673  1.0
  O  O37  1  0.789  0.013  0.547  1.0
  O  O38  1  0.211  0.987  0.453  1.0
  O  O39  1  0.058  0.264  0.423  1.0
  O  O40  1  0.602  0.370  0.372  1.0
  O  O41  1  0.817  0.635  0.353  1.0
  O  O42  1  0.531  0.915  0.327  1.0
  O  O43  1  0.221  0.461  0.337  1.0
  O  O44  1  0.424  0.331  0.281  1.0
  O  O45  1  0.924  0.169  0.219  1.0
  O  O46  1  0.031  0.585  0.173  1.0
  O  O47  1  0.721  0.039  0.163  1.0
[/CIF]
.
The compound described by Li2CrP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form distorted LiO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and corners with three equivalent Cr(1)O5 trigonal bipyramids. 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 two equivalent Li(1)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and corners with three equivalent Cr(1)O5 trigonal bipyramids. Cr(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CrO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent Li(1)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 Li(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra, and corners with three equivalent Cr(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, corners with three equivalent Li(1)O4 tetrahedra, and corners with two equivalent Cr(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 trigonal planar geometry to one Li(1), one Cr(1), and one P(2) atom. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Li(2), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(2), one Cr(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Cr(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 Cr(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_Li2CrP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.709
_cell_length_b   5.104
_cell_length_c   7.965
_cell_angle_alpha   86.567
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   556.367
_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  0.101  0.192  0.859  1.0
  Li  Li1  1  0.899  0.808  0.141  1.0
  Li  Li2  1  0.302  0.260  0.171  1.0
  Li  Li3  1  0.802  0.240  0.329  1.0
  Li  Li4  1  0.399  0.692  0.359  1.0
  Li  Li5  1  0.698  0.740  0.829  1.0
  Li  Li6  1  0.198  0.760  0.671  1.0
  Li  Li7  1  0.601  0.308  0.641  1.0
  Cr  Cr8  1  0.153  0.787  0.241  1.0
  Cr  Cr9  1  0.653  0.713  0.259  1.0
  Cr  Cr10  1  0.347  0.287  0.741  1.0
  Cr  Cr11  1  0.847  0.213  0.759  1.0
  P  P12  1  0.827  0.731  0.530  1.0
  P  P13  1  0.173  0.269  0.470  1.0
  P  P14  1  0.525  0.212  0.276  1.0
  P  P15  1  0.025  0.288  0.224  1.0
  P  P16  1  0.327  0.769  0.970  1.0
  P  P17  1  0.975  0.712  0.776  1.0
  P  P18  1  0.673  0.231  0.030  1.0
  P  P19  1  0.475  0.788  0.724  1.0
  O  O20  1  0.942  0.736  0.577  1.0
  O  O21  1  0.102  0.130  0.128  1.0
  O  O22  1  0.558  0.236  0.077  1.0
  O  O23  1  0.711  0.513  0.047  1.0
  O  O24  1  0.289  0.487  0.953  1.0
  O  O25  1  0.442  0.764  0.923  1.0
  O  O26  1  0.898  0.870  0.872  1.0
  O  O27  1  0.279  0.961  0.837  1.0
  O  O28  1  0.683  0.135  0.853  1.0
  O  O29  1  0.969  0.415  0.827  1.0
  O  O30  1  0.076  0.831  0.781  1.0
  O  O31  1  0.576  0.669  0.719  1.0
  O  O32  1  0.779  0.539  0.663  1.0
  O  O33  1  0.317  0.865  0.147  1.0
  O  O34  1  0.183  0.365  0.647  1.0
  O  O35  1  0.398  0.630  0.628  1.0
  O  O36  1  0.469  0.085  0.673  1.0
  O  O37  1  0.789  0.013  0.547  1.0
  O  O38  1  0.211  0.987  0.453  1.0
  O  O39  1  0.058  0.264  0.423  1.0
  O  O40  1  0.602  0.370  0.372  1.0
  O  O41  1  0.817  0.635  0.353  1.0
  O  O42  1  0.531  0.915  0.327  1.0
  O  O43  1  0.221  0.461  0.337  1.0
  O  O44  1  0.424  0.331  0.281  1.0
  O  O45  1  0.924  0.169  0.219  1.0
  O  O46  1  0.031  0.585  0.173  1.0
  O  O47  1  0.721  0.039  0.163  1.0
[/CIF]
.