The compound described by Li2Ni2Si2O7 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 3-coordinate geometry to one O(4), one O(5), and one O(7) atom. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(6), one O(7), and two equivalent O(3) atoms to form distorted NiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. In the second Ni site, Ni(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form NiO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-72°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Li(2), one Ni(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ni(2), two equivalent Ni(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Ni(2), and one Si(2) atom to form distorted OLi2SiNi tetrahedra that share corners with two equivalent O(7)LiSiNi2 tetrahedra and corners with four equivalent O(5)Li2SiNi tetrahedra. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Ni(2), and one Si(2) atom to form OLi2SiNi tetrahedra that share corners with two equivalent O(7)LiSiNi2 tetrahedra and corners with four equivalent O(4)Li2SiNi tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one Si(2) atom. In the seventh O site, O(7) is bonded to one Li(1), one Ni(1), one Ni(2), and one Si(1) atom to form corner-sharing OLiSiNi2 tetrahedra. is represented by the CIF card [CIF]
data_Li2Si2Ni2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.021
_cell_length_b   5.484
_cell_length_c   9.650
_cell_angle_alpha   56.615
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   575.454
_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  0.358  0.729  0.119  1.0
  Li  Li1  1  0.749  0.028  0.175  1.0
  Li  Li2  1  0.249  0.972  0.325  1.0
  Li  Li3  1  0.858  0.271  0.381  1.0
  Li  Li4  1  0.142  0.729  0.619  1.0
  Li  Li5  1  0.751  0.028  0.675  1.0
  Li  Li6  1  0.251  0.972  0.825  1.0
  Li  Li7  1  0.642  0.271  0.881  1.0
  Si  Si8  1  0.890  0.788  0.032  1.0
  Si  Si9  1  0.677  0.635  0.045  1.0
  Si  Si10  1  0.177  0.365  0.455  1.0
  Si  Si11  1  0.390  0.212  0.468  1.0
  Si  Si12  1  0.610  0.788  0.532  1.0
  Si  Si13  1  0.823  0.635  0.545  1.0
  Si  Si14  1  0.323  0.365  0.955  1.0
  Si  Si15  1  0.110  0.212  0.968  1.0
  Ni  Ni16  1  0.086  0.549  0.105  1.0
  Ni  Ni17  1  0.491  0.169  0.191  1.0
  Ni  Ni18  1  0.991  0.831  0.309  1.0
  Ni  Ni19  1  0.586  0.451  0.395  1.0
  Ni  Ni20  1  0.414  0.549  0.605  1.0
  Ni  Ni21  1  0.009  0.169  0.691  1.0
  Ni  Ni22  1  0.509  0.831  0.809  1.0
  Ni  Ni23  1  0.914  0.451  0.895  1.0
  O  O24  1  0.802  0.560  0.040  1.0
  O  O25  1  0.165  0.913  0.018  1.0
  O  O26  1  0.025  0.200  0.099  1.0
  O  O27  1  0.622  0.342  0.072  1.0
  O  O28  1  0.356  0.076  0.137  1.0
  O  O29  1  0.663  0.702  0.187  1.0
  O  O30  1  0.951  0.605  0.212  1.0
  O  O31  1  0.451  0.395  0.288  1.0
  O  O32  1  0.163  0.298  0.313  1.0
  O  O33  1  0.856  0.924  0.363  1.0
  O  O34  1  0.122  0.658  0.428  1.0
  O  O35  1  0.525  0.800  0.401  1.0
  O  O36  1  0.665  0.087  0.482  1.0
  O  O37  1  0.302  0.440  0.460  1.0
  O  O38  1  0.698  0.560  0.540  1.0
  O  O39  1  0.335  0.913  0.518  1.0
  O  O40  1  0.475  0.200  0.599  1.0
  O  O41  1  0.878  0.342  0.572  1.0
  O  O42  1  0.144  0.076  0.637  1.0
  O  O43  1  0.837  0.702  0.687  1.0
  O  O44  1  0.549  0.605  0.712  1.0
  O  O45  1  0.049  0.395  0.788  1.0
  O  O46  1  0.337  0.298  0.813  1.0
  O  O47  1  0.644  0.924  0.863  1.0
  O  O48  1  0.378  0.658  0.928  1.0
  O  O49  1  0.975  0.800  0.901  1.0
  O  O50  1  0.835  0.087  0.982  1.0
  O  O51  1  0.198  0.440  0.960  1.0
[/CIF]
.
The compound described by Li2Ni2Si2O7 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 3-coordinate geometry to one O(4), one O(5), and one O(7) atom. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(2), one O(6), one O(7), and two equivalent O(3) atoms to form distorted NiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra,  an edgeedge with one Ni(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. In the second Ni site, Ni(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form NiO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-72°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Ni(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Li(2), one Ni(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ni(2), two equivalent Ni(1), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Ni(2), and one Si(2) atom to form distorted OLi2SiNi tetrahedra that share corners with two equivalent O(7)LiSiNi2 tetrahedra and corners with four equivalent O(5)Li2SiNi tetrahedra. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Ni(2), and one Si(2) atom to form OLi2SiNi tetrahedra that share corners with two equivalent O(7)LiSiNi2 tetrahedra and corners with four equivalent O(4)Li2SiNi tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one Si(2) atom. In the seventh O site, O(7) is bonded to one Li(1), one Ni(1), one Ni(2), and one Si(1) atom to form corner-sharing OLiSiNi2 tetrahedra. is represented by the CIF card [CIF]
data_Li2Si2Ni2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.021
_cell_length_b   5.484
_cell_length_c   9.650
_cell_angle_alpha   56.615
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   575.454
_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  0.358  0.729  0.119  1.0
  Li  Li1  1  0.749  0.028  0.175  1.0
  Li  Li2  1  0.249  0.972  0.325  1.0
  Li  Li3  1  0.858  0.271  0.381  1.0
  Li  Li4  1  0.142  0.729  0.619  1.0
  Li  Li5  1  0.751  0.028  0.675  1.0
  Li  Li6  1  0.251  0.972  0.825  1.0
  Li  Li7  1  0.642  0.271  0.881  1.0
  Si  Si8  1  0.890  0.788  0.032  1.0
  Si  Si9  1  0.677  0.635  0.045  1.0
  Si  Si10  1  0.177  0.365  0.455  1.0
  Si  Si11  1  0.390  0.212  0.468  1.0
  Si  Si12  1  0.610  0.788  0.532  1.0
  Si  Si13  1  0.823  0.635  0.545  1.0
  Si  Si14  1  0.323  0.365  0.955  1.0
  Si  Si15  1  0.110  0.212  0.968  1.0
  Ni  Ni16  1  0.086  0.549  0.105  1.0
  Ni  Ni17  1  0.491  0.169  0.191  1.0
  Ni  Ni18  1  0.991  0.831  0.309  1.0
  Ni  Ni19  1  0.586  0.451  0.395  1.0
  Ni  Ni20  1  0.414  0.549  0.605  1.0
  Ni  Ni21  1  0.009  0.169  0.691  1.0
  Ni  Ni22  1  0.509  0.831  0.809  1.0
  Ni  Ni23  1  0.914  0.451  0.895  1.0
  O  O24  1  0.802  0.560  0.040  1.0
  O  O25  1  0.165  0.913  0.018  1.0
  O  O26  1  0.025  0.200  0.099  1.0
  O  O27  1  0.622  0.342  0.072  1.0
  O  O28  1  0.356  0.076  0.137  1.0
  O  O29  1  0.663  0.702  0.187  1.0
  O  O30  1  0.951  0.605  0.212  1.0
  O  O31  1  0.451  0.395  0.288  1.0
  O  O32  1  0.163  0.298  0.313  1.0
  O  O33  1  0.856  0.924  0.363  1.0
  O  O34  1  0.122  0.658  0.428  1.0
  O  O35  1  0.525  0.800  0.401  1.0
  O  O36  1  0.665  0.087  0.482  1.0
  O  O37  1  0.302  0.440  0.460  1.0
  O  O38  1  0.698  0.560  0.540  1.0
  O  O39  1  0.335  0.913  0.518  1.0
  O  O40  1  0.475  0.200  0.599  1.0
  O  O41  1  0.878  0.342  0.572  1.0
  O  O42  1  0.144  0.076  0.637  1.0
  O  O43  1  0.837  0.702  0.687  1.0
  O  O44  1  0.549  0.605  0.712  1.0
  O  O45  1  0.049  0.395  0.788  1.0
  O  O46  1  0.337  0.298  0.813  1.0
  O  O47  1  0.644  0.924  0.863  1.0
  O  O48  1  0.378  0.658  0.928  1.0
  O  O49  1  0.975  0.800  0.901  1.0
  O  O50  1  0.835  0.087  0.982  1.0
  O  O51  1  0.198  0.440  0.960  1.0
[/CIF]
.