The compound described by Li2Cu2Si2O7 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 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(7) atom. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(6) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(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 CuO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Cu(2)O4 trigonal pyramids,  an edgeedge with one Cu(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. In the second Cu site, Cu(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form distorted CuO4 trigonal pyramids that share corners with three equivalent Cu(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 59-79°. 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 Cu(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Cu(2)O4 trigonal pyramids, and edges with two equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles are 61°. 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 Cu(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Cu(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 37-58°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cu(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Cu(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Cu(2), two equivalent Cu(1), and one Si(1) atom to form distorted OCu3Si tetrahedra that share  a cornercorner with one O(4)Li2CuSi tetrahedra,  a cornercorner with one O(5)Li2CuSi tetrahedra, and  an edgeedge with one O(3)Cu3Si tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Cu(2), and one Si(2) atom to form distorted OLi2CuSi tetrahedra that share  a cornercorner with one O(3)Cu3Si tetrahedra and corners with four equivalent O(5)Li2CuSi tetrahedra. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Cu(2), and one Si(2) atom to form OLi2CuSi tetrahedra that share  a cornercorner with one O(3)Cu3Si tetrahedra and corners with four equivalent O(4)Li2CuSi tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(2), one Cu(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Li(1), one Cu(1), one Cu(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Li2Cu2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.153
_cell_length_b   5.493
_cell_length_c   9.693
_cell_angle_alpha   56.401
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   583.335
_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  0.350  0.724  0.121  1.0
  Li  Li1  1  0.743  0.029  0.180  1.0
  Li  Li2  1  0.243  0.971  0.320  1.0
  Li  Li3  1  0.850  0.276  0.379  1.0
  Li  Li4  1  0.150  0.724  0.621  1.0
  Li  Li5  1  0.757  0.029  0.680  1.0
  Li  Li6  1  0.257  0.971  0.820  1.0
  Li  Li7  1  0.650  0.276  0.879  1.0
  Cu  Cu8  1  0.082  0.553  0.100  1.0
  Cu  Cu9  1  0.489  0.170  0.185  1.0
  Cu  Cu10  1  0.989  0.830  0.315  1.0
  Cu  Cu11  1  0.582  0.447  0.400  1.0
  Cu  Cu12  1  0.418  0.553  0.600  1.0
  Cu  Cu13  1  0.011  0.170  0.685  1.0
  Cu  Cu14  1  0.511  0.830  0.815  1.0
  Cu  Cu15  1  0.918  0.447  0.900  1.0
  Si  Si16  1  0.883  0.790  0.039  1.0
  Si  Si17  1  0.669  0.634  0.054  1.0
  Si  Si18  1  0.169  0.366  0.446  1.0
  Si  Si19  1  0.383  0.210  0.461  1.0
  Si  Si20  1  0.617  0.790  0.539  1.0
  Si  Si21  1  0.831  0.634  0.554  1.0
  Si  Si22  1  0.331  0.366  0.946  1.0
  Si  Si23  1  0.117  0.210  0.961  1.0
  O  O24  1  0.793  0.571  0.046  1.0
  O  O25  1  0.169  0.897  0.027  1.0
  O  O26  1  0.027  0.217  0.081  1.0
  O  O27  1  0.620  0.330  0.089  1.0
  O  O28  1  0.360  0.075  0.131  1.0
  O  O29  1  0.654  0.709  0.193  1.0
  O  O30  1  0.931  0.615  0.225  1.0
  O  O31  1  0.431  0.385  0.275  1.0
  O  O32  1  0.154  0.291  0.307  1.0
  O  O33  1  0.860  0.925  0.369  1.0
  O  O34  1  0.120  0.670  0.411  1.0
  O  O35  1  0.527  0.783  0.419  1.0
  O  O36  1  0.669  0.103  0.473  1.0
  O  O37  1  0.293  0.429  0.454  1.0
  O  O38  1  0.707  0.571  0.546  1.0
  O  O39  1  0.331  0.897  0.527  1.0
  O  O40  1  0.473  0.217  0.581  1.0
  O  O41  1  0.880  0.330  0.589  1.0
  O  O42  1  0.140  0.075  0.631  1.0
  O  O43  1  0.846  0.709  0.693  1.0
  O  O44  1  0.569  0.615  0.725  1.0
  O  O45  1  0.069  0.385  0.775  1.0
  O  O46  1  0.346  0.291  0.807  1.0
  O  O47  1  0.640  0.925  0.869  1.0
  O  O48  1  0.380  0.670  0.911  1.0
  O  O49  1  0.973  0.783  0.919  1.0
  O  O50  1  0.831  0.103  0.973  1.0
  O  O51  1  0.207  0.429  0.954  1.0
[/CIF]
.
The compound described by Li2Cu2Si2O7 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 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(7) atom. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(6) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(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 CuO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Cu(2)O4 trigonal pyramids,  an edgeedge with one Cu(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. In the second Cu site, Cu(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form distorted CuO4 trigonal pyramids that share corners with three equivalent Cu(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 59-79°. 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 Cu(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Cu(2)O4 trigonal pyramids, and edges with two equivalent Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles are 61°. 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 Cu(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Cu(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 37-58°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cu(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Cu(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Cu(2), two equivalent Cu(1), and one Si(1) atom to form distorted OCu3Si tetrahedra that share  a cornercorner with one O(4)Li2CuSi tetrahedra,  a cornercorner with one O(5)Li2CuSi tetrahedra, and  an edgeedge with one O(3)Cu3Si tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Cu(2), and one Si(2) atom to form distorted OLi2CuSi tetrahedra that share  a cornercorner with one O(3)Cu3Si tetrahedra and corners with four equivalent O(5)Li2CuSi tetrahedra. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Cu(2), and one Si(2) atom to form OLi2CuSi tetrahedra that share  a cornercorner with one O(3)Cu3Si tetrahedra and corners with four equivalent O(4)Li2CuSi tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(2), one Cu(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Li(1), one Cu(1), one Cu(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Li2Cu2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.153
_cell_length_b   5.493
_cell_length_c   9.693
_cell_angle_alpha   56.401
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   583.335
_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  0.350  0.724  0.121  1.0
  Li  Li1  1  0.743  0.029  0.180  1.0
  Li  Li2  1  0.243  0.971  0.320  1.0
  Li  Li3  1  0.850  0.276  0.379  1.0
  Li  Li4  1  0.150  0.724  0.621  1.0
  Li  Li5  1  0.757  0.029  0.680  1.0
  Li  Li6  1  0.257  0.971  0.820  1.0
  Li  Li7  1  0.650  0.276  0.879  1.0
  Cu  Cu8  1  0.082  0.553  0.100  1.0
  Cu  Cu9  1  0.489  0.170  0.185  1.0
  Cu  Cu10  1  0.989  0.830  0.315  1.0
  Cu  Cu11  1  0.582  0.447  0.400  1.0
  Cu  Cu12  1  0.418  0.553  0.600  1.0
  Cu  Cu13  1  0.011  0.170  0.685  1.0
  Cu  Cu14  1  0.511  0.830  0.815  1.0
  Cu  Cu15  1  0.918  0.447  0.900  1.0
  Si  Si16  1  0.883  0.790  0.039  1.0
  Si  Si17  1  0.669  0.634  0.054  1.0
  Si  Si18  1  0.169  0.366  0.446  1.0
  Si  Si19  1  0.383  0.210  0.461  1.0
  Si  Si20  1  0.617  0.790  0.539  1.0
  Si  Si21  1  0.831  0.634  0.554  1.0
  Si  Si22  1  0.331  0.366  0.946  1.0
  Si  Si23  1  0.117  0.210  0.961  1.0
  O  O24  1  0.793  0.571  0.046  1.0
  O  O25  1  0.169  0.897  0.027  1.0
  O  O26  1  0.027  0.217  0.081  1.0
  O  O27  1  0.620  0.330  0.089  1.0
  O  O28  1  0.360  0.075  0.131  1.0
  O  O29  1  0.654  0.709  0.193  1.0
  O  O30  1  0.931  0.615  0.225  1.0
  O  O31  1  0.431  0.385  0.275  1.0
  O  O32  1  0.154  0.291  0.307  1.0
  O  O33  1  0.860  0.925  0.369  1.0
  O  O34  1  0.120  0.670  0.411  1.0
  O  O35  1  0.527  0.783  0.419  1.0
  O  O36  1  0.669  0.103  0.473  1.0
  O  O37  1  0.293  0.429  0.454  1.0
  O  O38  1  0.707  0.571  0.546  1.0
  O  O39  1  0.331  0.897  0.527  1.0
  O  O40  1  0.473  0.217  0.581  1.0
  O  O41  1  0.880  0.330  0.589  1.0
  O  O42  1  0.140  0.075  0.631  1.0
  O  O43  1  0.846  0.709  0.693  1.0
  O  O44  1  0.569  0.615  0.725  1.0
  O  O45  1  0.069  0.385  0.775  1.0
  O  O46  1  0.346  0.291  0.807  1.0
  O  O47  1  0.640  0.925  0.869  1.0
  O  O48  1  0.380  0.670  0.911  1.0
  O  O49  1  0.973  0.783  0.919  1.0
  O  O50  1  0.831  0.103  0.973  1.0
  O  O51  1  0.207  0.429  0.954  1.0
[/CIF]
.