The compound described by Li2Cr(Si2O5)3 crystallizes in the orthorhombic Imma space group. Li(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Cr(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with four equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 20°. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to two equivalent Li(1), one Cr(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Cr(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Cr(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.730
_cell_length_b   9.730
_cell_length_c   9.730
_cell_angle_alpha   132.812
_cell_angle_beta   118.581
_cell_angle_gamma   80.909
_symmetry_Int_Tables_number   1
_cell_volume   573.133
_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
  Li  Li0  1  0.244  0.244  0.500  1.0
  Li  Li1  1  0.244  0.744  0.000  1.0
  Li  Li2  1  0.756  0.756  0.500  1.0
  Li  Li3  1  0.756  0.256  0.000  1.0
  Cr  Cr4  1  0.500  0.000  0.500  1.0
  Cr  Cr5  1  0.000  0.500  0.500  1.0
  Si  Si6  1  0.879  0.652  0.227  1.0
  Si  Si7  1  0.075  0.848  0.227  1.0
  Si  Si8  1  0.390  0.545  0.230  1.0
  Si  Si9  1  0.390  0.160  0.845  1.0
  Si  Si10  1  0.185  0.955  0.845  1.0
  Si  Si11  1  0.185  0.340  0.230  1.0
  Si  Si12  1  0.610  0.840  0.155  1.0
  Si  Si13  1  0.610  0.455  0.770  1.0
  Si  Si14  1  0.815  0.045  0.155  1.0
  Si  Si15  1  0.815  0.660  0.770  1.0
  Si  Si16  1  0.121  0.348  0.773  1.0
  Si  Si17  1  0.925  0.152  0.773  1.0
  O  O18  1  0.951  0.250  0.701  1.0
  O  O19  1  0.739  0.068  0.671  1.0
  O  O20  1  0.103  0.432  0.671  1.0
  O  O21  1  0.768  0.811  0.293  1.0
  O  O22  1  0.768  0.475  0.957  1.0
  O  O23  1  0.474  0.371  0.103  1.0
  O  O24  1  0.982  0.689  0.957  1.0
  O  O25  1  0.982  0.025  0.293  1.0
  O  O26  1  0.233  0.129  0.103  1.0
  O  O27  1  0.157  0.393  0.408  1.0
  O  O28  1  0.157  0.749  0.765  1.0
  O  O29  1  0.515  0.751  0.408  1.0
  O  O30  1  0.515  0.107  0.765  1.0
  O  O31  1  0.326  0.991  0.817  1.0
  O  O32  1  0.326  0.509  0.335  1.0
  O  O33  1  0.674  0.009  0.183  1.0
  O  O34  1  0.674  0.491  0.665  1.0
  O  O35  1  0.843  0.251  0.235  1.0
  O  O36  1  0.843  0.607  0.592  1.0
  O  O37  1  0.485  0.249  0.592  1.0
  O  O38  1  0.485  0.893  0.235  1.0
  O  O39  1  0.526  0.629  0.897  1.0
  O  O40  1  0.232  0.525  0.043  1.0
  O  O41  1  0.232  0.189  0.707  1.0
  O  O42  1  0.767  0.871  0.897  1.0
  O  O43  1  0.018  0.311  0.043  1.0
  O  O44  1  0.018  0.975  0.707  1.0
  O  O45  1  0.262  0.932  0.329  1.0
  O  O46  1  0.897  0.568  0.329  1.0
  O  O47  1  0.049  0.750  0.299  1.0
[/CIF]
.
The compound described by Li2Cr(Si2O5)3 crystallizes in the orthorhombic Imma space group. Li(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Cr(1) is bonded to two equivalent O(2) and four equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with four equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 20°. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to two equivalent Li(1), one Cr(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(1), one Cr(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Cr(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.730
_cell_length_b   9.730
_cell_length_c   9.730
_cell_angle_alpha   132.812
_cell_angle_beta   118.581
_cell_angle_gamma   80.909
_symmetry_Int_Tables_number   1
_cell_volume   573.133
_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
  Li  Li0  1  0.244  0.244  0.500  1.0
  Li  Li1  1  0.244  0.744  0.000  1.0
  Li  Li2  1  0.756  0.756  0.500  1.0
  Li  Li3  1  0.756  0.256  0.000  1.0
  Cr  Cr4  1  0.500  0.000  0.500  1.0
  Cr  Cr5  1  0.000  0.500  0.500  1.0
  Si  Si6  1  0.879  0.652  0.227  1.0
  Si  Si7  1  0.075  0.848  0.227  1.0
  Si  Si8  1  0.390  0.545  0.230  1.0
  Si  Si9  1  0.390  0.160  0.845  1.0
  Si  Si10  1  0.185  0.955  0.845  1.0
  Si  Si11  1  0.185  0.340  0.230  1.0
  Si  Si12  1  0.610  0.840  0.155  1.0
  Si  Si13  1  0.610  0.455  0.770  1.0
  Si  Si14  1  0.815  0.045  0.155  1.0
  Si  Si15  1  0.815  0.660  0.770  1.0
  Si  Si16  1  0.121  0.348  0.773  1.0
  Si  Si17  1  0.925  0.152  0.773  1.0
  O  O18  1  0.951  0.250  0.701  1.0
  O  O19  1  0.739  0.068  0.671  1.0
  O  O20  1  0.103  0.432  0.671  1.0
  O  O21  1  0.768  0.811  0.293  1.0
  O  O22  1  0.768  0.475  0.957  1.0
  O  O23  1  0.474  0.371  0.103  1.0
  O  O24  1  0.982  0.689  0.957  1.0
  O  O25  1  0.982  0.025  0.293  1.0
  O  O26  1  0.233  0.129  0.103  1.0
  O  O27  1  0.157  0.393  0.408  1.0
  O  O28  1  0.157  0.749  0.765  1.0
  O  O29  1  0.515  0.751  0.408  1.0
  O  O30  1  0.515  0.107  0.765  1.0
  O  O31  1  0.326  0.991  0.817  1.0
  O  O32  1  0.326  0.509  0.335  1.0
  O  O33  1  0.674  0.009  0.183  1.0
  O  O34  1  0.674  0.491  0.665  1.0
  O  O35  1  0.843  0.251  0.235  1.0
  O  O36  1  0.843  0.607  0.592  1.0
  O  O37  1  0.485  0.249  0.592  1.0
  O  O38  1  0.485  0.893  0.235  1.0
  O  O39  1  0.526  0.629  0.897  1.0
  O  O40  1  0.232  0.525  0.043  1.0
  O  O41  1  0.232  0.189  0.707  1.0
  O  O42  1  0.767  0.871  0.897  1.0
  O  O43  1  0.018  0.311  0.043  1.0
  O  O44  1  0.018  0.975  0.707  1.0
  O  O45  1  0.262  0.932  0.329  1.0
  O  O46  1  0.897  0.568  0.329  1.0
  O  O47  1  0.049  0.750  0.299  1.0
[/CIF]
.