The structure described by Cr4Si4O13 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form distorted CrO6 octahedra that share  a cornercorner with one Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and edges with three equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form CrO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  a cornercorner with one Cr(3)O5 trigonal bipyramid,  an edgeedge with one Cr(2)O6 octahedra, and edges with three equivalent Cr(1)O6 octahedra. In the third Cr site, Cr(3) is bonded to one O(1), one O(10), one O(9), and two equivalent O(8) atoms to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one Cr(2)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Cr(4)O6 octahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 50-69°. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(3), one O(8), one O(9), and two equivalent O(7) atoms to form CrO6 octahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Cr(3)O5 trigonal bipyramids,  an edgeedge with one Cr(4)O6 octahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 57°. There are four 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(9) atom to form SiO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra,  an edgeedge with one Cr(4)O6 octahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-62°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(13), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(4)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-73°. In the third Si site, Si(3) is bonded to one O(11), one O(12), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-71°. In the fourth Si site, Si(4) is bonded to one O(11), one O(13), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(4)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-62°. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(1), one Cr(2), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Cr(2), two equivalent Cr(1), and one Si(3) atom to form distorted edge-sharing OCr3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Cr(1), two equivalent Cr(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Cr(4) and one Si(3) atom. In the eighth O site, O(8) is bonded to one Cr(4), two equivalent Cr(3), and one Si(4) atom to form distorted edge-sharing OCr3Si tetrahedra. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Cr(3), one Cr(4), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Cr(3), one Cr(4), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one Si(2) and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cr4Si4O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.979
_cell_length_b   7.779
_cell_length_c   9.953
_cell_angle_alpha   67.503
_cell_angle_beta   82.615
_cell_angle_gamma   79.435
_symmetry_Int_Tables_number   1
_cell_volume   489.700
_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
  Cr  Cr0  1  0.572  0.198  0.993  1.0
  Cr  Cr1  1  0.925  0.807  0.009  1.0
  Cr  Cr2  1  0.062  0.559  0.620  1.0
  Cr  Cr3  1  0.562  0.549  0.628  1.0
  Cr  Cr4  1  0.438  0.451  0.372  1.0
  Cr  Cr5  1  0.938  0.441  0.380  1.0
  Cr  Cr6  1  0.075  0.193  0.991  1.0
  Cr  Cr7  1  0.428  0.802  0.007  1.0
  Si  Si8  1  0.262  0.580  0.833  1.0
  Si  Si9  1  0.717  0.855  0.719  1.0
  Si  Si10  1  0.369  0.147  0.711  1.0
  Si  Si11  1  0.928  0.166  0.701  1.0
  Si  Si12  1  0.072  0.834  0.299  1.0
  Si  Si13  1  0.631  0.853  0.289  1.0
  Si  Si14  1  0.283  0.145  0.281  1.0
  Si  Si15  1  0.738  0.420  0.167  1.0
  O  O16  1  0.091  0.450  0.847  1.0
  O  O17  1  0.197  0.722  0.922  1.0
  O  O18  1  0.490  0.464  0.850  1.0
  O  O19  1  0.743  0.768  0.893  1.0
  O  O20  1  0.355  0.103  0.889  1.0
  O  O21  1  0.898  0.102  0.880  1.0
  O  O22  1  0.448  0.343  0.603  1.0
  O  O23  1  0.843  0.388  0.607  1.0
  O  O24  1  0.286  0.680  0.651  1.0
  O  O25  1  0.751  0.706  0.640  1.0
  O  O26  1  0.157  0.164  0.658  1.0
  O  O27  1  0.493  0.961  0.690  1.0
  O  O28  1  0.856  0.021  0.645  1.0
  O  O29  1  0.144  0.979  0.355  1.0
  O  O30  1  0.507  0.039  0.310  1.0
  O  O31  1  0.843  0.836  0.342  1.0
  O  O32  1  0.249  0.294  0.360  1.0
  O  O33  1  0.714  0.320  0.349  1.0
  O  O34  1  0.157  0.612  0.393  1.0
  O  O35  1  0.552  0.657  0.397  1.0
  O  O36  1  0.102  0.898  0.120  1.0
  O  O37  1  0.645  0.897  0.111  1.0
  O  O38  1  0.257  0.232  0.107  1.0
  O  O39  1  0.510  0.536  0.150  1.0
  O  O40  1  0.803  0.278  0.078  1.0
  O  O41  1  0.909  0.550  0.153  1.0
[/CIF]
.
The structure described by Cr4Si4O13 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form distorted CrO6 octahedra that share  a cornercorner with one Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and edges with three equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form CrO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  a cornercorner with one Cr(3)O5 trigonal bipyramid,  an edgeedge with one Cr(2)O6 octahedra, and edges with three equivalent Cr(1)O6 octahedra. In the third Cr site, Cr(3) is bonded to one O(1), one O(10), one O(9), and two equivalent O(8) atoms to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one Cr(2)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Cr(4)O6 octahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 50-69°. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(3), one O(8), one O(9), and two equivalent O(7) atoms to form CrO6 octahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Cr(3)O5 trigonal bipyramids,  an edgeedge with one Cr(4)O6 octahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 57°. There are four 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(9) atom to form SiO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra,  an edgeedge with one Cr(4)O6 octahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-62°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(13), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(4)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Cr(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-73°. In the third Si site, Si(3) is bonded to one O(11), one O(12), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-71°. In the fourth Si site, Si(4) is bonded to one O(11), one O(13), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(4)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-62°. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(1), one Cr(2), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Cr(2), two equivalent Cr(1), and one Si(3) atom to form distorted edge-sharing OCr3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Cr(1), two equivalent Cr(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Cr(4) and one Si(3) atom. In the eighth O site, O(8) is bonded to one Cr(4), two equivalent Cr(3), and one Si(4) atom to form distorted edge-sharing OCr3Si tetrahedra. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Cr(3), one Cr(4), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Cr(3), one Cr(4), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one Si(2) and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cr4Si4O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.979
_cell_length_b   7.779
_cell_length_c   9.953
_cell_angle_alpha   67.503
_cell_angle_beta   82.615
_cell_angle_gamma   79.435
_symmetry_Int_Tables_number   1
_cell_volume   489.700
_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
  Cr  Cr0  1  0.572  0.198  0.993  1.0
  Cr  Cr1  1  0.925  0.807  0.009  1.0
  Cr  Cr2  1  0.062  0.559  0.620  1.0
  Cr  Cr3  1  0.562  0.549  0.628  1.0
  Cr  Cr4  1  0.438  0.451  0.372  1.0
  Cr  Cr5  1  0.938  0.441  0.380  1.0
  Cr  Cr6  1  0.075  0.193  0.991  1.0
  Cr  Cr7  1  0.428  0.802  0.007  1.0
  Si  Si8  1  0.262  0.580  0.833  1.0
  Si  Si9  1  0.717  0.855  0.719  1.0
  Si  Si10  1  0.369  0.147  0.711  1.0
  Si  Si11  1  0.928  0.166  0.701  1.0
  Si  Si12  1  0.072  0.834  0.299  1.0
  Si  Si13  1  0.631  0.853  0.289  1.0
  Si  Si14  1  0.283  0.145  0.281  1.0
  Si  Si15  1  0.738  0.420  0.167  1.0
  O  O16  1  0.091  0.450  0.847  1.0
  O  O17  1  0.197  0.722  0.922  1.0
  O  O18  1  0.490  0.464  0.850  1.0
  O  O19  1  0.743  0.768  0.893  1.0
  O  O20  1  0.355  0.103  0.889  1.0
  O  O21  1  0.898  0.102  0.880  1.0
  O  O22  1  0.448  0.343  0.603  1.0
  O  O23  1  0.843  0.388  0.607  1.0
  O  O24  1  0.286  0.680  0.651  1.0
  O  O25  1  0.751  0.706  0.640  1.0
  O  O26  1  0.157  0.164  0.658  1.0
  O  O27  1  0.493  0.961  0.690  1.0
  O  O28  1  0.856  0.021  0.645  1.0
  O  O29  1  0.144  0.979  0.355  1.0
  O  O30  1  0.507  0.039  0.310  1.0
  O  O31  1  0.843  0.836  0.342  1.0
  O  O32  1  0.249  0.294  0.360  1.0
  O  O33  1  0.714  0.320  0.349  1.0
  O  O34  1  0.157  0.612  0.393  1.0
  O  O35  1  0.552  0.657  0.397  1.0
  O  O36  1  0.102  0.898  0.120  1.0
  O  O37  1  0.645  0.897  0.111  1.0
  O  O38  1  0.257  0.232  0.107  1.0
  O  O39  1  0.510  0.536  0.150  1.0
  O  O40  1  0.803  0.278  0.078  1.0
  O  O41  1  0.909  0.550  0.153  1.0
[/CIF]
.