The material structure described by Cr5(SiN3)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent N(1) and two equivalent N(3) atoms to form distorted CrN4 trigonal pyramids that share corners with four equivalent Si(1)N4 tetrahedra. In the second Cr site, Cr(2) is bonded in a distorted square co-planar geometry to one N(1), one N(3), and two equivalent N(2) atoms. In the third Cr site, Cr(3) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(3) atoms. Si(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form distorted SiN4 tetrahedra that share corners with two equivalent Cr(1)N4 trigonal pyramids and  an edgeedge with one Si(1)N4 tetrahedra. There are three inequivalent N sites. In the first N site, N(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cr(2) and two equivalent Si(1) atoms. In the second N site, N(3) is bonded to one Cr(1), one Cr(2), two equivalent Cr(3), and one Si(1) atom to form a mixture of distorted corner, edge, and face-sharing NCr4Si square pyramids. In the third N site, N(1) is bonded to one Cr(1), one Cr(2), two equivalent Cr(3), and one Si(1) atom to form a mixture of corner and edge-sharing NCr4Si square pyramids. is represented by the CIF file [CIF]
data_Cr5(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.796
_cell_length_b   5.062
_cell_length_c   14.078
_cell_angle_alpha   90.000
_cell_angle_beta   95.342
_cell_angle_gamma   121.851
_symmetry_Int_Tables_number   1
_cell_volume   288.577
_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  0.000  0.481  0.750  1.0
  Cr  Cr1  1  0.000  0.519  0.250  1.0
  Cr  Cr2  1  0.340  0.899  0.092  1.0
  Cr  Cr3  1  0.660  0.559  0.408  1.0
  Cr  Cr4  1  0.660  0.101  0.908  1.0
  Cr  Cr5  1  0.340  0.441  0.592  1.0
  Cr  Cr6  1  0.314  0.137  0.742  1.0
  Cr  Cr7  1  0.686  0.823  0.758  1.0
  Cr  Cr8  1  0.686  0.863  0.258  1.0
  Cr  Cr9  1  0.314  0.177  0.242  1.0
  Si  Si10  1  0.590  0.038  0.589  1.0
  Si  Si11  1  0.410  0.448  0.911  1.0
  Si  Si12  1  0.410  0.962  0.411  1.0
  Si  Si13  1  0.590  0.552  0.089  1.0
  N  N14  1  0.322  0.799  0.671  1.0
  N  N15  1  0.678  0.477  0.829  1.0
  N  N16  1  0.678  0.201  0.329  1.0
  N  N17  1  0.322  0.523  0.171  1.0
  N  N18  1  0.476  0.230  0.507  1.0
  N  N19  1  0.524  0.754  0.993  1.0
  N  N20  1  0.524  0.770  0.493  1.0
  N  N21  1  0.476  0.246  0.007  1.0
  N  N22  1  0.961  0.152  0.658  1.0
  N  N23  1  0.039  0.192  0.842  1.0
  N  N24  1  0.039  0.848  0.342  1.0
  N  N25  1  0.961  0.808  0.158  1.0
[/CIF]
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The material structure described by Cr5(SiN3)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent N(1) and two equivalent N(3) atoms to form distorted CrN4 trigonal pyramids that share corners with four equivalent Si(1)N4 tetrahedra. In the second Cr site, Cr(2) is bonded in a distorted square co-planar geometry to one N(1), one N(3), and two equivalent N(2) atoms. In the third Cr site, Cr(3) is bonded in a 4-coordinate geometry to two equivalent N(1) and two equivalent N(3) atoms. Si(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form distorted SiN4 tetrahedra that share corners with two equivalent Cr(1)N4 trigonal pyramids and  an edgeedge with one Si(1)N4 tetrahedra. There are three inequivalent N sites. In the first N site, N(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cr(2) and two equivalent Si(1) atoms. In the second N site, N(3) is bonded to one Cr(1), one Cr(2), two equivalent Cr(3), and one Si(1) atom to form a mixture of distorted corner, edge, and face-sharing NCr4Si square pyramids. In the third N site, N(1) is bonded to one Cr(1), one Cr(2), two equivalent Cr(3), and one Si(1) atom to form a mixture of corner and edge-sharing NCr4Si square pyramids. is represented by the CIF file [CIF]
data_Cr5(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.796
_cell_length_b   5.062
_cell_length_c   14.078
_cell_angle_alpha   90.000
_cell_angle_beta   95.342
_cell_angle_gamma   121.851
_symmetry_Int_Tables_number   1
_cell_volume   288.577
_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  0.000  0.481  0.750  1.0
  Cr  Cr1  1  0.000  0.519  0.250  1.0
  Cr  Cr2  1  0.340  0.899  0.092  1.0
  Cr  Cr3  1  0.660  0.559  0.408  1.0
  Cr  Cr4  1  0.660  0.101  0.908  1.0
  Cr  Cr5  1  0.340  0.441  0.592  1.0
  Cr  Cr6  1  0.314  0.137  0.742  1.0
  Cr  Cr7  1  0.686  0.823  0.758  1.0
  Cr  Cr8  1  0.686  0.863  0.258  1.0
  Cr  Cr9  1  0.314  0.177  0.242  1.0
  Si  Si10  1  0.590  0.038  0.589  1.0
  Si  Si11  1  0.410  0.448  0.911  1.0
  Si  Si12  1  0.410  0.962  0.411  1.0
  Si  Si13  1  0.590  0.552  0.089  1.0
  N  N14  1  0.322  0.799  0.671  1.0
  N  N15  1  0.678  0.477  0.829  1.0
  N  N16  1  0.678  0.201  0.329  1.0
  N  N17  1  0.322  0.523  0.171  1.0
  N  N18  1  0.476  0.230  0.507  1.0
  N  N19  1  0.524  0.754  0.993  1.0
  N  N20  1  0.524  0.770  0.493  1.0
  N  N21  1  0.476  0.246  0.007  1.0
  N  N22  1  0.961  0.152  0.658  1.0
  N  N23  1  0.039  0.192  0.842  1.0
  N  N24  1  0.039  0.848  0.342  1.0
  N  N25  1  0.961  0.808  0.158  1.0
[/CIF]
.