The crystal structure described by Ba3(SiAs2)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(2)As6 octahedra, corners with two equivalent Ba(3)As6 octahedra, corners with four equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(1)As6 octahedra, edges with three equivalent Ba(3)As6 octahedra, edges with four equivalent Ba(2)As6 octahedra, and edges with two equivalent Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 9-16°. In the second Ba site, Ba(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent Ba(3)As6 octahedra, corners with eight equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(2)As6 octahedra, edges with three equivalent Ba(3)As6 octahedra, and edges with four equivalent Ba(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 8-9°. In the third Ba site, Ba(3) is bonded to two equivalent As(2) and four equivalent As(1) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent Ba(2)As6 octahedra, corners with six equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(3)As6 octahedra, edges with three equivalent Ba(1)As6 octahedra, edges with three equivalent Ba(2)As6 octahedra, and edges with two equivalent Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 8-16°. Si(1) is bonded to one Si(1), one As(2), and two equivalent As(1) atoms to form distorted SiSiAs3 tetrahedra that share  a cornercorner with one As(2)Ba5Si octahedra, corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent As(1)Ba4Si2 octahedra, corners with three equivalent Ba(3)As6 octahedra, corners with four equivalent Ba(2)As6 octahedra,  an edgeedge with one Ba(1)As6 octahedra,  an edgeedge with one Ba(3)As6 octahedra, and  an edgeedge with one Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 16-81°. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), and two equivalent Si(1) atoms to form distorted AsBa4Si2 octahedra that share corners with four equivalent As(1)Ba4Si2 octahedra, corners with four equivalent As(2)Ba5Si octahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, edges with three equivalent As(1)Ba4Si2 octahedra, and edges with five equivalent As(2)Ba5Si octahedra. The corner-sharing octahedral tilt angles range from 5-97°. In the second As site, As(2) is bonded to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), and one Si(1) atom to form AsBa5Si octahedra that share corners with three equivalent As(2)Ba5Si octahedra, corners with four equivalent As(1)Ba4Si2 octahedra,  a cornercorner with one Si(1)SiAs3 tetrahedra, edges with five equivalent As(1)Ba4Si2 octahedra, and edges with five equivalent As(2)Ba5Si octahedra. The corner-sharing octahedral tilt angles range from 5-94°. is represented by the CIF file [CIF]
data_Ba3(SiAs2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.797
_cell_length_b   8.525
_cell_length_c   10.050
_cell_angle_alpha   107.832
_cell_angle_beta   105.035
_cell_angle_gamma   107.695
_symmetry_Int_Tables_number   1
_cell_volume   558.220
_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
  Ba  Ba0  1  0.693  0.943  0.886  1.0
  Ba  Ba1  1  0.307  0.057  0.114  1.0
  Ba  Ba2  1  0.815  0.565  0.131  1.0
  Ba  Ba3  1  0.185  0.435  0.869  1.0
  Ba  Ba4  1  0.060  0.810  0.620  1.0
  Ba  Ba5  1  0.940  0.190  0.380  1.0
  Si  Si6  1  0.622  0.466  0.637  1.0
  Si  Si7  1  0.514  0.171  0.636  1.0
  Si  Si8  1  0.378  0.534  0.363  1.0
  Si  Si9  1  0.486  0.829  0.364  1.0
  As  As10  1  0.648  0.445  0.397  1.0
  As  As11  1  0.250  0.952  0.397  1.0
  As  As12  1  0.443  0.189  0.853  1.0
  As  As13  1  0.910  0.665  0.853  1.0
  As  As14  1  0.557  0.811  0.147  1.0
  As  As15  1  0.090  0.335  0.147  1.0
  As  As16  1  0.750  0.048  0.603  1.0
  As  As17  1  0.352  0.555  0.603  1.0
[/CIF]
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The crystal structure described by Ba3(SiAs2)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(2)As6 octahedra, corners with two equivalent Ba(3)As6 octahedra, corners with four equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(1)As6 octahedra, edges with three equivalent Ba(3)As6 octahedra, edges with four equivalent Ba(2)As6 octahedra, and edges with two equivalent Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 9-16°. In the second Ba site, Ba(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent Ba(3)As6 octahedra, corners with eight equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(2)As6 octahedra, edges with three equivalent Ba(3)As6 octahedra, and edges with four equivalent Ba(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 8-9°. In the third Ba site, Ba(3) is bonded to two equivalent As(2) and four equivalent As(1) atoms to form BaAs6 octahedra that share corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent Ba(2)As6 octahedra, corners with six equivalent Si(1)SiAs3 tetrahedra, edges with two equivalent Ba(3)As6 octahedra, edges with three equivalent Ba(1)As6 octahedra, edges with three equivalent Ba(2)As6 octahedra, and edges with two equivalent Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 8-16°. Si(1) is bonded to one Si(1), one As(2), and two equivalent As(1) atoms to form distorted SiSiAs3 tetrahedra that share  a cornercorner with one As(2)Ba5Si octahedra, corners with two equivalent Ba(1)As6 octahedra, corners with two equivalent As(1)Ba4Si2 octahedra, corners with three equivalent Ba(3)As6 octahedra, corners with four equivalent Ba(2)As6 octahedra,  an edgeedge with one Ba(1)As6 octahedra,  an edgeedge with one Ba(3)As6 octahedra, and  an edgeedge with one Si(1)SiAs3 tetrahedra. The corner-sharing octahedral tilt angles range from 16-81°. There are two inequivalent As sites. In the first As site, As(1) is bonded to one Ba(1), one Ba(2), two equivalent Ba(3), and two equivalent Si(1) atoms to form distorted AsBa4Si2 octahedra that share corners with four equivalent As(1)Ba4Si2 octahedra, corners with four equivalent As(2)Ba5Si octahedra, corners with two equivalent Si(1)SiAs3 tetrahedra, edges with three equivalent As(1)Ba4Si2 octahedra, and edges with five equivalent As(2)Ba5Si octahedra. The corner-sharing octahedral tilt angles range from 5-97°. In the second As site, As(2) is bonded to one Ba(3), two equivalent Ba(1), two equivalent Ba(2), and one Si(1) atom to form AsBa5Si octahedra that share corners with three equivalent As(2)Ba5Si octahedra, corners with four equivalent As(1)Ba4Si2 octahedra,  a cornercorner with one Si(1)SiAs3 tetrahedra, edges with five equivalent As(1)Ba4Si2 octahedra, and edges with five equivalent As(2)Ba5Si octahedra. The corner-sharing octahedral tilt angles range from 5-94°. is represented by the CIF file [CIF]
data_Ba3(SiAs2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.797
_cell_length_b   8.525
_cell_length_c   10.050
_cell_angle_alpha   107.832
_cell_angle_beta   105.035
_cell_angle_gamma   107.695
_symmetry_Int_Tables_number   1
_cell_volume   558.220
_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
  Ba  Ba0  1  0.693  0.943  0.886  1.0
  Ba  Ba1  1  0.307  0.057  0.114  1.0
  Ba  Ba2  1  0.815  0.565  0.131  1.0
  Ba  Ba3  1  0.185  0.435  0.869  1.0
  Ba  Ba4  1  0.060  0.810  0.620  1.0
  Ba  Ba5  1  0.940  0.190  0.380  1.0
  Si  Si6  1  0.622  0.466  0.637  1.0
  Si  Si7  1  0.514  0.171  0.636  1.0
  Si  Si8  1  0.378  0.534  0.363  1.0
  Si  Si9  1  0.486  0.829  0.364  1.0
  As  As10  1  0.648  0.445  0.397  1.0
  As  As11  1  0.250  0.952  0.397  1.0
  As  As12  1  0.443  0.189  0.853  1.0
  As  As13  1  0.910  0.665  0.853  1.0
  As  As14  1  0.557  0.811  0.147  1.0
  As  As15  1  0.090  0.335  0.147  1.0
  As  As16  1  0.750  0.048  0.603  1.0
  As  As17  1  0.352  0.555  0.603  1.0
[/CIF]
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