data_MnSiAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.56
_cell_length_b   4.56
_cell_length_c   4.56
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MnSiAs2
_chemical_formula_sum   'Mn1 Si1 As2'
_cell_volume   67.02
_cell_formula_units_Z   1
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
  Mn  Mn2  1  0.61  0.61  0.61  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0
  As  As0  1  0.84  0.84  0.84  1.0
  As  As1  1  0.22  0.22  0.22  1.0

data_MnSiAs2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.56
_cell_length_b   4.56
_cell_length_c   11.17
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MnSiAs2
_chemical_formula_sum   'Mn3 Si3 As6'
_cell_volume   201.07
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Mn  Mn0  3  0.0  0.0  0.39  1.0
  Si  Si1  3  0.0  0.0  0.0  1.0
  As  As2  3  0.0  0.0  0.16  1.0
  As  As3  3  0.0  0.0  0.78  1.0

Mn Si As As
Mn Si As As 0 2 o - o 0 2 - o o 0 2 o o - 0 2 o o o 0 3 o o + 0 3 o + o 0 3 + o o 0 1 o + + 0 1 + o + 0 1 + + o 1 2 - - - 1 3 o o o 1 3 o o - 1 3 - o o 1 3 o - o 2 3 + + o 2 3 + o + 2 3 o + + 
MnSiAs2 crystallizes in the trigonal R3m space group. Mn(1) is bonded in a 10-coordinate geometry to three equivalent Si(1), three equivalent As(2), and four equivalent As(1) atoms. All Mn(1)-Si(1) bond lengths are 2.70 Å. All Mn(1)-As(2) bond lengths are 2.70 Å. There is one shorter (2.50 Å) and three longer (2.90 Å) Mn(1)-As(1) bond lengths. Si(1) is bonded in a 1-coordinate geometry to three equivalent Mn(1), one As(1), and one As(2) atom. The Si(1)-As(1) bond length is 1.83 Å. The Si(1)-As(2) bond length is 2.50 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded in a distorted linear geometry to four equivalent Mn(1) and one Si(1) atom. In the second As site, As(2) is bonded to three equivalent Mn(1) and one Si(1) atom to form distorted corner-sharing AsMn3Si tetrahedra.