data_Al2CoAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.79
_cell_length_b   2.79
_cell_length_c   7.64
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Al2CoAs
_chemical_formula_sum   'Al2 Co1 As1'
_cell_volume   59.52
_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
  Al  Al0  1  0.4  0.4  0.48  1.0
  Al  Al1  1  0.4  0.4  0.15  1.0
  Co  Co3  1  0.0  0.0  0.0  1.0
  As  As2  1  0.0  0.0  0.82  1.0

data_Al2CoAs
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.95
_cell_length_b   3.95
_cell_length_c   7.64
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Al2CoAs
_chemical_formula_sum   'Al4 Co2 As2'
_cell_volume   119.05
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Al  Al0  2  0.4  0.0  0.15  1.0
  Al  Al1  2  0.4  0.0  0.48  1.0
  Co  Co2  2  0.0  0.0  0.0  1.0
  As  As3  2  0.0  0.0  0.82  1.0

Al Al Co As
CoAl2As crystallizes in the monoclinic Cm space group. Co(1) is bonded in a 1-coordinate geometry to three equivalent Al(2) and one As(1) atom. There is one shorter (1.95 Å) and two longer (2.33 Å) Co(1)-Al(2) bond lengths. The Co(1)-As(1) bond length is 1.38 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one Al(2), four equivalent Al(1), and one As(1) atom to form a mixture of distorted corner and edge-sharing AlAl5As octahedra. The corner-sharing octahedra are not tilted. The Al(1)-Al(2) bond length is 2.53 Å. All Al(1)-Al(1) bond lengths are 2.79 Å. The Al(1)-As(1) bond length is 2.99 Å. In the second Al site, Al(2) is bonded in a 3-coordinate geometry to three equivalent Co(1) and one Al(1) atom. As(1) is bonded in a single-bond geometry to one Co(1) and one Al(1) atom.