The compound described by Co8As3O16 crystallizes in the monoclinic C2/m space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent As(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-17°. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CoO6 octahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent As(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one As(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-17°. In the third Co site, Co(3) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with three equivalent As(2)O4 tetrahedra,  an edgeedge with one As(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form AsO6 octahedra that share edges with two equivalent Co(3)O6 octahedra, edges with four equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. In the second As site, As(2) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form AsO4 tetrahedra that share corners with three equivalent Co(3)O6 octahedra and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-57°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Co(3), two equivalent Co(2), and one As(2) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one As(1) atom. In the third O site, O(3) is bonded to two equivalent Co(1), two equivalent Co(2), and one As(1) atom to form OCo4As square pyramids that share corners with three equivalent O(3)Co4As square pyramids and edges with three equivalent O(4)Co5 square pyramids. In the fourth O site, O(4) is bonded to one Co(3), two equivalent Co(1), and two equivalent Co(2) atoms to form OCo5 square pyramids that share corners with two equivalent O(4)Co5 square pyramids and edges with three equivalent O(3)Co4As square pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Co(2) and one As(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Co(2), one Co(3), and one As(2) atom. is represented by the CIF file [CIF]
data_Co8As3O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.076
_cell_length_b   6.076
_cell_length_c   9.913
_cell_angle_alpha   72.679
_cell_angle_beta   72.679
_cell_angle_gamma   60.940
_symmetry_Int_Tables_number   1
_cell_volume   300.207
_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
  Co  Co0  1  0.000  0.500  0.000  1.0
  Co  Co1  1  0.735  0.254  0.255  1.0
  Co  Co2  1  0.254  0.735  0.255  1.0
  Co  Co3  1  0.748  0.748  0.267  1.0
  Co  Co4  1  0.252  0.252  0.733  1.0
  Co  Co5  1  0.746  0.265  0.745  1.0
  Co  Co6  1  0.265  0.746  0.745  1.0
  Co  Co7  1  0.500  0.000  0.000  1.0
  As  As8  1  0.000  0.000  0.000  1.0
  As  As9  1  0.811  0.811  0.581  1.0
  As  As10  1  0.189  0.189  0.419  1.0
  O  O11  1  0.875  0.875  0.391  1.0
  O  O12  1  0.326  0.904  0.884  1.0
  O  O13  1  0.904  0.326  0.884  1.0
  O  O14  1  0.892  0.892  0.883  1.0
  O  O15  1  0.633  0.633  0.135  1.0
  O  O16  1  0.365  0.365  0.368  1.0
  O  O17  1  0.366  0.896  0.365  1.0
  O  O18  1  0.896  0.366  0.365  1.0
  O  O19  1  0.104  0.634  0.635  1.0
  O  O20  1  0.634  0.104  0.635  1.0
  O  O21  1  0.635  0.635  0.632  1.0
  O  O22  1  0.367  0.367  0.865  1.0
  O  O23  1  0.108  0.108  0.117  1.0
  O  O24  1  0.096  0.674  0.116  1.0
  O  O25  1  0.674  0.096  0.116  1.0
  O  O26  1  0.125  0.125  0.609  1.0
[/CIF]
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The compound described by Co8As3O16 crystallizes in the monoclinic C2/m space group. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Co(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent As(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-17°. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CoO6 octahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent As(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra,  an edgeedge with one As(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-17°. In the third Co site, Co(3) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(6) atoms to form CoO6 octahedra that share corners with three equivalent As(2)O4 tetrahedra,  an edgeedge with one As(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form AsO6 octahedra that share edges with two equivalent Co(3)O6 octahedra, edges with four equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. In the second As site, As(2) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form AsO4 tetrahedra that share corners with three equivalent Co(3)O6 octahedra and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-57°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Co(3), two equivalent Co(2), and one As(2) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one As(1) atom. In the third O site, O(3) is bonded to two equivalent Co(1), two equivalent Co(2), and one As(1) atom to form OCo4As square pyramids that share corners with three equivalent O(3)Co4As square pyramids and edges with three equivalent O(4)Co5 square pyramids. In the fourth O site, O(4) is bonded to one Co(3), two equivalent Co(1), and two equivalent Co(2) atoms to form OCo5 square pyramids that share corners with two equivalent O(4)Co5 square pyramids and edges with three equivalent O(3)Co4As square pyramids. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Co(2) and one As(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Co(2), one Co(3), and one As(2) atom. is represented by the CIF file [CIF]
data_Co8As3O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.076
_cell_length_b   6.076
_cell_length_c   9.913
_cell_angle_alpha   72.679
_cell_angle_beta   72.679
_cell_angle_gamma   60.940
_symmetry_Int_Tables_number   1
_cell_volume   300.207
_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
  Co  Co0  1  0.000  0.500  0.000  1.0
  Co  Co1  1  0.735  0.254  0.255  1.0
  Co  Co2  1  0.254  0.735  0.255  1.0
  Co  Co3  1  0.748  0.748  0.267  1.0
  Co  Co4  1  0.252  0.252  0.733  1.0
  Co  Co5  1  0.746  0.265  0.745  1.0
  Co  Co6  1  0.265  0.746  0.745  1.0
  Co  Co7  1  0.500  0.000  0.000  1.0
  As  As8  1  0.000  0.000  0.000  1.0
  As  As9  1  0.811  0.811  0.581  1.0
  As  As10  1  0.189  0.189  0.419  1.0
  O  O11  1  0.875  0.875  0.391  1.0
  O  O12  1  0.326  0.904  0.884  1.0
  O  O13  1  0.904  0.326  0.884  1.0
  O  O14  1  0.892  0.892  0.883  1.0
  O  O15  1  0.633  0.633  0.135  1.0
  O  O16  1  0.365  0.365  0.368  1.0
  O  O17  1  0.366  0.896  0.365  1.0
  O  O18  1  0.896  0.366  0.365  1.0
  O  O19  1  0.104  0.634  0.635  1.0
  O  O20  1  0.634  0.104  0.635  1.0
  O  O21  1  0.635  0.635  0.632  1.0
  O  O22  1  0.367  0.367  0.865  1.0
  O  O23  1  0.108  0.108  0.117  1.0
  O  O24  1  0.096  0.674  0.116  1.0
  O  O25  1  0.674  0.096  0.116  1.0
  O  O26  1  0.125  0.125  0.609  1.0
[/CIF]
.