The structure described by Co2As2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted CoO6 pentagonal pyramids that share corners with two equivalent As(2)O5 tetrahedra, edges with three equivalent Co(2)O6 pentagonal pyramids, and  an edgeedge with one As(2)O5 tetrahedra. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted CoO6 pentagonal pyramids that share corners with two equivalent As(2)O5 tetrahedra, edges with three equivalent Co(1)O6 pentagonal pyramids, and  an edgeedge with one As(2)O5 tetrahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. In the second As site, As(2) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted AsO5 tetrahedra that share corners with two equivalent Co(1)O6 pentagonal pyramids, corners with two equivalent Co(2)O6 pentagonal pyramids,  an edgeedge with one Co(1)O6 pentagonal pyramid, and  an edgeedge with one Co(2)O6 pentagonal pyramid. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Co(1), one Co(2), one As(1), and one As(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Co(1), one Co(2), one As(1), and one As(2) atom. In the fourth O site, O(4) is bonded in a linear geometry to one As(1) and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Co2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.906
_cell_length_b   5.348
_cell_length_c   5.463
_cell_angle_alpha   107.042
_cell_angle_beta   95.914
_cell_angle_gamma   97.264
_symmetry_Int_Tables_number   1
_cell_volume   134.455
_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  0.506  0.687  0.308  1.0
  Co  Co1  1  0.495  0.315  0.695  1.0
  As  As2  1  0.104  0.753  0.754  1.0
  As  As3  1  0.895  0.243  0.242  1.0
  O  O4  1  0.295  0.937  0.598  1.0
  O  O5  1  0.774  0.585  0.594  1.0
  O  O6  1  0.222  0.416  0.408  1.0
  O  O7  1  0.002  0.001  0.998  1.0
  O  O8  1  0.295  0.592  0.927  1.0
  O  O9  1  0.704  0.408  0.074  1.0
  O  O10  1  0.707  0.062  0.401  1.0
[/CIF]
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The structure described by Co2As2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted CoO6 pentagonal pyramids that share corners with two equivalent As(2)O5 tetrahedra, edges with three equivalent Co(2)O6 pentagonal pyramids, and  an edgeedge with one As(2)O5 tetrahedra. In the second Co site, Co(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted CoO6 pentagonal pyramids that share corners with two equivalent As(2)O5 tetrahedra, edges with three equivalent Co(1)O6 pentagonal pyramids, and  an edgeedge with one As(2)O5 tetrahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. In the second As site, As(2) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form distorted AsO5 tetrahedra that share corners with two equivalent Co(1)O6 pentagonal pyramids, corners with two equivalent Co(2)O6 pentagonal pyramids,  an edgeedge with one Co(1)O6 pentagonal pyramid, and  an edgeedge with one Co(2)O6 pentagonal pyramid. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Co(1), one Co(2), one As(1), and one As(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Co(1), one Co(2), one As(1), and one As(2) atom. In the fourth O site, O(4) is bonded in a linear geometry to one As(1) and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Co2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.906
_cell_length_b   5.348
_cell_length_c   5.463
_cell_angle_alpha   107.042
_cell_angle_beta   95.914
_cell_angle_gamma   97.264
_symmetry_Int_Tables_number   1
_cell_volume   134.455
_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  0.506  0.687  0.308  1.0
  Co  Co1  1  0.495  0.315  0.695  1.0
  As  As2  1  0.104  0.753  0.754  1.0
  As  As3  1  0.895  0.243  0.242  1.0
  O  O4  1  0.295  0.937  0.598  1.0
  O  O5  1  0.774  0.585  0.594  1.0
  O  O6  1  0.222  0.416  0.408  1.0
  O  O7  1  0.002  0.001  0.998  1.0
  O  O8  1  0.295  0.592  0.927  1.0
  O  O9  1  0.704  0.408  0.074  1.0
  O  O10  1  0.707  0.062  0.401  1.0
[/CIF]
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