The structure described by BaCuAs2O7 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(7), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(5), and one O(7) atom. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing AsO4 tetrahedra. In the second As site, As(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing AsO4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Cu(1), and one As(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1) and one As(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Ba(1), one Cu(1), and one As(1) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Cu(1), and one As(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ba(1), one Cu(1), and one As(2) atom. In the sixth O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one As(2) atom. In the seventh O site, O(4) is bonded in a bent 120 degrees geometry to one As(1) and one As(2) atom. is represented by the CIF file [CIF]
data_BaCuAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.525
_cell_length_b   6.012
_cell_length_c   14.333
_cell_angle_alpha   67.256
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   677.448
_cell_formula_units_Z   4
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  0.349  0.502  0.787  1.0
  Ba  Ba1  1  0.849  0.498  0.713  1.0
  Ba  Ba2  1  0.651  0.498  0.213  1.0
  Ba  Ba3  1  0.151  0.502  0.287  1.0
  Cu  Cu4  1  0.359  0.153  0.121  1.0
  Cu  Cu5  1  0.141  0.153  0.621  1.0
  Cu  Cu6  1  0.641  0.847  0.879  1.0
  Cu  Cu7  1  0.859  0.847  0.379  1.0
  As  As8  1  0.466  0.905  0.343  1.0
  As  As9  1  0.681  0.165  0.005  1.0
  As  As10  1  0.034  0.905  0.843  1.0
  As  As11  1  0.534  0.095  0.657  1.0
  As  As12  1  0.319  0.835  0.995  1.0
  As  As13  1  0.819  0.165  0.505  1.0
  As  As14  1  0.181  0.835  0.495  1.0
  As  As15  1  0.966  0.095  0.157  1.0
  O  O16  1  0.588  0.200  0.106  1.0
  O  O17  1  0.088  0.800  0.394  1.0
  O  O18  1  0.412  0.800  0.894  1.0
  O  O19  1  0.912  0.200  0.606  1.0
  O  O20  1  0.649  0.873  0.013  1.0
  O  O21  1  0.149  0.127  0.487  1.0
  O  O22  1  0.351  0.127  0.987  1.0
  O  O23  1  0.851  0.873  0.513  1.0
  O  O24  1  0.658  0.393  0.892  1.0
  O  O25  1  0.158  0.607  0.608  1.0
  O  O26  1  0.342  0.607  0.108  1.0
  O  O27  1  0.842  0.393  0.392  1.0
  O  O28  1  0.887  0.173  0.033  1.0
  O  O29  1  0.387  0.827  0.467  1.0
  O  O30  1  0.113  0.827  0.967  1.0
  O  O31  1  0.613  0.173  0.533  1.0
  O  O32  1  0.627  0.837  0.739  1.0
  O  O33  1  0.127  0.163  0.761  1.0
  O  O34  1  0.373  0.163  0.261  1.0
  O  O35  1  0.873  0.837  0.239  1.0
  O  O36  1  0.444  0.667  0.310  1.0
  O  O37  1  0.944  0.333  0.190  1.0
  O  O38  1  0.556  0.333  0.690  1.0
  O  O39  1  0.056  0.667  0.810  1.0
  O  O40  1  0.346  0.001  0.651  1.0
  O  O41  1  0.846  0.999  0.849  1.0
  O  O42  1  0.654  0.999  0.349  1.0
  O  O43  1  0.154  0.001  0.151  1.0
[/CIF]
.
The structure described by BaCuAs2O7 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(7), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Cu(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(5), and one O(7) atom. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing AsO4 tetrahedra. In the second As site, As(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing AsO4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Cu(1), and one As(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1) and one As(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Ba(1), one Cu(1), and one As(1) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Cu(1), and one As(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ba(1), one Cu(1), and one As(2) atom. In the sixth O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one As(2) atom. In the seventh O site, O(4) is bonded in a bent 120 degrees geometry to one As(1) and one As(2) atom. is represented by the CIF file [CIF]
data_BaCuAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.525
_cell_length_b   6.012
_cell_length_c   14.333
_cell_angle_alpha   67.256
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   677.448
_cell_formula_units_Z   4
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  0.349  0.502  0.787  1.0
  Ba  Ba1  1  0.849  0.498  0.713  1.0
  Ba  Ba2  1  0.651  0.498  0.213  1.0
  Ba  Ba3  1  0.151  0.502  0.287  1.0
  Cu  Cu4  1  0.359  0.153  0.121  1.0
  Cu  Cu5  1  0.141  0.153  0.621  1.0
  Cu  Cu6  1  0.641  0.847  0.879  1.0
  Cu  Cu7  1  0.859  0.847  0.379  1.0
  As  As8  1  0.466  0.905  0.343  1.0
  As  As9  1  0.681  0.165  0.005  1.0
  As  As10  1  0.034  0.905  0.843  1.0
  As  As11  1  0.534  0.095  0.657  1.0
  As  As12  1  0.319  0.835  0.995  1.0
  As  As13  1  0.819  0.165  0.505  1.0
  As  As14  1  0.181  0.835  0.495  1.0
  As  As15  1  0.966  0.095  0.157  1.0
  O  O16  1  0.588  0.200  0.106  1.0
  O  O17  1  0.088  0.800  0.394  1.0
  O  O18  1  0.412  0.800  0.894  1.0
  O  O19  1  0.912  0.200  0.606  1.0
  O  O20  1  0.649  0.873  0.013  1.0
  O  O21  1  0.149  0.127  0.487  1.0
  O  O22  1  0.351  0.127  0.987  1.0
  O  O23  1  0.851  0.873  0.513  1.0
  O  O24  1  0.658  0.393  0.892  1.0
  O  O25  1  0.158  0.607  0.608  1.0
  O  O26  1  0.342  0.607  0.108  1.0
  O  O27  1  0.842  0.393  0.392  1.0
  O  O28  1  0.887  0.173  0.033  1.0
  O  O29  1  0.387  0.827  0.467  1.0
  O  O30  1  0.113  0.827  0.967  1.0
  O  O31  1  0.613  0.173  0.533  1.0
  O  O32  1  0.627  0.837  0.739  1.0
  O  O33  1  0.127  0.163  0.761  1.0
  O  O34  1  0.373  0.163  0.261  1.0
  O  O35  1  0.873  0.837  0.239  1.0
  O  O36  1  0.444  0.667  0.310  1.0
  O  O37  1  0.944  0.333  0.190  1.0
  O  O38  1  0.556  0.333  0.690  1.0
  O  O39  1  0.056  0.667  0.810  1.0
  O  O40  1  0.346  0.001  0.651  1.0
  O  O41  1  0.846  0.999  0.849  1.0
  O  O42  1  0.654  0.999  0.349  1.0
  O  O43  1  0.154  0.001  0.151  1.0
[/CIF]
.