The material described by Pr2Ta2O7Cl2 crystallizes in the monoclinic C2/m space group. Pr(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), three equivalent O(4), and three equivalent Cl(1) atoms. Ta(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-14°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Pr(1) and two equivalent Ta(1) atoms to form distorted OPr2Ta2 trigonal pyramids that share corners with five equivalent O(4)Pr3Ta tetrahedra, corners with two equivalent O(2)Pr2Ta2 trigonal pyramids,  an edgeedge with one O(2)Pr2Ta2 trigonal pyramid, and  a faceface with one O(4)Pr3Ta tetrahedra. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Pr(1) and one Ta(1) atom to form distorted OPr3Ta tetrahedra that share corners with two equivalent O(4)Pr3Ta tetrahedra, corners with five equivalent O(2)Pr2Ta2 trigonal pyramids, edges with two equivalent O(4)Pr3Ta tetrahedra, and  a faceface with one O(2)Pr2Ta2 trigonal pyramid. Cl(1) is bonded in a trigonal non-coplanar geometry to three equivalent Pr(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2Ta2Cl2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.063
_cell_length_b   8.063
_cell_length_c   6.974
_cell_angle_alpha   67.084
_cell_angle_beta   67.084
_cell_angle_gamma   28.466
_symmetry_Int_Tables_number   1
_cell_volume   197.898
_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
  Pr  Pr0  1  0.692  0.692  0.835  1.0
  Pr  Pr1  1  0.308  0.308  0.165  1.0
  Ta  Ta2  1  0.034  0.034  0.202  1.0
  Ta  Ta3  1  0.966  0.966  0.798  1.0
  Cl  Cl4  1  0.321  0.321  0.566  1.0
  Cl  Cl5  1  0.679  0.679  0.434  1.0
  O  O6  1  0.545  0.545  0.165  1.0
  O  O7  1  0.455  0.455  0.835  1.0
  O  O8  1  0.080  0.080  0.848  1.0
  O  O9  1  0.000  0.000  0.500  1.0
  O  O10  1  0.174  0.174  0.070  1.0
  O  O11  1  0.920  0.920  0.152  1.0
  O  O12  1  0.826  0.826  0.930  1.0
[/CIF]
.
The material described by Pr2Ta2O7Cl2 crystallizes in the monoclinic C2/m space group. Pr(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), three equivalent O(4), and three equivalent Cl(1) atoms. Ta(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-14°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to two equivalent Pr(1) and two equivalent Ta(1) atoms to form distorted OPr2Ta2 trigonal pyramids that share corners with five equivalent O(4)Pr3Ta tetrahedra, corners with two equivalent O(2)Pr2Ta2 trigonal pyramids,  an edgeedge with one O(2)Pr2Ta2 trigonal pyramid, and  a faceface with one O(4)Pr3Ta tetrahedra. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Pr(1) and one Ta(1) atom to form distorted OPr3Ta tetrahedra that share corners with two equivalent O(4)Pr3Ta tetrahedra, corners with five equivalent O(2)Pr2Ta2 trigonal pyramids, edges with two equivalent O(4)Pr3Ta tetrahedra, and  a faceface with one O(2)Pr2Ta2 trigonal pyramid. Cl(1) is bonded in a trigonal non-coplanar geometry to three equivalent Pr(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2Ta2Cl2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.063
_cell_length_b   8.063
_cell_length_c   6.974
_cell_angle_alpha   67.084
_cell_angle_beta   67.084
_cell_angle_gamma   28.466
_symmetry_Int_Tables_number   1
_cell_volume   197.898
_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
  Pr  Pr0  1  0.692  0.692  0.835  1.0
  Pr  Pr1  1  0.308  0.308  0.165  1.0
  Ta  Ta2  1  0.034  0.034  0.202  1.0
  Ta  Ta3  1  0.966  0.966  0.798  1.0
  Cl  Cl4  1  0.321  0.321  0.566  1.0
  Cl  Cl5  1  0.679  0.679  0.434  1.0
  O  O6  1  0.545  0.545  0.165  1.0
  O  O7  1  0.455  0.455  0.835  1.0
  O  O8  1  0.080  0.080  0.848  1.0
  O  O9  1  0.000  0.000  0.500  1.0
  O  O10  1  0.174  0.174  0.070  1.0
  O  O11  1  0.920  0.920  0.152  1.0
  O  O12  1  0.826  0.826  0.930  1.0
[/CIF]
.