The structure described by Sr2NdTa(CuO4)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to one O(4), one O(6), two equivalent O(2), two equivalent O(5), and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one O(4), one O(6), two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Nd(1) is bonded in a body-centered cubic geometry to two equivalent O(4), two equivalent O(6), and four equivalent O(2) atoms. Ta(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and corners with two equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 29°. Cu(1) is bonded to one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form CuO5 square pyramids that share  a cornercorner with one Ta(1)O6 octahedra and corners with four equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 4°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(2) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Ta(1), and one Cu(1) atom. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the sixth O site, O(6) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. is represented by the CIF file [CIF]
data_Sr2NdTa(CuO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.530
_cell_length_b   5.530
_cell_length_c   12.548
_cell_angle_alpha   102.745
_cell_angle_beta   102.745
_cell_angle_gamma   90.104
_symmetry_Int_Tables_number   1
_cell_volume   364.517
_cell_formula_units_Z   2
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
  Sr  Sr0  1  0.598  0.098  0.200  1.0
  Sr  Sr1  1  0.905  0.405  0.801  1.0
  Sr  Sr2  1  0.095  0.595  0.199  1.0
  Sr  Sr3  1  0.402  0.902  0.800  1.0
  Nd  Nd4  1  0.249  0.749  0.500  1.0
  Nd  Nd5  1  0.751  0.251  0.500  1.0
  Ta  Ta6  1  0.000  0.000  0.000  1.0
  Ta  Ta7  1  0.500  0.500  0.000  1.0
  Cu  Cu8  1  0.675  0.674  0.354  1.0
  Cu  Cu9  1  0.826  0.825  0.646  1.0
  Cu  Cu10  1  0.174  0.175  0.354  1.0
  Cu  Cu11  1  0.325  0.326  0.646  1.0
  O  O12  1  0.187  0.313  0.000  1.0
  O  O13  1  0.438  0.426  0.370  1.0
  O  O14  1  0.591  0.571  0.165  1.0
  O  O15  1  0.573  0.073  0.632  1.0
  O  O16  1  0.683  0.183  0.992  1.0
  O  O17  1  0.940  0.440  0.372  1.0
  O  O18  1  0.929  0.909  0.835  1.0
  O  O19  1  0.071  0.091  0.165  1.0
  O  O20  1  0.074  0.062  0.630  1.0
  O  O21  1  0.317  0.817  0.008  1.0
  O  O22  1  0.427  0.927  0.368  1.0
  O  O23  1  0.409  0.429  0.835  1.0
  O  O24  1  0.562  0.574  0.630  1.0
  O  O25  1  0.813  0.687  0.000  1.0
  O  O26  1  0.926  0.938  0.370  1.0
  O  O27  1  0.060  0.560  0.628  1.0
[/CIF]
.
The structure described by Sr2NdTa(CuO4)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to one O(4), one O(6), two equivalent O(2), two equivalent O(5), and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one O(4), one O(6), two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Nd(1) is bonded in a body-centered cubic geometry to two equivalent O(4), two equivalent O(6), and four equivalent O(2) atoms. Ta(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and corners with two equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 29°. Cu(1) is bonded to one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form CuO5 square pyramids that share  a cornercorner with one Ta(1)O6 octahedra and corners with four equivalent Cu(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 4°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(2) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Ta(1), and one Cu(1) atom. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the sixth O site, O(6) is bonded to one Sr(1), one Sr(2), two equivalent Nd(1), and two equivalent Cu(1) atoms to form a mixture of distorted corner, face, and edge-sharing OSr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. is represented by the CIF file [CIF]
data_Sr2NdTa(CuO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.530
_cell_length_b   5.530
_cell_length_c   12.548
_cell_angle_alpha   102.745
_cell_angle_beta   102.745
_cell_angle_gamma   90.104
_symmetry_Int_Tables_number   1
_cell_volume   364.517
_cell_formula_units_Z   2
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
  Sr  Sr0  1  0.598  0.098  0.200  1.0
  Sr  Sr1  1  0.905  0.405  0.801  1.0
  Sr  Sr2  1  0.095  0.595  0.199  1.0
  Sr  Sr3  1  0.402  0.902  0.800  1.0
  Nd  Nd4  1  0.249  0.749  0.500  1.0
  Nd  Nd5  1  0.751  0.251  0.500  1.0
  Ta  Ta6  1  0.000  0.000  0.000  1.0
  Ta  Ta7  1  0.500  0.500  0.000  1.0
  Cu  Cu8  1  0.675  0.674  0.354  1.0
  Cu  Cu9  1  0.826  0.825  0.646  1.0
  Cu  Cu10  1  0.174  0.175  0.354  1.0
  Cu  Cu11  1  0.325  0.326  0.646  1.0
  O  O12  1  0.187  0.313  0.000  1.0
  O  O13  1  0.438  0.426  0.370  1.0
  O  O14  1  0.591  0.571  0.165  1.0
  O  O15  1  0.573  0.073  0.632  1.0
  O  O16  1  0.683  0.183  0.992  1.0
  O  O17  1  0.940  0.440  0.372  1.0
  O  O18  1  0.929  0.909  0.835  1.0
  O  O19  1  0.071  0.091  0.165  1.0
  O  O20  1  0.074  0.062  0.630  1.0
  O  O21  1  0.317  0.817  0.008  1.0
  O  O22  1  0.427  0.927  0.368  1.0
  O  O23  1  0.409  0.429  0.835  1.0
  O  O24  1  0.562  0.574  0.630  1.0
  O  O25  1  0.813  0.687  0.000  1.0
  O  O26  1  0.926  0.938  0.370  1.0
  O  O27  1  0.060  0.560  0.628  1.0
[/CIF]
.