Sr2NdTa(CuO4)2 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form distorted SrO12 cuboctahedra that share corners with eight equivalent Sr(1)O12 cuboctahedra, faces with five equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ta(1)O6 octahedra, and faces with four equivalent Cu(1)O5 square pyramids. Nd(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with two equivalent Cu(1)O5 square pyramids, and faces with eight equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Cu(1) is bonded to one O(1) and four equivalent O(3) atoms to form CuO5 square pyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1), one Ta(1), and one Cu(1) atom to form distorted OSr4TaCu octahedra that share corners with five equivalent O(1)Sr4TaCu octahedra, corners with eight equivalent O(3)Sr2Nd2Cu2 octahedra, edges with four equivalent O(1)Sr4TaCu octahedra, and faces with four equivalent O(3)Sr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-54°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Sr(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Nd(1), and two equivalent Cu(1) atoms to form distorted OSr2Nd2Cu2 octahedra that share corners with four equivalent O(1)Sr4TaCu octahedra, corners with eight equivalent O(3)Sr2Nd2Cu2 octahedra, edges with three equivalent O(3)Sr2Nd2Cu2 octahedra, faces with two equivalent O(1)Sr4TaCu octahedra, and faces with four equivalent O(3)Sr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°.
Sr2NdTa(CuO4)2 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form distorted SrO12 cuboctahedra that share corners with eight equivalent Sr(1)O12 cuboctahedra, faces with five equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Ta(1)O6 octahedra, and faces with four equivalent Cu(1)O5 square pyramids. All Sr(1)-O(1) bond lengths are 2.82 Å. All Sr(1)-O(2) bond lengths are 3.06 Å. All Sr(1)-O(3) bond lengths are 2.81 Å. Nd(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. All Nd(1)-O(3) bond lengths are 2.51 Å. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with two equivalent Cu(1)O5 square pyramids, and faces with eight equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Ta(1)-O(1) bond lengths are 1.98 Å. All Ta(1)-O(2) bond lengths are 1.98 Å. Cu(1) is bonded to one O(1) and four equivalent O(3) atoms to form CuO5 square pyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. The Cu(1)-O(1) bond length is 2.22 Å. All Cu(1)-O(3) bond lengths are 1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1), one Ta(1), and one Cu(1) atom to form distorted OSr4TaCu octahedra that share corners with five equivalent O(1)Sr4TaCu octahedra, corners with eight equivalent O(3)Sr2Nd2Cu2 octahedra, edges with four equivalent O(1)Sr4TaCu octahedra, and faces with four equivalent O(3)Sr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-54°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Sr(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Nd(1), and two equivalent Cu(1) atoms to form distorted OSr2Nd2Cu2 octahedra that share corners with four equivalent O(1)Sr4TaCu octahedra, corners with eight equivalent O(3)Sr2Nd2Cu2 octahedra, edges with three equivalent O(3)Sr2Nd2Cu2 octahedra, faces with two equivalent O(1)Sr4TaCu octahedra, and faces with four equivalent O(3)Sr2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°.