BaYNiCuO5 crystallizes in the tetragonal P4mm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ni(1)O5 square pyramids, and faces with four equivalent Cu(1)O5 square pyramids. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Ni(1) is bonded to one O(3) and four equivalent O(1) atoms to form NiO5 square pyramids that share  a cornercorner with one Cu(1)O5 square pyramid, corners with four equivalent Ni(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. Cu(1) is bonded to one O(3) and four equivalent O(2) atoms to form CuO5 square pyramids that share  a cornercorner with one Ni(1)O5 square pyramid, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded to four equivalent Ba(1), one Ni(1), and one Cu(1) atom to form a mixture of corner and edge-sharing OBa4CuNi octahedra. The corner-sharing octahedral tilt angles are 1°.
BaYNiCuO5 crystallizes in the tetragonal P4mm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ni(1)O5 square pyramids, and faces with four equivalent Cu(1)O5 square pyramids. All Ba(1)-O(1) bond lengths are 3.07 Å. All Ba(1)-O(2) bond lengths are 3.05 Å. All Ba(1)-O(3) bond lengths are 2.75 Å. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Y(1)-O(1) bond lengths are 2.39 Å. All Y(1)-O(2) bond lengths are 2.42 Å. Ni(1) is bonded to one O(3) and four equivalent O(1) atoms to form NiO5 square pyramids that share  a cornercorner with one Cu(1)O5 square pyramid, corners with four equivalent Ni(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The Ni(1)-O(3) bond length is 1.97 Å. All Ni(1)-O(1) bond lengths are 1.98 Å. Cu(1) is bonded to one O(3) and four equivalent O(2) atoms to form CuO5 square pyramids that share  a cornercorner with one Ni(1)O5 square pyramid, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The Cu(1)-O(3) bond length is 2.03 Å. All Cu(1)-O(2) bond lengths are 1.97 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded to four equivalent Ba(1), one Ni(1), and one Cu(1) atom to form a mixture of corner and edge-sharing OBa4CuNi octahedra. The corner-sharing octahedral tilt angles are 1°.