Pa2Ho2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Pa sites. In the first Pa site, Pa(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Pa site, Pa(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form PaO12 cuboctahedra that share corners with four equivalent Pa(2)O12 cuboctahedra, faces with four equivalent Pa(2)O12 cuboctahedra, and faces with eight equivalent Ho(1)O5 square pyramids. Ho(1) is bonded to one O(2) and four equivalent O(1) atoms to form HoO5 square pyramids that share corners with five equivalent Ho(1)O5 square pyramids and faces with four equivalent Pa(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Pa(1), two equivalent Pa(2), and two equivalent Ho(1) atoms to form a mixture of distorted face, corner, and edge-sharing OHo2Pa4 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Pa(2) and two equivalent Ho(1) atoms.
Pa2Ho2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Pa sites. In the first Pa site, Pa(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Pa(1)-O(1) bond lengths are 2.85 Å. In the second Pa site, Pa(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form PaO12 cuboctahedra that share corners with four equivalent Pa(2)O12 cuboctahedra, faces with four equivalent Pa(2)O12 cuboctahedra, and faces with eight equivalent Ho(1)O5 square pyramids. All Pa(2)-O(2) bond lengths are 3.08 Å. All Pa(2)-O(1) bond lengths are 2.90 Å. Ho(1) is bonded to one O(2) and four equivalent O(1) atoms to form HoO5 square pyramids that share corners with five equivalent Ho(1)O5 square pyramids and faces with four equivalent Pa(2)O12 cuboctahedra. The Ho(1)-O(2) bond length is 2.08 Å. All Ho(1)-O(1) bond lengths are 2.18 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Pa(1), two equivalent Pa(2), and two equivalent Ho(1) atoms to form a mixture of distorted face, corner, and edge-sharing OHo2Pa4 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a linear geometry to four equivalent Pa(2) and two equivalent Ho(1) atoms.