Pr2Fe16Al crystallizes in the trigonal R3m space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 19-coordinate geometry to one Fe(5), three equivalent Fe(2), three equivalent Fe(3), six equivalent Fe(1), and six equivalent Fe(4) atoms. In the second Pr site, Pr(2) is bonded in a 19-coordinate geometry to three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), six equivalent Fe(3), and one Al(1) atom. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to one Pr(1), one Pr(2), one Fe(5), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and one Al(1) atom. In the second Fe site, Fe(2) is bonded to one Pr(1), one Pr(2), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), four equivalent Fe(1), and one Al(1) atom to form distorted FePr2AlFe9 cuboctahedra that share corners with four equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with five equivalent Fe(3)Pr3AlFe8 cuboctahedra, corners with five equivalent Fe(4)Pr3Fe9 cuboctahedra, edges with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, edges with three equivalent Fe(4)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, faces with three equivalent Fe(4)Pr3Fe9 cuboctahedra, and faces with four equivalent Fe(2)Pr2AlFe9 cuboctahedra. In the third Fe site, Fe(3) is bonded to one Pr(1), two equivalent Pr(2), two equivalent Fe(2), two equivalent Fe(4), four equivalent Fe(1), and one Al(1) atom to form FePr3AlFe8 cuboctahedra that share corners with two equivalent Fe(3)Pr3AlFe8 cuboctahedra, corners with five equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with eight equivalent Fe(4)Pr3Fe9 cuboctahedra,  an edgeedge with one Fe(4)Pr3Fe9 cuboctahedra, edges with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, edges with four equivalent Fe(3)Pr3AlFe8 cuboctahedra, faces with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, faces with three equivalent Fe(4)Pr3Fe9 cuboctahedra, and faces with four equivalent Fe(3)Pr3AlFe8 cuboctahedra. In the fourth Fe site, Fe(4) is bonded to one Pr(2), two equivalent Pr(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form FePr3Fe9 cuboctahedra that share corners with two equivalent Fe(4)Pr3Fe9 cuboctahedra, corners with five equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with eight equivalent Fe(3)Pr3AlFe8 cuboctahedra,  an edgeedge with one Fe(3)Pr3AlFe8 cuboctahedra, edges with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, edges with four equivalent Fe(4)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, faces with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, and faces with four equivalent Fe(4)Pr3Fe9 cuboctahedra. In the fifth Fe site, Fe(5) is bonded in a 14-coordinate geometry to one Pr(1), three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), and one Al(1) atom. Al(1) is bonded in a 14-coordinate geometry to one Pr(2), one Fe(5), three equivalent Fe(2), three equivalent Fe(3), and six equivalent Fe(1) atoms.
Pr2Fe16Al crystallizes in the trigonal R3m space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 19-coordinate geometry to one Fe(5), three equivalent Fe(2), three equivalent Fe(3), six equivalent Fe(1), and six equivalent Fe(4) atoms. The Pr(1)-Fe(5) bond length is 3.06 Å. All Pr(1)-Fe(2) bond lengths are 3.31 Å. All Pr(1)-Fe(3) bond lengths are 3.11 Å. All Pr(1)-Fe(1) bond lengths are 3.08 Å. There are three shorter (3.23 Å) and three longer (3.25 Å) Pr(1)-Fe(4) bond lengths. In the second Pr site, Pr(2) is bonded in a 19-coordinate geometry to three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), six equivalent Fe(3), and one Al(1) atom. All Pr(2)-Fe(2) bond lengths are 3.33 Å. All Pr(2)-Fe(4) bond lengths are 3.09 Å. All Pr(2)-Fe(1) bond lengths are 3.08 Å. There are three shorter (3.23 Å) and three longer (3.24 Å) Pr(2)-Fe(3) bond lengths. The Pr(2)-Al(1) bond length is 3.13 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to one Pr(1), one Pr(2), one Fe(5), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and one Al(1) atom. The Fe(1)-Fe(5) bond length is 2.74 Å. There is one shorter (2.43 Å) and one longer (2.44 Å) Fe(1)-Fe(1) bond length. There is one shorter (2.44 Å) and one longer (2.45 Å) Fe(1)-Fe(2) bond length. There is one shorter (2.54 Å) and one longer (2.70 Å) Fe(1)-Fe(3) bond length. There is one shorter (2.54 Å) and one longer (2.70 Å) Fe(1)-Fe(4) bond length. The Fe(1)-Al(1) bond length is 2.71 Å. In the second Fe site, Fe(2) is bonded to one Pr(1), one Pr(2), one Fe(5), two equivalent Fe(3), two equivalent Fe(4), four equivalent Fe(1), and one Al(1) atom to form distorted FePr2AlFe9 cuboctahedra that share corners with four equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with five equivalent Fe(3)Pr3AlFe8 cuboctahedra, corners with five equivalent Fe(4)Pr3Fe9 cuboctahedra, edges with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, edges with three equivalent Fe(4)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, faces with three equivalent Fe(4)Pr3Fe9 cuboctahedra, and faces with four equivalent Fe(2)Pr2AlFe9 cuboctahedra. The Fe(2)-Fe(5) bond length is 2.61 Å. Both Fe(2)-Fe(3) bond lengths are 2.46 Å. Both Fe(2)-Fe(4) bond lengths are 2.46 Å. The Fe(2)-Al(1) bond length is 2.63 Å. In the third Fe site, Fe(3) is bonded to one Pr(1), two equivalent Pr(2), two equivalent Fe(2), two equivalent Fe(4), four equivalent Fe(1), and one Al(1) atom to form FePr3AlFe8 cuboctahedra that share corners with two equivalent Fe(3)Pr3AlFe8 cuboctahedra, corners with five equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with eight equivalent Fe(4)Pr3Fe9 cuboctahedra,  an edgeedge with one Fe(4)Pr3Fe9 cuboctahedra, edges with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, edges with four equivalent Fe(3)Pr3AlFe8 cuboctahedra, faces with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, faces with three equivalent Fe(4)Pr3Fe9 cuboctahedra, and faces with four equivalent Fe(3)Pr3AlFe8 cuboctahedra. Both Fe(3)-Fe(4) bond lengths are 2.50 Å. The Fe(3)-Al(1) bond length is 2.65 Å. In the fourth Fe site, Fe(4) is bonded to one Pr(2), two equivalent Pr(1), one Fe(5), two equivalent Fe(2), two equivalent Fe(3), and four equivalent Fe(1) atoms to form FePr3Fe9 cuboctahedra that share corners with two equivalent Fe(4)Pr3Fe9 cuboctahedra, corners with five equivalent Fe(2)Pr2AlFe9 cuboctahedra, corners with eight equivalent Fe(3)Pr3AlFe8 cuboctahedra,  an edgeedge with one Fe(3)Pr3AlFe8 cuboctahedra, edges with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, edges with four equivalent Fe(4)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(2)Pr2AlFe9 cuboctahedra, faces with three equivalent Fe(3)Pr3AlFe8 cuboctahedra, and faces with four equivalent Fe(4)Pr3Fe9 cuboctahedra. The Fe(4)-Fe(5) bond length is 2.64 Å. In the fifth Fe site, Fe(5) is bonded in a 14-coordinate geometry to one Pr(1), three equivalent Fe(2), three equivalent Fe(4), six equivalent Fe(1), and one Al(1) atom. The Fe(5)-Al(1) bond length is 2.43 Å. Al(1) is bonded in a 14-coordinate geometry to one Pr(2), one Fe(5), three equivalent Fe(2), three equivalent Fe(3), and six equivalent Fe(1) atoms.