Pr2Fe17 crystallizes in the trigonal R-3m space group. Pr(1) is bonded in a 19-coordinate geometry to one Fe(2), three equivalent Fe(3), six equivalent Fe(4), and nine equivalent Fe(1) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Pr(1), one Fe(2), two equivalent Fe(1), two equivalent Fe(3), and four equivalent Fe(4) atoms to form FePr3Fe9 cuboctahedra that share corners with five equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(4)Pr2Fe10 cuboctahedra, corners with ten equivalent Fe(1)Pr3Fe9 cuboctahedra, edges with two equivalent Fe(4)Pr2Fe10 cuboctahedra, edges with three equivalent Fe(3)Pr2Fe10 cuboctahedra, edges with five equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with seven equivalent Fe(1)Pr3Fe9 cuboctahedra, and faces with ten equivalent Fe(4)Pr2Fe10 cuboctahedra. In the second Fe site, Fe(2) is bonded in a 14-coordinate geometry to one Pr(1), one Fe(2), three equivalent Fe(1), three equivalent Fe(3), and six equivalent Fe(4) atoms. In the third Fe site, Fe(3) is bonded to two equivalent Pr(1), two equivalent Fe(2), four equivalent Fe(1), and four equivalent Fe(4) atoms to form FePr2Fe10 cuboctahedra that share corners with four equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(4)Pr2Fe10 cuboctahedra, corners with ten equivalent Fe(1)Pr3Fe9 cuboctahedra, edges with four equivalent Fe(4)Pr2Fe10 cuboctahedra, edges with six equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with four equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with six equivalent Fe(1)Pr3Fe9 cuboctahedra, and faces with eight equivalent Fe(4)Pr2Fe10 cuboctahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent Pr(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and four equivalent Fe(1) atoms to form distorted FePr2Fe10 cuboctahedra that share corners with four equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Pr3Fe9 cuboctahedra, corners with twelve equivalent Fe(4)Pr2Fe10 cuboctahedra,  an edgeedge with one Fe(4)Pr2Fe10 cuboctahedra, edges with two equivalent Fe(3)Pr2Fe10 cuboctahedra, edges with two equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with four equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with seven equivalent Fe(4)Pr2Fe10 cuboctahedra, and faces with ten equivalent Fe(1)Pr3Fe9 cuboctahedra.
Pr2Fe17 crystallizes in the trigonal R-3m space group. Pr(1) is bonded in a 19-coordinate geometry to one Fe(2), three equivalent Fe(3), six equivalent Fe(4), and nine equivalent Fe(1) atoms. The Pr(1)-Fe(2) bond length is 3.07 Å. All Pr(1)-Fe(3) bond lengths are 3.31 Å. All Pr(1)-Fe(4) bond lengths are 3.08 Å. There are a spread of Pr(1)-Fe(1) bond distances ranging from 3.13-3.28 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Pr(1), one Fe(2), two equivalent Fe(1), two equivalent Fe(3), and four equivalent Fe(4) atoms to form FePr3Fe9 cuboctahedra that share corners with five equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(4)Pr2Fe10 cuboctahedra, corners with ten equivalent Fe(1)Pr3Fe9 cuboctahedra, edges with two equivalent Fe(4)Pr2Fe10 cuboctahedra, edges with three equivalent Fe(3)Pr2Fe10 cuboctahedra, edges with five equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with three equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with seven equivalent Fe(1)Pr3Fe9 cuboctahedra, and faces with ten equivalent Fe(4)Pr2Fe10 cuboctahedra. The Fe(1)-Fe(2) bond length is 2.65 Å. Both Fe(1)-Fe(1) bond lengths are 2.52 Å. Both Fe(1)-Fe(3) bond lengths are 2.47 Å. There are two shorter (2.55 Å) and two longer (2.68 Å) Fe(1)-Fe(4) bond lengths. In the second Fe site, Fe(2) is bonded in a 14-coordinate geometry to one Pr(1), one Fe(2), three equivalent Fe(1), three equivalent Fe(3), and six equivalent Fe(4) atoms. The Fe(2)-Fe(2) bond length is 2.41 Å. All Fe(2)-Fe(3) bond lengths are 2.63 Å. All Fe(2)-Fe(4) bond lengths are 2.76 Å. In the third Fe site, Fe(3) is bonded to two equivalent Pr(1), two equivalent Fe(2), four equivalent Fe(1), and four equivalent Fe(4) atoms to form FePr2Fe10 cuboctahedra that share corners with four equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(4)Pr2Fe10 cuboctahedra, corners with ten equivalent Fe(1)Pr3Fe9 cuboctahedra, edges with four equivalent Fe(4)Pr2Fe10 cuboctahedra, edges with six equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with four equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with six equivalent Fe(1)Pr3Fe9 cuboctahedra, and faces with eight equivalent Fe(4)Pr2Fe10 cuboctahedra. All Fe(3)-Fe(4) bond lengths are 2.45 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent Pr(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and four equivalent Fe(1) atoms to form distorted FePr2Fe10 cuboctahedra that share corners with four equivalent Fe(3)Pr2Fe10 cuboctahedra, corners with eight equivalent Fe(1)Pr3Fe9 cuboctahedra, corners with twelve equivalent Fe(4)Pr2Fe10 cuboctahedra,  an edgeedge with one Fe(4)Pr2Fe10 cuboctahedra, edges with two equivalent Fe(3)Pr2Fe10 cuboctahedra, edges with two equivalent Fe(1)Pr3Fe9 cuboctahedra, faces with four equivalent Fe(3)Pr2Fe10 cuboctahedra, faces with seven equivalent Fe(4)Pr2Fe10 cuboctahedra, and faces with ten equivalent Fe(1)Pr3Fe9 cuboctahedra. Both Fe(4)-Fe(4) bond lengths are 2.48 Å.