Pr5Ni19 crystallizes in the trigonal R-3m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(6) atoms. In the second Pr site, Pr(2) is bonded in a 18-coordinate geometry to three equivalent Ni(2), three equivalent Ni(4), six equivalent Ni(5), and six equivalent Ni(6) atoms. In the third Pr site, Pr(3) is bonded in a 12-coordinate geometry to three equivalent Ni(1) and nine equivalent Ni(5) atoms. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to six equivalent Pr(3) and six equivalent Ni(5) atoms to form NiPr6Ni6 cuboctahedra that share corners with twelve equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(5)Pr5Ni7 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(5), and three equivalent Ni(6) atoms. In the third Ni site, Ni(3) is bonded in a 9-coordinate geometry to three equivalent Pr(1) and six equivalent Ni(6) atoms. In the fourth Ni site, Ni(4) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(5), and three equivalent Ni(6) atoms. In the fifth Ni site, Ni(5) is bonded to two equivalent Pr(2), three equivalent Pr(3), one Ni(1), one Ni(2), one Ni(4), and four equivalent Ni(5) atoms to form distorted NiPr5Ni7 cuboctahedra that share corners with two equivalent Ni(1)Pr6Ni6 cuboctahedra, corners with six equivalent Ni(6)Pr4Ni8 cuboctahedra, corners with nine equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with four equivalent Ni(6)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(5)Pr5Ni7 cuboctahedra,  a faceface with one Ni(6)Pr4Ni8 cuboctahedra, faces with three equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with ten equivalent Ni(5)Pr5Ni7 cuboctahedra. In the sixth Ni site, Ni(6) is bonded to two equivalent Pr(1), two equivalent Pr(2), one Ni(2), one Ni(4), two equivalent Ni(3), and four equivalent Ni(6) atoms to form NiPr4Ni8 cuboctahedra that share corners with six equivalent Ni(5)Pr5Ni7 cuboctahedra, corners with ten equivalent Ni(6)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(6)Pr4Ni8 cuboctahedra,  a faceface with one Ni(5)Pr5Ni7 cuboctahedra, and faces with nine equivalent Ni(6)Pr4Ni8 cuboctahedra.
Pr5Ni19 crystallizes in the trigonal R-3m space group. There are three inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 18-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(6) atoms. All Pr(1)-Ni(3) bond lengths are 2.90 Å. All Pr(1)-Ni(6) bond lengths are 3.20 Å. In the second Pr site, Pr(2) is bonded in a 18-coordinate geometry to three equivalent Ni(2), three equivalent Ni(4), six equivalent Ni(5), and six equivalent Ni(6) atoms. All Pr(2)-Ni(2) bond lengths are 2.91 Å. All Pr(2)-Ni(4) bond lengths are 2.91 Å. All Pr(2)-Ni(5) bond lengths are 3.32 Å. All Pr(2)-Ni(6) bond lengths are 3.10 Å. In the third Pr site, Pr(3) is bonded in a 12-coordinate geometry to three equivalent Ni(1) and nine equivalent Ni(5) atoms. All Pr(3)-Ni(1) bond lengths are 2.99 Å. There are six shorter (2.88 Å) and three longer (3.20 Å) Pr(3)-Ni(5) bond lengths. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to six equivalent Pr(3) and six equivalent Ni(5) atoms to form NiPr6Ni6 cuboctahedra that share corners with twelve equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(5)Pr5Ni7 cuboctahedra. All Ni(1)-Ni(5) bond lengths are 2.57 Å. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(5), and three equivalent Ni(6) atoms. All Ni(2)-Ni(5) bond lengths are 2.45 Å. All Ni(2)-Ni(6) bond lengths are 2.49 Å. In the third Ni site, Ni(3) is bonded in a 9-coordinate geometry to three equivalent Pr(1) and six equivalent Ni(6) atoms. All Ni(3)-Ni(6) bond lengths are 2.45 Å. In the fourth Ni site, Ni(4) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(5), and three equivalent Ni(6) atoms. All Ni(4)-Ni(5) bond lengths are 2.46 Å. All Ni(4)-Ni(6) bond lengths are 2.48 Å. In the fifth Ni site, Ni(5) is bonded to two equivalent Pr(2), three equivalent Pr(3), one Ni(1), one Ni(2), one Ni(4), and four equivalent Ni(5) atoms to form distorted NiPr5Ni7 cuboctahedra that share corners with two equivalent Ni(1)Pr6Ni6 cuboctahedra, corners with six equivalent Ni(6)Pr4Ni8 cuboctahedra, corners with nine equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with four equivalent Ni(6)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(5)Pr5Ni7 cuboctahedra,  a faceface with one Ni(6)Pr4Ni8 cuboctahedra, faces with three equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with ten equivalent Ni(5)Pr5Ni7 cuboctahedra. There are two shorter (2.50 Å) and two longer (2.52 Å) Ni(5)-Ni(5) bond lengths. In the sixth Ni site, Ni(6) is bonded to two equivalent Pr(1), two equivalent Pr(2), one Ni(2), one Ni(4), two equivalent Ni(3), and four equivalent Ni(6) atoms to form NiPr4Ni8 cuboctahedra that share corners with six equivalent Ni(5)Pr5Ni7 cuboctahedra, corners with ten equivalent Ni(6)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(5)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(6)Pr4Ni8 cuboctahedra,  a faceface with one Ni(5)Pr5Ni7 cuboctahedra, and faces with nine equivalent Ni(6)Pr4Ni8 cuboctahedra. There are two shorter (2.51 Å) and two longer (2.52 Å) Ni(6)-Ni(6) bond lengths.