Pr2Ni7 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 12-coordinate geometry to three equivalent Ni(1) and nine equivalent Ni(3) atoms. In the second Pr site, Pr(2) is bonded in a 18-coordinate geometry to three equivalent Ni(4), three equivalent Ni(5), six equivalent Ni(2), and six equivalent Ni(3) atoms. There are five inequivalent Ni sites. In the first Ni site, Ni(5) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(2), and three equivalent Ni(3) atoms. In the second Ni site, Ni(1) is bonded to six equivalent Pr(1) and six equivalent Ni(3) atoms to form NiPr6Ni6 cuboctahedra that share corners with twelve equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(3)Pr5Ni7 cuboctahedra. In the third Ni site, Ni(2) is bonded to four equivalent Pr(2), two equivalent Ni(4), two equivalent Ni(5), and four equivalent Ni(2) atoms to form NiPr4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Pr4Ni8 cuboctahedra, corners with twelve equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with two equivalent Ni(2)Pr4Ni8 cuboctahedra, edges with eight equivalent Ni(3)Pr5Ni7 cuboctahedra, faces with two equivalent Ni(3)Pr5Ni7 cuboctahedra, and faces with eight equivalent Ni(2)Pr4Ni8 cuboctahedra. In the fourth Ni site, Ni(3) is bonded to two equivalent Pr(2), three equivalent Pr(1), one Ni(1), one Ni(4), one Ni(5), and four equivalent Ni(3) atoms to form distorted NiPr5Ni7 cuboctahedra that share corners with two equivalent Ni(1)Pr6Ni6 cuboctahedra, corners with six equivalent Ni(2)Pr4Ni8 cuboctahedra, corners with nine equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with four equivalent Ni(2)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(3)Pr5Ni7 cuboctahedra,  a faceface with one Ni(2)Pr4Ni8 cuboctahedra, faces with three equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with ten equivalent Ni(3)Pr5Ni7 cuboctahedra. In the fifth Ni site, Ni(4) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(2), and three equivalent Ni(3) atoms.
Pr2Ni7 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 12-coordinate geometry to three equivalent Ni(1) and nine equivalent Ni(3) atoms. All Pr(1)-Ni(1) bond lengths are 3.02 Å. There are six shorter (2.91 Å) and three longer (3.25 Å) Pr(1)-Ni(3) bond lengths. In the second Pr site, Pr(2) is bonded in a 18-coordinate geometry to three equivalent Ni(4), three equivalent Ni(5), six equivalent Ni(2), and six equivalent Ni(3) atoms. All Pr(2)-Ni(4) bond lengths are 2.93 Å. All Pr(2)-Ni(5) bond lengths are 2.93 Å. All Pr(2)-Ni(2) bond lengths are 3.15 Å. All Pr(2)-Ni(3) bond lengths are 3.32 Å. There are five inequivalent Ni sites. In the first Ni site, Ni(5) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(2), and three equivalent Ni(3) atoms. All Ni(5)-Ni(2) bond lengths are 2.50 Å. All Ni(5)-Ni(3) bond lengths are 2.46 Å. In the second Ni site, Ni(1) is bonded to six equivalent Pr(1) and six equivalent Ni(3) atoms to form NiPr6Ni6 cuboctahedra that share corners with twelve equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with six equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(3)Pr5Ni7 cuboctahedra. All Ni(1)-Ni(3) bond lengths are 2.61 Å. In the third Ni site, Ni(2) is bonded to four equivalent Pr(2), two equivalent Ni(4), two equivalent Ni(5), and four equivalent Ni(2) atoms to form NiPr4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Pr4Ni8 cuboctahedra, corners with twelve equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with two equivalent Ni(2)Pr4Ni8 cuboctahedra, edges with eight equivalent Ni(3)Pr5Ni7 cuboctahedra, faces with two equivalent Ni(3)Pr5Ni7 cuboctahedra, and faces with eight equivalent Ni(2)Pr4Ni8 cuboctahedra. Both Ni(2)-Ni(4) bond lengths are 2.48 Å. There are two shorter (2.53 Å) and two longer (2.54 Å) Ni(2)-Ni(2) bond lengths. In the fourth Ni site, Ni(3) is bonded to two equivalent Pr(2), three equivalent Pr(1), one Ni(1), one Ni(4), one Ni(5), and four equivalent Ni(3) atoms to form distorted NiPr5Ni7 cuboctahedra that share corners with two equivalent Ni(1)Pr6Ni6 cuboctahedra, corners with six equivalent Ni(2)Pr4Ni8 cuboctahedra, corners with nine equivalent Ni(3)Pr5Ni7 cuboctahedra, edges with four equivalent Ni(2)Pr4Ni8 cuboctahedra, edges with four equivalent Ni(3)Pr5Ni7 cuboctahedra,  a faceface with one Ni(2)Pr4Ni8 cuboctahedra, faces with three equivalent Ni(1)Pr6Ni6 cuboctahedra, and faces with ten equivalent Ni(3)Pr5Ni7 cuboctahedra. The Ni(3)-Ni(4) bond length is 2.48 Å. There are two shorter (2.52 Å) and two longer (2.54 Å) Ni(3)-Ni(3) bond lengths. In the fifth Ni site, Ni(4) is bonded in a 9-coordinate geometry to three equivalent Pr(2), three equivalent Ni(2), and three equivalent Ni(3) atoms.