Gd2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 18-coordinate geometry to six equivalent Ni(1) and twelve equivalent Ni(2) atoms. In the second Gd site, Gd(2) is bonded in a 20-coordinate geometry to two equivalent Ni(4), six equivalent Ni(1), six equivalent Ni(2), and six equivalent Ni(3) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to one Gd(1), one Gd(2), two equivalent Ni(1), two equivalent Ni(3), two equivalent Ni(4), and four equivalent Ni(2) atoms. In the second Ni site, Ni(2) is bonded to one Gd(2), two equivalent Gd(1), one Ni(4), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(1) atoms to form distorted NiGd3Ni9 cuboctahedra that share corners with five equivalent Ni(3)Gd2Ni10 cuboctahedra, corners with ten equivalent Ni(2)Gd3Ni9 cuboctahedra, edges with three equivalent Ni(3)Gd2Ni10 cuboctahedra, edges with five equivalent Ni(2)Gd3Ni9 cuboctahedra, faces with two equivalent Ni(3)Gd2Ni10 cuboctahedra, and faces with eight equivalent Ni(2)Gd3Ni9 cuboctahedra. In the third Ni site, Ni(3) is bonded to two equivalent Gd(2), two equivalent Ni(4), four equivalent Ni(1), and four equivalent Ni(2) atoms to form NiGd2Ni10 cuboctahedra that share corners with four equivalent Ni(3)Gd2Ni10 cuboctahedra, corners with ten equivalent Ni(2)Gd3Ni9 cuboctahedra, edges with six equivalent Ni(2)Gd3Ni9 cuboctahedra, faces with four equivalent Ni(2)Gd3Ni9 cuboctahedra, and faces with six equivalent Ni(3)Gd2Ni10 cuboctahedra. In the fourth Ni site, Ni(4) is bonded in a 14-coordinate geometry to one Gd(2), one Ni(4), three equivalent Ni(2), three equivalent Ni(3), and six equivalent Ni(1) atoms.
Gd2Ni17 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 18-coordinate geometry to six equivalent Ni(1) and twelve equivalent Ni(2) atoms. All Gd(1)-Ni(1) bond lengths are 2.92 Å. There are six shorter (3.01 Å) and six longer (3.22 Å) Gd(1)-Ni(2) bond lengths. In the second Gd site, Gd(2) is bonded in a 20-coordinate geometry to two equivalent Ni(4), six equivalent Ni(1), six equivalent Ni(2), and six equivalent Ni(3) atoms. Both Gd(2)-Ni(4) bond lengths are 2.82 Å. All Gd(2)-Ni(1) bond lengths are 2.98 Å. All Gd(2)-Ni(2) bond lengths are 3.03 Å. All Gd(2)-Ni(3) bond lengths are 3.12 Å. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to one Gd(1), one Gd(2), two equivalent Ni(1), two equivalent Ni(3), two equivalent Ni(4), and four equivalent Ni(2) atoms. There is one shorter (2.35 Å) and one longer (2.49 Å) Ni(1)-Ni(1) bond length. Both Ni(1)-Ni(3) bond lengths are 2.38 Å. Both Ni(1)-Ni(4) bond lengths are 2.70 Å. There are two shorter (2.48 Å) and two longer (2.52 Å) Ni(1)-Ni(2) bond lengths. In the second Ni site, Ni(2) is bonded to one Gd(2), two equivalent Gd(1), one Ni(4), two equivalent Ni(2), two equivalent Ni(3), and four equivalent Ni(1) atoms to form distorted NiGd3Ni9 cuboctahedra that share corners with five equivalent Ni(3)Gd2Ni10 cuboctahedra, corners with ten equivalent Ni(2)Gd3Ni9 cuboctahedra, edges with three equivalent Ni(3)Gd2Ni10 cuboctahedra, edges with five equivalent Ni(2)Gd3Ni9 cuboctahedra, faces with two equivalent Ni(3)Gd2Ni10 cuboctahedra, and faces with eight equivalent Ni(2)Gd3Ni9 cuboctahedra. The Ni(2)-Ni(4) bond length is 2.60 Å. Both Ni(2)-Ni(2) bond lengths are 2.40 Å. Both Ni(2)-Ni(3) bond lengths are 2.40 Å. In the third Ni site, Ni(3) is bonded to two equivalent Gd(2), two equivalent Ni(4), four equivalent Ni(1), and four equivalent Ni(2) atoms to form NiGd2Ni10 cuboctahedra that share corners with four equivalent Ni(3)Gd2Ni10 cuboctahedra, corners with ten equivalent Ni(2)Gd3Ni9 cuboctahedra, edges with six equivalent Ni(2)Gd3Ni9 cuboctahedra, faces with four equivalent Ni(2)Gd3Ni9 cuboctahedra, and faces with six equivalent Ni(3)Gd2Ni10 cuboctahedra. Both Ni(3)-Ni(4) bond lengths are 2.53 Å. In the fourth Ni site, Ni(4) is bonded in a 14-coordinate geometry to one Gd(2), one Ni(4), three equivalent Ni(2), three equivalent Ni(3), and six equivalent Ni(1) atoms. The Ni(4)-Ni(4) bond length is 2.37 Å.