YNi3 crystallizes in the trigonal R-3m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 12-coordinate geometry to three equivalent Ni(2) and nine equivalent Ni(1) atoms. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(1) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Y(2), three equivalent Y(1), one Ni(2), two equivalent Ni(3), and four equivalent Ni(1) atoms to form distorted NiY5Ni7 cuboctahedra that share corners with two equivalent Ni(2)Y6Ni6 cuboctahedra, corners with fifteen equivalent Ni(1)Y5Ni7 cuboctahedra, edges with eight equivalent Ni(1)Y5Ni7 cuboctahedra, faces with three equivalent Ni(2)Y6Ni6 cuboctahedra, and faces with eleven equivalent Ni(1)Y5Ni7 cuboctahedra. In the second Ni site, Ni(2) is bonded to six equivalent Y(1) and six equivalent Ni(1) atoms to form NiY6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)Y5Ni7 cuboctahedra, edges with six equivalent Ni(2)Y6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)Y5Ni7 cuboctahedra. In the third Ni site, Ni(3) is bonded in a 9-coordinate geometry to three equivalent Y(2) and six equivalent Ni(1) atoms.
YNi3 crystallizes in the trigonal R-3m space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 12-coordinate geometry to three equivalent Ni(2) and nine equivalent Ni(1) atoms. All Y(1)-Ni(2) bond lengths are 2.93 Å. There are six shorter (2.83 Å) and three longer (3.08 Å) Y(1)-Ni(1) bond lengths. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to six equivalent Ni(3) and twelve equivalent Ni(1) atoms. All Y(2)-Ni(3) bond lengths are 2.85 Å. All Y(2)-Ni(1) bond lengths are 3.15 Å. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Y(2), three equivalent Y(1), one Ni(2), two equivalent Ni(3), and four equivalent Ni(1) atoms to form distorted NiY5Ni7 cuboctahedra that share corners with two equivalent Ni(2)Y6Ni6 cuboctahedra, corners with fifteen equivalent Ni(1)Y5Ni7 cuboctahedra, edges with eight equivalent Ni(1)Y5Ni7 cuboctahedra, faces with three equivalent Ni(2)Y6Ni6 cuboctahedra, and faces with eleven equivalent Ni(1)Y5Ni7 cuboctahedra. The Ni(1)-Ni(2) bond length is 2.51 Å. There is one shorter (2.42 Å) and one longer (2.43 Å) Ni(1)-Ni(3) bond length. There are two shorter (2.46 Å) and two longer (2.48 Å) Ni(1)-Ni(1) bond lengths. In the second Ni site, Ni(2) is bonded to six equivalent Y(1) and six equivalent Ni(1) atoms to form NiY6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)Y5Ni7 cuboctahedra, edges with six equivalent Ni(2)Y6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)Y5Ni7 cuboctahedra. In the third Ni site, Ni(3) is bonded in a 9-coordinate geometry to three equivalent Y(2) and six equivalent Ni(1) atoms.