YFeNi4 crystallizes in the hexagonal P-6m2 space group. Y(1) is bonded in a 18-coordinate geometry to three equivalent Fe(1), three equivalent Ni(1), and twelve equivalent Ni(2) atoms. Fe(1) is bonded to three equivalent Y(1), three equivalent Ni(1), and six equivalent Ni(2) atoms to form distorted FeY3Ni9 cuboctahedra that share corners with nine equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, corners with twelve equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with six equivalent Fe(1)Y3Ni9 cuboctahedra, faces with two equivalent Fe(1)Y3Ni9 cuboctahedra, faces with three equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, and faces with eighteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent Y(1), three equivalent Fe(1), and six equivalent Ni(2) atoms to form distorted NiY3Fe3Ni6 cuboctahedra that share corners with nine equivalent Fe(1)Y3Ni9 cuboctahedra, corners with twelve equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with six equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, faces with two equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, faces with three equivalent Fe(1)Y3Ni9 cuboctahedra, and faces with eighteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra. In the second Ni site, Ni(2) is bonded to four equivalent Y(1), two equivalent Fe(1), two equivalent Ni(1), and four equivalent Ni(2) atoms to form NiY4Fe2Ni6 cuboctahedra that share corners with four equivalent Fe(1)Y3Ni9 cuboctahedra, corners with four equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, corners with sixteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with ten equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, faces with six equivalent Fe(1)Y3Ni9 cuboctahedra, faces with six equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, and faces with ten equivalent Ni(2)Y4Fe2Ni6 cuboctahedra.
YFeNi4 crystallizes in the hexagonal P-6m2 space group. Y(1) is bonded in a 18-coordinate geometry to three equivalent Fe(1), three equivalent Ni(1), and twelve equivalent Ni(2) atoms. All Y(1)-Fe(1) bond lengths are 2.86 Å. All Y(1)-Ni(1) bond lengths are 2.86 Å. All Y(1)-Ni(2) bond lengths are 3.16 Å. Fe(1) is bonded to three equivalent Y(1), three equivalent Ni(1), and six equivalent Ni(2) atoms to form distorted FeY3Ni9 cuboctahedra that share corners with nine equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, corners with twelve equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with six equivalent Fe(1)Y3Ni9 cuboctahedra, faces with two equivalent Fe(1)Y3Ni9 cuboctahedra, faces with three equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, and faces with eighteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra. All Fe(1)-Ni(1) bond lengths are 2.86 Å. All Fe(1)-Ni(2) bond lengths are 2.43 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent Y(1), three equivalent Fe(1), and six equivalent Ni(2) atoms to form distorted NiY3Fe3Ni6 cuboctahedra that share corners with nine equivalent Fe(1)Y3Ni9 cuboctahedra, corners with twelve equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with six equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, faces with two equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, faces with three equivalent Fe(1)Y3Ni9 cuboctahedra, and faces with eighteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra. All Ni(1)-Ni(2) bond lengths are 2.43 Å. In the second Ni site, Ni(2) is bonded to four equivalent Y(1), two equivalent Fe(1), two equivalent Ni(1), and four equivalent Ni(2) atoms to form NiY4Fe2Ni6 cuboctahedra that share corners with four equivalent Fe(1)Y3Ni9 cuboctahedra, corners with four equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, corners with sixteen equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, edges with ten equivalent Ni(2)Y4Fe2Ni6 cuboctahedra, faces with six equivalent Fe(1)Y3Ni9 cuboctahedra, faces with six equivalent Ni(1)Y3Fe3Ni6 cuboctahedra, and faces with ten equivalent Ni(2)Y4Fe2Ni6 cuboctahedra. There are two shorter (2.47 Å) and two longer (2.48 Å) Ni(2)-Ni(2) bond lengths.