SmFeNi4 crystallizes in the hexagonal P-6m2 space group. Sm(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 Sm(1), three equivalent Ni(1), and six equivalent Ni(2) atoms to form distorted FeSm3Ni9 cuboctahedra that share corners with nine equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, corners with twelve equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with six equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with two equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with three equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, and faces with eighteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent Sm(1), three equivalent Fe(1), and six equivalent Ni(2) atoms to form distorted NiSm3Fe3Ni6 cuboctahedra that share corners with nine equivalent Fe(1)Sm3Ni9 cuboctahedra, corners with twelve equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with six equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, faces with two equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, faces with three equivalent Fe(1)Sm3Ni9 cuboctahedra, and faces with eighteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra. In the second Ni site, Ni(2) is bonded to four equivalent Sm(1), two equivalent Fe(1), two equivalent Ni(1), and four equivalent Ni(2) atoms to form NiSm4Fe2Ni6 cuboctahedra that share corners with four equivalent Fe(1)Sm3Ni9 cuboctahedra, corners with four equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, corners with sixteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with ten equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, faces with six equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with six equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, and faces with ten equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra.
SmFeNi4 crystallizes in the hexagonal P-6m2 space group. Sm(1) is bonded in a 18-coordinate geometry to three equivalent Fe(1), three equivalent Ni(1), and twelve equivalent Ni(2) atoms. All Sm(1)-Fe(1) bond lengths are 2.87 Å. All Sm(1)-Ni(1) bond lengths are 2.87 Å. All Sm(1)-Ni(2) bond lengths are 3.17 Å. Fe(1) is bonded to three equivalent Sm(1), three equivalent Ni(1), and six equivalent Ni(2) atoms to form distorted FeSm3Ni9 cuboctahedra that share corners with nine equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, corners with twelve equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with six equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with two equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with three equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, and faces with eighteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra. All Fe(1)-Ni(1) bond lengths are 2.87 Å. All Fe(1)-Ni(2) bond lengths are 2.44 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent Sm(1), three equivalent Fe(1), and six equivalent Ni(2) atoms to form distorted NiSm3Fe3Ni6 cuboctahedra that share corners with nine equivalent Fe(1)Sm3Ni9 cuboctahedra, corners with twelve equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with six equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, faces with two equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, faces with three equivalent Fe(1)Sm3Ni9 cuboctahedra, and faces with eighteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra. All Ni(1)-Ni(2) bond lengths are 2.44 Å. In the second Ni site, Ni(2) is bonded to four equivalent Sm(1), two equivalent Fe(1), two equivalent Ni(1), and four equivalent Ni(2) atoms to form NiSm4Fe2Ni6 cuboctahedra that share corners with four equivalent Fe(1)Sm3Ni9 cuboctahedra, corners with four equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, corners with sixteen equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, edges with ten equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra, faces with six equivalent Fe(1)Sm3Ni9 cuboctahedra, faces with six equivalent Ni(1)Sm3Fe3Ni6 cuboctahedra, and faces with ten equivalent Ni(2)Sm4Fe2Ni6 cuboctahedra. There are two shorter (2.48 Å) and two longer (2.49 Å) Ni(2)-Ni(2) bond lengths.