U4Ni7Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(1), nine equivalent Ni(1), and three equivalent Si(1) atoms. In the second U site, U(2) is bonded in a 16-coordinate geometry to one U(1), three equivalent U(2), three equivalent Ni(2), and nine equivalent Ni(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent U(1), three equivalent U(2), one Ni(2), four equivalent Ni(1), and one Si(1) atom to form NiU6SiNi5 cuboctahedra that share corners with two equivalent Ni(2)U6Ni6 cuboctahedra, corners with two equivalent Si(1)U6Ni6 cuboctahedra, corners with fourteen equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Ni(1)U6SiNi5 cuboctahedra, faces with three equivalent Ni(2)U6Ni6 cuboctahedra, faces with three equivalent Si(1)U6Ni6 cuboctahedra, and faces with twelve equivalent Ni(1)U6SiNi5 cuboctahedra. In the second Ni site, Ni(2) is bonded to six equivalent U(2) and six equivalent Ni(1) atoms to form NiU6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Ni(2)U6Ni6 cuboctahedra, faces with two equivalent Si(1)U6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)U6SiNi5 cuboctahedra. Si(1) is bonded to six equivalent U(1) and six equivalent Ni(1) atoms to form SiU6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Si(1)U6Ni6 cuboctahedra, faces with two equivalent Ni(2)U6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)U6SiNi5 cuboctahedra.
U4Ni7Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(1), nine equivalent Ni(1), and three equivalent Si(1) atoms. The U(1)-U(2) bond length is 2.79 Å. All U(1)-U(1) bond lengths are 3.20 Å. There are six shorter (2.85 Å) and three longer (2.96 Å) U(1)-Ni(1) bond lengths. All U(1)-Si(1) bond lengths are 3.00 Å. In the second U site, U(2) is bonded in a 16-coordinate geometry to one U(1), three equivalent U(2), three equivalent Ni(2), and nine equivalent Ni(1) atoms. All U(2)-U(2) bond lengths are 3.09 Å. All U(2)-Ni(2) bond lengths are 2.97 Å. There are three shorter (2.88 Å) and six longer (2.95 Å) U(2)-Ni(1) bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent U(1), three equivalent U(2), one Ni(2), four equivalent Ni(1), and one Si(1) atom to form NiU6SiNi5 cuboctahedra that share corners with two equivalent Ni(2)U6Ni6 cuboctahedra, corners with two equivalent Si(1)U6Ni6 cuboctahedra, corners with fourteen equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Ni(1)U6SiNi5 cuboctahedra, faces with three equivalent Ni(2)U6Ni6 cuboctahedra, faces with three equivalent Si(1)U6Ni6 cuboctahedra, and faces with twelve equivalent Ni(1)U6SiNi5 cuboctahedra. The Ni(1)-Ni(2) bond length is 2.48 Å. There are two shorter (2.52 Å) and two longer (2.55 Å) Ni(1)-Ni(1) bond lengths. The Ni(1)-Si(1) bond length is 2.43 Å. In the second Ni site, Ni(2) is bonded to six equivalent U(2) and six equivalent Ni(1) atoms to form NiU6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Ni(2)U6Ni6 cuboctahedra, faces with two equivalent Si(1)U6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)U6SiNi5 cuboctahedra. Si(1) is bonded to six equivalent U(1) and six equivalent Ni(1) atoms to form SiU6Ni6 cuboctahedra that share corners with twelve equivalent Ni(1)U6SiNi5 cuboctahedra, edges with six equivalent Si(1)U6Ni6 cuboctahedra, faces with two equivalent Ni(2)U6Ni6 cuboctahedra, and faces with eighteen equivalent Ni(1)U6SiNi5 cuboctahedra.