UCeC4 crystallizes in the orthorhombic Pmna space group. U(1) is bonded to two equivalent C(1) and six equivalent C(2) atoms to form UC8 hexagonal bipyramids that share edges with four equivalent Ce(1)C12 cuboctahedra, edges with six equivalent U(1)C8 hexagonal bipyramids, and faces with four equivalent Ce(1)C12 cuboctahedra. Ce(1) is bonded to four equivalent C(2) and eight equivalent C(1) atoms to form distorted CeC12 cuboctahedra that share edges with six equivalent Ce(1)C12 cuboctahedra, edges with four equivalent U(1)C8 hexagonal bipyramids, faces with four equivalent Ce(1)C12 cuboctahedra, and faces with four equivalent U(1)C8 hexagonal bipyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one U(1), four equivalent Ce(1), and one C(1) atom. In the second C site, C(2) is bonded in a 6-coordinate geometry to three equivalent U(1), two equivalent Ce(1), and one C(2) atom.
UCeC4 crystallizes in the orthorhombic Pmna space group. U(1) is bonded to two equivalent C(1) and six equivalent C(2) atoms to form UC8 hexagonal bipyramids that share edges with four equivalent Ce(1)C12 cuboctahedra, edges with six equivalent U(1)C8 hexagonal bipyramids, and faces with four equivalent Ce(1)C12 cuboctahedra. Both U(1)-C(1) bond lengths are 2.26 Å. There are two shorter (2.28 Å) and four longer (2.57 Å) U(1)-C(2) bond lengths. Ce(1) is bonded to four equivalent C(2) and eight equivalent C(1) atoms to form distorted CeC12 cuboctahedra that share edges with six equivalent Ce(1)C12 cuboctahedra, edges with four equivalent U(1)C8 hexagonal bipyramids, faces with four equivalent Ce(1)C12 cuboctahedra, and faces with four equivalent U(1)C8 hexagonal bipyramids. There are two shorter (2.97 Å) and two longer (3.05 Å) Ce(1)-C(2) bond lengths. There are a spread of Ce(1)-C(1) bond distances ranging from 2.57-3.05 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one U(1), four equivalent Ce(1), and one C(1) atom. The C(1)-C(1) bond length is 1.36 Å. In the second C site, C(2) is bonded in a 6-coordinate geometry to three equivalent U(1), two equivalent Ce(1), and one C(2) atom. The C(2)-C(2) bond length is 1.33 Å.