Materials Data on LaU3C8 by Materials Project
U3LaC8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. U+4.33+ is bonded to six C2- atoms to form UC6 octahedra that share corners with eight equivalent UC6 octahedra, corners with two equivalent CU3C tetrahedra, and edges with four equivalent LaC12 cuboctahedra. The corner-sharing octahedra tilt angles range from 68–71°. There are a spread of U–C bond distances ranging from 2.28–2.43 Å. La3+ is bonded to twelve equivalent C2- atoms to form LaC12 cuboctahedra that share edges with six equivalent LaC12 cuboctahedra and edges with twelve equivalent UC6 octahedra. There are six shorter (2.76 Å) and six longer (2.93 Å) La–C bond lengths. There are two inequivalent C2- sites. In the first C2- site, C2- is bonded in a 5-coordinate geometry to two equivalent U+4.33+, two equivalent La3+, and one C2- atom. The C–C bond length is 1.37 Å. In the second C2- site, C2- is bonded to three equivalent U+4.33+ and one C2- atom to form CU3C tetrahedra that share corners with three equivalent UC6 octahedra and corners with three equivalent CU3C tetrahedra. The corner-sharing octahedral tilt angles are 70°. The C–C bond length is 1.44 Å.