Materials Data on U2NiC3 by Materials Project
U2NiC3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent U5+ sites. In the first U5+ site, U5+ is bonded in a 6-coordinate geometry to eight C4- atoms. There are a spread of U–C bond distances ranging from 2.34–2.73 Å. In the second U5+ site, U5+ is bonded in a 5-coordinate geometry to eight C4- atoms. There are a spread of U–C bond distances ranging from 2.33–3.02 Å. Ni2+ is bonded to four C4- atoms to form NiC4 tetrahedra that share corners with two equivalent CU5C octahedra and corners with four equivalent NiC4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–70°. There are a spread of Ni–C bond distances ranging from 2.05–2.50 Å. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded in a 2-coordinate geometry to six U5+, two equivalent Ni2+, and one C4- atom. The C–C bond length is 1.46 Å. In the second C4- site, C4- is bonded to five U5+ and one C4- atom to form CU5C octahedra that share corners with two equivalent NiC4 tetrahedra and edges with four equivalent CU5C octahedra. In the third C4- site, C4- is bonded in a 6-coordinate geometry to five U5+ and two equivalent Ni2+ atoms.