UMnC2 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 5-coordinate geometry to two equivalent C(1) and three equivalent C(2) atoms. Mn(1) is bonded to one C(2) and four equivalent C(1) atoms to form a mixture of distorted corner and edge-sharing MnC5 trigonal bipyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent U(1) and four equivalent Mn(1) atoms to form a mixture of corner, edge, and face-sharing CU2Mn4 octahedra. The corner-sharing octahedral tilt angles are 38°. In the second C site, C(2) is bonded in a 6-coordinate geometry to three equivalent U(1), one Mn(1), and two equivalent C(2) atoms.
UMnC2 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 5-coordinate geometry to two equivalent C(1) and three equivalent C(2) atoms. There is one shorter (2.35 Å) and one longer (2.39 Å) U(1)-C(1) bond length. There is one shorter (2.48 Å) and two longer (2.50 Å) U(1)-C(2) bond lengths. Mn(1) is bonded to one C(2) and four equivalent C(1) atoms to form a mixture of distorted corner and edge-sharing MnC5 trigonal bipyramids. The Mn(1)-C(2) bond length is 2.10 Å. There are two shorter (2.00 Å) and two longer (2.03 Å) Mn(1)-C(1) bond lengths. There are two inequivalent C sites. In the first C site, C(1) is bonded to two equivalent U(1) and four equivalent Mn(1) atoms to form a mixture of corner, edge, and face-sharing CU2Mn4 octahedra. The corner-sharing octahedral tilt angles are 38°. In the second C site, C(2) is bonded in a 6-coordinate geometry to three equivalent U(1), one Mn(1), and two equivalent C(2) atoms. Both C(2)-C(2) bond lengths are 1.59 Å.