U2W2C3 crystallizes in the monoclinic C2/m space group. U(1) is bonded in a distorted pentagonal planar geometry to two equivalent C(2) and three equivalent C(1) atoms. W(1) is bonded to one C(2) and three equivalent C(1) atoms to form a mixture of distorted edge and corner-sharing WC4 trigonal pyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent U(1) and three equivalent W(1) atoms to form CU3W3 octahedra that share corners with six equivalent C(2)U4W2 octahedra, edges with six equivalent C(1)U3W3 octahedra, and  a faceface with one C(2)U4W2 octahedra. The corner-sharing octahedral tilt angles range from 40-59°. In the second C site, C(2) is bonded to four equivalent U(1) and two equivalent W(1) atoms to form CU4W2 octahedra that share corners with twelve equivalent C(1)U3W3 octahedra, edges with two equivalent C(2)U4W2 octahedra, and faces with two equivalent C(1)U3W3 octahedra. The corner-sharing octahedral tilt angles range from 40-59°.
U2W2C3 crystallizes in the monoclinic C2/m space group. U(1) is bonded in a distorted pentagonal planar geometry to two equivalent C(2) and three equivalent C(1) atoms. Both U(1)-C(2) bond lengths are 2.52 Å. There is one shorter (2.43 Å) and two longer (2.50 Å) U(1)-C(1) bond lengths. W(1) is bonded to one C(2) and three equivalent C(1) atoms to form a mixture of distorted edge and corner-sharing WC4 trigonal pyramids. The W(1)-C(2) bond length is 2.07 Å. There are two shorter (2.15 Å) and one longer (2.17 Å) W(1)-C(1) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent U(1) and three equivalent W(1) atoms to form CU3W3 octahedra that share corners with six equivalent C(2)U4W2 octahedra, edges with six equivalent C(1)U3W3 octahedra, and  a faceface with one C(2)U4W2 octahedra. The corner-sharing octahedral tilt angles range from 40-59°. In the second C site, C(2) is bonded to four equivalent U(1) and two equivalent W(1) atoms to form CU4W2 octahedra that share corners with twelve equivalent C(1)U3W3 octahedra, edges with two equivalent C(2)U4W2 octahedra, and faces with two equivalent C(1)U3W3 octahedra. The corner-sharing octahedral tilt angles range from 40-59°.