TmWC2 crystallizes in the orthorhombic Pnma space group. Tm(1) is bonded to three equivalent C(2) and four equivalent C(1) atoms to form distorted TmC7 pentagonal bipyramids that share corners with four equivalent Tm(1)C7 pentagonal bipyramids, corners with three equivalent W(1)C5 trigonal bipyramids, edges with four equivalent Tm(1)C7 pentagonal bipyramids, edges with seven equivalent W(1)C5 trigonal bipyramids, and faces with two equivalent Tm(1)C7 pentagonal bipyramids. W(1) is bonded to two equivalent C(1) and three equivalent C(2) atoms to form WC5 trigonal bipyramids that share corners with three equivalent Tm(1)C7 pentagonal bipyramids, corners with four equivalent W(1)C5 trigonal bipyramids, edges with seven equivalent Tm(1)C7 pentagonal bipyramids, and edges with two equivalent W(1)C5 trigonal bipyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded to four equivalent Tm(1) and two equivalent W(1) atoms to form CTm4W2 octahedra that share corners with four equivalent C(1)Tm4W2 octahedra, corners with nine equivalent C(2)Tm3W3 octahedra, edges with two equivalent C(1)Tm4W2 octahedra, edges with three equivalent C(2)Tm3W3 octahedra,  a faceface with one C(2)Tm3W3 octahedra, and faces with two equivalent C(1)Tm4W2 octahedra. The corner-sharing octahedral tilt angles range from 11-60°. In the second C site, C(2) is bonded to three equivalent Tm(1) and three equivalent W(1) atoms to form CTm3W3 octahedra that share corners with nine equivalent C(1)Tm4W2 octahedra, edges with three equivalent C(1)Tm4W2 octahedra, edges with six equivalent C(2)Tm3W3 octahedra, and  a faceface with one C(1)Tm4W2 octahedra. The corner-sharing octahedral tilt angles range from 11-60°.
TmWC2 crystallizes in the orthorhombic Pnma space group. Tm(1) is bonded to three equivalent C(2) and four equivalent C(1) atoms to form distorted TmC7 pentagonal bipyramids that share corners with four equivalent Tm(1)C7 pentagonal bipyramids, corners with three equivalent W(1)C5 trigonal bipyramids, edges with four equivalent Tm(1)C7 pentagonal bipyramids, edges with seven equivalent W(1)C5 trigonal bipyramids, and faces with two equivalent Tm(1)C7 pentagonal bipyramids. There is one shorter (2.42 Å) and two longer (2.55 Å) Tm(1)-C(2) bond lengths. There are two shorter (2.46 Å) and two longer (2.53 Å) Tm(1)-C(1) bond lengths. W(1) is bonded to two equivalent C(1) and three equivalent C(2) atoms to form WC5 trigonal bipyramids that share corners with three equivalent Tm(1)C7 pentagonal bipyramids, corners with four equivalent W(1)C5 trigonal bipyramids, edges with seven equivalent Tm(1)C7 pentagonal bipyramids, and edges with two equivalent W(1)C5 trigonal bipyramids. There is one shorter (2.00 Å) and one longer (2.11 Å) W(1)-C(1) bond length. There are two shorter (2.09 Å) and one longer (2.29 Å) W(1)-C(2) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded to four equivalent Tm(1) and two equivalent W(1) atoms to form CTm4W2 octahedra that share corners with four equivalent C(1)Tm4W2 octahedra, corners with nine equivalent C(2)Tm3W3 octahedra, edges with two equivalent C(1)Tm4W2 octahedra, edges with three equivalent C(2)Tm3W3 octahedra,  a faceface with one C(2)Tm3W3 octahedra, and faces with two equivalent C(1)Tm4W2 octahedra. The corner-sharing octahedral tilt angles range from 11-60°. In the second C site, C(2) is bonded to three equivalent Tm(1) and three equivalent W(1) atoms to form CTm3W3 octahedra that share corners with nine equivalent C(1)Tm4W2 octahedra, edges with three equivalent C(1)Tm4W2 octahedra, edges with six equivalent C(2)Tm3W3 octahedra, and  a faceface with one C(1)Tm4W2 octahedra. The corner-sharing octahedral tilt angles range from 11-60°.