Th2Mn17C2 crystallizes in the monoclinic C2/m space group. Th(1) is bonded in a distorted bent 120 degrees geometry to one Mn(3), one Mn(7), two equivalent Mn(5), three equivalent Mn(1), and two equivalent C(1) atoms. There are seven inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent Th(1), one Mn(7), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(5), and two equivalent Mn(6) atoms to form MnTh3Mn9 cuboctahedra that share corners with three equivalent Mn(3)Th2Mn10 cuboctahedra, corners with four equivalent Mn(1)Th3Mn9 cuboctahedra, corners with four equivalent C(1)Th2Mn4 octahedra,  an edgeedge with one Mn(3)Th2Mn10 cuboctahedra,  an edgeedge with one Mn(1)Th3Mn9 cuboctahedra,  a faceface with one Mn(3)Th2Mn10 cuboctahedra,  a faceface with one Mn(1)Th3Mn9 cuboctahedra, and faces with two equivalent C(1)Th2Mn4 octahedra. The corner-sharing octahedral tilt angles range from 64-72°. In the second Mn site, Mn(2) is bonded in a single-bond geometry to one Mn(1), one Mn(3), one Mn(4), one Mn(5), one Mn(7), and one C(1) atom. In the third Mn site, Mn(3) is bonded to two equivalent Th(1), two equivalent Mn(7), four equivalent Mn(2), and four equivalent Mn(6) atoms to form distorted MnTh2Mn10 cuboctahedra that share corners with six equivalent Mn(1)Th3Mn9 cuboctahedra, edges with two equivalent Mn(1)Th3Mn9 cuboctahedra, faces with two equivalent Mn(1)Th3Mn9 cuboctahedra, and faces with four equivalent C(1)Th2Mn4 octahedra. In the fourth Mn site, Mn(4) is bonded in a 10-coordinate geometry to two equivalent Mn(1), two equivalent Mn(2), two equivalent Mn(5), two equivalent Mn(6), and two equivalent Mn(7) atoms. In the fifth Mn site, Mn(5) is bonded in a 12-coordinate geometry to two equivalent Th(1), two equivalent Mn(1), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(6), and two equivalent Mn(7) atoms. In the sixth Mn site, Mn(6) is bonded in a single-bond geometry to one Mn(1), one Mn(3), one Mn(4), one Mn(5), two equivalent Mn(7), and one C(1) atom. In the seventh Mn site, Mn(7) is bonded in a 14-coordinate geometry to one Th(1), one Mn(1), one Mn(3), one Mn(7), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(5), and four equivalent Mn(6) atoms. C(1) is bonded to two equivalent Th(1), two equivalent Mn(2), and two equivalent Mn(6) atoms to form CTh2Mn4 octahedra that share corners with four equivalent Mn(1)Th3Mn9 cuboctahedra, corners with two equivalent C(1)Th2Mn4 octahedra, faces with two equivalent Mn(3)Th2Mn10 cuboctahedra, and faces with two equivalent Mn(1)Th3Mn9 cuboctahedra. The corner-sharing octahedral tilt angles are 58°.
Th2Mn17C2 crystallizes in the monoclinic C2/m space group. Th(1) is bonded in a distorted bent 120 degrees geometry to one Mn(3), one Mn(7), two equivalent Mn(5), three equivalent Mn(1), and two equivalent C(1) atoms. The Th(1)-Mn(3) bond length is 3.50 Å. The Th(1)-Mn(7) bond length is 3.37 Å. Both Th(1)-Mn(5) bond lengths are 3.32 Å. There are a spread of Th(1)-Mn(1) bond distances ranging from 3.23-3.52 Å. Both Th(1)-C(1) bond lengths are 2.64 Å. There are seven inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent Th(1), one Mn(7), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(5), and two equivalent Mn(6) atoms to form MnTh3Mn9 cuboctahedra that share corners with three equivalent Mn(3)Th2Mn10 cuboctahedra, corners with four equivalent Mn(1)Th3Mn9 cuboctahedra, corners with four equivalent C(1)Th2Mn4 octahedra,  an edgeedge with one Mn(3)Th2Mn10 cuboctahedra,  an edgeedge with one Mn(1)Th3Mn9 cuboctahedra,  a faceface with one Mn(3)Th2Mn10 cuboctahedra,  a faceface with one Mn(1)Th3Mn9 cuboctahedra, and faces with two equivalent C(1)Th2Mn4 octahedra. The corner-sharing octahedral tilt angles range from 64-72°. The Mn(1)-Mn(7) bond length is 2.78 Å. Both Mn(1)-Mn(2) bond lengths are 2.77 Å. Both Mn(1)-Mn(4) bond lengths are 2.63 Å. Both Mn(1)-Mn(5) bond lengths are 2.86 Å. Both Mn(1)-Mn(6) bond lengths are 2.81 Å. In the second Mn site, Mn(2) is bonded in a single-bond geometry to one Mn(1), one Mn(3), one Mn(4), one Mn(5), one Mn(7), and one C(1) atom. The Mn(2)-Mn(3) bond length is 2.61 Å. The Mn(2)-Mn(4) bond length is 2.57 Å. The Mn(2)-Mn(5) bond length is 2.83 Å. The Mn(2)-Mn(7) bond length is 2.79 Å. The Mn(2)-C(1) bond length is 2.00 Å. In the third Mn site, Mn(3) is bonded to two equivalent Th(1), two equivalent Mn(7), four equivalent Mn(2), and four equivalent Mn(6) atoms to form distorted MnTh2Mn10 cuboctahedra that share corners with six equivalent Mn(1)Th3Mn9 cuboctahedra, edges with two equivalent Mn(1)Th3Mn9 cuboctahedra, faces with two equivalent Mn(1)Th3Mn9 cuboctahedra, and faces with four equivalent C(1)Th2Mn4 octahedra. Both Mn(3)-Mn(7) bond lengths are 2.79 Å. All Mn(3)-Mn(6) bond lengths are 2.62 Å. In the fourth Mn site, Mn(4) is bonded in a 10-coordinate geometry to two equivalent Mn(1), two equivalent Mn(2), two equivalent Mn(5), two equivalent Mn(6), and two equivalent Mn(7) atoms. Both Mn(4)-Mn(5) bond lengths are 2.58 Å. Both Mn(4)-Mn(6) bond lengths are 2.64 Å. Both Mn(4)-Mn(7) bond lengths are 2.81 Å. In the fifth Mn site, Mn(5) is bonded in a 12-coordinate geometry to two equivalent Th(1), two equivalent Mn(1), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(6), and two equivalent Mn(7) atoms. Both Mn(5)-Mn(6) bond lengths are 2.54 Å. Both Mn(5)-Mn(7) bond lengths are 2.95 Å. In the sixth Mn site, Mn(6) is bonded in a single-bond geometry to one Mn(1), one Mn(3), one Mn(4), one Mn(5), two equivalent Mn(7), and one C(1) atom. There is one shorter (2.82 Å) and one longer (2.95 Å) Mn(6)-Mn(7) bond length. The Mn(6)-C(1) bond length is 1.99 Å. In the seventh Mn site, Mn(7) is bonded in a 14-coordinate geometry to one Th(1), one Mn(1), one Mn(3), one Mn(7), two equivalent Mn(2), two equivalent Mn(4), two equivalent Mn(5), and four equivalent Mn(6) atoms. The Mn(7)-Mn(7) bond length is 2.62 Å. C(1) is bonded to two equivalent Th(1), two equivalent Mn(2), and two equivalent Mn(6) atoms to form CTh2Mn4 octahedra that share corners with four equivalent Mn(1)Th3Mn9 cuboctahedra, corners with two equivalent C(1)Th2Mn4 octahedra, faces with two equivalent Mn(3)Th2Mn10 cuboctahedra, and faces with two equivalent Mn(1)Th3Mn9 cuboctahedra. The corner-sharing octahedral tilt angles are 58°.