Er12(MnC3)5 crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Er sites. In the first Er site, Er(1) is bonded in a rectangular see-saw-like geometry to one C(8), one C(9), and two equivalent C(3) atoms. In the second Er site, Er(2) is bonded in a rectangular see-saw-like geometry to two equivalent C(4) and two equivalent C(7) atoms. In the third Er site, Er(3) is bonded to one C(1), one C(4), one C(6), and two equivalent C(7) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. In the fourth Er site, Er(4) is bonded to one C(2), one C(3), one C(5), and two equivalent C(8) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. In the fifth Er site, Er(5) is bonded to one C(1), one C(3), one C(5), and two equivalent C(9) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. In the sixth Er site, Er(6) is bonded in a 8-coordinate geometry to one C(7), one C(8), two equivalent C(1), two equivalent C(5), and two equivalent C(9) atoms. In the seventh Er site, Er(7) is bonded in a 8-coordinate geometry to two equivalent C(2), two equivalent C(6), two equivalent C(7), and two equivalent C(8) atoms. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 3-coordinate geometry to one C(1), one C(3), and one C(4) atom. In the second Mn site, Mn(2) is bonded in a 3-coordinate geometry to one C(2) and two equivalent C(3) atoms. In the third Mn site, Mn(3) is bonded in a trigonal planar geometry to one C(7), one C(8), and one C(9) atom. There are nine inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one Er(3), one Er(5), two equivalent Er(6), one Mn(1), and one C(5) atom. In the second C site, C(2) is bonded in a 6-coordinate geometry to two equivalent Er(4), two equivalent Er(7), one Mn(2), and one C(6) atom. In the third C site, C(3) is bonded to one Er(4), one Er(5), two equivalent Er(1), one Mn(1), and one Mn(2) atom to form CEr4Mn2 octahedra that share  a cornercorner with one C(4)Er4Mn2 octahedra, corners with three equivalent C(3)Er4Mn2 octahedra, edges with two equivalent C(8)Er5Mn octahedra, and edges with two equivalent C(9)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 1-31°. In the fourth C site, C(4) is bonded to two equivalent Er(2), two equivalent Er(3), and two equivalent Mn(1) atoms to form CEr4Mn2 octahedra that share corners with two equivalent C(3)Er4Mn2 octahedra, corners with two equivalent C(4)Er4Mn2 octahedra, and edges with four equivalent C(7)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 2-31°. In the fifth C site, C(5) is bonded in a 5-coordinate geometry to one Er(4), one Er(5), two equivalent Er(6), and one C(1) atom. In the sixth C site, C(6) is bonded in a 5-coordinate geometry to two equivalent Er(3), two equivalent Er(7), and one C(2) atom. In the seventh C site, C(7) is bonded to one Er(2), one Er(6), one Er(7), two equivalent Er(3), and one Mn(3) atom to form distorted CEr5Mn octahedra that share  a cornercorner with one C(9)Er5Mn octahedra, corners with two equivalent C(7)Er5Mn octahedra, corners with two equivalent C(8)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra,  an edgeedge with one C(8)Er5Mn octahedra,  an edgeedge with one C(9)Er5Mn octahedra, and edges with two equivalent C(4)Er4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 9-42°. In the eighth C site, C(8) is bonded to one Er(1), one Er(6), one Er(7), two equivalent Er(4), and one Mn(3) atom to form distorted CEr5Mn octahedra that share corners with two equivalent C(7)Er5Mn octahedra, corners with three equivalent C(8)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra, edges with two equivalent C(3)Er4Mn2 octahedra, and edges with two equivalent C(9)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 10-43°. In the ninth C site, C(9) is bonded to one Er(1), two equivalent Er(5), two equivalent Er(6), and one Mn(3) atom to form distorted CEr5Mn octahedra that share  a cornercorner with one C(7)Er5Mn octahedra, corners with four equivalent C(9)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra, edges with two equivalent C(3)Er4Mn2 octahedra, and edges with two equivalent C(8)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 9-42°.
Er12(MnC3)5 crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Er sites. In the first Er site, Er(1) is bonded in a rectangular see-saw-like geometry to one C(8), one C(9), and two equivalent C(3) atoms. The Er(1)-C(8) bond length is 2.51 Å. The Er(1)-C(9) bond length is 2.50 Å. Both Er(1)-C(3) bond lengths are 2.49 Å. In the second Er site, Er(2) is bonded in a rectangular see-saw-like geometry to two equivalent C(4) and two equivalent C(7) atoms. Both Er(2)-C(4) bond lengths are 2.49 Å. Both Er(2)-C(7) bond lengths are 2.48 Å. In the third Er site, Er(3) is bonded to one C(1), one C(4), one C(6), and two equivalent C(7) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. The Er(3)-C(1) bond length is 2.42 Å. The Er(3)-C(4) bond length is 2.32 Å. The Er(3)-C(6) bond length is 2.50 Å. Both Er(3)-C(7) bond lengths are 2.49 Å. In the fourth Er site, Er(4) is bonded to one C(2), one C(3), one C(5), and two equivalent C(8) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. The Er(4)-C(2) bond length is 2.41 Å. The Er(4)-C(3) bond length is 2.30 Å. The Er(4)-C(5) bond length is 2.51 Å. Both Er(4)-C(8) bond lengths are 2.50 Å. In the fifth Er site, Er(5) is bonded to one C(1), one C(3), one C(5), and two equivalent C(9) atoms to form a mixture of distorted edge and corner-sharing ErC5 square pyramids. The Er(5)-C(1) bond length is 2.43 Å. The Er(5)-C(3) bond length is 2.30 Å. The Er(5)-C(5) bond length is 2.50 Å. Both Er(5)-C(9) bond lengths are 2.49 Å. In the sixth Er site, Er(6) is bonded in a 8-coordinate geometry to one C(7), one C(8), two equivalent C(1), two equivalent C(5), and two equivalent C(9) atoms. The Er(6)-C(7) bond length is 2.70 Å. The Er(6)-C(8) bond length is 2.66 Å. Both Er(6)-C(1) bond lengths are 2.70 Å. Both Er(6)-C(5) bond lengths are 2.51 Å. There is one shorter (2.66 Å) and one longer (2.71 Å) Er(6)-C(9) bond length. In the seventh Er site, Er(7) is bonded in a 8-coordinate geometry to two equivalent C(2), two equivalent C(6), two equivalent C(7), and two equivalent C(8) atoms. Both Er(7)-C(2) bond lengths are 2.71 Å. Both Er(7)-C(6) bond lengths are 2.50 Å. Both Er(7)-C(7) bond lengths are 2.63 Å. Both Er(7)-C(8) bond lengths are 2.71 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 3-coordinate geometry to one C(1), one C(3), and one C(4) atom. The Mn(1)-C(1) bond length is 1.81 Å. The Mn(1)-C(3) bond length is 1.94 Å. The Mn(1)-C(4) bond length is 1.94 Å. In the second Mn site, Mn(2) is bonded in a 3-coordinate geometry to one C(2) and two equivalent C(3) atoms. The Mn(2)-C(2) bond length is 1.80 Å. Both Mn(2)-C(3) bond lengths are 1.94 Å. In the third Mn site, Mn(3) is bonded in a trigonal planar geometry to one C(7), one C(8), and one C(9) atom. The Mn(3)-C(7) bond length is 1.77 Å. The Mn(3)-C(8) bond length is 1.76 Å. The Mn(3)-C(9) bond length is 1.76 Å. There are nine inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one Er(3), one Er(5), two equivalent Er(6), one Mn(1), and one C(5) atom. The C(1)-C(5) bond length is 1.35 Å. In the second C site, C(2) is bonded in a 6-coordinate geometry to two equivalent Er(4), two equivalent Er(7), one Mn(2), and one C(6) atom. The C(2)-C(6) bond length is 1.35 Å. In the third C site, C(3) is bonded to one Er(4), one Er(5), two equivalent Er(1), one Mn(1), and one Mn(2) atom to form CEr4Mn2 octahedra that share  a cornercorner with one C(4)Er4Mn2 octahedra, corners with three equivalent C(3)Er4Mn2 octahedra, edges with two equivalent C(8)Er5Mn octahedra, and edges with two equivalent C(9)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 1-31°. In the fourth C site, C(4) is bonded to two equivalent Er(2), two equivalent Er(3), and two equivalent Mn(1) atoms to form CEr4Mn2 octahedra that share corners with two equivalent C(3)Er4Mn2 octahedra, corners with two equivalent C(4)Er4Mn2 octahedra, and edges with four equivalent C(7)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 2-31°. In the fifth C site, C(5) is bonded in a 5-coordinate geometry to one Er(4), one Er(5), two equivalent Er(6), and one C(1) atom. In the sixth C site, C(6) is bonded in a 5-coordinate geometry to two equivalent Er(3), two equivalent Er(7), and one C(2) atom. In the seventh C site, C(7) is bonded to one Er(2), one Er(6), one Er(7), two equivalent Er(3), and one Mn(3) atom to form distorted CEr5Mn octahedra that share  a cornercorner with one C(9)Er5Mn octahedra, corners with two equivalent C(7)Er5Mn octahedra, corners with two equivalent C(8)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra,  an edgeedge with one C(8)Er5Mn octahedra,  an edgeedge with one C(9)Er5Mn octahedra, and edges with two equivalent C(4)Er4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 9-42°. In the eighth C site, C(8) is bonded to one Er(1), one Er(6), one Er(7), two equivalent Er(4), and one Mn(3) atom to form distorted CEr5Mn octahedra that share corners with two equivalent C(7)Er5Mn octahedra, corners with three equivalent C(8)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra, edges with two equivalent C(3)Er4Mn2 octahedra, and edges with two equivalent C(9)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 10-43°. In the ninth C site, C(9) is bonded to one Er(1), two equivalent Er(5), two equivalent Er(6), and one Mn(3) atom to form distorted CEr5Mn octahedra that share  a cornercorner with one C(7)Er5Mn octahedra, corners with four equivalent C(9)Er5Mn octahedra,  an edgeedge with one C(7)Er5Mn octahedra, edges with two equivalent C(3)Er4Mn2 octahedra, and edges with two equivalent C(8)Er5Mn octahedra. The corner-sharing octahedral tilt angles range from 9-42°.