Er7Ru2C11 crystallizes in the orthorhombic Cmcm space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded to two equivalent C(1), two equivalent C(2), and two equivalent C(5) atoms to form ErC6 octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with two equivalent C(7)Er4RuC octahedra, and edges with two equivalent Er(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°. In the second Er site, Er(2) is bonded in a 5-coordinate geometry to one C(1), two equivalent C(6), and two equivalent C(7) atoms. In the third Er site, Er(3) is bonded in a 5-coordinate geometry to two equivalent C(6), two equivalent C(7), and three equivalent C(4) atoms. In the fourth Er site, Er(4) is bonded in a 9-coordinate geometry to one C(5), two equivalent C(2), two equivalent C(3), two equivalent C(4), and two equivalent C(6) atoms. There are two inequivalent Ru sites. In the first Ru site, Ru(1) is bonded in a distorted linear geometry to two equivalent C(6) and two equivalent C(7) atoms. In the second Ru site, Ru(2) is bonded in a distorted trigonal planar geometry to one C(3) and two equivalent C(1) atoms. There are seven inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Er(1), two equivalent Er(2), and two equivalent Ru(2) atoms to form CEr4Ru2 octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with four equivalent C(7)Er4RuC octahedra, and edges with two equivalent C(1)Er4Ru2 octahedra. The corner-sharing octahedral tilt angles range from 52-74°. In the second C site, C(2) is bonded in a 7-coordinate geometry to two equivalent Er(1), four equivalent Er(4), and one C(3) atom. In the third C site, C(3) is bonded to four equivalent Er(4), one Ru(2), and one C(2) atom to form distorted CEr4RuC octahedra that share corners with two equivalent Er(1)C6 octahedra, corners with two equivalent C(1)Er4Ru2 octahedra, corners with four equivalent C(4)Er5C octahedra, edges with two equivalent C(3)Er4RuC octahedra, and edges with two equivalent C(4)Er5C octahedra. The corner-sharing octahedral tilt angles range from 15-52°. In the fourth C site, C(4) is bonded to two equivalent Er(4), three equivalent Er(3), and one C(6) atom to form CEr5C octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with four equivalent C(7)Er4RuC octahedra,  an edgeedge with one C(3)Er4RuC octahedra,  an edgeedge with one C(7)Er4RuC octahedra, and edges with four equivalent C(4)Er5C octahedra. The corner-sharing octahedral tilt angles range from 15-70°. In the fifth C site, C(5) is bonded in a 3-coordinate geometry to one Er(1), one Er(4), and one C(7) atom. In the sixth C site, C(6) is bonded in a 8-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Er(4), one Ru(1), and one C(4) atom. In the seventh C site, C(7) is bonded to two equivalent Er(2), two equivalent Er(3), one Ru(1), and one C(5) atom to form CEr4RuC octahedra that share  a cornercorner with one Er(1)C6 octahedra,  a cornercorner with one C(7)Er4RuC octahedra, corners with two equivalent C(1)Er4Ru2 octahedra, corners with four equivalent C(4)Er5C octahedra,  an edgeedge with one C(4)Er5C octahedra, and edges with two equivalent C(7)Er4RuC octahedra. The corner-sharing octahedral tilt angles range from 0-74°.
Er7Ru2C11 crystallizes in the orthorhombic Cmcm space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded to two equivalent C(1), two equivalent C(2), and two equivalent C(5) atoms to form ErC6 octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with two equivalent C(7)Er4RuC octahedra, and edges with two equivalent Er(1)C6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°. Both Er(1)-C(1) bond lengths are 2.42 Å. Both Er(1)-C(2) bond lengths are 2.58 Å. Both Er(1)-C(5) bond lengths are 2.54 Å. In the second Er site, Er(2) is bonded in a 5-coordinate geometry to one C(1), two equivalent C(6), and two equivalent C(7) atoms. The Er(2)-C(1) bond length is 2.45 Å. Both Er(2)-C(6) bond lengths are 2.57 Å. Both Er(2)-C(7) bond lengths are 2.52 Å. In the third Er site, Er(3) is bonded in a 5-coordinate geometry to two equivalent C(6), two equivalent C(7), and three equivalent C(4) atoms. Both Er(3)-C(6) bond lengths are 2.72 Å. Both Er(3)-C(7) bond lengths are 2.52 Å. There is one shorter (2.34 Å) and two longer (2.47 Å) Er(3)-C(4) bond lengths. In the fourth Er site, Er(4) is bonded in a 9-coordinate geometry to one C(5), two equivalent C(2), two equivalent C(3), two equivalent C(4), and two equivalent C(6) atoms. The Er(4)-C(5) bond length is 2.48 Å. Both Er(4)-C(2) bond lengths are 2.70 Å. Both Er(4)-C(3) bond lengths are 2.56 Å. Both Er(4)-C(4) bond lengths are 2.49 Å. Both Er(4)-C(6) bond lengths are 2.69 Å. There are two inequivalent Ru sites. In the first Ru site, Ru(1) is bonded in a distorted linear geometry to two equivalent C(6) and two equivalent C(7) atoms. Both Ru(1)-C(6) bond lengths are 2.68 Å. Both Ru(1)-C(7) bond lengths are 1.98 Å. In the second Ru site, Ru(2) is bonded in a distorted trigonal planar geometry to one C(3) and two equivalent C(1) atoms. The Ru(2)-C(3) bond length is 1.93 Å. Both Ru(2)-C(1) bond lengths are 2.15 Å. There are seven inequivalent C sites. In the first C site, C(1) is bonded to two equivalent Er(1), two equivalent Er(2), and two equivalent Ru(2) atoms to form CEr4Ru2 octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with four equivalent C(7)Er4RuC octahedra, and edges with two equivalent C(1)Er4Ru2 octahedra. The corner-sharing octahedral tilt angles range from 52-74°. In the second C site, C(2) is bonded in a 7-coordinate geometry to two equivalent Er(1), four equivalent Er(4), and one C(3) atom. The C(2)-C(3) bond length is 1.33 Å. In the third C site, C(3) is bonded to four equivalent Er(4), one Ru(2), and one C(2) atom to form distorted CEr4RuC octahedra that share corners with two equivalent Er(1)C6 octahedra, corners with two equivalent C(1)Er4Ru2 octahedra, corners with four equivalent C(4)Er5C octahedra, edges with two equivalent C(3)Er4RuC octahedra, and edges with two equivalent C(4)Er5C octahedra. The corner-sharing octahedral tilt angles range from 15-52°. In the fourth C site, C(4) is bonded to two equivalent Er(4), three equivalent Er(3), and one C(6) atom to form CEr5C octahedra that share corners with two equivalent C(3)Er4RuC octahedra, corners with four equivalent C(7)Er4RuC octahedra,  an edgeedge with one C(3)Er4RuC octahedra,  an edgeedge with one C(7)Er4RuC octahedra, and edges with four equivalent C(4)Er5C octahedra. The corner-sharing octahedral tilt angles range from 15-70°. The C(4)-C(6) bond length is 1.38 Å. In the fifth C site, C(5) is bonded in a 3-coordinate geometry to one Er(1), one Er(4), and one C(7) atom. The C(5)-C(7) bond length is 1.30 Å. In the sixth C site, C(6) is bonded in a 8-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Er(4), one Ru(1), and one C(4) atom. In the seventh C site, C(7) is bonded to two equivalent Er(2), two equivalent Er(3), one Ru(1), and one C(5) atom to form CEr4RuC octahedra that share  a cornercorner with one Er(1)C6 octahedra,  a cornercorner with one C(7)Er4RuC octahedra, corners with two equivalent C(1)Er4Ru2 octahedra, corners with four equivalent C(4)Er5C octahedra,  an edgeedge with one C(4)Er5C octahedra, and edges with two equivalent C(7)Er4RuC octahedra. The corner-sharing octahedral tilt angles range from 0-74°.