Ce5(C2Br)3 crystallizes in the monoclinic C2/m space group. There are five inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 10-coordinate geometry to two equivalent C(1), two equivalent C(2), two equivalent C(5), three equivalent C(4), and one Br(3) atom. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one C(5), one C(6), two equivalent C(1), two equivalent C(4), and two equivalent Br(1) atoms. In the third Ce site, Ce(3) is bonded in a 8-coordinate geometry to one C(2), four equivalent C(3), one Br(2), and two equivalent Br(3) atoms. In the fourth Ce site, Ce(4) is bonded in a 8-coordinate geometry to one C(3), two equivalent C(2), two equivalent C(5), one Br(1), and two equivalent Br(2) atoms. In the fifth Ce site, Ce(5) is bonded in a 8-coordinate geometry to one C(1), four equivalent C(6), one Br(1), and two equivalent Br(3) atoms. There are six inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one Ce(5), two equivalent Ce(1), two equivalent Ce(2), and one C(4) atom. In the second C site, C(2) is bonded in a 6-coordinate geometry to one Ce(3), two equivalent Ce(1), two equivalent Ce(4), and one C(5) atom. In the third C site, C(3) is bonded in a 6-coordinate geometry to one Ce(4), four equivalent Ce(3), and one C(3) atom. In the fourth C site, C(4) is bonded in a 6-coordinate geometry to two equivalent Ce(2), three equivalent Ce(1), and one C(1) atom. In the fifth C site, C(5) is bonded to one Ce(2), two equivalent Ce(1), two equivalent Ce(4), and one C(2) atom to form distorted CCe5C octahedra that share corners with two equivalent Br(3)Ce5 square pyramids and edges with two equivalent C(5)Ce5C octahedra. In the sixth C site, C(6) is bonded in a 6-coordinate geometry to one Ce(2), four equivalent Ce(5), and one C(6) atom. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a rectangular see-saw-like geometry to one Ce(4), one Ce(5), and two equivalent Ce(2) atoms. In the second Br site, Br(2) is bonded in a distorted T-shaped geometry to one Ce(3) and two equivalent Ce(4) atoms. In the third Br site, Br(3) is bonded to one Ce(1), two equivalent Ce(3), and two equivalent Ce(5) atoms to form distorted BrCe5 square pyramids that share corners with two equivalent C(5)Ce5C octahedra and edges with two equivalent Br(3)Ce5 square pyramids. The corner-sharing octahedral tilt angles are 79°.
Ce5(C2Br)3 crystallizes in the monoclinic C2/m space group. There are five inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 10-coordinate geometry to two equivalent C(1), two equivalent C(2), two equivalent C(5), three equivalent C(4), and one Br(3) atom. Both Ce(1)-C(1) bond lengths are 2.82 Å. Both Ce(1)-C(2) bond lengths are 2.84 Å. Both Ce(1)-C(5) bond lengths are 2.72 Å. There is one shorter (2.41 Å) and two longer (2.72 Å) Ce(1)-C(4) bond lengths. The Ce(1)-Br(3) bond length is 3.42 Å. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one C(5), one C(6), two equivalent C(1), two equivalent C(4), and two equivalent Br(1) atoms. The Ce(2)-C(5) bond length is 2.50 Å. The Ce(2)-C(6) bond length is 2.43 Å. Both Ce(2)-C(1) bond lengths are 2.65 Å. Both Ce(2)-C(4) bond lengths are 2.69 Å. Both Ce(2)-Br(1) bond lengths are 3.06 Å. In the third Ce site, Ce(3) is bonded in a 8-coordinate geometry to one C(2), four equivalent C(3), one Br(2), and two equivalent Br(3) atoms. The Ce(3)-C(2) bond length is 2.42 Å. There are two shorter (2.61 Å) and two longer (2.68 Å) Ce(3)-C(3) bond lengths. The Ce(3)-Br(2) bond length is 3.10 Å. Both Ce(3)-Br(3) bond lengths are 3.05 Å. In the fourth Ce site, Ce(4) is bonded in a 8-coordinate geometry to one C(3), two equivalent C(2), two equivalent C(5), one Br(1), and two equivalent Br(2) atoms. The Ce(4)-C(3) bond length is 2.32 Å. Both Ce(4)-C(2) bond lengths are 2.64 Å. Both Ce(4)-C(5) bond lengths are 2.71 Å. The Ce(4)-Br(1) bond length is 3.16 Å. Both Ce(4)-Br(2) bond lengths are 3.01 Å. In the fifth Ce site, Ce(5) is bonded in a 8-coordinate geometry to one C(1), four equivalent C(6), one Br(1), and two equivalent Br(3) atoms. The Ce(5)-C(1) bond length is 2.41 Å. There are two shorter (2.61 Å) and two longer (2.68 Å) Ce(5)-C(6) bond lengths. The Ce(5)-Br(1) bond length is 3.16 Å. Both Ce(5)-Br(3) bond lengths are 3.04 Å. There are six inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to one Ce(5), two equivalent Ce(1), two equivalent Ce(2), and one C(4) atom. The C(1)-C(4) bond length is 1.33 Å. In the second C site, C(2) is bonded in a 6-coordinate geometry to one Ce(3), two equivalent Ce(1), two equivalent Ce(4), and one C(5) atom. The C(2)-C(5) bond length is 1.34 Å. In the third C site, C(3) is bonded in a 6-coordinate geometry to one Ce(4), four equivalent Ce(3), and one C(3) atom. The C(3)-C(3) bond length is 1.38 Å. In the fourth C site, C(4) is bonded in a 6-coordinate geometry to two equivalent Ce(2), three equivalent Ce(1), and one C(1) atom. In the fifth C site, C(5) is bonded to one Ce(2), two equivalent Ce(1), two equivalent Ce(4), and one C(2) atom to form distorted CCe5C octahedra that share corners with two equivalent Br(3)Ce5 square pyramids and edges with two equivalent C(5)Ce5C octahedra. In the sixth C site, C(6) is bonded in a 6-coordinate geometry to one Ce(2), four equivalent Ce(5), and one C(6) atom. The C(6)-C(6) bond length is 1.37 Å. There are three inequivalent Br sites. In the first Br site, Br(1) is bonded in a rectangular see-saw-like geometry to one Ce(4), one Ce(5), and two equivalent Ce(2) atoms. In the second Br site, Br(2) is bonded in a distorted T-shaped geometry to one Ce(3) and two equivalent Ce(4) atoms. In the third Br site, Br(3) is bonded to one Ce(1), two equivalent Ce(3), and two equivalent Ce(5) atoms to form distorted BrCe5 square pyramids that share corners with two equivalent C(5)Ce5C octahedra and edges with two equivalent Br(3)Ce5 square pyramids. The corner-sharing octahedral tilt angles are 79°.