Tb2Co7 crystallizes in the trigonal R-3m space group. There are six inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4,4); and six equivalent Co(5) atoms. In the second Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2), three equivalent Co(3), six equivalent Co(4), and six equivalent Co(5) atoms. In the third Tb site, Tb(2) is bonded in a 12-coordinate geometry to three equivalent Co(1) and nine equivalent Co(5) atoms. In the fourth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4); and six equivalent Co(5) atoms. In the fifth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4,4); and six equivalent Co(5) atoms. In the sixth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4); and six equivalent Co(5) atoms. There are seven inequivalent Co sites. In the first Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four Co(4,4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra; corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra; edges with two equivalent Co(4)Tb4Co8 cuboctahedra; edges with eight equivalent Co(5)Tb5Co7 cuboctahedra; faces with two equivalent Co(5)Tb5Co7 cuboctahedra; and faces with eight Co(4,4)Tb4Co8 cuboctahedra. In the second Co site, Co(1) is bonded to six equivalent Tb(2) and six equivalent Co(5) atoms to form CoTb6Co6 cuboctahedra that share corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra, edges with six equivalent Co(1)Tb6Co6 cuboctahedra, and faces with eighteen equivalent Co(5)Tb5Co7 cuboctahedra. In the third Co site, Co(2) is bonded in a 9-coordinate geometry to three equivalent Tb(1), three equivalent Co(4), and three equivalent Co(5) atoms. In the fourth Co site, Co(3) is bonded in a 9-coordinate geometry to three equivalent Tb(1); three Co(4,4,4); and three equivalent Co(5) atoms. In the fifth Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four equivalent Co(4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra, corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra, edges with two equivalent Co(4)Tb4Co8 cuboctahedra, edges with eight equivalent Co(5)Tb5Co7 cuboctahedra, faces with two equivalent Co(5)Tb5Co7 cuboctahedra, and faces with eight equivalent Co(4)Tb4Co8 cuboctahedra. In the sixth Co site, Co(5) is bonded to two equivalent Tb(1), three equivalent Tb(2), one Co(1), one Co(2), one Co(3), and four equivalent Co(5) atoms to form distorted CoTb5Co7 cuboctahedra that share corners with two equivalent Co(1)Tb6Co6 cuboctahedra; corners with six Co(4,4,4)Tb4Co8 cuboctahedra; corners with nine equivalent Co(5)Tb5Co7 cuboctahedra; edges with four Co(4,4)Tb4Co8 cuboctahedra; edges with four equivalent Co(5)Tb5Co7 cuboctahedra;  a faceface with one Co(4)Tb4Co8 cuboctahedra; faces with three equivalent Co(1)Tb6Co6 cuboctahedra; and faces with ten equivalent Co(5)Tb5Co7 cuboctahedra. In the seventh Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four Co(4,4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra; corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra; edges with two equivalent Co(4)Tb4Co8 cuboctahedra; edges with eight equivalent Co(5)Tb5Co7 cuboctahedra; faces with two equivalent Co(5)Tb5Co7 cuboctahedra; and faces with eight Co(4,4)Tb4Co8 cuboctahedra.
Tb2Co7 crystallizes in the trigonal R-3m space group. There are six inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4,4); and six equivalent Co(5) atoms. All Tb(1)-Co(2) bond lengths are 2.87 Å. All Tb(1)-Co(3) bond lengths are 2.87 Å. All Tb(1)-Co(4,4,4) bond lengths are 3.11 Å. All Tb(1)-Co(5) bond lengths are 3.23 Å. In the second Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2), three equivalent Co(3), six equivalent Co(4), and six equivalent Co(5) atoms. All Tb(1)-Co(2) bond lengths are 2.87 Å. All Tb(1)-Co(3) bond lengths are 2.87 Å. All Tb(1)-Co(4) bond lengths are 3.11 Å. All Tb(1)-Co(5) bond lengths are 3.23 Å. In the third Tb site, Tb(2) is bonded in a 12-coordinate geometry to three equivalent Co(1) and nine equivalent Co(5) atoms. All Tb(2)-Co(1) bond lengths are 2.94 Å. There are six shorter (2.86 Å) and three longer (3.09 Å) Tb(2)-Co(5) bond lengths. In the fourth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4); and six equivalent Co(5) atoms. All Tb(1)-Co(2) bond lengths are 2.87 Å. All Tb(1)-Co(3) bond lengths are 2.87 Å. All Tb(1)-Co(4,4) bond lengths are 3.11 Å. All Tb(1)-Co(5) bond lengths are 3.23 Å. In the fifth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4,4); and six equivalent Co(5) atoms. All Tb(1)-Co(2) bond lengths are 2.87 Å. All Tb(1)-Co(3) bond lengths are 2.87 Å. All Tb(1)-Co(4,4,4) bond lengths are 3.11 Å. All Tb(1)-Co(5) bond lengths are 3.23 Å. In the sixth Tb site, Tb(1) is bonded in a 18-coordinate geometry to three equivalent Co(2); three equivalent Co(3); six Co(4,4); and six equivalent Co(5) atoms. All Tb(1)-Co(2) bond lengths are 2.87 Å. All Tb(1)-Co(3) bond lengths are 2.87 Å. All Tb(1)-Co(4,4) bond lengths are 3.11 Å. All Tb(1)-Co(5) bond lengths are 3.23 Å. There are seven inequivalent Co sites. In the first Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four Co(4,4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra; corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra; edges with two equivalent Co(4)Tb4Co8 cuboctahedra; edges with eight equivalent Co(5)Tb5Co7 cuboctahedra; faces with two equivalent Co(5)Tb5Co7 cuboctahedra; and faces with eight Co(4,4)Tb4Co8 cuboctahedra. Both Co(4)-Co(2) bond lengths are 2.44 Å. Both Co(4)-Co(3) bond lengths are 2.45 Å. All Co(4)-Co(4,4) bond lengths are 2.48 Å. In the second Co site, Co(1) is bonded to six equivalent Tb(2) and six equivalent Co(5) atoms to form CoTb6Co6 cuboctahedra that share corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra, edges with six equivalent Co(1)Tb6Co6 cuboctahedra, and faces with eighteen equivalent Co(5)Tb5Co7 cuboctahedra. All Co(1)-Co(5) bond lengths are 2.52 Å. In the third Co site, Co(2) is bonded in a 9-coordinate geometry to three equivalent Tb(1), three equivalent Co(4), and three equivalent Co(5) atoms. All Co(2)-Co(4) bond lengths are 2.44 Å. All Co(2)-Co(5) bond lengths are 2.43 Å. In the fourth Co site, Co(3) is bonded in a 9-coordinate geometry to three equivalent Tb(1); three Co(4,4,4); and three equivalent Co(5) atoms. Both Co(3)-Co(4,4) bond lengths are 2.45 Å. All Co(3)-Co(5) bond lengths are 2.42 Å. In the fifth Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four equivalent Co(4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra, corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra, edges with two equivalent Co(4)Tb4Co8 cuboctahedra, edges with eight equivalent Co(5)Tb5Co7 cuboctahedra, faces with two equivalent Co(5)Tb5Co7 cuboctahedra, and faces with eight equivalent Co(4)Tb4Co8 cuboctahedra. All Co(4)-Co(4) bond lengths are 2.48 Å. In the sixth Co site, Co(5) is bonded to two equivalent Tb(1), three equivalent Tb(2), one Co(1), one Co(2), one Co(3), and four equivalent Co(5) atoms to form distorted CoTb5Co7 cuboctahedra that share corners with two equivalent Co(1)Tb6Co6 cuboctahedra; corners with six Co(4,4,4)Tb4Co8 cuboctahedra; corners with nine equivalent Co(5)Tb5Co7 cuboctahedra; edges with four Co(4,4)Tb4Co8 cuboctahedra; edges with four equivalent Co(5)Tb5Co7 cuboctahedra;  a faceface with one Co(4)Tb4Co8 cuboctahedra; faces with three equivalent Co(1)Tb6Co6 cuboctahedra; and faces with ten equivalent Co(5)Tb5Co7 cuboctahedra. All Co(5)-Co(5) bond lengths are 2.48 Å. In the seventh Co site, Co(4) is bonded to four Tb(1,1); two equivalent Co(2); two equivalent Co(3); and four Co(4,4) atoms to form CoTb4Co8 cuboctahedra that share corners with four equivalent Co(4)Tb4Co8 cuboctahedra; corners with twelve equivalent Co(5)Tb5Co7 cuboctahedra; edges with two equivalent Co(4)Tb4Co8 cuboctahedra; edges with eight equivalent Co(5)Tb5Co7 cuboctahedra; faces with two equivalent Co(5)Tb5Co7 cuboctahedra; and faces with eight Co(4,4)Tb4Co8 cuboctahedra. Both Co(4)-Co(2) bond lengths are 2.44 Å. Both Co(4)-Co(4) bond lengths are 2.48 Å.