GdSmCo17 crystallizes in the trigonal R3m space group. Gd(1) is bonded in a 19-coordinate geometry to one Co(5), three equivalent Co(2), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(3) atoms. Sm(1) is bonded in a 19-coordinate geometry to one Co(6), three equivalent Co(3), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(2) atoms. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one Gd(1), one Sm(1), one Co(5), one Co(6), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), and two equivalent Co(4) atoms to form distorted CoSmGdCo10 cuboctahedra that share corners with four equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with four equivalent Co(3)SmGd2Co9 cuboctahedra, corners with four equivalent Co(4)SmGdCo10 cuboctahedra, corners with twelve equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(2)Sm2GdCo9 cuboctahedra,  an edgeedge with one Co(3)SmGd2Co9 cuboctahedra,  an edgeedge with one Co(1)SmGdCo10 cuboctahedra, edges with two equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(4)SmGdCo10 cuboctahedra, faces with five equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with five equivalent Co(3)SmGd2Co9 cuboctahedra, and faces with seven equivalent Co(1)SmGdCo10 cuboctahedra. In the second Co site, Co(2) is bonded to one Gd(1), two equivalent Sm(1), one Co(6), two equivalent Co(3), two equivalent Co(4), and four equivalent Co(1) atoms to form CoSm2GdCo9 cuboctahedra that share corners with two equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with five equivalent Co(4)SmGdCo10 cuboctahedra, corners with eight equivalent Co(3)SmGd2Co9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(3)SmGd2Co9 cuboctahedra, edges with two equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(4)SmGdCo10 cuboctahedra, edges with four equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(3)SmGd2Co9 cuboctahedra, faces with three equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(2)Sm2GdCo9 cuboctahedra, and faces with ten equivalent Co(1)SmGdCo10 cuboctahedra. In the third Co site, Co(3) is bonded to two equivalent Gd(1), one Sm(1), one Co(5), two equivalent Co(2), two equivalent Co(4), and four equivalent Co(1) atoms to form CoSmGd2Co9 cuboctahedra that share corners with two equivalent Co(3)SmGd2Co9 cuboctahedra, corners with five equivalent Co(4)SmGdCo10 cuboctahedra, corners with eight equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(2)Sm2GdCo9 cuboctahedra, edges with two equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(4)SmGdCo10 cuboctahedra, edges with four equivalent Co(3)SmGd2Co9 cuboctahedra, faces with three equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(3)SmGd2Co9 cuboctahedra, and faces with ten equivalent Co(1)SmGdCo10 cuboctahedra. In the fourth Co site, Co(4) is bonded to one Gd(1), one Sm(1), one Co(5), one Co(6), two equivalent Co(2), two equivalent Co(3), and four equivalent Co(1) atoms to form CoSmGdCo10 cuboctahedra that share corners with four equivalent Co(4)SmGdCo10 cuboctahedra, corners with five equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with five equivalent Co(3)SmGd2Co9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(2)Sm2GdCo9 cuboctahedra, edges with three equivalent Co(3)SmGd2Co9 cuboctahedra, edges with four equivalent Co(1)SmGdCo10 cuboctahedra, faces with three equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(3)SmGd2Co9 cuboctahedra, faces with four equivalent Co(4)SmGdCo10 cuboctahedra, and faces with eight equivalent Co(1)SmGdCo10 cuboctahedra. In the fifth Co site, Co(5) is bonded in a 14-coordinate geometry to one Gd(1), one Co(6), three equivalent Co(3), three equivalent Co(4), and six equivalent Co(1) atoms. In the sixth Co site, Co(6) is bonded in a 14-coordinate geometry to one Sm(1), one Co(5), three equivalent Co(2), three equivalent Co(4), and six equivalent Co(1) atoms.
GdSmCo17 crystallizes in the trigonal R3m space group. Gd(1) is bonded in a 19-coordinate geometry to one Co(5), three equivalent Co(2), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(3) atoms. The Gd(1)-Co(5) bond length is 3.02 Å. All Gd(1)-Co(2) bond lengths are 2.99 Å. All Gd(1)-Co(4) bond lengths are 3.21 Å. All Gd(1)-Co(1) bond lengths are 2.97 Å. There are three shorter (3.11 Å) and three longer (3.15 Å) Gd(1)-Co(3) bond lengths. Sm(1) is bonded in a 19-coordinate geometry to one Co(6), three equivalent Co(3), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(2) atoms. The Sm(1)-Co(6) bond length is 3.02 Å. All Sm(1)-Co(3) bond lengths are 2.99 Å. All Sm(1)-Co(4) bond lengths are 3.22 Å. All Sm(1)-Co(1) bond lengths are 2.97 Å. There are three shorter (3.11 Å) and three longer (3.15 Å) Sm(1)-Co(2) bond lengths. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one Gd(1), one Sm(1), one Co(5), one Co(6), two equivalent Co(1), two equivalent Co(2), two equivalent Co(3), and two equivalent Co(4) atoms to form distorted CoSmGdCo10 cuboctahedra that share corners with four equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with four equivalent Co(3)SmGd2Co9 cuboctahedra, corners with four equivalent Co(4)SmGdCo10 cuboctahedra, corners with twelve equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(2)Sm2GdCo9 cuboctahedra,  an edgeedge with one Co(3)SmGd2Co9 cuboctahedra,  an edgeedge with one Co(1)SmGdCo10 cuboctahedra, edges with two equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(4)SmGdCo10 cuboctahedra, faces with five equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with five equivalent Co(3)SmGd2Co9 cuboctahedra, and faces with seven equivalent Co(1)SmGdCo10 cuboctahedra. The Co(1)-Co(5) bond length is 2.65 Å. The Co(1)-Co(6) bond length is 2.65 Å. There is one shorter (2.39 Å) and one longer (2.40 Å) Co(1)-Co(1) bond length. There is one shorter (2.48 Å) and one longer (2.57 Å) Co(1)-Co(2) bond length. There is one shorter (2.47 Å) and one longer (2.58 Å) Co(1)-Co(3) bond length. There is one shorter (2.36 Å) and one longer (2.37 Å) Co(1)-Co(4) bond length. In the second Co site, Co(2) is bonded to one Gd(1), two equivalent Sm(1), one Co(6), two equivalent Co(3), two equivalent Co(4), and four equivalent Co(1) atoms to form CoSm2GdCo9 cuboctahedra that share corners with two equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with five equivalent Co(4)SmGdCo10 cuboctahedra, corners with eight equivalent Co(3)SmGd2Co9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(3)SmGd2Co9 cuboctahedra, edges with two equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(4)SmGdCo10 cuboctahedra, edges with four equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(3)SmGd2Co9 cuboctahedra, faces with three equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(2)Sm2GdCo9 cuboctahedra, and faces with ten equivalent Co(1)SmGdCo10 cuboctahedra. The Co(2)-Co(6) bond length is 2.58 Å. Both Co(2)-Co(3) bond lengths are 2.43 Å. Both Co(2)-Co(4) bond lengths are 2.39 Å. In the third Co site, Co(3) is bonded to two equivalent Gd(1), one Sm(1), one Co(5), two equivalent Co(2), two equivalent Co(4), and four equivalent Co(1) atoms to form CoSmGd2Co9 cuboctahedra that share corners with two equivalent Co(3)SmGd2Co9 cuboctahedra, corners with five equivalent Co(4)SmGdCo10 cuboctahedra, corners with eight equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra,  an edgeedge with one Co(2)Sm2GdCo9 cuboctahedra, edges with two equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(4)SmGdCo10 cuboctahedra, edges with four equivalent Co(3)SmGd2Co9 cuboctahedra, faces with three equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(4)SmGdCo10 cuboctahedra, faces with four equivalent Co(3)SmGd2Co9 cuboctahedra, and faces with ten equivalent Co(1)SmGdCo10 cuboctahedra. The Co(3)-Co(5) bond length is 2.57 Å. Both Co(3)-Co(4) bond lengths are 2.38 Å. In the fourth Co site, Co(4) is bonded to one Gd(1), one Sm(1), one Co(5), one Co(6), two equivalent Co(2), two equivalent Co(3), and four equivalent Co(1) atoms to form CoSmGdCo10 cuboctahedra that share corners with four equivalent Co(4)SmGdCo10 cuboctahedra, corners with five equivalent Co(2)Sm2GdCo9 cuboctahedra, corners with five equivalent Co(3)SmGd2Co9 cuboctahedra, corners with eight equivalent Co(1)SmGdCo10 cuboctahedra, edges with three equivalent Co(2)Sm2GdCo9 cuboctahedra, edges with three equivalent Co(3)SmGd2Co9 cuboctahedra, edges with four equivalent Co(1)SmGdCo10 cuboctahedra, faces with three equivalent Co(2)Sm2GdCo9 cuboctahedra, faces with three equivalent Co(3)SmGd2Co9 cuboctahedra, faces with four equivalent Co(4)SmGdCo10 cuboctahedra, and faces with eight equivalent Co(1)SmGdCo10 cuboctahedra. The Co(4)-Co(5) bond length is 2.55 Å. The Co(4)-Co(6) bond length is 2.55 Å. In the fifth Co site, Co(5) is bonded in a 14-coordinate geometry to one Gd(1), one Co(6), three equivalent Co(3), three equivalent Co(4), and six equivalent Co(1) atoms. The Co(5)-Co(6) bond length is 2.28 Å. In the sixth Co site, Co(6) is bonded in a 14-coordinate geometry to one Sm(1), one Co(5), three equivalent Co(2), three equivalent Co(4), and six equivalent Co(1) atoms.