Y2Co12As7 crystallizes in the hexagonal P-6 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 18-coordinate geometry to three equivalent Co(1), three equivalent Co(3), six equivalent Co(4), and six equivalent As(2) atoms. In the second Y site, Y(2) is bonded in a 15-coordinate geometry to three equivalent Co(4), six equivalent Co(1), and six equivalent As(3) atoms. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one Y(1), two equivalent Y(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted CoY3As4 tetrahedra that share corners with four equivalent Co(4)Y3As4 tetrahedra, corners with four equivalent Co(3)YAs4 tetrahedra, corners with six equivalent Co(1)Y3As4 tetrahedra,  an edgeedge with one Co(3)YAs4 tetrahedra, edges with two equivalent Co(1)Y3As4 tetrahedra, edges with four equivalent Co(4)Y3As4 tetrahedra,  a faceface with one Co(3)YAs4 tetrahedra, faces with two equivalent Co(1)Y3As4 tetrahedra, and faces with two equivalent Co(4)Y3As4 tetrahedra. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. In the third Co site, Co(3) is bonded to one Y(1), one As(1), one As(3), and two equivalent As(2) atoms to form distorted CoYAs4 tetrahedra that share corners with two equivalent Co(4)Y3As4 tetrahedra, corners with four equivalent Co(1)Y3As4 tetrahedra, corners with six equivalent Co(3)YAs4 tetrahedra,  an edgeedge with one Co(1)Y3As4 tetrahedra, edges with two equivalent Co(4)Y3As4 tetrahedra,  a faceface with one Co(1)Y3As4 tetrahedra, and faces with two equivalent Co(4)Y3As4 tetrahedra. In the fourth Co site, Co(4) is bonded to one Y(2), two equivalent Y(1), two equivalent As(2), and two equivalent As(3) atoms to form distorted CoY3As4 tetrahedra that share corners with two equivalent Co(3)YAs4 tetrahedra, corners with four equivalent Co(1)Y3As4 tetrahedra, corners with six equivalent Co(4)Y3As4 tetrahedra, edges with two equivalent Co(4)Y3As4 tetrahedra, edges with two equivalent Co(3)YAs4 tetrahedra, edges with four equivalent Co(1)Y3As4 tetrahedra, faces with two equivalent Co(1)Y3As4 tetrahedra, faces with two equivalent Co(4)Y3As4 tetrahedra, and faces with two equivalent Co(3)YAs4 tetrahedra. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Co(3) and six equivalent Co(2) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Y(1), one Co(2), two equivalent Co(1), two equivalent Co(3), and two equivalent Co(4) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Y(2), one Co(3), two equivalent Co(1), two equivalent Co(2), and two equivalent Co(4) atoms.
Y2Co12As7 crystallizes in the hexagonal P-6 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 18-coordinate geometry to three equivalent Co(1), three equivalent Co(3), six equivalent Co(4), and six equivalent As(2) atoms. All Y(1)-Co(1) bond lengths are 3.30 Å. All Y(1)-Co(3) bond lengths are 3.16 Å. All Y(1)-Co(4) bond lengths are 3.09 Å. All Y(1)-As(2) bond lengths are 2.95 Å. In the second Y site, Y(2) is bonded in a 15-coordinate geometry to three equivalent Co(4), six equivalent Co(1), and six equivalent As(3) atoms. All Y(2)-Co(4) bond lengths are 3.22 Å. All Y(2)-Co(1) bond lengths are 3.06 Å. All Y(2)-As(3) bond lengths are 2.92 Å. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to one Y(1), two equivalent Y(2), two equivalent As(2), and two equivalent As(3) atoms to form distorted CoY3As4 tetrahedra that share corners with four equivalent Co(4)Y3As4 tetrahedra, corners with four equivalent Co(3)YAs4 tetrahedra, corners with six equivalent Co(1)Y3As4 tetrahedra,  an edgeedge with one Co(3)YAs4 tetrahedra, edges with two equivalent Co(1)Y3As4 tetrahedra, edges with four equivalent Co(4)Y3As4 tetrahedra,  a faceface with one Co(3)YAs4 tetrahedra, faces with two equivalent Co(1)Y3As4 tetrahedra, and faces with two equivalent Co(4)Y3As4 tetrahedra. Both Co(1)-As(2) bond lengths are 2.39 Å. There is one shorter (2.32 Å) and one longer (2.35 Å) Co(1)-As(3) bond length. In the second Co site, Co(2) is bonded in a 5-coordinate geometry to one As(2), two equivalent As(1), and two equivalent As(3) atoms. The Co(2)-As(2) bond length is 2.36 Å. Both Co(2)-As(1) bond lengths are 2.61 Å. Both Co(2)-As(3) bond lengths are 2.59 Å. In the third Co site, Co(3) is bonded to one Y(1), one As(1), one As(3), and two equivalent As(2) atoms to form distorted CoYAs4 tetrahedra that share corners with two equivalent Co(4)Y3As4 tetrahedra, corners with four equivalent Co(1)Y3As4 tetrahedra, corners with six equivalent Co(3)YAs4 tetrahedra,  an edgeedge with one Co(1)Y3As4 tetrahedra, edges with two equivalent Co(4)Y3As4 tetrahedra,  a faceface with one Co(1)Y3As4 tetrahedra, and faces with two equivalent Co(4)Y3As4 tetrahedra. The Co(3)-As(1) bond length is 2.25 Å. The Co(3)-As(3) bond length is 2.28 Å. Both Co(3)-As(2) bond lengths are 2.35 Å. In the fourth Co site, Co(4) is bonded to one Y(2), two equivalent Y(1), two equivalent As(2), and two equivalent As(3) atoms to form distorted CoY3As4 tetrahedra that share corners with two equivalent Co(3)YAs4 tetrahedra, corners with four equivalent Co(1)Y3As4 tetrahedra, corners with six equivalent Co(4)Y3As4 tetrahedra, edges with two equivalent Co(4)Y3As4 tetrahedra, edges with two equivalent Co(3)YAs4 tetrahedra, edges with four equivalent Co(1)Y3As4 tetrahedra, faces with two equivalent Co(1)Y3As4 tetrahedra, faces with two equivalent Co(4)Y3As4 tetrahedra, and faces with two equivalent Co(3)YAs4 tetrahedra. There is one shorter (2.35 Å) and one longer (2.40 Å) Co(4)-As(2) bond length. Both Co(4)-As(3) bond lengths are 2.36 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Co(3) and six equivalent Co(2) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Y(1), one Co(2), two equivalent Co(1), two equivalent Co(3), and two equivalent Co(4) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Y(2), one Co(3), two equivalent Co(1), two equivalent Co(2), and two equivalent Co(4) atoms.