Y2CoGa8 crystallizes in the tetragonal P4/mmm space group. Y(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form YGa12 cuboctahedra that share corners with eight equivalent Y(1)Ga12 cuboctahedra, edges with four equivalent Ga(3)Y4Ga8 cuboctahedra, edges with eight equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Ga(3)Y4Ga8 cuboctahedra, and faces with five equivalent Y(1)Ga12 cuboctahedra. Co(1) is bonded in a body-centered cubic geometry to eight equivalent Ga(1) atoms. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Y(1), two equivalent Co(1), two equivalent Ga(3), and five equivalent Ga(1) atoms. In the second Ga site, Ga(2) is bonded to four equivalent Y(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form distorted GaY4Ga8 cuboctahedra that share corners with four equivalent Ga(2)Y4Ga8 cuboctahedra, edges with eight equivalent Y(1)Ga12 cuboctahedra, edges with eight equivalent Ga(3)Y4Ga8 cuboctahedra, faces with four equivalent Y(1)Ga12 cuboctahedra, faces with four equivalent Ga(3)Y4Ga8 cuboctahedra, and faces with eight equivalent Ga(2)Y4Ga8 cuboctahedra. In the third Ga site, Ga(3) is bonded to four equivalent Y(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaY4Ga8 cuboctahedra that share corners with eight equivalent Ga(3)Y4Ga8 cuboctahedra, edges with four equivalent Y(1)Ga12 cuboctahedra, edges with eight equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Y(1)Ga12 cuboctahedra, faces with four equivalent Ga(2)Y4Ga8 cuboctahedra, and faces with five equivalent Ga(3)Y4Ga8 cuboctahedra.
Y2CoGa8 crystallizes in the tetragonal P4/mmm space group. Y(1) is bonded to four equivalent Ga(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form YGa12 cuboctahedra that share corners with eight equivalent Y(1)Ga12 cuboctahedra, edges with four equivalent Ga(3)Y4Ga8 cuboctahedra, edges with eight equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Ga(3)Y4Ga8 cuboctahedra, and faces with five equivalent Y(1)Ga12 cuboctahedra. All Y(1)-Ga(1) bond lengths are 2.97 Å. All Y(1)-Ga(2) bond lengths are 3.01 Å. All Y(1)-Ga(3) bond lengths are 2.97 Å. Co(1) is bonded in a body-centered cubic geometry to eight equivalent Ga(1) atoms. All Co(1)-Ga(1) bond lengths are 2.45 Å. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 11-coordinate geometry to two equivalent Y(1), two equivalent Co(1), two equivalent Ga(3), and five equivalent Ga(1) atoms. Both Ga(1)-Ga(3) bond lengths are 2.97 Å. There is one shorter (2.54 Å) and four longer (2.97 Å) Ga(1)-Ga(1) bond lengths. In the second Ga site, Ga(2) is bonded to four equivalent Y(1), four equivalent Ga(2), and four equivalent Ga(3) atoms to form distorted GaY4Ga8 cuboctahedra that share corners with four equivalent Ga(2)Y4Ga8 cuboctahedra, edges with eight equivalent Y(1)Ga12 cuboctahedra, edges with eight equivalent Ga(3)Y4Ga8 cuboctahedra, faces with four equivalent Y(1)Ga12 cuboctahedra, faces with four equivalent Ga(3)Y4Ga8 cuboctahedra, and faces with eight equivalent Ga(2)Y4Ga8 cuboctahedra. All Ga(2)-Ga(2) bond lengths are 2.97 Å. All Ga(2)-Ga(3) bond lengths are 3.01 Å. In the third Ga site, Ga(3) is bonded to four equivalent Y(1), four equivalent Ga(1), and four equivalent Ga(2) atoms to form distorted GaY4Ga8 cuboctahedra that share corners with eight equivalent Ga(3)Y4Ga8 cuboctahedra, edges with four equivalent Y(1)Ga12 cuboctahedra, edges with eight equivalent Ga(2)Y4Ga8 cuboctahedra, faces with four equivalent Y(1)Ga12 cuboctahedra, faces with four equivalent Ga(2)Y4Ga8 cuboctahedra, and faces with five equivalent Ga(3)Y4Ga8 cuboctahedra.