PuCo3 crystallizes in the trigonal R-3m space group. There are two inequivalent Pu sites. In the first Pu site, Pu(1) is bonded in a distorted hexagonal planar geometry to six equivalent Co(2) and twelve equivalent Co(3) atoms. In the second Pu site, Pu(2) is bonded in a 12-coordinate geometry to three equivalent Co(1) and nine equivalent Co(3) atoms. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent Pu(2) and six equivalent Co(3) atoms to form CoPu6Co6 cuboctahedra that share corners with six equivalent Co(2)Pu3Co9 cuboctahedra, corners with twelve equivalent Co(3)Pu5Co7 cuboctahedra, edges with six equivalent Co(1)Pu6Co6 cuboctahedra, faces with two equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eighteen equivalent Co(3)Pu5Co7 cuboctahedra. In the second Co site, Co(2) is bonded to three equivalent Pu(1), three equivalent Co(2), and six equivalent Co(3) atoms to form distorted CoPu3Co9 cuboctahedra that share corners with three equivalent Co(2)Pu3Co9 cuboctahedra, corners with three equivalent Co(1)Pu6Co6 cuboctahedra, corners with twelve equivalent Co(3)Pu5Co7 cuboctahedra, edges with six equivalent Co(2)Pu3Co9 cuboctahedra,  a faceface with one Co(1)Pu6Co6 cuboctahedra, faces with three equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eighteen equivalent Co(3)Pu5Co7 cuboctahedra. In the third Co site, Co(3) is bonded to two equivalent Pu(1), three equivalent Pu(2), one Co(1), two equivalent Co(2), and four equivalent Co(3) atoms to form CoPu5Co7 cuboctahedra that share corners with two equivalent Co(1)Pu6Co6 cuboctahedra, corners with four equivalent Co(2)Pu3Co9 cuboctahedra, corners with fifteen equivalent Co(3)Pu5Co7 cuboctahedra, edges with eight equivalent Co(3)Pu5Co7 cuboctahedra, faces with three equivalent Co(1)Pu6Co6 cuboctahedra, faces with six equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eleven equivalent Co(3)Pu5Co7 cuboctahedra.
PuCo3 crystallizes in the trigonal R-3m space group. There are two inequivalent Pu sites. In the first Pu site, Pu(1) is bonded in a distorted hexagonal planar geometry to six equivalent Co(2) and twelve equivalent Co(3) atoms. All Pu(1)-Co(2) bond lengths are 2.74 Å. All Pu(1)-Co(3) bond lengths are 3.11 Å. In the second Pu site, Pu(2) is bonded in a 12-coordinate geometry to three equivalent Co(1) and nine equivalent Co(3) atoms. All Pu(2)-Co(1) bond lengths are 2.79 Å. There are six shorter (2.84 Å) and three longer (2.89 Å) Pu(2)-Co(3) bond lengths. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent Pu(2) and six equivalent Co(3) atoms to form CoPu6Co6 cuboctahedra that share corners with six equivalent Co(2)Pu3Co9 cuboctahedra, corners with twelve equivalent Co(3)Pu5Co7 cuboctahedra, edges with six equivalent Co(1)Pu6Co6 cuboctahedra, faces with two equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eighteen equivalent Co(3)Pu5Co7 cuboctahedra. All Co(1)-Co(3) bond lengths are 2.46 Å. In the second Co site, Co(2) is bonded to three equivalent Pu(1), three equivalent Co(2), and six equivalent Co(3) atoms to form distorted CoPu3Co9 cuboctahedra that share corners with three equivalent Co(2)Pu3Co9 cuboctahedra, corners with three equivalent Co(1)Pu6Co6 cuboctahedra, corners with twelve equivalent Co(3)Pu5Co7 cuboctahedra, edges with six equivalent Co(2)Pu3Co9 cuboctahedra,  a faceface with one Co(1)Pu6Co6 cuboctahedra, faces with three equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eighteen equivalent Co(3)Pu5Co7 cuboctahedra. All Co(2)-Co(2) bond lengths are 2.74 Å. There are three shorter (2.43 Å) and three longer (2.44 Å) Co(2)-Co(3) bond lengths. In the third Co site, Co(3) is bonded to two equivalent Pu(1), three equivalent Pu(2), one Co(1), two equivalent Co(2), and four equivalent Co(3) atoms to form CoPu5Co7 cuboctahedra that share corners with two equivalent Co(1)Pu6Co6 cuboctahedra, corners with four equivalent Co(2)Pu3Co9 cuboctahedra, corners with fifteen equivalent Co(3)Pu5Co7 cuboctahedra, edges with eight equivalent Co(3)Pu5Co7 cuboctahedra, faces with three equivalent Co(1)Pu6Co6 cuboctahedra, faces with six equivalent Co(2)Pu3Co9 cuboctahedra, and faces with eleven equivalent Co(3)Pu5Co7 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.39 Å) Co(3)-Co(3) bond lengths.