Co3Ta is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ta(1) is bonded to twelve Co(1,1) atoms to form TaCo12 cuboctahedra that share corners with six equivalent Ta(1)Co12 cuboctahedra; corners with twelve Co(1,1)Ta4Co8 cuboctahedra; edges with eighteen Co(1,1)Ta4Co8 cuboctahedra; faces with eight equivalent Ta(1)Co12 cuboctahedra; and faces with twelve Co(1,1)Ta4Co8 cuboctahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to four equivalent Ta(1) and eight Co(1,1) atoms to form distorted CoTa4Co8 cuboctahedra that share corners with four equivalent Ta(1)Co12 cuboctahedra; corners with fourteen Co(1,1)Ta4Co8 cuboctahedra; edges with six equivalent Ta(1)Co12 cuboctahedra; edges with twelve Co(1,1)Ta4Co8 cuboctahedra; faces with four equivalent Ta(1)Co12 cuboctahedra; and faces with sixteen Co(1,1)Ta4Co8 cuboctahedra. In the second Co site, Co(1) is bonded to four equivalent Ta(1) and eight Co(1,1) atoms to form distorted CoTa4Co8 cuboctahedra that share corners with four equivalent Ta(1)Co12 cuboctahedra; corners with fourteen Co(1,1)Ta4Co8 cuboctahedra; edges with six equivalent Ta(1)Co12 cuboctahedra; edges with twelve Co(1,1)Ta4Co8 cuboctahedra; faces with four equivalent Ta(1)Co12 cuboctahedra; and faces with sixteen Co(1,1)Ta4Co8 cuboctahedra.
Co3Ta is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ta(1) is bonded to twelve Co(1,1) atoms to form TaCo12 cuboctahedra that share corners with six equivalent Ta(1)Co12 cuboctahedra; corners with twelve Co(1,1)Ta4Co8 cuboctahedra; edges with eighteen Co(1,1)Ta4Co8 cuboctahedra; faces with eight equivalent Ta(1)Co12 cuboctahedra; and faces with twelve Co(1,1)Ta4Co8 cuboctahedra. There are six shorter (2.56 Å) and six longer (2.58 Å) Ta(1)-Co(1,1) bond lengths. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to four equivalent Ta(1) and eight Co(1,1) atoms to form distorted CoTa4Co8 cuboctahedra that share corners with four equivalent Ta(1)Co12 cuboctahedra; corners with fourteen Co(1,1)Ta4Co8 cuboctahedra; edges with six equivalent Ta(1)Co12 cuboctahedra; edges with twelve Co(1,1)Ta4Co8 cuboctahedra; faces with four equivalent Ta(1)Co12 cuboctahedra; and faces with sixteen Co(1,1)Ta4Co8 cuboctahedra. There are a spread of Co(1)-Co(1,1) bond distances ranging from 2.42-2.70 Å. In the second Co site, Co(1) is bonded to four equivalent Ta(1) and eight Co(1,1) atoms to form distorted CoTa4Co8 cuboctahedra that share corners with four equivalent Ta(1)Co12 cuboctahedra; corners with fourteen Co(1,1)Ta4Co8 cuboctahedra; edges with six equivalent Ta(1)Co12 cuboctahedra; edges with twelve Co(1,1)Ta4Co8 cuboctahedra; faces with four equivalent Ta(1)Co12 cuboctahedra; and faces with sixteen Co(1,1)Ta4Co8 cuboctahedra. Both Co(1)-Co(1) bond lengths are 2.49 Å.