CaCu9Sn4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal I4/mcm space group. Ca(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Sn(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Sn(1) atoms. In the second Cu site, Cu(2) is bonded to two equivalent Ca(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Sn(1) atoms to form distorted CuCa2Cu6Sn4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Sn4 cuboctahedra, corners with seven equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, edges with four equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, faces with two equivalent Cu(3)Cu8Sn4 cuboctahedra, and faces with five equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Sn(1) atoms to form a mixture of corner and face-sharing CuCu8Sn4 cuboctahedra. Sn(1) is bonded in a 11-coordinate geometry to two equivalent Ca(1), one Cu(3), four equivalent Cu(1), and four equivalent Cu(2) atoms.
CaCu9Sn4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal I4/mcm space group. Ca(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Sn(1) atoms. All Ca(1)-Cu(1) bond lengths are 3.60 Å. All Ca(1)-Cu(2) bond lengths are 3.65 Å. All Ca(1)-Sn(1) bond lengths are 3.52 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Sn(1) atoms. The Cu(1)-Cu(3) bond length is 2.63 Å. Both Cu(1)-Cu(2) bond lengths are 2.77 Å. There are two shorter (2.56 Å) and one longer (2.99 Å) Cu(1)-Cu(1) bond length. There are two shorter (2.75 Å) and two longer (2.79 Å) Cu(1)-Sn(1) bond lengths. In the second Cu site, Cu(2) is bonded to two equivalent Ca(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Sn(1) atoms to form distorted CuCa2Cu6Sn4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Sn4 cuboctahedra, corners with seven equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, edges with four equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, faces with two equivalent Cu(3)Cu8Sn4 cuboctahedra, and faces with five equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra. The Cu(2)-Cu(3) bond length is 2.54 Å. There is one shorter (2.65 Å) and two longer (2.66 Å) Cu(2)-Cu(2) bond lengths. There are a spread of Cu(2)-Sn(1) bond distances ranging from 2.60-2.70 Å. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Sn(1) atoms to form a mixture of corner and face-sharing CuCu8Sn4 cuboctahedra. All Cu(3)-Sn(1) bond lengths are 2.77 Å. Sn(1) is bonded in a 11-coordinate geometry to two equivalent Ca(1), one Cu(3), four equivalent Cu(1), and four equivalent Cu(2) atoms.