CaEuSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Ca(1) is bonded to four Si(2,2) and eight Si(1,1) atoms to form CaSi12 cuboctahedra that share edges with four equivalent Ca(1)Si12 cuboctahedra, edges with eight equivalent Eu(1)Si12 cuboctahedra, faces with four equivalent Ca(1)Si12 cuboctahedra, and faces with four equivalent Eu(1)Si12 cuboctahedra. Eu(1) is bonded to four equivalent Si(1) and eight equivalent Si(2) atoms to form EuSi12 cuboctahedra that share edges with four equivalent Eu(1)Si12 cuboctahedra, edges with eight equivalent Ca(1)Si12 cuboctahedra, faces with four equivalent Ca(1)Si12 cuboctahedra, and faces with four equivalent Eu(1)Si12 cuboctahedra. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), four equivalent Eu(1), one Si(2), and two equivalent Si(1) atoms. In the third Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), four equivalent Eu(1), one Si(2), and two equivalent Si(1) atoms. In the fifth Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms.
CaEuSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Ca(1) is bonded to four Si(2,2) and eight Si(1,1) atoms to form CaSi12 cuboctahedra that share edges with four equivalent Ca(1)Si12 cuboctahedra, edges with eight equivalent Eu(1)Si12 cuboctahedra, faces with four equivalent Ca(1)Si12 cuboctahedra, and faces with four equivalent Eu(1)Si12 cuboctahedra. All Ca(1)-Si(2,2) bond lengths are 3.10 Å. All Ca(1)-Si(1,1) bond lengths are 3.23 Å. Eu(1) is bonded to four equivalent Si(1) and eight equivalent Si(2) atoms to form EuSi12 cuboctahedra that share edges with four equivalent Eu(1)Si12 cuboctahedra, edges with eight equivalent Ca(1)Si12 cuboctahedra, faces with four equivalent Ca(1)Si12 cuboctahedra, and faces with four equivalent Eu(1)Si12 cuboctahedra. All Eu(1)-Si(1) bond lengths are 3.10 Å. All Eu(1)-Si(2) bond lengths are 3.23 Å. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.30 Å. Both Si(1)-Si(2) bond lengths are 2.40 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), four equivalent Eu(1), one Si(2), and two equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.29 Å. In the third Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms. Both Si(1)-Eu(1) bond lengths are 3.10 Å. Both Si(1)-Si(2) bond lengths are 2.40 Å. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), four equivalent Eu(1), one Si(2), and two equivalent Si(1) atoms. All Si(2)-Eu(1) bond lengths are 3.23 Å. The Si(2)-Si(2) bond length is 2.29 Å. In the fifth Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent Ca(1), two equivalent Eu(1), one Si(1), and two equivalent Si(2) atoms. All Si(1)-Ca(1) bond lengths are 3.23 Å. Both Si(1)-Eu(1) bond lengths are 3.10 Å. The Si(1)-Si(1) bond length is 2.30 Å. Both Si(1)-Si(2) bond lengths are 2.40 Å.