ThCeSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Th(1) is bonded to four equivalent Si(1) and eight Si(2,2) atoms to form ThSi12 cuboctahedra that share edges with four equivalent Th(1)Si12 cuboctahedra, edges with eight equivalent Ce(1)Si12 cuboctahedra, faces with four equivalent Th(1)Si12 cuboctahedra, and faces with four equivalent Ce(1)Si12 cuboctahedra. Ce(1) is bonded to four Si(2,2) and eight equivalent Si(1) atoms to form CeSi12 cuboctahedra that share edges with four equivalent Ce(1)Si12 cuboctahedra, edges with eight equivalent Th(1)Si12 cuboctahedra, faces with four equivalent Th(1)Si12 cuboctahedra, and faces with four equivalent Ce(1)Si12 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Ce(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 four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms.
ThCeSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Th(1) is bonded to four equivalent Si(1) and eight Si(2,2) atoms to form ThSi12 cuboctahedra that share edges with four equivalent Th(1)Si12 cuboctahedra, edges with eight equivalent Ce(1)Si12 cuboctahedra, faces with four equivalent Th(1)Si12 cuboctahedra, and faces with four equivalent Ce(1)Si12 cuboctahedra. All Th(1)-Si(1) bond lengths are 3.15 Å. All Th(1)-Si(2,2) bond lengths are 3.15 Å. Ce(1) is bonded to four Si(2,2) and eight equivalent Si(1) atoms to form CeSi12 cuboctahedra that share edges with four equivalent Ce(1)Si12 cuboctahedra, edges with eight equivalent Th(1)Si12 cuboctahedra, faces with four equivalent Th(1)Si12 cuboctahedra, and faces with four equivalent Ce(1)Si12 cuboctahedra. All Ce(1)-Si(2,2) bond lengths are 3.13 Å. All Ce(1)-Si(1) bond lengths are 3.14 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Ce(1), one Si(1), and two equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.35 Å. Both Si(1)-Si(2) bond lengths are 2.38 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.40 Å. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms. All Si(2)-Th(1) bond lengths are 3.15 Å. The Si(2)-Si(2) bond length is 2.40 Å. Both Si(2)-Si(1) bond lengths are 2.38 Å. In the fourth Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Th(1), two equivalent Ce(1), one Si(2), and two equivalent Si(1) atoms. Both Si(2)-Ce(1) bond lengths are 3.13 Å. Both Si(2)-Si(1) bond lengths are 2.38 Å.