Th2OsSi3 is hexagonal omega structure-derived structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded to four equivalent Os(1), two equivalent Si(1), two equivalent Si(3), and four equivalent Si(2) atoms to form ThSi8Os4 cuboctahedra that share edges with four equivalent Th(1)Si8Os4 cuboctahedra, edges with eight equivalent Th(2)Si10Os2 cuboctahedra, faces with four equivalent Th(2)Si10Os2 cuboctahedra, and faces with four equivalent Th(1)Si8Os4 cuboctahedra. In the second Th site, Th(2) is bonded to two equivalent Os(1), two equivalent Si(2), four equivalent Si(1), and four equivalent Si(3) atoms to form ThSi10Os2 cuboctahedra that share edges with four equivalent Th(2)Si10Os2 cuboctahedra, edges with eight equivalent Th(1)Si8Os4 cuboctahedra, faces with four equivalent Th(2)Si10Os2 cuboctahedra, and faces with four equivalent Th(1)Si8Os4 cuboctahedra. Os(1) is bonded in a 9-coordinate geometry to two equivalent Th(2), four equivalent Th(1), one Si(2), and two equivalent Si(1) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Th(2), two equivalent Os(1), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Th(2), four equivalent Th(1), one Os(1), and two equivalent Si(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Th(2), one Si(1), and two equivalent Si(2) atoms.
Th2OsSi3 is hexagonal omega structure-derived structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded to four equivalent Os(1), two equivalent Si(1), two equivalent Si(3), and four equivalent Si(2) atoms to form ThSi8Os4 cuboctahedra that share edges with four equivalent Th(1)Si8Os4 cuboctahedra, edges with eight equivalent Th(2)Si10Os2 cuboctahedra, faces with four equivalent Th(2)Si10Os2 cuboctahedra, and faces with four equivalent Th(1)Si8Os4 cuboctahedra. All Th(1)-Os(1) bond lengths are 3.17 Å. Both Th(1)-Si(1) bond lengths are 3.12 Å. Both Th(1)-Si(3) bond lengths are 3.24 Å. All Th(1)-Si(2) bond lengths are 3.17 Å. In the second Th site, Th(2) is bonded to two equivalent Os(1), two equivalent Si(2), four equivalent Si(1), and four equivalent Si(3) atoms to form ThSi10Os2 cuboctahedra that share edges with four equivalent Th(2)Si10Os2 cuboctahedra, edges with eight equivalent Th(1)Si8Os4 cuboctahedra, faces with four equivalent Th(2)Si10Os2 cuboctahedra, and faces with four equivalent Th(1)Si8Os4 cuboctahedra. Both Th(2)-Os(1) bond lengths are 3.10 Å. Both Th(2)-Si(2) bond lengths are 3.27 Å. All Th(2)-Si(1) bond lengths are 3.16 Å. All Th(2)-Si(3) bond lengths are 3.19 Å. Os(1) is bonded in a 9-coordinate geometry to two equivalent Th(2), four equivalent Th(1), one Si(2), and two equivalent Si(1) atoms. The Os(1)-Si(2) bond length is 2.36 Å. Both Os(1)-Si(1) bond lengths are 2.43 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Th(2), two equivalent Os(1), and one Si(3) atom. The Si(1)-Si(3) bond length is 2.37 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Th(2), four equivalent Th(1), one Os(1), and two equivalent Si(3) atoms. Both Si(2)-Si(3) bond lengths are 2.40 Å. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Th(1), four equivalent Th(2), one Si(1), and two equivalent Si(2) atoms.