Os2Si3 crystallizes in the orthorhombic Pbcn space group. There are three inequivalent Os sites. In the first Os site, Os(3) is bonded in a 7-coordinate geometry to two equivalent Si(1), two equivalent Si(3), and three equivalent Si(2) atoms. In the second Os site, Os(1) is bonded to two equivalent Si(3) and four equivalent Si(1) atoms to form distorted edge-sharing OsSi6 octahedra. In the third Os site, Os(2) is bonded in a 8-coordinate geometry to four equivalent Si(2) and four equivalent Si(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to two equivalent Os(1) and two equivalent Os(3) atoms. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to two equivalent Os(2) and three equivalent Os(3) atoms. In the third Si site, Si(3) is bonded in a 5-coordinate geometry to one Os(1), two equivalent Os(2), and two equivalent Os(3) atoms.
Os2Si3 crystallizes in the orthorhombic Pbcn space group. There are three inequivalent Os sites. In the first Os site, Os(3) is bonded in a 7-coordinate geometry to two equivalent Si(1), two equivalent Si(3), and three equivalent Si(2) atoms. There is one shorter (2.43 Å) and one longer (2.47 Å) Os(3)-Si(1) bond length. There is one shorter (2.52 Å) and one longer (2.53 Å) Os(3)-Si(3) bond length. There are a spread of Os(3)-Si(2) bond distances ranging from 2.37-2.53 Å. In the second Os site, Os(1) is bonded to two equivalent Si(3) and four equivalent Si(1) atoms to form distorted edge-sharing OsSi6 octahedra. Both Os(1)-Si(3) bond lengths are 2.39 Å. There are two shorter (2.34 Å) and two longer (2.48 Å) Os(1)-Si(1) bond lengths. In the third Os site, Os(2) is bonded in a 8-coordinate geometry to four equivalent Si(2) and four equivalent Si(3) atoms. There are two shorter (2.39 Å) and two longer (2.79 Å) Os(2)-Si(2) bond lengths. There are two shorter (2.43 Å) and two longer (2.56 Å) Os(2)-Si(3) bond lengths. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 4-coordinate geometry to two equivalent Os(1) and two equivalent Os(3) atoms. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to two equivalent Os(2) and three equivalent Os(3) atoms. In the third Si site, Si(3) is bonded in a 5-coordinate geometry to one Os(1), two equivalent Os(2), and two equivalent Os(3) atoms.