ScFeSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 12-coordinate geometry to one Fe(2), three equivalent Fe(1), one Si(4), one Si(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Sc site, Sc(2) is bonded in a 7-coordinate geometry to two equivalent Fe(2), four equivalent Fe(1), two equivalent Si(1), two equivalent Si(2), and three equivalent Si(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to two equivalent Sc(2), three equivalent Sc(1), one Fe(2), one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. In the second Fe site, Fe(2) is bonded to two equivalent Sc(1), two equivalent Sc(2), two equivalent Fe(1), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms to form a mixture of distorted edge and face-sharing FeSc4Fe2Si6 cuboctahedra. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Sc(2), four equivalent Sc(1), two equivalent Fe(1), and one Si(2) atom. In the second Si site, Si(3) is bonded in a 7-coordinate geometry to four equivalent Sc(1), two equivalent Fe(1), and one Si(3) atom. In the third Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Sc(1), three equivalent Sc(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fifth Si site, Si(1) is bonded in a 7-coordinate geometry to one Sc(2), two equivalent Sc(1), one Fe(2), two equivalent Fe(1), and one Si(1) atom.
ScFeSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 12-coordinate geometry to one Fe(2), three equivalent Fe(1), one Si(4), one Si(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. The Sc(1)-Fe(2) bond length is 2.94 Å. There are a spread of Sc(1)-Fe(1) bond distances ranging from 2.94-2.99 Å. The Sc(1)-Si(4) bond length is 2.71 Å. The Sc(1)-Si(5) bond length is 2.82 Å. Both Sc(1)-Si(1) bond lengths are 2.77 Å. There is one shorter (2.78 Å) and one longer (2.82 Å) Sc(1)-Si(2) bond length. There is one shorter (2.85 Å) and one longer (2.87 Å) Sc(1)-Si(3) bond length. In the second Sc site, Sc(2) is bonded in a 7-coordinate geometry to two equivalent Fe(2), four equivalent Fe(1), two equivalent Si(1), two equivalent Si(2), and three equivalent Si(4) atoms. Both Sc(2)-Fe(2) bond lengths are 3.00 Å. There are two shorter (2.98 Å) and two longer (3.09 Å) Sc(2)-Fe(1) bond lengths. Both Sc(2)-Si(1) bond lengths are 2.69 Å. Both Sc(2)-Si(2) bond lengths are 2.69 Å. There are a spread of Sc(2)-Si(4) bond distances ranging from 2.69-2.82 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 12-coordinate geometry to two equivalent Sc(2), three equivalent Sc(1), one Fe(2), one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. The Fe(1)-Fe(2) bond length is 2.64 Å. The Fe(1)-Si(2) bond length is 2.30 Å. The Fe(1)-Si(3) bond length is 2.28 Å. The Fe(1)-Si(4) bond length is 2.46 Å. The Fe(1)-Si(5) bond length is 2.49 Å. There is one shorter (2.46 Å) and one longer (2.47 Å) Fe(1)-Si(1) bond length. In the second Fe site, Fe(2) is bonded to two equivalent Sc(1), two equivalent Sc(2), two equivalent Fe(1), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms to form a mixture of distorted edge and face-sharing FeSc4Fe2Si6 cuboctahedra. Both Fe(2)-Si(1) bond lengths are 2.38 Å. Both Fe(2)-Si(4) bond lengths are 2.43 Å. Both Fe(2)-Si(5) bond lengths are 2.40 Å. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Sc(2), four equivalent Sc(1), two equivalent Fe(1), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.44 Å. In the second Si site, Si(3) is bonded in a 7-coordinate geometry to four equivalent Sc(1), two equivalent Fe(1), and one Si(3) atom. The Si(3)-Si(3) bond length is 2.58 Å. In the third Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Sc(1), three equivalent Sc(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fifth Si site, Si(1) is bonded in a 7-coordinate geometry to one Sc(2), two equivalent Sc(1), one Fe(2), two equivalent Fe(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.38 Å.