ScMnSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 8-coordinate geometry to 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 to two equivalent Si(1), two equivalent Si(3), and three equivalent Si(5) atoms to form a mixture of distorted corner and edge-sharing ScSi7 pentagonal bipyramids. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 2-coordinate geometry to four equivalent Sc(1) and two equivalent Mn(1) atoms. In the second Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Sc(2), four equivalent Sc(1), two equivalent Mn(1), and one Si(3) atom. In the third Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Mn(1), and two equivalent Mn(2) atoms. In the fourth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Sc(1), three equivalent Sc(2), two equivalent Mn(1), and two equivalent Mn(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 Mn(2), two equivalent Mn(1), and one Si(1) atom.
ScMnSi2 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 8-coordinate geometry to one Si(4), one Si(5), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. The Sc(1)-Si(4) bond length is 2.85 Å. The Sc(1)-Si(5) bond length is 2.73 Å. There is one shorter (2.75 Å) and one longer (2.78 Å) Sc(1)-Si(1) bond length. There is one shorter (2.87 Å) and one longer (2.88 Å) Sc(1)-Si(2) bond length. There is one shorter (2.81 Å) and one longer (2.82 Å) Sc(1)-Si(3) bond length. In the second Sc site, Sc(2) is bonded to two equivalent Si(1), two equivalent Si(3), and three equivalent Si(5) atoms to form a mixture of distorted corner and edge-sharing ScSi7 pentagonal bipyramids. Both Sc(2)-Si(1) bond lengths are 2.74 Å. There is one shorter (2.70 Å) and one longer (2.71 Å) Sc(2)-Si(3) bond length. There are a spread of Sc(2)-Si(5) bond distances ranging from 2.73-2.81 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one Si(2), one Si(3), one Si(4), one Si(5), and two equivalent Si(1) atoms. The Mn(1)-Si(2) bond length is 2.32 Å. The Mn(1)-Si(3) bond length is 2.33 Å. The Mn(1)-Si(4) bond length is 2.46 Å. The Mn(1)-Si(5) bond length is 2.44 Å. Both Mn(1)-Si(1) bond lengths are 2.48 Å. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(4), and two equivalent Si(5) atoms. Both Mn(2)-Si(1) bond lengths are 2.46 Å. Both Mn(2)-Si(4) bond lengths are 2.47 Å. Both Mn(2)-Si(5) bond lengths are 2.48 Å. There are five inequivalent Si sites. In the first Si site, Si(2) is bonded in a 2-coordinate geometry to four equivalent Sc(1) and two equivalent Mn(1) atoms. In the second Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Sc(2), four equivalent Sc(1), two equivalent Mn(1), and one Si(3) atom. The Si(3)-Si(3) bond length is 2.47 Å. In the third Si site, Si(4) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Mn(1), and two equivalent Mn(2) atoms. In the fourth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Sc(1), three equivalent Sc(2), two equivalent Mn(1), and two equivalent Mn(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 Mn(2), two equivalent Mn(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.40 Å.