Sc2Si2O7 crystallizes in the monoclinic C2/m space group. Sc(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form distorted ScO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Sc(1)O6 pentagonal pyramids. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with six equivalent Sc(1)O6 pentagonal pyramids and  a cornercorner with one Si(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Sc(1) and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Sc(1) and one Si(1) atom.
Sc2Si2O7 crystallizes in the monoclinic C2/m space group. Sc(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form distorted ScO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Sc(1)O6 pentagonal pyramids. Both Sc(1)-O(3) bond lengths are 2.11 Å. There are two shorter (2.09 Å) and two longer (2.19 Å) Sc(1)-O(1) bond lengths. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with six equivalent Sc(1)O6 pentagonal pyramids and  a cornercorner with one Si(1)O4 tetrahedra. The Si(1)-O(2) bond length is 1.61 Å. The Si(1)-O(3) bond length is 1.63 Å. Both Si(1)-O(1) bond lengths are 1.63 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Sc(1) and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Sc(1) and one Si(1) atom.