CaScSi3HO9 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(6), and two equivalent O(1) atoms. Sc(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(2) atoms to form ScO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Sc(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Sc(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Sc(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-62°. In the third Si site, Si(3) is bonded to one O(3), one O(6), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Sc(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. H(1) is bonded in a distorted linear geometry to one O(4) and one O(5) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), one Sc(1), and one Si(1) atom to form distorted edge-sharing OCa2ScSi tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Sc(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Sc(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Si(1), and one H(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Sc(1), one Si(2), and one H(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ca(1), one Sc(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(3) atom.
CaScSi3HO9 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(6), and two equivalent O(1) atoms. The Ca(1)-O(2) bond length is 2.58 Å. The Ca(1)-O(3) bond length is 2.37 Å. The Ca(1)-O(4) bond length is 2.34 Å. The Ca(1)-O(6) bond length is 2.36 Å. There is one shorter (2.41 Å) and one longer (2.60 Å) Ca(1)-O(1) bond length. Sc(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(2) atoms to form ScO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Sc(1)O6 octahedra. The Sc(1)-O(1) bond length is 2.20 Å. The Sc(1)-O(3) bond length is 2.05 Å. The Sc(1)-O(5) bond length is 2.06 Å. The Sc(1)-O(6) bond length is 2.07 Å. There is one shorter (2.21 Å) and one longer (2.33 Å) Sc(1)-O(2) bond length. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Sc(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.65 Å. The Si(1)-O(7) bond length is 1.62 Å. The Si(1)-O(9) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Sc(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-62°. The Si(2)-O(2) bond length is 1.66 Å. The Si(2)-O(5) bond length is 1.63 Å. The Si(2)-O(7) bond length is 1.64 Å. The Si(2)-O(8) bond length is 1.64 Å. In the third Si site, Si(3) is bonded to one O(3), one O(6), one O(8), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Sc(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. The Si(3)-O(3) bond length is 1.63 Å. The Si(3)-O(6) bond length is 1.62 Å. The Si(3)-O(8) bond length is 1.63 Å. The Si(3)-O(9) bond length is 1.67 Å. H(1) is bonded in a distorted linear geometry to one O(4) and one O(5) atom. The H(1)-O(4) bond length is 1.02 Å. The H(1)-O(5) bond length is 1.60 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1), one Sc(1), and one Si(1) atom to form distorted edge-sharing OCa2ScSi tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Sc(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Sc(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Si(1), and one H(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Sc(1), one Si(2), and one H(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ca(1), one Sc(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(3) atom.