LiSc4(Si2O7)2 crystallizes in the orthorhombic Imm2 space group. Li(1) is bonded to one O(3), one O(4), and four equivalent O(1) atoms to form LiO6 octahedra that share corners with six equivalent Sc(1)O8 hexagonal bipyramids, corners with six equivalent Sc(2)O8 hexagonal bipyramids, faces with two equivalent Si(1)O6 octahedra, and faces with two equivalent Si(2)O6 octahedra. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to one O(4), one O(5), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form distorted ScO8 hexagonal bipyramids that share corners with three equivalent Li(1)O6 octahedra, edges with two equivalent Sc(1)O8 hexagonal bipyramids, edges with four equivalent Sc(2)O8 hexagonal bipyramids, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Si(2)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. In the second Sc site, Sc(2) is bonded to one O(3), one O(5), one O(6), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted ScO8 hexagonal bipyramids that share corners with three equivalent Li(1)O6 octahedra, edges with two equivalent Sc(2)O8 hexagonal bipyramids, edges with four equivalent Sc(1)O8 hexagonal bipyramids, edges with two equivalent Si(2)O6 octahedra, and edges with four equivalent Si(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted SiO6 octahedra that share corners with two equivalent Si(1)O6 octahedra, corners with four equivalent Si(2)O6 octahedra, edges with two equivalent Sc(1)O8 hexagonal bipyramids, edges with four equivalent Sc(2)O8 hexagonal bipyramids, and  a faceface with one Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-50°. In the second Si site, Si(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form distorted SiO6 octahedra that share corners with two equivalent Si(2)O6 octahedra, corners with four equivalent Si(1)O6 octahedra, edges with two equivalent Sc(2)O8 hexagonal bipyramids, edges with four equivalent Sc(1)O8 hexagonal bipyramids, and  a faceface with one Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Li(1), one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Li(1), two equivalent Sc(2), and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Li(1), two equivalent Sc(1), and two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form corner-sharing OSc4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form corner-sharing OSc4 tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sc(1) and two equivalent Si(2) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Sc(2) and two equivalent Si(1) atoms.
LiSc4(Si2O7)2 crystallizes in the orthorhombic Imm2 space group. Li(1) is bonded to one O(3), one O(4), and four equivalent O(1) atoms to form LiO6 octahedra that share corners with six equivalent Sc(1)O8 hexagonal bipyramids, corners with six equivalent Sc(2)O8 hexagonal bipyramids, faces with two equivalent Si(1)O6 octahedra, and faces with two equivalent Si(2)O6 octahedra. The Li(1)-O(3) bond length is 1.87 Å. The Li(1)-O(4) bond length is 1.88 Å. All Li(1)-O(1) bond lengths are 1.88 Å. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to one O(4), one O(5), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form distorted ScO8 hexagonal bipyramids that share corners with three equivalent Li(1)O6 octahedra, edges with two equivalent Sc(1)O8 hexagonal bipyramids, edges with four equivalent Sc(2)O8 hexagonal bipyramids, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Si(2)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. The Sc(1)-O(4) bond length is 2.38 Å. The Sc(1)-O(5) bond length is 2.05 Å. The Sc(1)-O(6) bond length is 2.06 Å. The Sc(1)-O(7) bond length is 2.39 Å. Both Sc(1)-O(1) bond lengths are 2.38 Å. Both Sc(1)-O(2) bond lengths are 2.39 Å. In the second Sc site, Sc(2) is bonded to one O(3), one O(5), one O(6), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted ScO8 hexagonal bipyramids that share corners with three equivalent Li(1)O6 octahedra, edges with two equivalent Sc(2)O8 hexagonal bipyramids, edges with four equivalent Sc(1)O8 hexagonal bipyramids, edges with two equivalent Si(2)O6 octahedra, and edges with four equivalent Si(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. The Sc(2)-O(3) bond length is 2.37 Å. The Sc(2)-O(5) bond length is 2.06 Å. The Sc(2)-O(6) bond length is 2.06 Å. The Sc(2)-O(8) bond length is 2.39 Å. Both Sc(2)-O(1) bond lengths are 2.38 Å. Both Sc(2)-O(2) bond lengths are 2.39 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted SiO6 octahedra that share corners with two equivalent Si(1)O6 octahedra, corners with four equivalent Si(2)O6 octahedra, edges with two equivalent Sc(1)O8 hexagonal bipyramids, edges with four equivalent Sc(2)O8 hexagonal bipyramids, and  a faceface with one Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-50°. The Si(1)-O(3) bond length is 1.88 Å. The Si(1)-O(8) bond length is 1.75 Å. Both Si(1)-O(1) bond lengths are 1.87 Å. Both Si(1)-O(2) bond lengths are 1.75 Å. In the second Si site, Si(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form distorted SiO6 octahedra that share corners with two equivalent Si(2)O6 octahedra, corners with four equivalent Si(1)O6 octahedra, edges with two equivalent Sc(2)O8 hexagonal bipyramids, edges with four equivalent Sc(1)O8 hexagonal bipyramids, and  a faceface with one Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-49°. The Si(2)-O(4) bond length is 1.87 Å. The Si(2)-O(7) bond length is 1.76 Å. Both Si(2)-O(1) bond lengths are 1.87 Å. Both Si(2)-O(2) bond lengths are 1.75 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Li(1), one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Li(1), two equivalent Sc(2), and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Li(1), two equivalent Sc(1), and two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form corner-sharing OSc4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form corner-sharing OSc4 tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sc(1) and two equivalent Si(2) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to two equivalent Sc(2) and two equivalent Si(1) atoms.