Cs2TiSi6O15 crystallizes in the monoclinic C2/c space group. Cs(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), two equivalent O(7), and two equivalent O(8) atoms. Ti(1) is bonded to two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Ti(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Si(3) atoms. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Cs(1), one Ti(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Ti(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(1), and one Si(2) atom.
Cs2TiSi6O15 crystallizes in the monoclinic C2/c space group. Cs(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(6), two equivalent O(7), and two equivalent O(8) atoms. The Cs(1)-O(2) bond length is 3.48 Å. The Cs(1)-O(3) bond length is 3.31 Å. The Cs(1)-O(4) bond length is 3.13 Å. The Cs(1)-O(6) bond length is 3.17 Å. There is one shorter (3.12 Å) and one longer (3.26 Å) Cs(1)-O(7) bond length. There is one shorter (3.03 Å) and one longer (3.64 Å) Cs(1)-O(8) bond length. Ti(1) is bonded to two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. Both Ti(1)-O(4) bond lengths are 1.95 Å. Both Ti(1)-O(6) bond lengths are 1.96 Å. Both Ti(1)-O(7) bond lengths are 1.95 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. The Si(1)-O(1) bond length is 1.61 Å. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(6) bond length is 1.59 Å. The Si(1)-O(8) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. The Si(2)-O(2) bond length is 1.62 Å. The Si(2)-O(3) bond length is 1.62 Å. The Si(2)-O(7) bond length is 1.59 Å. The Si(2)-O(8) bond length is 1.63 Å. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. The Si(3)-O(1) bond length is 1.63 Å. The Si(3)-O(3) bond length is 1.63 Å. The Si(3)-O(4) bond length is 1.58 Å. The Si(3)-O(5) bond length is 1.61 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Ti(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Si(3) atoms. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Cs(1), one Ti(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Cs(1), one Ti(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(1), and one Si(2) atom.