K2TiSi3O9 crystallizes in the hexagonal P6_3/m space group. K(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. Ti(1) is bonded to six equivalent O(1) atoms to form TiO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ti(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms.
K2TiSi3O9 crystallizes in the hexagonal P6_3/m space group. K(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. All K(1)-O(2) bond lengths are 3.16 Å. There are three shorter (2.85 Å) and three longer (3.11 Å) K(1)-O(1) bond lengths. Ti(1) is bonded to six equivalent O(1) atoms to form TiO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All Ti(1)-O(1) bond lengths are 1.97 Å. Si(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. Both Si(1)-O(1) bond lengths are 1.62 Å. There is one shorter (1.66 Å) and one longer (1.67 Å) Si(1)-O(2) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1), one Ti(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms.