In2Si2O7 crystallizes in the cubic Fd-3m space group. In(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted InO8 hexagonal bipyramids that share edges with six equivalent In(1)O8 hexagonal bipyramids and edges with six equivalent Si(1)O6 octahedra. Si(1) is bonded to six equivalent O(1) atoms to form SiO6 octahedra that share corners with six equivalent Si(1)O6 octahedra and edges with six equivalent In(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent In(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded to four equivalent In(1) atoms to form corner-sharing OIn4 tetrahedra.
In2Si2O7 crystallizes in the cubic Fd-3m space group. In(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted InO8 hexagonal bipyramids that share edges with six equivalent In(1)O8 hexagonal bipyramids and edges with six equivalent Si(1)O6 octahedra. Both In(1)-O(2) bond lengths are 2.07 Å. All In(1)-O(1) bond lengths are 2.40 Å. Si(1) is bonded to six equivalent O(1) atoms to form SiO6 octahedra that share corners with six equivalent Si(1)O6 octahedra and edges with six equivalent In(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. All Si(1)-O(1) bond lengths are 1.82 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent In(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded to four equivalent In(1) atoms to form corner-sharing OIn4 tetrahedra.