Cs6Si2O7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(1), and three equivalent O(4) atoms. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. In the third Cs site, Cs(3) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Cs(1), two equivalent Cs(3), and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), three equivalent Cs(1), and one Si(1) atom.
Cs6Si2O7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(1), and three equivalent O(4) atoms. The Cs(1)-O(2) bond length is 3.26 Å. The Cs(1)-O(3) bond length is 3.18 Å. There is one shorter (3.03 Å) and one longer (3.62 Å) Cs(1)-O(1) bond length. There are a spread of Cs(1)-O(4) bond distances ranging from 3.00-3.47 Å. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Cs(2)-O(4) bond length is 3.18 Å. There is one shorter (2.98 Å) and one longer (3.01 Å) Cs(2)-O(1) bond length. There is one shorter (2.98 Å) and one longer (3.09 Å) Cs(2)-O(3) bond length. In the third Cs site, Cs(3) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Cs(3)-O(2) bond length is 3.20 Å. The Cs(3)-O(4) bond length is 3.08 Å. There is one shorter (3.06 Å) and one longer (3.11 Å) Cs(3)-O(1) bond length. There is one shorter (2.95 Å) and one longer (3.10 Å) Cs(3)-O(3) bond length. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(2) bond length is 1.70 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.64 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Cs(1), two equivalent Cs(3), and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), three equivalent Cs(1), and one Si(1) atom.