Hg6Si2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. In the second Hg site, Hg(2) is bonded in a single-bond geometry to one O(3) atom. Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Hg(1) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Hg(2), two equivalent Hg(1), and one Si(1) atom.
Hg6Si2O7 crystallizes in the monoclinic C2/m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a 3-coordinate geometry to one O(3) and two equivalent O(2) atoms. The Hg(1)-O(3) bond length is 2.61 Å. There is one shorter (2.17 Å) and one longer (2.53 Å) Hg(1)-O(2) bond length. In the second Hg site, Hg(2) is bonded in a single-bond geometry to one O(3) atom. The Hg(2)-O(3) bond length is 2.15 Å. Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.62 Å. The Si(1)-O(3) bond length is 1.65 Å. Both Si(1)-O(2) bond lengths are 1.63 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Hg(1) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Hg(2), two equivalent Hg(1), and one Si(1) atom.