Ag6HgSiSe6 crystallizes in the orthorhombic Pmn2_1 space group. There are four inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to one Se(3), one Se(5), and two equivalent Se(2) atoms to form distorted AgSe4 tetrahedra that share corners with two equivalent Si(1)Se4 tetrahedra and corners with six equivalent Ag(3)Se4 tetrahedra. In the second Ag site, Ag(2) is bonded in a trigonal planar geometry to one Se(1), one Se(2), and one Se(3) atom. In the third Ag site, Ag(3) is bonded to one Se(2), one Se(3), one Se(4), and one Se(5) atom to form distorted AgSe4 tetrahedra that share  a cornercorner with one Ag(3)Se4 tetrahedra, corners with two equivalent Si(1)Se4 tetrahedra, corners with three equivalent Ag(1)Se4 tetrahedra, and  an edgeedge with one Ag(3)Se4 tetrahedra. In the fourth Ag site, Ag(4) is bonded in a distorted trigonal planar geometry to one Se(1), one Se(3), and one Se(4) atom. Hg(1) is bonded in a linear geometry to one Se(3) and one Se(5) atom. Si(1) is bonded to one Se(1), one Se(4), and two equivalent Se(2) atoms to form SiSe4 tetrahedra that share corners with two equivalent Ag(1)Se4 tetrahedra and corners with four equivalent Ag(3)Se4 tetrahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ag(4), two equivalent Ag(2), and one Si(1) atom to form corner-sharing SeSiAg3 tetrahedra. In the second Se site, Se(2) is bonded to one Ag(1), one Ag(2), one Ag(3), and one Si(1) atom to form corner-sharing SeSiAg3 tetrahedra. In the third Se site, Se(3) is bonded in a 7-coordinate geometry to one Ag(1), one Ag(4), two equivalent Ag(2), two equivalent Ag(3), and one Hg(1) atom. In the fourth Se site, Se(4) is bonded to one Ag(4), two equivalent Ag(3), and one Si(1) atom to form distorted corner-sharing SeSiAg3 tetrahedra. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one Ag(1), two equivalent Ag(3), and one Hg(1) atom.
Ag6HgSiSe6 crystallizes in the orthorhombic Pmn2_1 space group. There are four inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to one Se(3), one Se(5), and two equivalent Se(2) atoms to form distorted AgSe4 tetrahedra that share corners with two equivalent Si(1)Se4 tetrahedra and corners with six equivalent Ag(3)Se4 tetrahedra. The Ag(1)-Se(3) bond length is 2.82 Å. The Ag(1)-Se(5) bond length is 2.71 Å. Both Ag(1)-Se(2) bond lengths are 2.78 Å. In the second Ag site, Ag(2) is bonded in a trigonal planar geometry to one Se(1), one Se(2), and one Se(3) atom. The Ag(2)-Se(1) bond length is 2.62 Å. The Ag(2)-Se(2) bond length is 2.62 Å. The Ag(2)-Se(3) bond length is 2.67 Å. In the third Ag site, Ag(3) is bonded to one Se(2), one Se(3), one Se(4), and one Se(5) atom to form distorted AgSe4 tetrahedra that share  a cornercorner with one Ag(3)Se4 tetrahedra, corners with two equivalent Si(1)Se4 tetrahedra, corners with three equivalent Ag(1)Se4 tetrahedra, and  an edgeedge with one Ag(3)Se4 tetrahedra. The Ag(3)-Se(2) bond length is 2.72 Å. The Ag(3)-Se(3) bond length is 2.80 Å. The Ag(3)-Se(4) bond length is 2.79 Å. The Ag(3)-Se(5) bond length is 2.70 Å. In the fourth Ag site, Ag(4) is bonded in a distorted trigonal planar geometry to one Se(1), one Se(3), and one Se(4) atom. The Ag(4)-Se(1) bond length is 2.63 Å. The Ag(4)-Se(3) bond length is 2.64 Å. The Ag(4)-Se(4) bond length is 2.62 Å. Hg(1) is bonded in a linear geometry to one Se(3) and one Se(5) atom. The Hg(1)-Se(3) bond length is 2.58 Å. The Hg(1)-Se(5) bond length is 2.51 Å. Si(1) is bonded to one Se(1), one Se(4), and two equivalent Se(2) atoms to form SiSe4 tetrahedra that share corners with two equivalent Ag(1)Se4 tetrahedra and corners with four equivalent Ag(3)Se4 tetrahedra. The Si(1)-Se(1) bond length is 2.30 Å. The Si(1)-Se(4) bond length is 2.29 Å. Both Si(1)-Se(2) bond lengths are 2.31 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ag(4), two equivalent Ag(2), and one Si(1) atom to form corner-sharing SeSiAg3 tetrahedra. In the second Se site, Se(2) is bonded to one Ag(1), one Ag(2), one Ag(3), and one Si(1) atom to form corner-sharing SeSiAg3 tetrahedra. In the third Se site, Se(3) is bonded in a 7-coordinate geometry to one Ag(1), one Ag(4), two equivalent Ag(2), two equivalent Ag(3), and one Hg(1) atom. In the fourth Se site, Se(4) is bonded to one Ag(4), two equivalent Ag(3), and one Si(1) atom to form distorted corner-sharing SeSiAg3 tetrahedra. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one Ag(1), two equivalent Ag(3), and one Hg(1) atom.