Hg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to one O(6), two equivalent O(3), and two equivalent O(5) atoms to form distorted HgO5 square pyramids that share corners with two equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with two equivalent Hg(1)O5 square pyramids. In the second Hg site, Hg(2) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(6), one O(7), and one O(8) atom. In the third Hg site, Hg(3) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(8), and two equivalent O(2) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with two equivalent Hg(1)O5 square pyramids. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with three equivalent Hg(1)O5 square pyramids. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Hg(2), one Hg(3), and one As(1) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Hg(1) and one As(2) atom. In the third O site, O(6) is bonded in a 3-coordinate geometry to one Hg(1), one Hg(2), and one As(2) atom. In the fourth O site, O(7) is bonded in a bent 120 degrees geometry to one Hg(2) and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Hg(2), one Hg(3), and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted single-bond geometry to one Hg(2), one Hg(3), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Hg(3) and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Hg(1) and one As(1) atom.
Hg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Hg sites. In the first Hg site, Hg(1) is bonded to one O(6), two equivalent O(3), and two equivalent O(5) atoms to form distorted HgO5 square pyramids that share corners with two equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with two equivalent Hg(1)O5 square pyramids. The Hg(1)-O(6) bond length is 2.15 Å. There is one shorter (2.12 Å) and one longer (2.51 Å) Hg(1)-O(3) bond length. There is one shorter (2.50 Å) and one longer (2.55 Å) Hg(1)-O(5) bond length. In the second Hg site, Hg(2) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(6), one O(7), and one O(8) atom. The Hg(2)-O(1) bond length is 2.52 Å. The Hg(2)-O(4) bond length is 2.74 Å. The Hg(2)-O(6) bond length is 2.64 Å. The Hg(2)-O(7) bond length is 2.08 Å. The Hg(2)-O(8) bond length is 2.09 Å. In the third Hg site, Hg(3) is bonded in a 5-coordinate geometry to one O(1), one O(4), one O(8), and two equivalent O(2) atoms. The Hg(3)-O(1) bond length is 2.57 Å. The Hg(3)-O(4) bond length is 2.13 Å. The Hg(3)-O(8) bond length is 2.66 Å. There is one shorter (2.15 Å) and one longer (2.57 Å) Hg(3)-O(2) bond length. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with two equivalent Hg(1)O5 square pyramids. The As(1)-O(1) bond length is 1.67 Å. The As(1)-O(2) bond length is 1.71 Å. The As(1)-O(3) bond length is 1.71 Å. The As(1)-O(4) bond length is 1.72 Å. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with three equivalent Hg(1)O5 square pyramids. The As(2)-O(5) bond length is 1.67 Å. The As(2)-O(6) bond length is 1.72 Å. The As(2)-O(7) bond length is 1.72 Å. The As(2)-O(8) bond length is 1.72 Å. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Hg(2), one Hg(3), and one As(1) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Hg(1) and one As(2) atom. In the third O site, O(6) is bonded in a 3-coordinate geometry to one Hg(1), one Hg(2), and one As(2) atom. In the fourth O site, O(7) is bonded in a bent 120 degrees geometry to one Hg(2) and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Hg(2), one Hg(3), and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted single-bond geometry to one Hg(2), one Hg(3), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Hg(3) and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Hg(1) and one As(1) atom.