Hg3Se3O10, a mercury(II) compound with mixed‐valence oxoselenium(IV/VI) anions

The title compound, trimercury(II) bis­selenite(IV)] selen­ate(VI), contains three crystallographically inequivalent Hg^II cations with coordination numbers of eight (denoted Hg1 and Hg2) and five (denoted Hg3). The corresponding coordination polyhedra around the metal atoms might be described as intermediates between a square antiprism and a triangulated dodecahedron for both Hg1 and Hg2, and a strongly distorted truncated octahedron for Hg3. HgO_8/2] layers of edge‐sharing HgO₈] polyhedra propagate parallel to the bc plane, and are connected via Se^VIO₄ tetrahedra and Hg3O₅] polyhedra along the a axis, forming an arrangement with channels propagating parallel to the b axis. The two independent Se^IVO₃ pyramids bridge the Hg atoms, and the non‐bonding orbitals of the Se^IV ions protrude into the channels from opposite sides.