ChemInform Abstract: Hg3Se3O10, a Mercury(II) Compound with Mixed-Valence Oxoselenium(IV)/(VI) Anions

The title compound, trimercury(II) bis­[selenite(IV)] selen­ate(VI), contains three crystallographically inequivalent HgII 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. {_{\infty}^{\kern 4pt 2}}[HgO8/2] layers of edge-sharing [HgO8] polyhedra propagate parallel to the bc plane, and are connected via SeVIO4 tetrahedra and [Hg3O5] polyhedra along the a axis, forming an arrangement with channels propagating parallel to the b axis. The two independent SeIVO3 pyramids bridge the Hg atoms, and the non-bonding orbitals of the SeIV ions protrude into the channels from opposite sides.