M2(SeO3)F2 (M = Zn, Cd): understanding the structure directing effect of [SeO3]2− groups on constructing ordered oxyfluorides

As a great deal of attention has been paid to studying the role of fluorine in functional oxyfluorides, the question that arises now is how to orderly incorporate the fluorine atoms into the compounds. Herein, we proposed an original strategy using [SeO3]2− anionic groups as the effective structure directing blocks to orderly introduce the F atoms into the [MOxFy] (M = metal) polyhedra. Accordingly, two ordered metal selenite fluorides with [MO3F3]7− groups, M2(SeO3)F2 (M = Zn, Cd), were successfully synthesized through hydrothermal reactions. The stabilities of these structures were confirmed by thermogravimetry tests, bond valence sum analysis and phonon spectrum calculations.