Mo16O53F2]12-: a new polyoxofluoromolybdate anion

Single crystals of a new beta-octamolybdate salt containing protonated 1,4-diazabicyclo2.2.2]octane cations were prepared under mild hydrothermal conditions. This compound, C6H13N2]2C6H14N2]Mo8O26], was then used as a starting material in the synthesis of C6H13N2]6Mo16O53F2].4H2O, which contains previously unreported Mo16O53F2]12- anions. The structure-directing properties of gamma-Mo8O26]4-, a likely intermediate in this pH-dependent transformation, are responsible for the site selection of the fluoride incorporation. Mo16O53F2]12-, the largest reported polyoxofluoromolybdate cluster, expands upon the limited number of such anions in the literature. The structures of both compounds were determined using single-crystal X-ray diffraction.