[Mo₁₆O₅₃F₂]^12-:  a New Polyoxofluoromolybdate Anion

Abstract

Single crystals of a new beta-octamolybdate salt containing protonated 1,4-diazabicyclo[2.2.2]octane cations were prepared under mild hydrothermal conditions. This compound, [C6H13N2]2[C6H14N2][Mo8O26], was then used as a starting material in the synthesis of [C6H13N2]6[Mo16O53F2].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.

Lewis Acidic Behavior of MoOF4 towards the Alkali Metal Fluorides in Anhydrous Hydrogen Fluoride Solutions

“…[3] In order to exploit potential promising physical and chemical properties, many molybdenum oxide fluorides have been synthesized to date. [4][5][6][7][8] However, little remains known regarding the chemical properties of the simplest Mo VI molybdenum oxide fluoride, MoOF 4 .…”

“…MoOF 4 was first synthesized in 1907 by Ruff and Eisner, whereby aHF was condensed onto molybdenum oxide tetrachloride (MoOCl 4 ). [9] MoOF 4 is a white solid having a melting point of 97°C and a boiling point of 186°C (under ambient atmospheric pressure).…”

“…is related to that of VF 5 , [10] is characterized by essentially octahedrally-coordinated Mo atoms linked into infinite chains by cisbridging fluorine atoms. [11] The solid-state structure of MoOF 4 features Mo atoms in distorted octahedral surroundings and alternating Mo-(μ-F) atomic distances, see Figure 1. [3] Figure 1.…”

Formation Principles for Vanadium Selenites: The Role of pH on Product Composition

“…The relative concentrations of the reactive species also directly influence composition and structure. [14][15][16][17][18][19][20][21]29,31 The secondary inf luence is charge density matching 4,7 between the inorganic anionic and organic cationic components of these reactions. While the charge densities of the organic cations are largely fixed by solution pH, as that dictates their protonation states, the inorganic components can access a range of charge densities through the formation of different secondary building units (SBUs).…”

New structural units in molybdenum oxyfluoride chemistry

“…We note that the majority of these examples are purely inorganic, though there are a couple of 'hybrid' cases. In addition, there are further examples of 'fluorinated polyoxomolybdates', which have typically higher O/F ratios 21,22 . We have now begun to explore the solvothermal chemistry of molybdenum in fluorine-rich environments, and here we report some of our preliminary results, in which we isolate three novel structural/compositional building units, each containing Mo in a partially reduced oxidation state.…”