Transition metal complexes oxide fluorides

Phosphoryl fluoride reacts as a base and, with BF , AsF5, and SbF5, oxygen-bridged 1 1 adducts are produced (88, 89). In liquid sulfur dioxide POF3 is weakly basic and it was in such a medium that the first transition-metal complex of this oxide fluoride, [Mn(OPF j)4]2v[AsF6l2, was produced in 1979 via the intermediate Mn(S02)v 2 AsFe]2 (90). 

One of the most important parameters that defines the structure and stability of inorganic crystals is their stoichiometry - the quantitative relationship between the anions and the cations [134]. Oxygen and fluorine ions, O2 and F, have very similar ionic radii of 1.36 and 1.33 A, respectively. The steric similarity enables isomorphic substitution of oxygen and fluorine ions in the anionic sub-lattice as well as the combination of complex fluoride, oxyfluoride and some oxide compounds in the same system. On the other hand, tantalum or niobium, which are the central atoms in the fluoride and oxyfluoride complexes, have identical ionic radii equal to 0.66 A. Several other cations of transition metals are also sterically similar or even identical to tantalum and niobium, which allows for certain isomorphic substitutions in the cation sublattice. 

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