Polyfluoroxometalates (PFOMs) that have a quasi Wells–Dawson structure and have low valent transition metal substitution at the so-called “belt” position, α1-[H2F6NaM(H2O)W17O55]q–, can reversibly interchange between dimeric and monomeric structures. The dimers have two unique M–µO–W bridges between two PFOM units. The dimerization occurs through dehydration and was studied as a function of temperature using the visible spectrum that is sensitive to the wavelength and extinction coefficient of the d-d transition. The calculated thermodynamic parameters of the dimerization reaction were iteratively fitted using a function derived from the equilibrium constant and the Beer–Lambert law. Such reversible dimerization reactions have not been observed for similar α1-[P2M(H2O)W17O61]q– structures, thus fluorine atoms in an axial position to the transition metal are apparently critical for dimerization by reducing the bond strength of the transition metal–aqua bond trans to the fluorine atom.
ASJC Scopus subject areas
- Inorganic Chemistry