Scandium has been declared one of the ‘nationally critical materials’ due to its widespread utility in commercial applications and difficulty in establishing a reliable supply chain. Initial efforts focused on dissolution of the metal, which was successfully accomplished using hydrohalic acids to generate hydrated monomers of [Sc(H2O)n]3(X) (n = 6, X = Cl; n = 7, X = Br, I) or hydroxy dimers of [(H2O)5Sc(OH)]24(X)n(H2O) (n = 2, X = Cl; n = 0, X = Br or I). Attempts to dry the chloride salts with thionyl chloride (SoCl2) and excess solvent produced products that were not completely anhydrous, such as [(H2O)ScCl3(THF)2](THF). This route was ultimately optimized to generate [ScCl3(THF)3]. Solvate complexes were isolated from additional solvents including Py, iPrOH, CH3CN, MeOH, DMF, and DMSO. Three structure types were isolated when Py was incorporated: [ScCl3(Py)3], [ScCl4(Py)2]2(Py)2(HPy), and [ScCl2(µ-OH)Py2](Py). Additional efforts to dehydrate our salt precursors in the absence of caustic SOCl2 were built upon the work by Levason et al where (O)AsPh3 and (O)PPh3 were found to displace water molecules. Similarly, the use of Ph2NCHO led to the isolation of an anhydrous product [ScCl3(κ1-(O)Ph2NCHO)3].These complexes were fully characterized using 45Sc solution and solid state NMR spectroscopy as well as single crystal X-ray diffraction. The synthesis of the various solvates and their structures will be presented.

Scandium salt dehydration for recycling efforts

253rd National Meeting (2017)

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