Disproportionation of AlF3 • 9H2O in donor solvents

AlF3. 9H(2)O was found to disproportionate in dimethylformamide, dimethyl sulfoxide, tetramethylurea, and hexamethylphosphoramide solutions to produce six-coordinate fluoro solvate species AlF(n)Sol(6-n) (Sol is water or donor solvent) and the tetrafluoroaluminate anion. The mononuclear tetrahedral configuration of AlF4- was supported by F-19 and Al-27 NMR spectra. For AlF4- anion in donor solvents, chemical shifts and F-19-Al-27 spin coupling constants were determined. Disproportionation depends on the donor solvent : water molar ratio (R): at R > 20, AlF4- incorporates 58-80% of aluminum in solution. At 265-310 K, the intermolecular ligand exchange between six- and four-coordinate aluminum fluoro species is not observed.