Resumen de Probing Halide Distribution in [AlX4]− Anions via 27Al NMR: Application of the Pairwise-Additivity Model
Craig M. Davis, Bridget M. Dixon
A laboratory exercise using 27Al NMR spectrometry to study the tetrahedral tetrahaloaluminate anions has been developed. Spectra of the homoleptic complexes [AlX4]− and the dihalide anions [AlX4Y4−n]− (X, Y = Cl, Br, or I) are acquired, then the pairwise-additivity concept developed by Vladimiroff and Malinowski is used to predict the chemical shifts of the trihalide anions [AlClmBrnI4−m−n]−. The relationship between the 27Al NMR chemical shift and the charge on the central aluminum atom (calculated with molecular modeling) is investigated, as well as the relationship between the symmetry of the anions and the line width of their respective resonances.
