NMR Chemical Shifts of Aluminum: Experimental Data and Variational Calculation

Abstract

Chemical shifts of Al²⁷ for aluminum alkyl halides, halides, alkyls, alkoxides, AlH₄^—, and Al(OH)₄^— are given. The magnitude of the resonance line width of aluminum compounds as liquids or in solution is indicative of the cubic or noncubic molecular symmetry around the Al²⁷ nucleus. The chemical shift of Al²⁷ in AlH₄^— is calculated by a variation procedure using both valence bond and molecular orbital type wave functions. Requirements on variational functions due to time reversal and inversion symmetry are given. Factors determining the shifts of other aluminum compounds are discussed.