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We report herein on a rigorous analysis of unique electrolyte solutions for novel rechargeable magnesium batteries and nonaqueous magnesium electrochemistry, which contain organometallic complex electrolyte species, by Raman spectroscopy. These solutions comprise ethereal solvents and products of reactions between R2Mg Lewis base species and AlCl2R Lewis acid species that exist in solution in dynamic multiple equilibria. The reactions involve the exchange of ligands between the magnesium and the aluminum to form ions such as MgCl+, Mg2Cl3 +, and AlCl4- n R- n (n ≤ 4), stabilized by the ether molecules. The Raman peak assignments were based on a rigorous study of solutions containing reference compounds and some quantum-mechanical calculations. Raman spectroscopy enabled a quantitative analysis of the various species in solution.

MM3-derived full conformational schemes are proposed as a powerful and convenient tool for the currently problematic assignment of NMR-measured barriers for flexible systems that possess more than one type of independent intramolecular motion. Hindered piperidines were chosen as a molecular model with seven possible intramolecular dynamic processes. The free energies of activation for methyl group topomerization in 1,2,2,5,5-pentamethyl-, 1-ethyl-2,2,6,6-tetramethyl-, and 1-butyl-2,2,6,6-tetramethylpiperidines were determined at different temperatures by means of line-shape analysis of 13 C NMR spectra. Schemes of conformational transformations for the N-Me and N-Et compounds were created with MM3-based methodology. These schemes permit the assignment of the measured barriers to ring inversion for the N-Me compound and to ring inversion ± nitrogen inversion, ring inversion, and CÀN rotation for the NAlk primary piperidines (for the N-Et and N-Pr derivatives the experimental barriers had previously been attributed to isolated CÀN rotation only). A unique dynamic process for tertiary amines, isolated nitrogen inversion, is described for the N-alkylpiperidines with an Nsubstituent bulkier than Me.

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