Modern NMR Spectroscopy of Organolithium Compounds

Modern methods of NMR spectroscopy, in particular the two-dimensional techniques, offer new chances for structure determinations in the field of organolithium compounds, where the combination of ¹H-, ¹³C-, and ⁶⁽⁷⁾Li-NMR spectroscopy is an especially useful feature. Chemical shift correlations which also include the lithium nuclei allow a complete assignment of the ¹H-, ¹³C-, and ⁶Li-NMR spectra and thereby a better characterization of the various aggregates and complexes present in solution. Spatial proximities of ⁶Li and ¹H can be detected by nuclear Overhauser experiments, and ⁶⁽⁷⁾Li-NMR exchange spectroscopy can provide new information with regard to the mechanisms and energetics of dynamic processes like aggregate interchange and complexation. After a short resumé of the experimental aspects of the NMR spectroscopy of organolithium compounds and a discussion of the NMR parameters of these systems, new experimental techniques are presented. Areas of application of these newly conceived one- and two-dimensional NMR experiments are illustrated with selected examples. The results show that even more detailed information about the structure and reactivity of organolithium compounds, which are so important for organic synthesis, can be expected in the future.