ABSTRACT
NMR is applicable to any nuclei that possess nonzero magnetic moments. Nevertheless, results of NMR applications will depend strongly on the nature of materials and target nuclei, and adequacy of formulated tasks. Although NMR can be applied, in principle, for most of the nuclei in the periodic table, in reality the range of nuclei is remarkably limited by NMR sensitivity and sensitivity of measured NMR parameters to environments of nuclei. Convenience of experiments and simplicity of their interpretations also play an important role. Generally such nuclei as 1H, 2H, 19F, 13C, 29Si, 17O, 31P, 51V, 93Nb, 181Ta, and the halogen nuclei are mostly attractive and more often used as probes in studying different materials. Sometimes even the simple well-recorded NMR spectra are sufœcient to describe complex molecular systems, for example, the immobilized phosphine linkers situated on the surface of silica-based matrix [1]. Figure 4.1 illustrates two types of such linkers that exhibit the very sharp 31P resonances observed at 22.4 and −3.9 ppm for groups [RʹPR2Et]+ and [RʹPR2], respectively.
