Great advances have been made in the past decade in the field of NMR spectroscopy. Apart from the development of completely new areas of application, such as in solid-state chemistry, in materials science, in physiological chemistry, and in medicine, with the introduction of new pulse spectroscopic methods and the application of high magnetic field strengths important progress has also been made in the traditional field of high-resolution N M R spectroscopy. Thus, among other things, the observation of metal resonances has been facilitated and new areas of application have been opened u p in inorganic and organometallic chemistry. In this review, recent detection methods for spin-112 and quadrupolar metal nuclei are presented and discussed. The use of metal-NMR spectroscopy with respect to problems of a typical chemical nature, mainly from the field of organometallics, is demonstrated for a number of selected metal nuclei ("Mg, 27Al, 49Ti, "Fe, 59C0, 61Ni, "Zr, Io3Rh, and I9'Pt). Relations found empirically between chemical shifts and coordination number, oxidation number, and electronic configuration of a metal bound in a complex are emphasized. Furthermore, cases in which the chemical shifts of metal nuclei can be interpreted in terms of the energy difference of frontier orbitals are presented. This aspect leads to the establishment of a relationship between chemical reactivity and NMR parameters for a series of related compounds.

The introduction of Fourier transform methods has not only remarkably enhanced the sensitivity of high‐resolution NMR spectroscopy, thus allowing measurements to be made on less sensitive nuclei of the Periodic Table, but also has paved the way for the development of a large number of new experimental techniques. On the one hand, procedures already known have been improved and can now be performed more rapidly, and, on the other, completely new experimental approaches have become available. This situation resulted mainly from the introduction of programmable pulse transmitters and the separation of the experiment into preparation, evolution, and detection. In particular, the concept of two‐dimensional spectroscopy has opened up new possibilities important for the analysis of complicated spectra and is able to provide information previously not accessible. As elsewhere, optimum application of the techniques and correct interpretation of the results require sound understanding of the underlying physical principles. Since a rigorous mathematical treatment is complicated and does not necessarily improve the comprehensibility, this article attempts to give an illustrative presentation of the new pulse techniques within the framework of the Bloch vector model. After a short introduction covering the basic principles, one‐dimensional pulse techniques that can be applied using standard experimental equipment are dealt with. The main areas of application are signal assignment, sensitivity enhancement for measurements on less abundant nuclei, and selective excitation of individual resonances. Subsequently, the various techniques of two‐dimensional NMR spectroscopy are treated: these enable shift correlations for different types of nuclei to be made, the presentation of spin multiplets without overlap, and the analysis of geometrical relations as well as of chemical exchange phenomena.

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Whether the allyl ligand is η1‐ (1), η1, η2‐ (2) or η3‐bound (3) can be ascertained by high‐resolution solid‐state CP‐MAS 13C‐NMR spectroscopy in the case of 3,3‐dimethylallylzinc chloride (η1), bis(2‐methylallyl)zinc (η1,η2), bis(allyl)zinc and 2‐methylallylzinc chloride (each η3). In contrast, in donor solvents the allyl groups in all four cases are bound in an η1‐like fashion to zinc.

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