High resolution NMR of solids

Some of these diverse methods will be discussed qualitatively in the following few sections wherein several excellent reviews such as those by Haeberlen (1976), Mehring (1976), and Slichter (1978), are referenced. Before going on, we stop to consider one last question Why do we want to try 

There are several reasons for performing high resolution NMR in solid samples. A pragmatic reason is that the sample preparation would be easier if the compound of interest need 

In the particular example of benzene, there are three inequivalent principal directions for the tensor at the carbon nucleus. It should be quite clear by inspection that the three directions are defined by 1) the line from the center of the hexagon through the corner, 2) the line through the corner and perpendicular to the plane of the hexagon, and 3) the 

In general, there are six components to a chemical shift tensor [see, for example, Chapter 2 in Mehring (1976) referenced in IV.E.3.]. Thus the chemical shift tensor at a site on a molecule can tell you a great deal about the site s immediate surroundings, possibly quantitative indication of the bonding, in addition to the site symmetry. 

In solution NMR, the chemical shift ends up being a scalar, which means just a number, because of the rapid rotation of the molecule. For example, as far as an individual carbon at a corner of a benzene molecule goes, it sees the external field orient equally probably along the three principal axes as do all the other carbons so the resulting NMR spectrum consists of just one line, if the effects of protons are ignored. Therefore, high resolution solution NMR yields relatively little information compared to what might be available if we could get the full chemical shift information by some means. 

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In general, high-resolution NMR of solids is found to be very much complementary to diffraction techniques in the investigation of solid-state structures. The applications may be classified into three very general groupings ... 

Dipolar broadening constitutes a routinely-overcome barrier in high-resolution NMR of solids, and the consequences are readily removed in the... 

In conclusion, I hope that I have shown that fast-atom bombardment mass spectrometry is a potentially useful tool for the synthetic chemist working in many areas of inorganic, organometallic, and coordination chemistry. In addition, as further fundamental research is done in the field with these applications in mind, the technique should become as routine as IR or NMR. Combined with developments in high-resolution NMR of solids, FAB should provide particularly useful data on supported catalytic reactions. Certainly FAB and the other complementary mass spectrometric techniques, mentioned in less detail, constitute a major way of quickly characterizing new compounds. 

The Theoretical and Practical Limits of Resolution in Multiple-Pulse High-Resolution NMR of Solids... 

Mehring, M, (1983) High Resolution NMR of Solids, Springer-Verlag, Berlin. 

U. Haeberlen, High resolution NMR of solids, Adv. Magn. Reson.. Suppl. 1. Academic Press, San Diego, 1976. 

Wasylishen RE and Fyfe CA (1982) High resolution NMR of solids. Annual Reports in NMR Spectroscopy 12 1-80. 

The three major problems in the recording of high-resolution NMR of solids mentioned above have been solved by (a) high-power decoupling, (b) magic angle spinning (MAS), and (c) cross-polarization (CP). 

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