Some Aspects of Proton Chemical Shifts

Because of the importance and wide utility of H NMR, we look particularly at factors that determine H chemical shifts. These features can be used semiquanti-tatively to predict and/or rationalize specific ranges of H chemical shifts. 

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This review is intended to cover most of the aspects of NMR in phosphorus chemistry, especially stressing those aspects directly related to electronic and structural factors. Some subjects will only be briefly reviewed, e.g. resonances in solid compounds, in metal complexes [this subject has been treated in a previous article in this seriesa969,1)] and biological applications. All the compounds reviewed are tabulated in either Formula Index I (inorganics) or Formula Index II (organics), the whole comprising of more than four thousand five hundred entries. These indicesf list all available chemical shifts for phosphorus and fluorine those for other nuclei (except protons) are reported in the text of this review. 

In an almost simultaneous publication by Bruch [53] concerning the same class of E/V copolymers, the chemical and steric sequence assignments were established by two-dimensional NMR methods. Also, the vieinal CH—OH proton coupling constants were found to be smaller in V units with a meso-V neighbor than with a racemic-V neighbor. This information could be utilized for characterizing some eonformational aspects of the polymer chain. Likewise the chemical shifts in C NMR spectra that are sensitive to the orientation of substituents in y position (the y-gauche effect) [7] could be considered for conformational characterization of these polymers. 

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