Abstract
The NMR spectroscopic data for organometallic allyl and related derivatives have been examined. It is suggested that allyl compounds of transition metals be classified solely as σ- and π-derivatives and NMR spectroscopic criteria for the assignment of the test compounds to one of these types have been formulated. The effects of the structural non-equivalence of allyl ligands in a series of compounds, certain types of isomerism of allyl derivatives and also their possible lack of stereochemical rigidity have been considered. The validity, from the standpoint of NMR experiments, of the hypothesis of the σ–π transformations of allyl derivatives of transition metals in the presence of bases has been discussed. Hypotheses have been put forward concerning the geometry of the allyl compounds of certain non-transition metals.
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