Nitrogen-reduction ratio nature

In short, polarisation transfer methods provide greatest benefits for those nuclei that have low magnetogyric ratios and are slow to relax. It is also the preferred approach to direct observation for those nuclei with negative ys where the NOE may lead to an overall signal reduction. Nitrogen-15 [32] (Fig. 4.28) and silicon-29 routinely benefit from PT methods, as does the observation of metals, in particular transition metals which often posses very low ys and are extremely insensitive, despite their sometimes high natural abundance, some examples being Fe, ° Rh, ° Ag, and W. 

The nucleophilic strength of the nitrogen, the substitution pattern of the alkyne, the absence or the presence—as well as the nature—of phosphine ligands, the solvents, the added salts, and even the ratios between them are among the main factors influencing the conrse of the aminopalladation-reductive elimination domino reaction. 

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