Exchange reactions and equilibria

Although exchange reactions, where bonds are broken and formed, are fundamentally different from a chemical point of view to the intramolecular dynamic phenomena that we have discussed so far, in principle they are the same in terms of observation by NMR spectroscopy. Consider a very simple chemical process, the exchange of protons between HCl and HBr. NMR spectroscopy shows exchange between two sites with resonant frequencies Va and Vb and mean lifetimes Ta and Tb- The lifetimes are equal if the two 

2D P EXSY spectrum of the rhodium complex measured at 300 K. Reproduced with permission from [67]. Copyright 2008 American Chemical Society. 

Addition of successively increasing amounts of the bases DMP, DMMP and DMSO to the adduct of the bis-Lewis acid [o-C6F4(HgCl)2] with acetone, as observed by NMR spectroscopy. 

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