Proton-exchange processes

Water and Proton Exchange Processes on Metal Ions... 

This section deals with the quantitative description of the proton transfer processes (denoted by Eqs. (4) and (6) in Scheme 1), identified by the qualitative NMR experiments on the acid/base behavior of the Mo(IV), W(IV), Re(V), Tc(V), and Os(VI) systems as described in Section II. The data obtained on the signal behavior from these similar complexes were used to simulate spectra and model the proton exchange processes to finally obtain rate constants associated therewith. 

It was shown in Section III,D that the proton exchange processes, which can take place via two different pathways, induce oscillation of the metal center along the O-M-O axis. The inversion rate constants, inv, were calculated over a selected pH range using Eq. (18) [W(IV) and Mo(IV)] and Eq. (19) [Re(V) and Tc(V)], the appropriate proton exchange rate constants (Table IV), and the acid dissociation constants (Table II). The resulting values are presented by curves BB in Figs. 19 and 20 respectively (6). 

N.M.R. Spectra and exchange processes The fact that aromatic substances are relatively weak bases always requires the use of strong acids. However, proton exchange processes take place in such media, and these can interfere to an extraordinary extent with this particular method of measurement. 

WATER AND PROTON EXCHANGE PROCESSES ON METAL IONS... 

WATER AND PROTON EXCHANGE PROCESSES ON METAL IONS TACI = 1,3,5-triamino-1,3,5-trideoxy-cis-inositol =... 

Figure 8.63 Variable temperature H NMR spectra of the Ir—H and N—H regions in 8.50 showing the proton exchange process. (Reproduced with permission from The Royal Society of Chemistry).

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