Strategies for relaxation studies

Consider the longitudinal relaxation rate, Tq for quadrupolar mechanism under extreme narrowing conditions  

Following the approach of Werbelow and co-workers, the lineshape of a spin-1/2 nucleus scalar-coupled to a quadrupolar nucleus may be simulated in terms of the relaxation parameters of the quadrupolar nucleus, provided that 

As an approximate method for the analyses of the relaxation data of Co systems without significant cobalt-ligand 7r-bonding, in Eq. (32) has 

For complex ions of similar size within a homologous series, it is expected that t//tc remains relatively constant for different solvents at a given temperature, in accordance with the Stokes-Einstein-Debye model. From the slope of the plot 5iso versus y/(Az/f/2)/A av shown in Fig. 16, the correlation time constants of a series of tra 5 -[Co(acac)2XY] complexes were estimated and the results were compared favourably with the Tc obtained from the relaxation measurements of the methene carbons (see Table 5). 

Working in dilute solution ( 80 mmolP ) is recommended whenever the Stokes-Einstein-Debye model is employed for data analysis, as illustrated in the study of Co longitudinal relaxation time of Co(acac)3 in CH3CN.  

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