Formation and exchange reactions of metal complexes

however, more usual for rapid exchange to occur between the free and coordinated ligand molecules giving rise to a single averaged signal such that  

This implies that the larger the contribution to the relaxation rate, the more dilute the solution needs to be. 

Reuben (291) has latterly suggested that the way round this problem is to investigate both proton and deuteron relaxation rates. In the Solomon expression for Tj [equation (17)] the deuterons are less susceptible than protons to the dipolar relaxation by a factor ( h/ d) which equals 424. Thus if Tm Tim the ratio of the induced relaxation of protons to that of deuterons is unity, but this ratio increases with increasing TimAm values until it reaches a value of 424 for the case when Tm T m- When applied to the Gd system it is found that 0 03Tim = 3-3 X 10 s. 

Miscellaneous kinetic data for water exchange reactions are given in Table XIII. Equilibrium constants for deaquation of M(H20)g [M = Co(il),Ni(ii)] have been obtained for complexes involving nitrate ions (294) and ethyl alcohol molecules. (295) For the equilibrium  

Kinetic parameters for alcohol exchange have been deduced from H and studies on Co(ii), (296) Ni(ii), (297) and Mn(ii) (298) systems. The complex [Co(CH30H)5py] (296) provides a clear example of the operation of the trans effect in a labile octahedral complex, in that the exchange rate constants for cis and trans methanol sites with respect to pyridine are 410s and 1200s respectively. 

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