THE ION-DIPOLE INTERACTION MECHANISM OF MACROCYCLIC ETHERS WITH C-13 DIPOLE-DIPOLE RELAXATION-TIME MEASUREMENTS .6.

The stabilities of various stoichiometries of the 12-crown-4 ether complexes with LiCl in methanol-d were estimated by an NMR method using 13C T1 relaxation time measurements. The experimental coordination conditions are established by maintaining an identical host/guest concentration in order to achieve the actual compositions. The evidence was evaluated with the expression for the dependence of the mole fraction of the bound ligand, PAE, to the experimental values of the dipole-dipole relaxation time, T1obs, PAE = (1/T1obs - 1/TE)/(1/TAE; - 1/TE). The equilibrium constants Ke for Li+ complex formation in methanol-d were obtained through the expression and regression of 1/Ke[E0]n+m-1 = (1 - nP′)n(1 - mP′)m/P′, where P′ = PAE/(1 + PAE(m - 1)). Although the method presented is entirely different from the common analytical methods, the results are excellent in terms of agreement with earlier studies. The extension of a further degree of complexing ratios has also been proven with the simulation of TAE. © 1990 American Chemical Society.