Precision measurements of PMR chemical shifts in a strong magnetic field and structure of aqueous solutions of perchloric acid

Labile supramolecular structures and their dynamics in associated liquids based on NMR data

“…14,43 This is evidence that, under the above men tioned conditions, H 3 O + centered structures are more favorable, although the situation is more complicated at higher temperatures and concentrations, and there is evi dence that H 5 O 2 + centered structures become domi nant. 43 These results are consistent with the modern con cepts presented in the beginning of this section.…”

“…This is consistent with our data. 14, 43 In the case of a larger energy difference, the less favorable solvation complex would be expected to serve as a transition state, whereas the more favorable complex will serve as a proton trap. 7, 8 In spite of the complexity of the structural motifs of water and pro ton solvation complexes in water, simulations demon strated 8 that the H bond network is easily rearranged.…”

“…14,15,17,43,45-49 In some cases, the de pendences were characterized 48 by sharp changes at spe cial points not only of the derivatives of NMR parameters but also of 1/T 2 . There are data on the nonsmooth char acter of the concentration plots for other physicochemi cal properties, such as the conductivity, 50 the density, 43 and the heat of mixing. 48 At special points, the composi tions are generally characterized by magic integer molar concentration ratios.…”

“…14,15, 43 The NO 3 -ions are symmetric planar and contain partially double bonds and two lone electron pairs at sp 2 hybridized oxy gen atoms. These lone electron pairs are efficient proton acceptors.…”

“…To check the correctness of this method, the latter was also applied to aqueous solutions. 14, 43 The method consists in the following. For the depen dences of the averaged chemical shifts on the composi tion for the B-HA systems (B is a base and HA is an acid), in which the A -anion is weakly solvated by H bonds compared to the proton, the plots of δ vs. q (q is the generalized Gutovskii coordinate, 14 i.e., the proportion of the protons of the acid of all the protons involved in the exchange) are nonsmooth linear bent curves.…”