A distinctive feature in the IR spectra of proton disolvates [L2H+] and polysolvates [(L2H+)center dot nL]: unusual strong broadening of some absorption bands of ligands L bound with H+

An IR study of proton disolvates in organic solutions of L2H+FeCl4-, where L=tributyl phosphate (TBP), butyl acetate, diethyl ether, acetone and ethan ol, or proton polysolvates of L2H+. nL . FeCl4- or (L'H+L)L'. FeCl4- (L=eth anol, L'=TBP) under the weak polarizing influence of FeCl4- anion on the ca tion led to the discovery of an unusual, very strong broadening of the abso rption bands of the molecular groups of ligands L, which are directly bound with H+. These bands belong to (i) highly characteristic vibrations of dou ble bonds P=O(-H+), C=O(-H+), etc., weakly mixed with the vibration of conj ugated bonds, and (ii) strongly interacting group vibrations experiencing t he influence of the proton. This effect is best exhibited in the IR spectra of proton solvates H+. nL with the positive charge located mainly on one O -H+-O group. The following explanation of this effect has been proposed. Th e potential function of the proton in the O-H+-O group is almost a single m inimum with a flat bottom. Therefore, H+ is delocalized in a certain spatia l interval between the oxygen atoms. As a result, the force constants of th e bands of ligands L influenced by H+ change with the same frequencies as t he proton migrates at the bottom of the flat potential minimum. This freque ncy may be comparable to those of some normal vibrations or exceed them. It has been shown that the same effect also takes place in the IR spectra of proton hydrates H5O2+. nL, where L=H2O or organic bases. The effect reporte d can form a basis for a new interpretation of the peculiarities in the IR spectra of proton hydrates.