EXCESS PROTON HYDRATE STRUCTURES WITH LARGE PROTON POLARIZABILITY, SCREENED BY TRIS(2-ETHYLHEXYL) PHOSPHATE

Complexes of tris(2-ethylhexyl) phosphate (EHPO) with HAuCl4 and its h ydrates with various amounts of water were studied by FT-IR spectrosco py. In the water free solution of HAuCl4 in EHPO homoconjugated P = O ... H+... O = P hydrogen bonds with proton polarizability are formed. We demonstrate that in the 1:1 and 1:2 mixture with water only the H5O 2+ species is present and no H3O+ species is formed. In the 1:1 mixtur e with water in addition to the H5O2+ species, 50% homoconjugated hydr ogen bonds of protonated EHPO are still present. This homoconjugated h ydrogen bond, as well as the central bond in H5O2+ shows large proton polarizability, as indicated by IR continua. In the 1:3 mixture of the homoconjugated complex with water a cyclic hydrogen-bonded system wit h a three-minima proton potential is present. The proton polarizabilit y of this system is the largest, as indicated by a particularly intens e IR continuum. In the case of the 1:4 mixture, a cyclic hydrogen-bond ed arrangement with a four-minima proton potential is present, in whic h the barriers between the minima are larger than in the three-minima potential.