Electron bound to hydrated hydrogen fluoric acids

Abstract

Electron(e)-binding hydrated hydrogen fluoride clusters [e–HF(H 2O) n=1–10 ] have been studied with density functional and ab intio calculations. The hydrofluoric acid in e–HF(H 2O) n clusters is found to be undissociated at 0 K till n = 10. The e–HF(H 2O) 3 cluster is particularly unstable compared with the corresponding neutral structures, which reflects the particularly unstable antimagic number of e–water tetramer. The characteristic of “magic” numbers of electron–water clusters appears in these e–(HF)(H 2O) n clusters. The vertical detachment energies of e–HF(H 2O) n are enhanced by the HF acid as compared with those of the e-binding water clusters [e–(H 2O) n + 1 ], and the excess electron is surface bound near the terminal water molecule with two dangling hydrogen atoms. The coordination number of HF is one for n = 1–4 as a linear structure in contrast to two for n = 5–6, and three for n = 7–10. The phase transition from 2- to 3-dimensional structures appears at penta-hydrated system in contrast to hepta-hydrated system for neutral HF–water clusters. The structures for e–HF(H 2O) n=2,3 are quite different from those of the corresponding e–(H 2O) n + 1 = 3,4 , and the structures for e–HF(H 2O) n = 2–6 are quite different from those of the corresponding HF(H 2O) n = 2–6.