Electron-driven acid-base chemistry: proton transfer from hydrogen chloride to ammonia.

Eustis, Soren N; Radisic, Dunja; Bowen, Kit H; Bachorz, Rafal A; Haranczyk, Maciej; Schenter, Gregory K; Gutowski, Maciej · Science · 2008

basic_science · Level V

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Abstract

In contrast to widely familiar acid-base behavior in solution, single molecules of NH3 and HCl do not react to form the ionic salt, NH+4Cl-, in isolation. We applied anion photoelectron spectroscopy and ab initio theory to investigate the interaction of an excess electron with the hydrogen-bonded complex NH3...HCl. Our results show that an excess electron induces this complex to form the ionic salt. We propose a mechanism that proceeds through a dipole-bound state to form the negative ion of ionic ammonium chloride, a species that can also be characterized as a deformed Rydberg radical, NH4, polarized by a chloride anion, Cl-.