IR spectrum and structure of protonated ethanol dimer:: Implications for the mobility of excess protons in solution

This Communication reports IR spectra and density functional calculations for the isolated protonated ethanol dimer and its N2-microsolvated complexes, (EtOH)2H+-(N2)n (n = 0-2) to investigate the degree of delocalization of the excess proton in this fundamental building block of an alcohol proton wire. The first spectroscopic characterization of isolated and microsolvated (EtOH)2H+ suggests that the excess proton is (nearly) equally shared between both EtOH units under symmetric solvation conditions (Zundel-type ion, n = 0 and 2), whereas it is largely localized on a single EtOH molecule for asymmetric solvation (Eigen-type ion, n = 1). Copyright © 2004 American Chemical Society.