Probing the Hydrogen Bonding in Microsolvated Clusters of Au1,2-(Solv)n (Solv = C2H5OH, n-C3H7OH; n = 1-3 for Au-; n =1 for Au2-).

Abstract

The microsolvation of gold anions in different alcohol solvents is demonstrated by the combination of anion photoelectron spectroscopy and quantum chemical calculations on the Au1,2-(Solv)n (Solv = C2H5OH, n-C3H7OH; n = 1-3 for Au-; n = 1 for Au2-). The microsolvation structures of these clusters and their corresponding neutrals are assigned by comparing calculations with experiments. In terms of overall regularity, the increasing solvation number (n) and carbon chain extension both can increase the stability of the anion. When n ≥ 2, these clusters have low-energy isomers, where conventional hydrogen bonds (HBs) compete with nonconventional HBs (NHBs). NHBs are dominant when n ≤ 2 and when n is increased, vice versa. Interestingly, a variety of theoretical calculations show that after the hydroxy H atom of the ethanol molecule forms a weak ionic HB with Au-, there are two lowest conformations of ethanol, trans and gauche, which could be coexisting in the molecular beams. Some theoretical methods also suggest that the gauche isomer is more stable than the trans one, which indicates that Au- may exist as a gold gauche effect similar to fluorine.