Ab Initio Study of Hydrogen-Bonded Complexes of Small Organic Molecules with Water

Abstract

Hydrogen bonding between water and a series of small organic molecules was examined via electronic structure calculations. Several computational methods were examined, including both a hybrid density functional procedure (Becke3LYP) and second-order Moller−Plesset theory (MP2) coupled with a double-ζ basis set augmented by diffuse polarization functions on heteroatoms. The agreement between Becke3LYP and MP2 energies was generally good, as was the agreement with energies obtained using more sophisticated and costly methods. The energies and structures of 53 hydrogen-bonded complexes of water with various small organic molecules, including alcohols, thiols, ethers, thioethers, carboxylic acids, esters, amines, amides, nitriles, and nitro compounds, were then examined systematically using the Becke3LYP and MP2 procedures. The hydrogen bond geometries were generally linear, and acceptor sites corresponded closely to the positions of lone pairs as predicted by simple hybridization arguments. Structures with s...