Hydrogen bonding and cooperative effects in mixed dimers and trimers of methanol and trifluoromethanol: An ab initio study

Abstract

, "Hydrogen bonding and cooperative effects in mixed dimers and trimers of methanol and trifluoromethanol: An ab initio study" (1999 Ab initio calculations are used to provide information on the mixed dimers and cyclic trimers of the methanol-trifluoromethanol system. In order to better understand the systems, the monomers and their corresponding dimers and trimers are also investigated. Molecular structures and harmonic frequencies are obtained at the B3LYP/6-311ϩϩG(d,p) level. Interaction energies are calculated with the MP2 and B3LYP methods using the 6-311ϩϩG(d,p), 6-311ϩϩG(2d,2p), and 6-311ϩϩG(3d,2p) basis sets for the dimers and heterodimers. The 6-311ϩϩG(d,p) basis set was used to calculate the interaction energies for the trimers and heterotrimers. Because the primary goal of this study is to examine cooperative effects, particular attention is given to parameters such as O...O distances, electronic charge densities at the bond critical points, enhanced dipole moments, shifts in the stretching frequencies of the donor O-H bond, and the length of the donor O-H bond.

On the structures of the methanol trimer and their cooperative effects

“…The most stable trimer (T1) presents one methyl group (m2) in approximate antiperiplanar arrangement with regard to the other two, what agrees with previous theoretical studies [10,14,16,17,20] and experimental evidences [19][20][21]. In the second most stable structure, T2, all the methyl groups are in approximate synperiplanar arrangement [10].…”

Energetics and cooperativity in three-center hydrogen bonding interactions. II. Intramolecular hydrogen bonding systems

“…This enhanced lengthening of the N-H bond is commonly used as one index to quantify cooperative effects. 4,8 The N-H bond in 4 presents no further elongation with respect to 4a.…”

α‐Fluoroalcohols: Synthesis and Characterization of Perfluorinated Methanol, Ethanol and n‐Propanol, and their Oxonium Salts

“…In addition to the experimental study described above, electronic structure computations were carried out to gain a better understanding of the nature of these perfluoroalcohols. Although numerous theoretical studies have been previously carried out on free gaseous CF 3 OH, very little is known on its condensed‐phase chemistry and, particularly, on the higher perfluoroalcohols. Therefore, extensive calculations were carried out at the G3MP2 level of theory for all three fluoroalcohols both in the gas phase and in aqueous solutions.…”