Hydrogen Bond Rearrangements and Interconversions of H⁺(CH₃OH)₄H₂O Cluster Isomers

Abstract

Rearrangement of hydrogen bonds in the protonated methanol-water cluster ion H + (CH 3 OH) 4 H 2 O is analyzed. The analysis, based on ab initio calculations performed at the B3LYP/aug-cc-pVTZ//6-31+G* and MP4/ 6-311+G*//B3LYP/6-31+G* levels of computation, provides information about potential minima, transition states, and pathways for the hydrogen bond rearrangement processes. Results of the analysis are compared systematically to the experimental measurements for H + (CH 3 OH) 4 H 2 O, where two distinct charge-centered (H 3 O + and CH 3 OH 2 + ) isomers have been identified in a supersonic expansion by fragment-dependent vibrational predissociation spectroscopy (Chaudhuri et al. J. Chem. Phys. 2000, 112, 7279). Revealed by the calculations, the lowest energy pathway for the transition from an open noncyclic hydronium-centered isomer [H 3 O + (CH 3 OH) 4 ] to a linear methyloxoium-centered isomer [CH 3 OH 2 + (CH 3 OH) 3 H 2 O] involves three stable intermediates and four transition states. The transition can go through either all four-membered ring isomers or a mixture of four-membered and five-membered ring intermediates. The latter is an energetically more favorable process because of less strain involved in the five-membered ring formation. A barrier height of <2.5 kcal/mol (after zero-point energy corrections) is predicted, suggesting that rapid interconversions among different isomers can occur at room temperature for this particular cluster cation.

TiS2and ZrS2single- and double-wall nanotubes: First-principles study

“…The band gaps calculated in this work indicate that all considered phases pertain to low-gap semiconductors. This disagrees with the results of previous DFT calculations [34,36,38,43] of 1T-o phases. The one of the possible explanation of appearance of nonzero gap between the valence and conductance states is the type of Hamiltonian.…”

“…The most of previous DFT calculations [34,36,38,43] have indicated that layered disulfides of titanium and zirconium should [36] 3.598 5.660 0.257 Semimetal PBEsol [36] 3.629 5.884 0.247 0.8 Experiment [d] 3.630 5.850 0.250 17.7 [c] 1.7 [37] [a] Ref. [38]; the relaxed cell constants have not been reported.…”

Infrared studies of ionic clusters: The influence of Yuan T. Lee

“…173 Both zeropoint energy and hydrogen bond cooperativity had a major impact on the location of the proton. 177 Studies of proton transfer using infrared laser spectroscopy preceded the investigations from the Lee group. The initial study focused on the sequential hydration of CH 3 OH 2 + with one to six waters.…”

Hydrogen-bonded ring closing and opening of protonated methanol clusters H+(CH3OH)n (n = 4–8) with the inert gas tagging

“…40 In this work, we apply a first-principles based multi-model method proposed by Nguyen et al to systematically search the local minimum structures of H + (MeOH) n so that conformational isomers within a H-bond morphological groups can be faithfully represented. 1,37,[49][50][51] The importance of the dispersion correction in the evaluation of the absolute binding energy has been demonstrated for the protonated methanol clusters by Fifen and co-workers. This level of theory and basis set were chosen because of its computational efficiency and reasonable accuracy.…”