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The Reaction between Bromine and the Water Dimer and the Highly Exothermic Reverse Reaction
Author(s) -
Li Guoliang,
Wang Hui,
Li QianShu,
Xie Yaoming,
Schaefer Henry F.
Publication year - 2016
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23951
Subject(s) - chemistry , bromine , dimer , exothermic reaction , endothermic process , transition state , valence (chemistry) , reaction rate constant , computational chemistry , kinetics , catalysis , adsorption , biochemistry , organic chemistry , physics , quantum mechanics
The entrance complex, transition state, and exit complex for the bromine atom plus water dimer reaction Br + (H 2 O) 2 → HBr + (H 2 O)OH and its reverse reaction have been investigated using the CCSD(T) method with correlation consistent basis sets up to cc‐pVQZ‐PP. Based on the CCSD(T)/cc‐pVQZ‐PP results, the reaction is endothermic by 31.7 kcal/mol. The entrance complex Br⋯(H 2 O) 2 is found to lie 6.5 kcal/mol below the separated reactants. The classical barrier lies 28.3 kcal/mol above the reactants. The exit complex HBr⋯(H 2 O)OH is bound by 6.0 kcal/mol relative to the separated products. Compared with the corresponding water monomer reaction Br + H 2 O → HBr + OH, the second water molecule lowers the relative energies of the entrance complex, transition state, and exit complex by 3.0, 3.8, and 3.7 kcal/mol, respectively. Both zero‐point vibrational energies and spin‐orbit coupling effects make significant changes to the above classical energetics. Including both effects, the predicted energies relation to separated Br + (H 2 O) 2 are −3.0 kcal/mol [Br···(H 2 O) 2 ], 28.2 kcal/mol [transition state], 26.4 kcal/mol [HBr···(H 2 O)OH], and 30.5 kcal/mol [separated HBr + (H 2 O)OH]. The potential energy surface for the Br + (H 2 O) 2 reaction is related to that for the valence isoelectronic Cl + (H 2 O) 2 system but radically different from the F + (H 2 O) 2 system. © 2015 Wiley Periodicals, Inc.