TY - JOUR
T1 - A model study on the mechanism and kinetics for the dissociation of water anion
AU - Huyen, Trinh Le
AU - Duong, Long Van
AU - Nguyen, Minh Tho
AU - Lin, Ming Chang
PY - 2019/8
Y1 - 2019/8
N2 - Quantum chemical computations using both density functional theory (B3LYP functional) and wavefunction (MP2 and CCSD(T)) methods, with the 6-311++G(3df,2p) and aug-cc-pVnZ (n = D,T,Q) basis sets, in conjunction with a polarizable continuum model (PCM) method for treating structures in solution, were carried out to look again at a series of small negatively charged water species [(H2O)n]•–. For each size n of [(H2O)n]•– in aqueous solution with n = 2, 3, and 4, two distinct structural motifs can be identified: a classical water radical anion formed by hydrogen bonds and a molecular pincer in which the excess electron is directly interacting with H atoms. In aqueous solution, both motifs have comparable energy content and likely coexist and compete for the ground state. Some water anion isomers can dissociate when interaction with a water molecule, [(H2O)n]•– + H2O → H•(H2O)m + OH–(H2O)n–m, through successive hydrogen transfers with moderate energy barriers. This reaction can also be regarded as a water-splitting process in which the H transfers involved take place mainly within a water trimer, whereas other water molecules tend to stabilize transition structures through microsolvation rather than direct participation. Calculated absolute rate constants for the reversed reaction H•(H2O)2 + OH–(H2O)2 → [(H2O)4]•־ + H2O with both H and D isotopes agree well with the experimentally evaluated counterpart and lend a kinetic support for the involvement of a tetramer unit.
AB - Quantum chemical computations using both density functional theory (B3LYP functional) and wavefunction (MP2 and CCSD(T)) methods, with the 6-311++G(3df,2p) and aug-cc-pVnZ (n = D,T,Q) basis sets, in conjunction with a polarizable continuum model (PCM) method for treating structures in solution, were carried out to look again at a series of small negatively charged water species [(H2O)n]•–. For each size n of [(H2O)n]•– in aqueous solution with n = 2, 3, and 4, two distinct structural motifs can be identified: a classical water radical anion formed by hydrogen bonds and a molecular pincer in which the excess electron is directly interacting with H atoms. In aqueous solution, both motifs have comparable energy content and likely coexist and compete for the ground state. Some water anion isomers can dissociate when interaction with a water molecule, [(H2O)n]•– + H2O → H•(H2O)m + OH–(H2O)n–m, through successive hydrogen transfers with moderate energy barriers. This reaction can also be regarded as a water-splitting process in which the H transfers involved take place mainly within a water trimer, whereas other water molecules tend to stabilize transition structures through microsolvation rather than direct participation. Calculated absolute rate constants for the reversed reaction H•(H2O)2 + OH–(H2O)2 → [(H2O)4]•־ + H2O with both H and D isotopes agree well with the experimentally evaluated counterpart and lend a kinetic support for the involvement of a tetramer unit.
KW - dissociation of water anions
KW - hydrated electrons
KW - reactions of water anions
KW - water anions
KW - water split by water anions
UR - http://www.scopus.com/inward/record.url?scp=85065176516&partnerID=8YFLogxK
U2 - 10.1002/kin.21281
DO - 10.1002/kin.21281
M3 - Article
AN - SCOPUS:85065176516
SN - 0538-8066
VL - 51
SP - 610
EP - 617
JO - International Journal of Chemical Kinetics
JF - International Journal of Chemical Kinetics
IS - 8
ER -
