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On the Search for H 5 O 2 + centered Water Clusters in the Gas Phase
Author(s) -
Chang HuanCheng,
Jiang JyhChiang,
Chang HaiChou,
Wang YiSheng,
Lin Sheng H.,
Lee Yuan T.
Publication year - 1999
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199900059
Subject(s) - chemistry , protonation , molecule , ab initio quantum chemistry methods , ab initio , crystallography , ion , hydrogen bond , spectroscopy , hydrogen , gas phase , solvent , computational chemistry , organic chemistry , physics , quantum mechanics
In searching for H 5 O 2 + ‐centered water clusters, we employed vibrational predissociation spectroscopy and ab initio calculations. Structures of the clusters were characterized by the free‐ and hydrogen‐bonded‐OH stretches of ion cores and solvent molecules. Systematic examination of H + (H 2 O) 5–7 in a supersonic expansion reveals the presence of both cyclic and noncyclic forms of H 5 O 2 + ‐centered water clusters. The proton transfer intermediate H 5 O 2 + (H 2 O) 4 was identified, for the first time, by its characteristic hydrogen‐bonded‐OH stretches of the ion core at 3178 cm −1 . Also discovered at n = 7 is the H 5 O 2 + ‐containing five‐membered ring isomer, whose existence is evidenced by the observation of a bonded‐OH stretching doublet at 3544 and 3555 cm −1 of the solvent molecules. The observations are in accord with ab initio calculations which forecast that H 5 O 2 + (H 2 O) 4 and H 5 O 2 + (H 2 O) 5 are, respectively, the lowest‐energy isomers of protonated water hexamers and heptamers.