Gerhards M, Jansen A, Unterberg C, Gerlach A
Heinrich-Heine-Universität Düsseldorf, Institut für Physikalische Chemie I, 40225 Düsseldorf, Germany.
J Chem Phys. 2005 Aug 15;123(7):074320. doi: 10.1063/1.2008255.
In this paper the structures of 4-aminophenol(H2O)1+ and 3-aminophenol(H2O)1+ clusters are investigated in molecular beam experiments by different IR/UV-double resonance techniques as well as the mass analyzed threshold ionization spectroscopy yielding both inter- and intramolecular vibrations of the ionic and neutral species. Possible structures are extensively calculated at the level of density functional theory (DFT) or at the ab initio level of theory. From the experimental and theoretical investigations it can be concluded that in the case of 4-aminophenol(H2O)1 one O-H...O hydrogen-bonded structure exists in the neutral cluster but two structures containing either an O-H...O or a N-H...O hydrogen-bonded arrangement are observed in the spectra of the ionic species. This observation is a result of an intramolecular rearrangement reaction within the ion which can only take place if high excess energies are used. A reaction path via the CH bonds is calculated and explains the experimental observations. In the case of 3-aminophenol(H2O)1+ only one O-H...O bound structure is observed both in the neutral and ionic species. Ab initio and DFT calculations show that due to geometrical and energetical reasons a rearrangement cannot be observed in the 3-aminophenol(H2O)1+ cluster ion.
在本文中，通过不同的红外/紫外双共振技术以及质量分析阈值电离光谱，在分子束实验中研究了4-氨基苯酚（H₂O）₁⁺和3-氨基苯酚（H₂O）₁⁺团簇的结构，得到了离子和中性物种的分子间和分子内振动。在密度泛函理论（DFT）水平或从头算理论水平上广泛计算了可能的结构。从实验和理论研究可以得出结论，对于4-氨基苯酚（H₂O）₁，中性团簇中存在一种O-H...O氢键结构，但在离子物种的光谱中观察到两种包含O-H...O或N-H...O氢键排列的结构。这一观察结果是离子内分子重排反应的结果，只有在使用高过剩能量时才会发生。计算了通过C-H键的反应路径并解释了实验观察结果。对于3-氨基苯酚（H₂O）₁⁺，在中性和离子物种中仅观察到一种O-H...O键合结构。从头算和DFT计算表明，由于几何和能量原因，在3-氨基苯酚（H₂O）₁⁺团簇离子中未观察到重排。
