Transition from moderate to strong hydrogen bonds: its identification and physical bases in the case of O-H...O intramolecular hydrogen bonds.
Transition from moderate to strong hydrogen bonds: its identification and physical bases in the case of O-H...O intramolecular hydrogen bonds.
复制标题
DOI：
10.1021/jp076668i
复制
发表时间：
2008-01
期刊：
影响因子：
--
通讯作者：
Y. Mariam;R. N. Musin
中科院分区：
文献类型：
--
作者：
Y. Mariam;R. N. Musin
利用分子原子量子理论（QTAIM）进行了一项系统的研究，旨在确定从中等(M)到强(S)氢键（HBs）的转变，以及文献中报道的主要基于几何的HB强度分类的物理基础。研究了O…H氢键临界点处电子密度（rho）的拉普拉斯量nabla2rhohb之间的关系，特别是更直观的参数Lhb = -nabla2rhohb与其他QTAIM参数之间的关系。从MHBs到SHBs的转变已被确定为Lhb （nabla2rhohb）几何依赖性的最小（最大）值。地……O分子内（IM） HBs（包括共振辅助HBs），得到了转变，与现有的基于几何的HB强度分类非常一致，当O…O （O…H）距离约为2.51（约1.55）A，势能密度（|Vhb|）与动能密度（Ghb）之比约为1.3。据此，shb和mhb的| - Vhb和|/Ghb比值范围分别为| -1.3和1.3-1。当O…O距离不是HB强度的真正指标，|Vhb|/Ghb比值等参数应该被考虑来表征HB的强度。通过解码转变的物理基础，根据rho的性质和创造hbcp的相互作用的力学特征，提供了合理化。Lhb被发现与至少三个参数(除了O…O和O…H距离和IMHB能量)、Vhb/Ghb、Hhb/rhohb（总能量密度Hhb与电子密度rhohb（所谓的键度参数）之比）和deltahb(O，H)（离域指数），证明了Lhb （nabla2rhohb）对于HB相互作用研究的重要性和实用性。一种新的基于能量学的O-H精细分类…O IMHB的优势得到了提升。本研究采用的方法可以推广到其他HB系统。
A systematic investigation aimed at identifying the transition from moderate (M) to strong (S) hydrogen bonds (HBs) and the physical bases of the main geometry-based HB strength classifications reported in the literature has been undertaken using the quantum theory of atoms in molecules (QTAIM). Correlations between the Laplacian of the electron density (rho) at the O...H hydrogen bond critical points (HBCPs), nabla2rhohb, specifically between the more intuitive parameter Lhb = -nabla2rhohb and other QTAIM parameters, have also been explored. The transition from MHBs to SHBs has been identified as the minimum (maximum) in the geometric dependence of Lhb (nabla2rhohb). For O-H...O intramolecular (IM) HBs (including resonance-assisted HBs), the transition is obtained, in a truly remarkable agreement with the existing geometry-based HB strength classifications, when the O...O (O...H) distance is approximately 2.51 ( approximately 1.55) A and when the ratio of the potential energy density (|Vhb|) to the kinetic energy density (Ghb) approximately 1.3. Accordingly, the ranges of the |Vhb|/Ghb ratios are >2-1.3 and 1.3-1 for, respectively, SHBs and MHBs. When the O...O distance is not a genuine indicator of HB strength, the |Vhb|/Ghb ratio and other parameters should be considered to characterize the strength of the HBs. Rationalizations have been provided by way of decoding the physical bases of the transition in terms of the properties of rho and the mechanical characteristics of the interactions that created the HBCPs. Lhb was found to correlate, with a very high degree of fidelity, with at least three parameters (in addition to O...O and O...H distances and the IMHB energy), Vhb/Ghb, Hhb/rhohb (the ratio of the total energy density, Hhb, to the electron density, rhohb (the so-called bond degree parameter)), and deltahb(O,H) (the delocalization index), demonstrating the importance and utility of Lhb (nabla2rhohb) for the study of HB interactions. A new refined energetics-based classification of O-H...O IMHB strengths has been advanced. The approach taken in this investigation can be extended to other HB systems.