Blue-shifting hydrogen bonds
Blue-shifting hydrogen bonds
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DOI：
10.1021/jp0143948
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发表时间：
2002-05-09
影响因子：
2.9
通讯作者：
Hermansson, K
中科院分区：
文献类型：
--
作者：
Hermansson, K
本文提出了文献中讨论的各种“不适当的蓝移”氢键体系本质上都是相同的，并且是由于三种必要的情况而发生的：（i）孤立氢键供体分子存在负的偶极矩导数dmu（0）/dr（XH）;（ii）这种分子与氢键受体上的任何电子密度浓度（π系统密度、孤对密度、离子电荷......）其在大的分子间距离产生场主导的，适度的振动蓝移;（iii）由于电子交换重叠的额外的蓝移。负偶极矩导数是形成蓝移氢键的必要条件，但不是充分条件：因此，蓝移的CH 4、F3 CH和Cl 3CH分子及其亲属也可以产生“正常”的红移氢键。这是蓝移性质的逻辑延伸，并且当来自受体的电场在分子间平衡距离处足够强时发生（例如，对于F-和Cl-受体）。
In this paper we put forward the idea that the various "improper, blue-shifting" hydrogen bond systems discussed in the literature are all of essentially the same nature and occur because of three necessary circumstances: (i) the presence of a negative dipole moment derivative, dmu(0)/dr(XH), for the isolated H-bond donor molecule; (ii) the interaction between such a molecule and any electron density concentration on the H-bond acceptor ( pi-system density, lone-pair density, ionic charge,...) which at large intermolecular distances gives rise to a field-dominated, modest vibrational blue shift; (iii) an additional blue shift due to electronic exchange overlap. The negative dipole moment derivative is a necessary but not sufficient condition for the formation of a blue-shifted H-bond: thus, the blue-shifting CH4, F3CH, and Cl3CH molecules and their relatives can also give rise to "normal", red-shifted H-bonds. This is a logical extension of the blue-shifting property and occurs when the electric field from the acceptor is sufficiently strong at the intermolecular equilibrium distance (e.g., for F- and Cl- acceptors).