Blue shifted hydrogen bond in 3-methylindole.CHX(3) complexes (X = Cl, F).
Blue shifted hydrogen bond in 3-methylindole.CHX(3) complexes (X = Cl, F).
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DOI：
10.1039/b924288k
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发表时间：
2010-06
期刊：
影响因子：
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通讯作者：
P. R. Shirhatti;S. Wategaonkar
中科院分区：
文献类型：
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作者：
P. R. Shirhatti;S. Wategaonkar
虽然关于气相中蓝移氢键的第一个实验报告出现在大约十年前，但此后文献中报道的例子并不多。然而，从那时起，对表现出这种蓝移氢键的系统的计算研究已经很丰富了。这些理论预测中有许多还有待实验验证。本文报道了在3-甲基吲哚与CHX（3）（X = F，Cl）弱结合配合物中观察到的蓝移氢键的一个例子。采用超音速射流膨胀法制备了配合物，并采用激光光谱法对其进行了研究。关键的发现是，这些配合物表现出C-Hpi型氢键相互作用和CH结合到芳香平面的苯基部分。CHCl（3）和CHF（3）的CH伸缩分别蓝移2和16 cm（-1）。从头算计算、分子中原子分析和自然键轨道分析沿着支持实验结果。在DFT/MP2水平上的计算结果还表明，CHCl（3）配合物的氢键给体CH伸缩的红外强度增加了2 ~ 3个数量级，而氟仿配合物的氢键给体CH伸缩的红外强度降低了1个数量级，这与C-HO型蓝移氢键的红外强度变化趋势一致.
Although the first experimental report on the blue shifted hydrogen bond in gas phase appeared about a decade ago, not many examples have been reported in the literature thereafter. Computational studies on systems exhibiting such blue shifted hydrogen bond however have been abundant since then. Many of these theoretical predictions remain to be verified experimentally. In this work we present an example of blue shifted hydrogen bond observed in the weakly bound complexes of 3-methylindole and CHX(3) (X = F, Cl). The complexes were prepared using the supersonic jet expansion method and studied using the laser spectroscopic methods. The key findings were that these complexes exhibit C-Hpi type hydrogen bonding interaction and the CH is bound to the phenyl part of the aromatic plane. The CH stretch was found to be blue shifted by 2 and 16 cm(-1) in the case of CHCl(3) and CHF(3), respectively. Ab initio calculations along with atoms-in-molecule analysis and natural bond orbital analysis support the experimental findings. The computed results at the DFT/MP2 level also indicated that the IR intensity of the H-bond donor CH-stretch increases by two to three orders of magnitude for the CHCl(3) complex whereas for the fluoroform complex the same decreases by an order of magnitude, which are consistent with the trend reported in the case of C-HO type of blue shifting hydrogen bonds.