Blue-shifted hydrogen bonding in the gas phase CH/D 3 CN···HCCl 3 complexes

Behera, B and Das, PK (2019) Blue-shifted hydrogen bonding in the gas phase CH/D 3 CN···HCCl 3 complexes. In: Journal of Physical Chemistry A .

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Abstract

Blue-shifting H-bonded complexes between CHCl 3 and CH/D 3 CN have been identified by Fourier transform infrared spectroscopy in the gas phase at room temperature. The change in FTIR peak intensity of the mixture of the two components as a function of temperature and composition provides the basis for identification of the H-bonded band in the infrared spectrum. On complex formation with CH 3 CN and CD 3 CN, the Câ'H stretching frequency of CHCl 3 shifts to the blue by +8.7 and +8.6 cm â'1 , respectively. The molecular electrostatic potential calculation at the MP2/6-311++G� level has been used to arrive at the geometry of the complex. It has been reported in the literature that CHCl 3 and CH/D 3 CN form red-shifting H-bonded complex in Ar matrix. The red shifting has been verified by doing ab initio calculations in the presence of Ar atoms, which has been attributed to the matrix effect at low temperature. The interaction of Ar with CH 3 CN makes the CH 3 CN more basic and as a result it becomes better hydrogen bond acceptor and causes red shift. The potential energy scans and NBO analysis of the Cl 3 CH···NCCH 3 complex have been compared with those of F 3 CH···NCCH 3 and Cl 3 CH···NH 3 complexes. The change in electron density of the CHCl 3 as a function of Câ'H···N distance shows that the approach of CH 3 CN to CHCl 3 induces a shift in electron density from the H atom to the Cl atoms of CHCl 3 which leads to Câ'H bond contraction and blue shifting of Câ'H stretching frequency. However, in the complex Cl 3 CH···NH 3 , where frequency shift to the red is reported, charge transfer and electrostatic interaction dominate. © 2019 American Chemical Society.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry A
Publisher:	American Chemical Society
Additional Information:	Copyright for this article belongs to American Chemical Society.
Keywords:	Ammonia; Argon; Atoms; Calculations; Carrier concentration; Charge transfer; Electron density measurement; Electrostatics; Fourier transform infrared spectroscopy; Gases; Hydrogen bonds; Potential energy; Red Shift; Temperature, Ab initio calculations; Complex formations; H-bonded complexes; Hydrogen bond acceptors; Infrared spectrum; Low temperatures; Molecular electrostatic potentials; Stretching frequency, Blue shift
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	08 Apr 2019 11:56
Last Modified:	08 Apr 2019 11:56
URI:	http://eprints.iisc.ac.in/id/eprint/62033

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