Blue-Shifted Hydrogen Bonding in the Gas Phase CH/D3CN center dot center dot center dot HCCl3 Complexes

Behera, B and Das, Puspendu K (2019) Blue-Shifted Hydrogen Bonding in the Gas Phase CH/D3CN center dot center dot center dot HCCl3 Complexes. In: JOURNAL OF PHYSICAL CHEMISTRY A, 123 (9). pp. 1830-1839.

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Abstract

Blue-shifting H-bonded complexes between CHCl3 and CH/D3CN 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 CH3CN and CD3CN, the C-H stretching frequency of CHCl3 shifts to the blue by +8.7 and +8.6 cm(-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 CHCl3 and CH/D3CN 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 CH3CN makes the CH3CN 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 Cl3CH center dot center dot center dot NCCH3 complex have been compared with those of F3CH center dot center dot center dot NCCH3 and Cl3CH center dot center dot center dot NH3 complexes. The change in electron density of the CHCl3 as a function of C-H center dot center dot center dot N distance shows that the approach of CH3CN to CHCl3 induces a shift in electron density from the H atom to the Cl atoms of CHCl3 which leads to C-H bond contraction and blue shifting of C-H stretching frequency. However, in the complex Cl3CH center dot center dot center dot NH3, where frequency shift to the red is reported, charge transfer and electrostatic interaction dominate.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY A
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copyriht of this article belongs to AMER CHEMICAL SOC
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	30 May 2019 10:45
Last Modified:	30 May 2019 10:45
URI:	http://eprints.iisc.ac.in/id/eprint/62481

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