Structure And Dynamics Of The Weakly Bound Trimer ( H2s)2 ( H2o) Observed Using Rotational Spectroscopy

Das, Arijit

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https://hdl.handle.net/2142/116663 Copy

Description

Title

Structure And Dynamics Of The Weakly Bound Trimer ( H2s)2 ( H2o) Observed Using Rotational Spectroscopy

Author(s)

Das, Arijit

Contributor(s)

• Arunan, Elangannan
• Walker, Nick
• Gougoula, Eva

Issue Date

2022-06-24

Keyword(s)

Mini-symposium: Spectroscopy meets Chemical Dynamics

Abstract

The weakly bound complex between two hydrogen sulfide molecules and one water molecule, ($ H_{2}$$S)_{2} $($ H_{2}$O), was identified from its rotational spectrum observed at conditions of supersonic expansion. The spectra of parent species were obtained using a chirped-pulse Fourier transform microwave spectrometer (Newcastle, UK). The isotopologues were identified with Balle-Flygare Fourier transform microwave spectrometer (Bangalore, India). Distinct physical properties of $ H_{2}$O and $ H_{2}$S under ambient settings have long been recognized as a result of their significantly different hydrogen-bonding capabilities. It has conclusively shown ($ H_{2}$$S)_{2} $ is hydrogen-bonded similar to ($ H_{2}$$O)_{2} $ at very low temperature\footnote{A. Das, P. K. Mandal, F. J. Lovas, C. Medcraft, N. R. Walker, and E. Arunan. \textit{Angewandte Chemie International Edition}, 2018, 57, 15199-15203.}. The break with axial molecular symmetry and the simplified internal dynamics allowed us to investigate ($ H_{2}$$S)_{2} $($ H_{2}$O) at a level of structural detail that has not yet been possible for ($ H_{2}$$O)_{3} $ and ($ H_{2}$$S)_{3} $ with rotational spectroscopy due to their zero-dipole moment. The rotational spectrum of ($ H_{2}$$S)_{2} $($ H_{2}$O) shows a doubling of the lines, close to 1:3 relative intensity for the parent species, caused by the internal rotation of the $ H_{2}$O moiety about its $ C_{2}$ axis. Analysis of experimental results reveals that the three monomers are bound in a triangular arrangement through the S-H$\cdot$$\cdot$$\cdot$S, O-H$\cdot$$\cdot$$\cdot$S and S-H$\cdot$$\cdot$$\cdot$O hydrogen bonds. The $ r_{s}$ and $ r_{0}$ structural parameters have been evaluated, and the three heavy atom distances $ r_{s}$(S-H$\cdot$$\cdot$$\cdot$S)=4.067(2)Å, $ r_{s}$(O-H$\cdot$$\cdot$$\cdot$S)=3.412(11)Å and $ r_{s}$(S-H$\cdot$$\cdot$$\cdot$O)=3.454(11)Å are appreciably shorter than the respective distances in ($ H_{2}$$S)_{2}$, \textit{HOH}$\cdot$$\cdot$$\cdot$S$ H_{2}$ and \textit{HSH}$\cdot$$\cdot$$\cdot$O$ H_{2}$\footnote{P. K. Mandal, Ph.D. Dissertation, Indian Institute of Science, 2005.}. The geometry contains numerous characteristics that indicate the cooperative nature of the intermolecular interaction. The experimental results for all observables determinable from the rotational spectrum are found to be in excellent agreement with \textit{ab initio} predictions.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116663

DOI

https://doi.org/10.15278/isms.2022.FA07

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