Large Amplitude Motions And π-hydrogen Bonding In The Thiophene–water Complex Characterized By Rotational Spectroscopy And Quantum Chemical Calculations

Silva, Weslley G. D. P.

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https://hdl.handle.net/2142/111272 Copy

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Title

Large Amplitude Motions And π-hydrogen Bonding In The Thiophene–water Complex Characterized By Rotational Spectroscopy And Quantum Chemical Calculations

Author(s)

Silva, Weslley G. D. P.

Contributor(s)

van Wijngaarden, Jennifer

Issue Date

2021-06-23

Keyword(s)

Mini-symposium: Large Amplitude Motions

Abstract

The rotational spectrum of the thiophene–water (thiophene–w) complex was studied for the first-time using Fourier transform microwave (FTMW) spectroscopy from 7 to 20 GHz. Supported by density functional theory (DFT) calculations, transitions belonging to a single dominant conformer were observed in the spectrum. By comparing the experimentally derived spectroscopic parameters, which includes data for the singly substituted $^{18}$O isotopic species, with the results from quantum chemical calculations at the B2PLYP-D3(BJ)/def2-TZVP level of theory, we show that the observed pattern of transitions is consistent with a structure that is highly averaged over a large amplitude rocking motion of the water. This effective geometry, stabilized via a primary O–H...$\pi$ hydrogen bond, has the oxygen atom of water sitting above the plane of the thiophene molecule centered on the ring’s $\sigma$$_{v}$ plane of symmetry. The spectrum also reveals a tunneling splitting with a characteristic 3:1 intensity ratio that arises from a water-centered internal rotation about its C$_{2}$ axis which exchanges its hydrogen atoms with an estimated barrier of approximately 2.7 kJ/mol (B2PLYP-D3(BJ)/def2-TZVP). Based on symmetry-adapted perturbation theory (SAPT) calculations, electrostatic and dispersive interactions are shown to be the most stabilizing contributors behind the formation of thiophene–w.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111272

DOI

10.15278/isms.2021.WA06

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