Rotational Spectra, Conformational Structures and Dipole Moments of 2-(Ethylthio) Ethanol by Jet-Cooled FTMW and Ab Initio Calculations

Published

January 1, 2004

Author(s)

R D. Suenram, David F. Plusquellic, Francis J. Lovas, A H. Walker, Q Liu, L H. Xu, J O. Jensen, A C. Samuels

Abstract

The rotational spectra of three low-energy conformers of 2-(ethylthio)ethanol also known as ethyl 2-hydroxyethylsulfide or hydroxyethylethyl sulfide (HOEES), together with the monosubstituted C and 34S isotopic forms of the two lowest energy conformers, have beenmeasured in a molecular beam using a pulsed-nozzle Fourier-transform microwave spectrometer. To search for the likely conformationalstructures, ab initio calculations were performed at the MP2/6-3 I G* level for reduced dimensionality potential energy mapping and at theMP2=FULL/6-31 I G** and B3LYP/6-31 IG** levels for full structural optimization and electronic energy calculations of possible lowerenergy conformers. In all, five low-energy conformers, each of C, point group symmetry, were located in the ab initio search withcomplete information obtained on rotational constants, dipole moments and structures. Rotational constants for three of the conformersagree well with the experimental observations, leaving the other two with no experimental partners. The three having experimentalmatches display relatively open chain-like structures corresponding to TG-, and GG-like forms, while the two with no experimentalmatches display relatively closed or folded structures with significantly different rotational constants. Although results using differentab initio level theories with and without zero point energy corrections alter the conforiner energy ordering slightly, the no-matchconformers always stay in the lower energy group, leaving an unsolved question as to why these lower energy confon-ners with folded-like structures were not observed in the jet-cooled FTMW spectra.

Citation

Journal of Molecular Spectroscopy

Volume

223

Issue

No. 1

Pub Type

Journals

Keywords

2-(Ethylthio)ethanol, FT spectroscopy, hydroxyethyl-ethylsulfide, microwave spectrum, molecular beam spectroscopy, molecular structure, rotational spectrum

Citation

Suenram, R. , Plusquellic, D. , Lovas, F. , Walker, A. , Liu, Q. , Xu, L. , Jensen, J. and Samuels, A. (2004), Rotational Spectra, Conformational Structures and Dipole Moments of 2-(Ethylthio) Ethanol by Jet-Cooled FTMW and Ab Initio Calculations, Journal of Molecular Spectroscopy (Accessed April 23, 2024)