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Title:A Microwave Spectroscopic Study Of Methylated Indoles: Internal Rotation And Nuclear Quadrupole Coupling
Author(s):Gurusinghe, Ranil
Contributor(s):Tubergen, Michael
Subject(s):Large amplitude motions, internal rotation
Abstract:The barrier to methyl internal rotation of an asymmetric two ring system depends on the position of the methyl substitution. A cavity based Fourier transform microwave spectrometer was used to record rotational spectra of different methyl substituted indoles in the range of 10.5 - 20 GHz. About 160 hyperfine components arising from about 30 rotational transitions were assigned for each 1- and 3-methylindole. The program XIAM$^{a}$ was used to fit the rotational constants, distortion constants, nuclear quadrupole coupling constants and barrier to internal rotation to the measured transition frequencies of the A and E internal rotation states.\\ The best fit values for the rotational constants are A = 2651.12(2) MHz, B = 1305.266(2) MHz, C = 879.800(2) MHz for 1-methylindole and A = 2603.7224(5) MHz, B = 1268.7886(1) MHz, C = 857.8091(1) MHz for 3-methylindole. The different values observed for the barrier to internal rotation, 279.8(3) \wn for 1-methylindole and 433(1) \wn for 3-methylindole, may be due to the different rotor axis lengths and differences in local $\pi$-electron density.\\ Progress on the assignment of additional methylated indoles will also be presented.\\ $^{a}$H. Hartwig and H. Dreizler, Z. Naturforsch, 51a, 923 - 932.
Issue Date:2014-06-19
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:Gurusinghe, R.; Tubergen, M. A MICROWAVE SPECTROSCOPIC STUDY OF METHYLATED INDOLES: INTERNAL ROTATION AND NUCLEAR QUADRUPOLE COUPLING. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.RJ03
Rights Information:Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License.
Date Available in IDEALS:2014-09-17

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