DSpace
 

DSpace at IIT Bombay >
IITB Publications >
Article >

Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/4410

Title: Origin of methyl torsional barrier in 1-methyl-2-(1H)-pyridone
Authors: PRADHAN, B
SINGH, BP
NANDI, CK
CHAKRABORTY, T
KUNDU, T
Keywords: pi(asterisk)-sigma(asterisk) hyperconjugation mechanism
internal-rotation barriers
staggered conformation
substituted toluenes
anionic states
ethane
2-pyridone
s-1
Issue Date: 2005
Publisher: AMER INST PHYSICS
Citation: JOURNAL OF CHEMICAL PHYSICS, 122(20), -
Abstract: The laser induced fluorescence excitation and single vibronic excitation dispersed fluorescence spectra have been studied for supersonic jet cooled 1-methyl-2(1h)-pyridone. The methyl torsional bands and some low frequency vibrational transitions were assigned for both ground and excited states. The torsional parameters V-3=244 cm(-1) and V-6=15 cm(-1) for the ground state and V-3 = 164 cm(-1) and V-6= 40 cm(-1) for the excited state were obtained. To get the insight into the methyl torsional barrier, ab initio calculations were performed and compared with the experimental results. Origin of potential barrier was traced by partitioning the barrier energy into changes in bond antibond interaction, structural, and steric energies accompanying methyl rotation using natural bond orbital analysis. The role of local interactions in ascertaining the barrier potential reveals that its nature cannot be understood without considering the molecular flexing. The hyperconjugation between CH sigma* and ring pi* observed in lowest unoccupied molecular orbital (LUMO) stabilizes the methyl group conformer that undergoes a 60 degrees rotation in the excited state with respect to that of the ground state, and it is the change in LUMO that plays important role in the excited state barrier formation. (c) 2005
URI: http://dx.doi.org/10.1063/1.1901567
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4410
http://hdl.handle.net/10054/4410
ISSN: 0021-9606
Appears in Collections:Article

Files in This Item:

File SizeFormat
124.pdf1.1 MBAdobe PDFView/Open
View Statistics

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback