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Symmetric ring puckering potential in thietane-1,1-dioxide compared with experiment and analysis of theoretical vibrational spectra

All Rights Reserved. Symmetric ring puckering potential in thietane-1,1-dioxide compared with experiment and analysis of theoretical vibrational spectra. Forner, Wolfgang; Badawi, Hassan M. (Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia). International Journal of Quantum Chemistry, Volume Date 2007, 107(2), 469-479 (English) 2006 John Wiley & Sons, Inc. CODEN: IJQCB2. ISSN: 0020-7608. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) We studied the ring puckering potential in thietane-1,1-dioxide with different methods, using a suitable basis set, 6-311+G**. We obtained a barrier to ring puckering of 153 cal/mol with the DFT/B3LYP (Becke3 exchange-Lee, Yang, Parr correlation functional) method, ~60% too small compared with expt. However, using MP2, MP3, and MP4 we obtained values around 200% too large. The MP series turned out to converge far too slowly to the exptl.In this article, certain chemicals are used. Some of their cas registry numbers are 7782-39-0 and 5687-92-3 barrier value, showing no sign of convergence even at MP4, while higher orders are out of our reach for such a system. Obviously, of all methods used, DFT worked best despite some shortcomings. The barrier corresponds to 77 K; thus, there should be rapid interconversion over the barrier at room temp., a phenomenon actually obsd. at room temp., the measured barrier corresponding to 201 K. Thus, we decided to use the DFT/6-311+G** calcns. to predict reasonable vibrational spectra and assignments of the lines found. The ring puckering mode is found at 80 cm-1 in DFT in good agreement with the exptl. value of 78.3 cm-1 for this vibration. .