Premium
The Cope Rearrangement of 1,5‐Dimethylsemibullvalene‐2(4)‐d 1 : Experimental Evidence for Heavy‐Atom Tunneling
Author(s) -
Schleif Tim,
MieresPerez Joel,
Henkel Stefan,
Ertelt Melanie,
Borden Weston Thatcher,
Sander Wolfram
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201704787
Subject(s) - isotopomers , quantum tunnelling , chemistry , degenerate energy levels , atom (system on chip) , reaction rate constant , matrix isolation , spectroscopy , scanning tunneling microscope , analytical chemistry (journal) , infrared spectroscopy , kinetics , condensed matter physics , molecule , physics , organic chemistry , chromatography , quantum mechanics , computer science , embedded system
As an experimental test of the theoretical prediction that heavy‐atom tunneling is involved in the degenerate Cope rearrangement of semibullvalenes at cryogenic temperatures, monodeuterated 1,5‐dimethylsemibullvalene isotopomers were prepared and investigated by IR spectroscopy using the matrix isolation technique. As predicted, the less thermodynamically stable isotopomer rearranges at cryogenic temperatures in the dark to the more stable one, while broadband IR irradiation above 2000 cm −1 results in an equilibration of the isotopomeric ratio. Since this reaction proceeds with a rate constant in the order of 10 −4 s −1 despite an experimental barrier of E a =4.8 kcal mol −1 and with only a shallow temperature dependence, the results are interpreted in terms of heavy‐atom tunneling.