The radical cations generated from 4-methyl-and 4, 7-dimethylindanone, as well as their deuterated isotopomers, isolated in Argon matrices, were found to undergo enolization to the corresponding enol radical cations at rates that differ by orders of magnitude. It is shown
[Schreiner, Peter R.; Wittkopp, Alexander; Gunchenko, Pavel A.; Yaroshinsky, Alexander I.; Peleshanko, Sergey A.; Fokin, Andrey A. Chemistry - A European Journal, 2001 , vol. 7, # 13 p. 2739 - 2744]