98775-15-6Relevant articles and documents
Dynamics of Internal Rotation in 2-(Cycloalkenyl)ethyl Radicals
Walton, John C.
, p. 1809 - 1814 (2007/10/02)
2-(Cycloalkenyl)ethyl radicals having C4 to C7 rings were observed by e.s.r. spectroscopy.The barriers to rotation about the -Cβ bonds were determined from the temperature variation of the β-hydrogen hyperfine splitting and shown to decrease with increasing ring size.In all cases, the preferred conformation about the Cβ-Cγ bond was found to be the one in which the -Cβ bond makes an angle of 90 deg with the plane of the ring.Exchange broadening due to restricted rotation about the Cβ-Cγ bond was observed and the rotation barriers were determined for the radicals with C6 and C7 rings.The radicals were studied using the semi-empirical MINDO/3 and MNDO methods and the corresponding hydrocarbons were investigated by the MM2 force field approach.The variation in the rotational barrier heights were attributed to steric effects.