At low temperatures the PhCMe2CH2CH2 radical preferentially adopts a conformation in which the radical center and the phenyl substituent are gauche to each other when viewed along the Cβ-Cγ bond. The β-hydrogens are magnetically nonequivalent and the magnitudes of their hyperfine splitting represent an average over rotation about the Cα-Cβ bond. On the basis of the equation αHβ= 54〈cos2 θ〉 G, we have derived a simple, two-component rotational potential which supports the suggestion that there is a weak, attractive interaction between the singly occupied Cα 2pz orbital and the π-cloud of the phenyl substituent. The conformations of some related radicals are also discussed.
The Journal of Physical Chemistry88, no. 9 (1984): 1675–1678.