ESR spectra of sterically hindered silicon-containing phenoxyls

Autor: Klimov, E. S., Muslin, D. V., Lyapina, N. Sh., Shpakov, A. V., Okhlobystin, O. Yu.
Zdroj: Theoretical and Experimental Chemistry; January 1992, Vol. 28 Issue: 1 p61-64, 4p
Abstrakt: The ESR method was used to study a series of sterically hindered silicon-containing phenoxyls — 2-trialkyl(dialkylalkoxy)silyl-4,6-di-tert-butylphenoxyls. The parameters of the ESR spectra were determined: the constants of splitting of the unpaired electron on meta-protons of the phenoxyl ring, protons of the organosilyl substituents, and magnetic silicon nuclei, as well as the spectroscopic splitting factors. The stability of the silicon-containing phenoxyls relative to one another was determined. The influence of a second Si-containing substituent in the ortho-position and an alkyl substituent in the para-position was followed on the example of 2,6-triphenylsilyl-4-tert-butylphenoxyl and the 2,6-trimethylsilyl-4-ethylphenoxyl radical. The stability of the aroxyls is determined primarily by the steric shielding of the radical site responsible for the dimerization-rearrangement reaction.
Databáze: Supplemental Index