An asymmetrically distorted structure of the 1-methylsilacyclohexane radical cation: ESR evidence

Electronic and geometric structure of the 1-methylsilacyclohexane (1-Me-cSiC5) radical cation in a solid perfluoromethylcy-clohexane matrix at low temperature were used studied by ESR spectroscopy with the aid of three selectively deuteriated 1-methyl-silacyclohexanes, 1-Me-cSiC5-2,2- d 2 , 1-Me-cSiC5-2,2,6,6- d 4 , and 1-Me- d 3 -cSiC5. The radical cation was found to have an asymmetrically distorted geometrical structure with one of the SiC bonds elongated with its electronic ground state proposed to be 2 A in C 1 symmetry. This conclusion was derived from an analysis of the temperature -dependent ESR spectra employing a dynamic model of interconversion between two energetically equivalent distorted mirror image structures.