| Abstract: | Electron spin resonance spectra have been measured under uniform conditions for a series of trimethylsilyl-substituted benzene anion radicals. These ESR results have been used to derive a general set of Hückel molecular orbital parameters by treating the organosilyl substituent as a pseudo-heteroatom. ESR data for radical anions of organosilyl-substituted benzenes, biphenyls and naphthalenes are reproduced accurately by MO calculations employing hSi = –2.0 and kCSi = 0.7. For these series of compounds, the silicon-methyl proton ESR splittings, while not related to the π electron density on silicon alone or to the density on the aromatic carbon to which silicon is bonded, may be related to a combination of the π spin densities by a semiempirical relation: |
