Methyl radical molecular orbitals

Methoxy radical 210 Methyl-de-diazoniation 253 Methylene, energy of triplet state 178 Molecular orbital method, applications to ArNj structure and to dediazoniations - ab initio 84ff., 177ff., 270, 280... 

To permit the a and P spins to occupy different regions of space, it is necessary to treat them individually in the construction of the molecular orbitals. Following this formalism, we would rewrite our methyl radical wave function Eq. (6.6) as... 

In addition to meso-ionic examples, molecular orbital (MO) calculations have also been applied to radical work. 5-Methyl-1,3,2,4-dithiadiazolyl radical 8 has been reported to undergo a concerted rearrangement to 4-methyl-l,2,3,5-dithiazolyl radical 9 <1986CC140>. 

Fig. 8. Schematic representations and contour maps of the molecular orbitals on the carbonyl part of the methyl isobutyrate radical-anion with the fixed geometry of neutral molecule (left) and the fully optimized geometry (right).

As with all molecules, it is the energy of the electrons in the molecular orbitals of the radical that dictate its stability. Any interaction that can decrease the energy levels of the filled molecular orbitals increases the stability of the radical (in other words, decreases its reactivity). Before we use this energy level diagram of the methyl radical to explain the stability of radicals, we need to look at some experimental data that allow us to judge just how stable different radicals are. 

The present experiment involves an investigation of the ESR spectra of the unsubstituted ortho and para-benzosemiquinone radical anions, along with one or more of the methyl and t-butyl derivatives. Aspects of interest include the elucidation of splitting constants from complex spectra, the examination of substituent effects in ESR spectra, and the interpretation of spectra using molecular-orbital (MO) calculations. 

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