Triarylmethyl and Related Radicals - Stable Radicals: Fundamentals and Applied Aspects of Odd-Electron Compounds - page 22

Cl Cl

Cl Cl

Cl Cl

Cl Cl

Cl Cl Cl Cl

Cl Cl

• C C •

Cl Cl

Cl Cl Cl Cl

Cl Cl

Cl Cl

Cl Cl

Cl Cl

102

Cl

Cl

Cl

OMe

Cl

Cl Cl

Cl

C

•

Cl N

Cl Cl

Cl

Cl

Cl

OMe

Cl

103

The dependence of the UV spectra of the transition from radical 104 to the zwitterion 105 was examined
as the solvent composition was varied and the process changed from the normal to the inverted Marcus
region (Equation 1.32). 37b

The redox properties of the two species were also examined.

Cl Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl Cl

Cl

Cl

Cl

∆ or h ν

_

C

(1.32)

C •

Cl

Cl

Cl Cl

Cl Cl

Fe •+

Fe

Cl

Cl

Cl

Cl

Cl

Cl

Cl Cl

104 105

Perfluorinated triphenylmethyl radical 106 was generated by reduction of the corresponding carbocation
and gave an EPR spectrum measured in benzene (Equation 1.33). 38a The product was recrystallized from
benzene giving material with a melting point of 158 ◦ C containing an undetermined amount of free radicals
as detected by EPR. Tris(4-nitro-2,3,5,6-tetrafluorophenyl)methyl radical 107 was formed by oxidation
of the corresponding carbanion with potassium permanganate and characterized by its EPR spectrum
(Equation 1.34). 38b