Photochemical Formation of Ruthenium Phthalocyanine φ-Cation Radical Species

Abstract

Upon Q-band excitation (irradiation wavelength > 580 nm) ruthenium(II) phthalocyanine complexes can be quantitatively photooxidized to stable φ- cation radical species. The photooxidation can be carried out at either room temperature using CH 2Cl 2 solutions containing CBr 4 as an 'irreversible' electron acceptor, or in low-temperature (79 K) 2-methyl- tetrahydrofurane solutions containing 2,3-dichloro- 5,6-dicyanobenzoquinone as a 'reversible' acceptor. Absorption and magnetic circular dichroism (MCD) spectra indicate that there are two major, resolved transitions in the visible region, one at 510 nm and the other at 700 nm. The MCD spectra of the transition at 510 nm shows that it is non-degenerate, while the transition at 700 nm is seen to be degenerate in the case of photooxidized Ru(II)Pc(−2)(CO)DMF at room temperature.