Weitz-type redox system

Recently, a hybrid radiaannulene 90 containing electron-donating TTFs and electron-accepting TEE moieties has been prepared by Nielsen and coworkers [86]. This system can be considered as a two-stage Weitz-type redox system, which leads to the aromatic 144t-annulene structure by either oxidation or reduction. Thus, CV analysis clearly showed three reversible oxidation waves corresponding to the formation of three redox states (+1/+2/+4) and showed two reversible reduction waves corresponding to two redox states (—1/—2). From the... 

Two Step Reversible Redox Systems of the Weitz Type... 

Naturally the redox properties of the general structures A-C ould strongly be influenced by different heteroatoms X. Since this report deals mainly with Weitz type systems, X is incorporated into a heterocyclic ring. 

Five-membered heterocycles with two heteroatoms connected in 2-position also form two step redox systems of the Weitz type which may be described as hetero-tetrasubstituted ethylenes on the level of RED . The great significance of tetrathia (selena) flilvalenes 17 as a basis for organic metals has already been discussed ... 

The remarkable variety of redox systems which can already be derived from the Weitz type underline the wide scope of the general structure A and C as a basic principle for two step redox systems. The empirical material as well as general rules regarding structural influences on potentials and Ksem have been developed to such an extent, that redox systems can be taylored to meet special purposes. Catalysts for electron transfer, light positive systems and compounds of high electrical conductivity are some fields in which these redox systems could occupy key positions. Some applications have already been discussed in a previous review of wider scope h)... 

Hi n,M. B. Determination of Molecular Weights by Light Scattering. 77, 141-232(1978). Hiinig, S. H., Berneth, H. Two Step Reversible Redox Systems of the Weitz Type. 92,1-44... 

---