ISSN:
1434-193X
Keywords:
1,4-Benzoquinones
;
[2.2]Paracyclophanes
;
1,4,8,11-Pentacenetetrones
;
Cyclic voltammetry
;
Radical anions
;
ESR/ENDOR spectroscopy
;
Intramolecular electron transfer
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Three types of tetrone radical anions in which two 1,4-benzoquinone units are connected by ethano (1·-, 2·-), [2.2]paracyclophane (3·-, 4·-), and anthracene bridges (5·-, 6·-) have been studied by ESR and ENDOR spectroscopy. The displacement of the unpaired electron over the two π moieties in the [2.2]cyclophane radical anions 1·--4·- and the marked difference between the first and second reduction potentials, ΔE = |E20 - E10| ≥ 0.20 V, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Similar ΔE data for the syn- (3) and anti-naphthalenophanes (4) indicate that most of the intramolecular electronic interaction takes place through the [2.2]paracyclophane bridge. When ion pairing is inhibited by complexation of the cation, the unpaired electron in 5·- and 6·- is also delocalized over the whole pentacenetetrone system at temperatures as low as 160 K.
Type of Medium:
Electronic Resource
Permalink
