ISSN:
1434-4475
Keywords:
McMurry reaction
;
1H-NMR
;
Crystal structure
;
Voltammetry
;
Coulometry
;
Spectroelectrochemistry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary The reductive carbonyl coupling (McMurry reaction) of 5,5′-diformyl-2,2′-bithiophene affords the fourfold sulfur bridged [20]annulene5 and its [30]annulene homologue10 in 8 and 3% yields. Coupling of 5,5″-diformyl-2,2′:5′,2″-terthiophene produces structurally related macrocycles, albeit in very low yields. As shown by X-ray crystallographic investigation, the bridged annulenes5 and10 are non-planar cyclophanes exhibiting transannular electronic interaction. The sulfur bridged [20] annulene5 constitutes the central molecule of the tetrathiaporphycene redox system emcompassing the dicationic tetrathiaporphycene3, the annulene5, the 22π dianion8 and the two intermediate radical ion species. Compound5 is reduced in one two-electron step giving the diatropic 22-π dianion8 which is characterized by cyclovoltammetry, coulometry, spectroelectrochemistry and1H-NMR spectroscopy. By contrast,5 fails to undergo oxidation with formation of the dicationic 18π tetrathioporphycene.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00816416
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