Abstract
| - Oligothiophene S,S-dioxides from dimers to pentamers were obtained in good yields by reaction ofmono- and dibrominated thiophene S,S-dioxides with the appropriate thienyl stannanes in thepresence of Pd(AsPh3)4 generated in situ. The reaction rate with brominated thiophene S,S-dioxidesis greatly accelerated compared to that employing thienyl bromides to obtain the parentoligothiophenes. HF/6-31G*ab initio calculations on 2,2‘-bithiophene and the corresponding mono-and bis-S,S-dioxides show that the functionalization of the thienyl sulfur to the S,S-dioxide doesnot affect the π,π* nature of the frontier orbitals, decreases the energy of the LUMO much morethan that of the HOMO, increases the degree of planarity of the molecular skeleton, and leads tohigher syn anti rotation barriers about the carbon−carbon bond.
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