THIOPHENE OLIGOMERS AS POLYTHIOPHENE MODELS .1. ANODIC COUPLING OF THIOPHENE OLIGOMERS TO DIMERS - A KINETIC INVESTIGATION

被引:100
作者
ZOTTI, G
SCHIAVON, G
BERLIN, A
PAGANI, G
机构
[1] UNIV MILAN,DIPARTIMENTO CHIM ORGAN & IND,I-20133 MILAN,ITALY
[2] CNR,CTR SPECIALI SINTESI ORGAN,I-20133 MILAN,ITALY
关键词
D O I
10.1021/cm00028a006
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The kinetics of anodic coupling to dimers of thiophene oligomers (n = 3-5), methyl protected at one alpha-terminal position, has been investigated in 1,2-dichloroethane by cyclic voltammetry and chronoamperometry. The process, second-order in oligomer concentration, is characterized by relatively high activation enthalpies (25/70 kJ mol-1) and negative activation entropies (-100/-4 J K-1 mol-1). Though activation free energies are linearly related to the inverse of the oligomer length n (the dimerization rate decreases as n is increased), the activation enthalpy and entropy for the pentameric radical cation are peculiarly high, reflecting strong electron delocalization and ring coplanarization.
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页码:430 / 436
页数:7
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