Five regio-isomeric alkyl azulenecarboxylates were prepared. Additional substituents such as tertbutyl groups or deuterium were introduced in certain positions of the azulene skeleton in order to facilitate the assignment of the proton hyperfine structure (hfs) coupling constants of the EPR spectra. The electrochemical behavior of the esters was studied by means of differential pulse polarography and cyclovoltammetry. In-situ electroreduction of the azulenecarboxylic esters led to the corresponding radical anions, the EPR spectra of which were recorded. The spin density distribution in these non-alternant systems as determined from hfs coupling constants was compared with the results of MO calculations and discussed with respect to the influence of substituents.
制备了五种烷基偶氮烯羧酸异构体。在氮烯骨架的某些位置引入了额外的取代基,如叔丁基或氘,以便于确定 EPR 光谱的质子超精细结构(hfs)耦合常数。通过微分脉冲极谱法和环形伏安法研究了这些酯的电化学行为。偶氮羧酸酯的原位电还原产生了相应的自由基阴离子,并记录了其 EPR 光谱。根据 hfs 耦合常数确定的这些非互变体系的自旋密度分布与 MO 计算的结果进行了比较,并讨论了取代基的影响。