Reinvestigation of Dimer Formation in the Reaction of Tri-2-thienylmethyl Anion with 2-Chloro-5-nitrothiophene

In order to obtain the dimeric products of tri-2-thienylmethyl radical (Th3C·), we reinvestigated the reaction of the corresponding anion (Th3C-) with 2-chloro-5-nitrothiophene, in which Th3C· would be involved by a single electron transfer (SET) process from Th3C- to 2-chloro-5-nitrothiophene. In addition to the previously reported compound, 2-(di-2-thienylmethyl)-5-(tri-2-thienylmethyl)-thiophene (1), we successfully isolated the 5,α'-dimer of Th3C·, 2-(di-2-thienylmethylene)-2,5-dihydro-5-(tri-2-thienylmethyl)thiophene (2). Furthermore, we unexpectedly obtained the new compound, bis(tri-2-thienylmethyl) peroxides (3), which appears to form via the reaction of Th3C· with trace amounts of molecular oxygen.