[1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazolidyl: a long-lived radical anion and its stable salts

Alexander Yu Makarov; Irina G Irtegova; Nadezhda V Vasilieva; Irina Yu Bagryanskaya; Tobias Borrmann; Yuri V Gatilov; Enno Lork; Ruediger Mews; Wolf-Dieter Stohrer; Andrey V Zibarev

doi:10.1021/ic050583j

[1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazolidyl: a long-lived radical anion and its stable salts

Inorg Chem. 2005 Oct 3;44(20):7194-9. doi: 10.1021/ic050583j.

Authors

Alexander Yu Makarov¹, Irina G Irtegova, Nadezhda V Vasilieva, Irina Yu Bagryanskaya, Tobias Borrmann, Yuri V Gatilov, Enno Lork, Ruediger Mews, Wolf-Dieter Stohrer, Andrey V Zibarev

Affiliation

¹ Institute for Inorganic and Physical Chemistry, University of Bremen, Germany.

PMID: 16180884
DOI: 10.1021/ic050583j

Abstract

[1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazole (1) is synthesized in 62% yield by fluoride ion-induced condensation of 3,4-difluoro-1,2,5-thiadiazole with (Me(3)SiN=)(2)S. The reversible electrochemical reduction of 1 leads to the long-lived [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazolidyl radical anion (2) and further to the dianion (3). The radical anion 2 is also obtained by the chemical reduction of the precursor 1 with t-BuOK in MeCN. The radical anion 2 is characterized by ESR spectroscopy in solution and in the crystalline state. The stable salts [K(18-crown-6)][2] and [K(18-crown-6)][2].MeCN (8 and 9, respectively) are isolated from the spontaneous decomposition of the [K(18-crown-6)][PhXNSN] (6, X = S; 7, X = Se) salts in MeCN solution followed by XRD characterization. The radical anion 2 acts as a bridging ligand in 8 and as chelating ligand in 9. The structural changes observed by XRD in going from 1 to 2 are explained by means of DFT/(U)B3LYP/6-311+G calculations.