Early Alkali Metal (Li, Na, K) and Tris(dimethylamino)sulfonium (TAS) Salts of [1,2,5]Thiadiazolo[3,4-c][1,2,5]thiadiazolidyl Radical Anion: Rational Syntheses, Structures and Magnetic Properties

Salts of the [1,2,5]thiadiazolo[3,4‐c][1,2,5]thiadiazolidyl radical anion (1) and the early alkali metals, [Li(12‐crown‐4)2][1] (3), [Na(15‐crown‐5)][1] (4), and [K(18‐crown‐6)][1] (5) as well as the salt [(Me2N)3S][1] (6) can be prepared by reduction of [1,2,5]thiadiazolo[3,4‐c][1,2,5]thiadiazole (2) with PhS– anion followed by XRD and ESR characterization. These salts are thermally stable and soluble in MeCN. Low‐temperature crystallization of salt 5 from MeCN or storage of 5 under MeCN for a few days at ambient temperature gives the solvate 5·MeCN (7). The radical anion 1 acts as bridging ligand in salts 4 and 5 and as chelating ligand in salt 7. In salt 3, the radical anion 1 is not coordinated to the cation and can be considered as “naked” anion. In salt 6, one of the two crystallographically independent 1 acts as bridging ligand, whilst the other is not coordinated to the cation. Magnetic susceptibility data obtained for salts 4 and 5 in the temperature range of 2–300 K revealed antiferromagnetic exchange interactions between paramagnetic centers: 4, J = –3.42, αJ = –1.12 cm–1; 5, J = –1.22 cm–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)