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 [(Me 2 N) 3 S][ 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, α J = –1.12 cm –1 ; 5 , J = –1.22 cm –1 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)