文摘
A series of diradical containing salts CxF2x(CNSSS)22+(AsF6-)2 {x = 2, 1[AsF6]2; x = 3, 3[AsF6]2; x = 4, 2[AsF6]2}have been prepared. 1[AsF6]2 and 2[AsF6]2 were fully characterized by X-ray, variable-temperature magneticsusceptibility, and solid-state EPR measurements, further allowing us to extend the number of examples of thefamily of rare 7 RCNSSS+ radical cations. 1[AsF6]2: a = 6.5314(7) Å, b = 7.5658(9) Å, c = 9.6048(11) Å, = 100.962(2), = 96.885(2), = 107.436(2), triclinic, space group P, Z = 1, T = 173 K. 2[AsF6]2: a =10.6398(16) Å, b = 7.9680(11) Å, c = 12.7468(19) Å, = 99.758(2), monoclinic, space group P21/c, Z = 2, T= 173 K. In the solid-state, CxF2x(CNSSS)22+ (x = 2, 4) formed one-dimensional polymeric chains of dicationscontaining discrete centrosymmetric radical pairs in which radicals were linked by four centered two-electron *-* bonds [12+, d(S···S) = 3.455(1) Å; 22+, d(S···S) = 3.306(2) Å]. The exchange interactions in these bondswere determined to be -500 ± 30 and -900 ± 90 cm-1, by variable temperature magnetic susceptibilitymeasurements, respectively, providing rare experimental data on the singlet-triplet gaps in the field of thiazylradicals. For 2[AsF6]2, the thermally excited triplet state was unambiguously characterized by EPR techniques [D= 0.0254(8) cm-1, E = 0.0013(8) cm-1]. These experimental data implied a weakly associated nature of theradical moieties contained in the solids 1[AsF6]2 and 2[AsF6]2. Computational analysis of the dimerization processis presented, and we show that the 2c 4 electron *-* bonds in 1[AsF6]2 and 2[AsF6]2 have ca. 50% and 40%diradical character, respectively. In contrast, 3[AsF6]2·SO2, containing diradical C3F6(CNSSS)22+ with an odd numberof CF2 spacers, showed magnetic behavior that was consistent with the presence of monomeric radical centers inthe solid state.
