Preparation and Structural Characterization of [K(18‐crown‐6)] + Salts of [RNSN] − Anions and the [NSN] 2− Dianion

[K(18‐crown‐6)] + salts of the [RNSN] − anions (R = Alk, Ar) and the [NSN] 2− dianion, which are thermally stable and very soluble in aprotic organic solvents, were prepared from [K(18‐crown‐6)] + [ t BuO] − and the corresponding R−N=S=N−SiMe 3 and (Me 3 Si−N=) 2 S, respectively. The salts are characterized by multinuclear ( 1 H, 13 C, 14 N, 19 F, 29 Si and 39 K) NMR spectroscopy in solution and by X‐ray diffraction in the solid state. The experimentally determined bond lengths confirm that the [RNSN] − anions are thiazylamides, R−N − −S≡N rather than sulfur diimides, R−N=S=N − . Relative to O=S=O, in the [NSN] 2− dianion, which is the genuine aza‐analogue of sulfur dioxide, the bond lengths are elongated and the bond angle is widened. This might reflect electrostatic repulsion between the negatively charged N atoms. The experimental results are in agreement with theoretical calculations (RHF, B3LYP, MP2). In the nitrogen NMR spectra, when going from [AlkNSN] − to [ArNSN] − , the low‐field signal of the terminal (unsubstituted) N atom reveals further deshielding, whereas the high‐field signal of the internal (substituted) N atom displays further shielding. The 14 N NMR resonance for the [NSN] 2− dianion is practically insensitive to the counterion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)