Nitrogen NMR of some sulphur diimide anions and calculated (GIAO) nitrogen shielding constants

Abstract

Sulphur diimide anions of the type [NSN]2− (1), [RNSN]− (1), [R = tBu (3), SiMe3 (4), tBu2P (5)] were prepared with the counter ions [nBu4N]+ or [(Me2N)3S]+ (for 1, 3, 4) and K+ (for 5) and studied in solution by 14N NMR, and for assignment purposes by 15N NMR (4). The experimentally determined 14N chemical shifts (δN) were compared with nitrogen shielding constants calculated by the gauge included atomic orbitals (GIAO) technique, and a linear relationship between σN(calc) and δN was obtained. This correlation serves to support the Z configuration of the anions [RNSN]−, analogous to the isoelectronic N-sulphinylamines. On this basis, two 14N resonance signals reported in the literature with uncertain assignment can be attributed to [HNSN]− (2), and the previously assigned δN values suggest that the anion [HNSNS]− (6) adopts the Z/E configuration.