Alkali Metal Based Triimidosulfite Cages as Versatile Precursors for Single-Molecule Magnets.

Based on the potassium [{S(tBuN) 2 (tBuNH)} 2 K 3 (tmeda)-K 3 {(HNtBu)(NtBu) 2 S} 2 ] (1) and sodium precursors [S(tBuN) 3 (thf) 3 -Na 3 SNa 3 (thf) 3 (NtBu) 3 S] (2), [S(tBuN) 3 (thf) 3 Na 3 {(HNtBu)(NtBu) 2 S}] (3) and [(tmeda) 3 S-{Na 3 (NtBu) 3 S} 2 ] (4) the syntheses and magnetic properties of three mixed metal triimidosulfite based alkali-lanthanide-metal-cages [(tBuNH)Dy{K(0.5tmeda)} 2 {(NtBu) 3 S} 2 ] n (5) and [ClLn{Na(thf)} 2 {(NtBu) 3 S} 2 ] with Ln=Dy (6), Er (7) are reported. The corresponding potassium (1) and sodium (2-4) based cages are characterized through XRD and NMR experiments. Preventing lithium chloride co-complexation led to a significant increase of SMM performance to previously reported sulfur-nitrogen ligands. The subsequent Dy III -complexes 5 and 6 display slow relaxation of magnetization at zero field, with relaxation barriers U=77.0 cm -1 for 5, 512.9 and 316.3 cm -1 for 6, respectively. Significantly, the latter complex 6 also exhibits a butterfly-shaped hysteresis up to 7 K.