Heterolanthanide three-nuclear iodide-sulfide-nitride clusters. Unusual synthesis way and structure

Abstract Three-nuclear clusters Nd 2 LnI 5 (S 2 )(S 2 N 2 )(THF) 9 (Ln = Tb, Tm) were prepared by the disproportionation reaction of iodide-nitride [(NdI) 3 N 2 ](THF) 6 with LnI 3 (THF) 3 in the presence of sulfur. Molecule of the cluster contains a flat inorganic core formed by two Nd and Ln atoms connected by dithiadiazine group. One of the Nd atoms is bound to the Ln 3+ ion, besides terminal N atom of the bridge S 2 N 2 fragment, by a bridge fragment S2. The second Nd atom is coordinated by two iodine anions and SN group forming unusual NdSN tree-member cycle. Structure of inorganic framework of the complexes is similar to that of earlier obtained monometallic analogues Ln 3 I 5 (S 2 )(S 2 N 2 )(THF) 10 (Ln = Nd, Dy). In both new clusters the Ln atoms have the same coordination surrounding consisting of one iodine anion, S 2 group and N atom of dithiadiazine ligand and occupy in the framework Nd 2 Ln(S 2 )(S 2 N 2 ) the same position which corresponds to the lowest energy of the molecule. The nitride [(NdI) 3 N 2 ](THF) 6 in the presence of sulfur easy reacts as well with triiodides of La and Sm. Products isolated in these reactions do not form crystals suitable for X-ray study but the data of elemental analysis, fragment analysis, the found Nd: Ln ratio, spectroscopic and magnetic measurements allow to conclude that the structure of La, Sm products is similar to that of the above Tb, Tm analogs.