Octanuclear Lanthanide Sulfido Clusters: Synthesis, Structure, and Coordination Chemistry

Octanuclear (THF)(8)Ln(8)S(6)(SPh)(12).xTHF clusters (Ln = lanthanide ion) can be isolated from the reactions of Ln(SPh)(3) with elemental S. Complexes have been isolated successfully for Ln = Ce (1), Pr (2), Nd (3), Sm (5), Gd (6), Tb (7), Dy (8), Ho (9), and Er (10). Only the Ce and Sm compounds are intensely colored, due to a relatively low energy f( )(1)-to-d(1) promotion for 1 and a S(2)(-) to Sm charge transfer absorption for 5. The complexes are all thermally unstable with respect to loss of THF at room temperature. The reaction of Sm(SPh)(3) with S in a THF/DME mixture gives thermally unstable (THF)(8)Ln(8)S(6)(SPh)(12).6DME (4). The analogous pyridine (py) complexes (py)(8)Ln(8)S(6)(SPh)(12).xpy (Ln = Nd (11), Sm (12), Er (13)) were also found to desolvate at room temperature. All compounds have been characterized by conventional methods and by low-temperature single-crystal X-ray diffraction. Complete structural analyses have been obtained for compounds 4, 7, 12, and 13, and the structures of the rest were confirmed by unit cell determinations. In each case, the same basic octanuclear framework, with a cube of metal atoms connected by S(2)(-) ligands capping the faces of the cube, and SPh ligands spanning the edges of the cube, is observed. Differences in the structures originate either in the relative orientation of the Ph moieties or in the number and orientations of the lattice solvent molecules. The Ce cluster is isostructural with (THF)(8)Sm(8)Se(6)(SePh)(12), compounds 2 and 3 are isostructural with the previously reported structure of 6, clusters 5 and 8-10 are isostructural with 7, and cluster 11 is isostructural with 12.