(THF)(8)Ln(8)E(6)(EPh)(12) cluster reactivity: Systematic control of Ln, E, EPh, and neutral donor ligands

Octametallic (L)(8)Ln(8)E(6)(EPh)(12) clusters (L = Lewis base; Ln = lantha nide ion; E = S, Se; EPh = SPh, SePh) can be prepared either by the reducti on of Se-C bonds with low-valent Ln or by the reaction of Ln(SePh)(3) with elemental E. Because all possible ligand sites (i.e., L, E, EPh) are reacti ve, the ligands can be varied systematically to further the understanding o f structure/property relationships. Chalcogenolate ligands can be selective ly varied, as in the reaction of (THF)(8)Sm8Se6(SePh)(12) with PhSSPh to fo rm (THF)(8)Sm8Se6(SPh)(12). Neutral L can be altered without disrupting str ucture, as in the replacement of THF with pyridine to give (py)(8)Sm8Se6(Se Ph)(12). Even chalcogenido ligands can be chemically replaced: the reaction of (THF)(8)Sm8Se6(SPh)(12) with elemental S gives the all-sulfur cluster ( THF)(8)Sm8S6(SPh)(12). All compounds were isolated and characterized by IR and UV-visible spectroscopy and by low-temperature single-crystal X-ray dif fraction to confirm that the structures contain cubes of Ln(III) ions with E2- capping the faces and EPh bridging the edges of the cube. The Sm8Se6(EP h)(12) clusters are intensely colored because of a Se2- to Sm(III) charge t ransfer absorption, while the sulfide clusters exhibit the light yellow col or characteristic of Sm(III) complexes. The light green Nd complex (py)(8)N d8Se6(SePh)(12) was isolated from the reaction of Nd(SePh)3 with Se to conf irm that chalcogenolate displacement is general to the redox-inactive lanth anides and that the intense colors of the Sm selenido clusters are related to the redox activity of the Ln. The two pyridine complexes (py)(8)LnSe(6)( SePh)(12) (Ln = Nd, Sm) are isostructural. Crystal data (Mo K alpha, 153(2) K) are as follows. (THF)(8)Sm8Se6(SPh)(12): triclinic space group P (1) ov er bar, a 17.637(7) Angstrom, b = 18.337(5) Angstrom, c = 20.466(12) Angstr om, alpha 103.03(4)degrees, beta= 94.71(4)degrees, gamma = 94.28(3)degrees, Z = 2. (py)(8)Sm8Se6(SePh)(12): monoclinic space group C2/m, a 18.770(2) A ngstrom b = 28.113(4) Angstrom, c 16.461(3) Angstrom, beta = 120.65(1)degre es, Z = 2. (THF)(8)Sm8S6(SePh)(12): orthorhombic space group Pcab, a = 19.8 03(3) Angstrom, b = 22.446(3) Angstrom, c = 26.072(4) Angstrom, Z = 8.