RESUMEN
Reductive cleavage of C(6)F(5)SeSeC(6)F(5) with elemental M (M = Zn, Cd, and Hg) in pyridine results in the formation of (py)(2)Zn(SeC(6)F(5))(2), (py)(2)Cd(SeC(6)F(5))(2), and Hg(SeC(6)F(5))(2). Structural characterization of the Zn and Cd compounds reveals tetrahedral coordination environments, while the Hg compound shows a complicated series of linear structures with two short, nearly linear Hg-Se bonds, up to two longer and perpendicular Hg...Se interactions, and no coordinated pyridine ligands. All three compounds exhibit well-defined intermolecular pi-pi-stacking interactions in the solid state. They are volatile and decompose at elevated temperatures to give MSe and either (SeC(6)F(5))(2) or Se(C(6)F(5))(2).
RESUMEN
A pair of mer-octahedral lanthanide chalcogenolate coordination complexes [(THF)(3)Ln(EC(6)F(5))(3) (Ln = Er, E = Se; Ln = Yb, E = S)] have been isolated and structurally characterized. Both compounds show geometry-dependent bond lengths, with the Ln-E bonds trans to the neutral donor tetrahydrofuran (THF) significantly shorter than the Ln-E bonds that are trans to negatively charged EC(6)F(5) ligands. Density functional theory calculations indicate that the structural trans influence evidenced by the differences in these bond lengths results from a covalent Ln-E interaction involving ligand p and Ln 5d orbitals.
RESUMEN
The title salt, [Yb(C(4)H(10)O(2))(4)][Hg(2)(C(6)H(5)Se)(6)], consists of eight-coordinate homoleptic [Yb(DME)(4)](2+) dications (DME is 1,2-dimethoxy-ethane) countered with [Hg(2)(SePh)(6)](2-) di-anions. The cations and anions have twofold rotation and inversion symmetry, respectively. The Yb centre displays a square-anti-prismatic coordination geometry and the Hg centre has a distorted tetra-hedral coordination environment. One phenyl-selenolate anion and one methyl group of a DME ligand are disordered over two positions with equal occupancies. This structure is unique in that it represents a less common mol-ecular lanthanide species in which the lanthanide ion is not directly bonded to an anionic ligand. There are no occurrences of the [Hg(2)(SePh)(6)](2-) dianion in the Cambridge Structural Database (Version of November 2007), but there are similar oligomeric and polymeric Hg(x)(SePh)(y) species. The crystal structure is characterized by alternating layers of cations and anions stacked along the c axis.
RESUMEN
Reactions of Ln(SePh)3 with SeO2 in THF give octanuclear oxoselenido clusters with the general formula (THF)8Ln8O2Se2(SePh)16 (Ln = Ce, Pr, Nd, Sm). In this isomorphous series, the eight Ln(III) ions are connected in the center by a pair of mu3-O2- ligands and mu5-Se2- ligands, with 14 bridging and two terminal selenolate ligands capping the cluster surface. Thermal decomposition at 700 degrees C of the Nd compound in vacuo led to the formation of a phase mixture of NdSe2, Nd2Se3, and Nd2O3. Near-IR emission experiments on the (THF)8Nd8O2Se2(SePh)16 and the fluorinated thiolate compound (DME)2Nd(SC6F5)3 demonstrate that clusters with oxo ligands are not only highly emissive, but also they emit at wavelengths not found in conventional oxides.