Syntheses, structures, and optical limiting capability of tetranuclear cubane, hexanuclear prism-cage, and octanuclear double-cubane argento-selenotungstates

Treatment of [Et4N]2[WSe4] with AgX (X = Br, I) in a 1:3 ratio in DMF or DMF/CH3CN afforded tetranuclear cubane-like heteroselenometallic clusters [Et4N]3[(μ3-X)(μ3-WQSe3)(AgX)3] (X = Br, Q = Se 1; X = Br, Q = O 2; X = I, Q = Se 3). While the reaction of [Et4N]2[WSe4] with two equivalents of AgBr in DMF gave a hexanuclear cage heteroselenometallic cluster [Et4N]4[(μ3-WO0.83Se3.17)2(AgBr)4] (4). Treatment of [Et4N]2[WSe4] with three equivalents of AgCl in DMF in the presence of the bidentate phosphine ligand bis-(diphenylphosphino)-ethane (dppe) or bis-(diphenylphosphino)-propane (dppp) resulted in the isolation of octanuclear heteroselenometallic clusters [Et4N]4[{(μ3-Cl)(μ3-WSe4)Ag3Cl2}2(μ-dppe)] (5) and [Et4N]2[{(μ3-WSe4)Ag3Cl2}2(μ-dppp)2] (6) with double-cubane. All clusters are anionic and air-stable in the solid-state, and were characterized by electronic, infrared, mass and NMR spectroscopies, and their molecular structures have been also established by X-ray crystallography. The nonlinear optical properties of clusters 1–6 were examined by z-scan techniques with 7 ns pulses at 532 nm, and the optical limiting effects of clusters 1–6 were also determined for the comparison with the related argentoselenometallic clusters in this paper.

A series of tetra-, hexa- and octa-nuclear anionic argento-selenotungstates have been synthesized and characterized by spectroscopy and X-ray crystallography. The nonlinear optical properties and optical limiting effects of these silver-containing heteroselenometallic clusters were also determined for the investigation of the structure–property relationship.Figure optionsDownload as PowerPoint slide