Syntheses, Structures, and Nonlinear Optical Properties of Two Crown-like Heteroselenometallic Compounds [Et 4 N] 4 [(μ 5 -WSe 4 )(CuX) 5 (μ-X) 2 ] (X = Cl, Br)

Two isostructural crown-like heteroselenometallic cluster compounds, [Et 4 N] 4 [(μ 5 -WSe 4 )(CuX) 5 (μ-X) 2 ] (X = Cl 1 , Br 2 ), were prepared from the reactions of [Et 4 N] 2 [WSe 4 ] with CuX and [Et 4 N]X· x H 2 O in the presence of 2-picoline and characterized by single-crystal diffraction analysis. The [(μ 5 -WSe 4 )(Cu-X) 5 (μ- X ) 2 ] 4− anions in the cluster compounds consists of five CuX fragments coordinated to the five edges of the tetrahedral [WSe 4 ] 2− moiety along with two bridging halides connected to each of the two pairs of the symmetric copper atoms, exhibiting a novel crown-like core structure. The nonlinear optical absorption and refraction of cluster compound 2 were determined to be α 2 = 6.15 × 10 −10 m/W and n 2 = 4.18 × 10 −11 esu, respectively.