Syntheses, structures, and nonlinear optical properties of two polynuclear homometallic and heterometallic cluster compounds containing silver(I) bromide species

Interaction of [Et4N]2[WSe4] and AgBr in the presence of [Et4N]Br·xH2O in a DMF/MeCN/2-picoline solution (3 : 2 : 1) at room temperature afforded a colorless crystalline compound [Et4N]6[(AgBr)6(μ3-Br)2(μ4-Br)3]Br (1) in 21% yield and a red crystalline compound [Et4N]4[(μ5-WSe4)(AgBr)5(μ-Br)2] (2) in 48% yield. The cluster anion in 1 comprises six AgBr fragments bridged by three bromides and capped by two bromides, forming a trigonal prism structure. The cluster anion in 2 consists of five AgBr fragments coordinated to five edges of the tetrahedral [WSe4]2− along with two bridging bromides connected to each of the two pairs of symmetric silvers, exhibiting a crown-like core structure. The nonlinear optical absorption and refraction of 2 were determined to be α2 = 5.72 × 10−9 m W−1 and n2 = 3.64 × 10−9 esu, respectively.