Synthesis, crystal structure and non-linear optical properties of the heterobimetallic polymeric compound {[n-Bu₄N][W₂Ag ₃S₈]} _n

The heterobimetallic, polymeric compound has been synthesized by the reaction of (NH₄)₂WS₄ and AgBr with n-Bu ₄NBr in CH₂Cl₂ solution under a purified nitrogen atmosphere using standard Schlenk techniques. The crystals were characterized by elemental analysis, IR and single-crystal X-ray crystallography. The polymeric anion has a hanging ladder-like polymeric chain which can also be described as double helical chains bridged by silver atoms. Its non-linear optical properties (NLO) were investigated using Z-scan techniques with an 8 ns pulsed laser at 532 nm, and the cluster also exhibits both strong non-linear optical absorption and an optical self-defocusing effect (effective a₂ = 1.11 × 10^-10 m W^-1, n₂ = 3.67 × 10^-18 m² W^-1, when measured with a 1.2 × 10^-4 mol dm^-3 DMF suspension).