Syntheses, crystal structures and third-order nonlinear optical properties of [PPh4](2)[(WS4)M(mu-dppe)(2)M(WS4)]center dot 2CH(2)Cl(2) from the preformed polymeric clusters {[PPh4][WS4M]}(n) (M = Ag, Cu)

摘要

Reactions of {[PPh4][WS4M]}(n) (1: M = Ag; 2: M = Cu) with equimolar 1,2-bis(diphenylphosphino)ethane (dppe) in CH2Cl2 produced two tetranuclear anionic clusters [PPh4](2)[(WS4)M(mu-dppe)(2)M(WS4)]center dot 2CH(2)Cl(2) (3: M = Ag; 4: M = Cu). Both clusters were characterized by elemental analysis, IR, UV-vis, H-1 NMR and single-crystal X-ray analysis. The centrosymmetric structure of the cluster dianion of 3 or 4 consists of two [WS4M] cluster fragments linked by a pair of dppe ligands. The third-order nonlinear optical (NLO) properties of 3 and 4 in solution were investigated by femtosecond degenerate four-wave mixing (DFWM) technique with a 80-fs pulsed laser at 800 nm. Both compounds exhibited strong NLO performances with chi((3)) = 3.30 x 10(-14) esu or 2.89 x 10(-14) esu (4), and gamma = 1.064 x 10(-31) esu (3) or 1.059 x 10(-31) esu (4).