Syntheses, crystal structures and non-linear optical responses of two new heteroselenometallic cluster compounds containing dithiocarbamate ligands

Two novel dialkyldithiocarbamate-containing heteroselenometallic clusters, [NEt4](2)[(WSe4)(Et2NCS2Cu)(3)] 1 and [NEt4](2)[(WSe4)(Me2NCS2Cu)(4)] 2, ha ve been synthesized through reactions of [NEt4](2)[WSe4] with CuCl and R2NC S2Na (R=Et or Me) in DMF. The [(WSe4)(Et2NCS2Cu)(3)](2-) anion in 1 compris es three Et2NCS2Cu fragments ligated by a slightly distorted tetrahedral WS e4 moiety. The [(WSe4)(Me2NCS2Cu)(4)](2-) anion structure in 2 possesses a nearly planar WCu4 core and consists of four Me2NCS2Cu fragments co-ordinat ed across four edges of the tetrahedral [WSe4](2-) moiety. The optical limi ting effects of the two clusters were examined at a 0.5 Hz repetition rate. The thresholds of two samples were 6.0 and 1.1 J cm(-1) for 1 and 2, respe ctively. The non-linear responses for the two clusters in DMF have also bee n studied in picosecond time-resolved pump-probe experiments.