Syntheses, crystal structures and nonlinear optical properties of MS4Pd(dppp) (M=Mo, W)

The title compounds [MS4Pd(dppp)] [M=Mo (1), W (2); dppp=Ph2PCH2CH2CH2PPh2] were synthesized for nonlinear optical studies by the reaction of (Et4N)2MS4 (M=Mo, W) and (dppp)PdCl2 in the CH2Cl2CH3CN. Single-crystal X-ray analyses revealed that the two compounds consisted of a distorted tetrahedral MS4 (M=Mo, W) unit with a Pd atom and two S atom bridges. The Pd atom has a cis-quasisquare coordination geometry with two P donors of dppp and two S donors of MS4. The nonlinear optical properties of 1 and 2 were investigated by a Z-scan technique with 7 ns laser pulses at 532 nm. It was observed that the nonlinear absorption for 1 is very small, but it has considerable large nonlinear refractive index; no nonlinear optical behavior was observed for 2, although it shows a similar structure to that of compound 1.