Crystal structures and nonlinear optical properties of new clusters [MOS3Cu3(PPh3)3{S2P(OCH2Ph)2}] (M = Mo, W)

Two new isostructural Off-dialkyl dithiophosphate-containing sulfido clusters, MOS3Cu3(PPh3)(3){S2P(OCH2Ph)(2)}] (M = MO (1); M = W (2)), were synthesized through reaction of [NH4[MOS3] with [CuS2P(OCH2Ph)(2)]. They possess an incomplete cubane-like structure, in which the dithiophosphate ligand adopts a triply bridging role, employing one sulfur atom to bind to one Cu atom and the other to two Cu atoms. High third-order nonlinear optical properties of the two clusters were observed, and Z-scan data measured with 532 nm nanosecond laser pulses showed effective third-order optical nonlinearities alpha(2) = 0.78 x 10(-10) and 1.16 x 10(-10)m W-1. and n(2) = -7.8 x 10(-18) and 4.0 x 10(-18)m(2) W-1, respectively, for DMF solution of compound I and DMF solution of 2. These two clusters exhibit large optical limiting performance with limiting threshold values of 220 mJ cm(-2) for 1 and 600 mJ cm(-2) for 2. (C) 2003 Elsevier Science B.V. All rights reserved.