The title compounds WCu2OS3(PPh(3))(4) (I) and MoCu2OS3(PPh(3))(3) (II) were synthesized by reactions of (NH4)(2)MO(2)S(2) (M = W, Mo), Cu2S, and PPh(3) in the solid state for nonlinear optical studies. A wide transparent window (lambda = 400 similar to 1000 nm) was observed for both clusters, which makes them attractive for nonlinear optical applications. Nonlinear optical (NLO) properties of the clusters were studied with a 7-ns pulsed laser at 532 nm. Cluster I exhibits mainly optical self-focusing (n(2) = 8 x 10(-18) m(2) W-1, as measured with an 1.2 x 10(-4) mol dm(-3) acetonitrile solution) with negligibly small nonlinear absorption. Cluster II exhibits both optical self-focusing (n(2) = 5 x 10(-17) m(2) W-1, as measured with a 7.4 x 10(-5) mol dm(-3) acetonitrile solution) and optical nonlinear absorption (alpha(2) = 2.6 x 10(-10) m W-1). The third-order NLO susceptibilities (chi((3))) of the two clusters at the above-mentioned concentrations are 2 x 10(-11) esu for I and 1.2 x 10(-10) esu for II, respectively. These nonlinear optical properties of the clusters were compared with those of cubic cage shaped and nest-shaped clusters to reveal a qualitative structure/NLO property correlation.