A novel cluster WCu2S4(dPPf)(2).4DMF was synthesized by the reaction of(NH4)(2)WS4 with CuCl and 1,1'-bis(diphenylphosphino)ferrocene (dppf) in the solid state. and its crystal structure has been characterized by X-ray diffraction. The cluster has a novel new skeletal structure with five metal atoms nearly in a line. Investigation of third-order optical nonlinear z-scan shows that it exhibits good nonlinear optical properties in a 1.2 x 10(-4) mol.dm(-3) DMF solution.