Three new 11-metal-atom Pt-Au-Cu duster compounds are reported : [Pt(PPh(3))(AuPPh(3))(6)(Cu(4)Cl(3)PPh(3))]-(NO3) (1), [Pt(PPh(3))(AuPPh(3))(6)(Cu4Br3(PPh(3))(y))](NO3) (2) (y = 0 or 1), and [Pt(PPh(3))(AuPPh(3))(6)(Cu4I3)](NO3) (3). These clusters are obtained from the reaction of [Pt(AuPPh(3))(8)](NO3)(2) with [PPh(3)CuX](4) (in which X = Cl, Br, or I, respectively). Cluster 1 was characterized by elemental analysis, ICP analysis, FAB-MS, (variable-temperature) P-31 NMR and P-31 COSY spectroscopy, Pt-195 NMR spectroscopy, and IR spectroscopy. The crystal and molecular structure of 1 has been determined by a single-crystal X-ray analysis. The compound crystallizes as the NO3- salt in the triclinic space group with Z = 2, a = 17.501(3) Angstrom, b = 21.152(6) Angstrom, c = 23.581(5) Angstrom, alpha = 92.18(2)degrees, beta 94.61(1)degrees, gamma = 109.69(2)degrees, and V = 8172 Angstrom(3). Mo K alpha radiation was used. The residuals are R = 0.068 and wR(2) = 0.162 for 11040 observed reflections and 788 variables. Cluster 3 was characterized by P-31 NMR spectroscopy and FAB-MS; its solid-state structure was determined by means of a single-crystal X-ray analysis. This duster compound crystallizes as the NO3- salt in the monoclinic space group P2(1)/c, with Z = 4, a = 17.871(4) Angstrom, b = 34.687(3) Angstrom, c = 23.357(2) Angstrom, beta = 95.49(2)degrees, and V = 14412 Angstrom(3). Mo K alpha radiation was used. The residuals are R = 0.117 and wR(2) = 0.285 for 2957 observed reflections and 340 variables. Both clusters, 1 and 3, have a tetrahedral Cu-4 unit which is face (eta(3)) bonded to the (central) platinum atom, which is furthermore surrounded by six gold atoms. Short copper-gold and copper-platinum distances show that the copper atoms, although coagulated, are part of the metal cluster core. In cluster 1 an additional PPh(3) ligand is present on the Cu-4 unit as compared to 3; in solution this copper-bonded phosphine of 1 is shown to dissociate reversibly. The cluster compound 2 was characterized by means of P-31 NMR spectroscopy, which indicates this cluster to be analogous to clusters 1 and 3.