The synthesis and characterization of a series of mononuclear d(8) complexes with at least two P-coordinated alkynylphosphine ligands and their reactivity toward CiS-[Pt(C6F5)(2)(THF)(2)] are reported. The cationic [Pt(C6F5)(PPh2C=CPh)(3)](CF3SO3), 1, [M(COD)(PPh(2)CdropCPh)(2)](ClO4) (M = Rh, 2, and Ir, 3), and neutral [Pt(o-C6H4E2)(PPh(2)CdropCPh)(2)] (E = 0, 6, and S, 7) complexes have been prepared, and the crystal structures of 1, 2, and 7.CH3COCH3 have been determined by X-ray crystallography. The course of the reactions of the mononuclear complexes 1-3, 6, and 7 with CiS-[Pt(C6F5)(2)(THF)(2)] is strongly influenced by the metal and the ligands. Thus, treatment of 1 with 1 equiv of CiS-[Pt(C6F5)(2)(THF)(2)] gives the double inserted cationic product [Pt(C6F5)(S)mu-{C(Ph)=C(PPh2)C(PPh2)=C(Ph)(C6F5)}Pt(C6F5)(Pph(2)CdropCPh )](CF3SO3) (S = THF, H2O), 8 (S = H2O, X-ray), which evolves in solution to the mononuclear complex [(C6F5)(PPh(2)CdropCPh)Pt{C10H4-1-C6F5-4-Ph-2,3-kappaPP'(PPh2)(2)}](CF3 SO3), 9 (X-ray), containing a 1-pentafluorophenyl-2,3-bis(diphenylphosphine)-4-phenylnaphthalene ligand, formed by annulation of a phenyl group and loss of the Pt(C6F5) unit. However, analogous reactions using 2 or 3 as precursors afford mixtures of complexes, from which we have characterized by X-ray crystallography the alkynylphosphine oxide compound [(C6F5)(2)Pt(mu-kappaO:eta(2)-PPh2(O)CdropCPh)](2), 10, in the reaction with the iridium complex (3). Complexes 6 and 7, which contain additional potential bridging donor atoms (0, S), react with CiS-[Pt(C6F5)(2)(THF)(2)] in the appropriate molar ratio (1:1 or 1:2) to give homo- bi- or trinuclear [Pt(PPh(2)CdropCPh)(mu-kappaE-o-C6H4E2)(mu-kappaP:eta -PPh(2)CdropCPh)Pt(C6F5)(2)] (E = 0, 11, and S, 12) and [{Pt(mu(3)-kappa(2)EE'-o-C6H4E2)(mu-kappaP:eta(2)-PPh(2)Cdrop CPh)(2)}{Pt(C6F5)(2)}(2)] (E = 0, 13, and S, 14) complexes. The molecular structure of 14 has been confirmed by X-ray diffraction, and the cyclic voltammetric behavior of precursor complexes 6 and 7 and polymetallic derivatives 11-14 has been examined.