The synthesis and full characterization of a series of heterobimetallic mixed-bridge alkynyl/phosphido platinum-rhodium and alkynyl/phosphinite platinum-rhodium and platinum-iridium complexes is presented. Treatment of trans-[Pt(C6F5)(C=CR)(PPh2H)(2)] [2; R = t-Bu (a), Ph (b)] [generated through the rupture of the homobridged trans,sym-[Pt(mu-kappa C-alpha:eta(2)-C=CR)(C6F5)(PPh2H)](2) (1) with PPh2H] or cis-[Pt(C=CR)(2)(PPh2H)(2)] with rhodium acetylacetonate species [Rh(acac)L-2] (L-2 = COD, 2CO) in acetone produces the corresponding alkynyl/diphenylphosphido-bridged complexes trans,cis-[(C6F5)(PPh2H)Pt(mu-kappa C-alpha:eta(2)-C=CR)(mu-PPh2)RhL2] [L-2 = COD (3), 2CO (4a)] and cis,cis-[(C=CR)(PPh2H)Pt(mu-kappa C-alpha:eta(2)-C=CR)(mu-PPh2)RhL2] [L-2 = COD (5), 2CO (6a)]. The related mixed alkynyl/phosphinite complexes [{(PPh2O)(2)H}Pt(mu-kappa C-alpha:eta(2)-C=CR)(mu-kappa P,kappa O-PPh2O)ML2] [ML2 = RhCOD (7), Rh(CO)(2) (8), IrCOD (9)] can be prepared by reacting [Pt(C=CR){(PPh2O)(2)H}(PPh2OH)] with [M(acac)L-2] (M = Rh, Ir). The molecular structure of 6a, determined by X-ray diffraction, shows that the alkynyl ligand is sigma-bonded to platinum and eta(2)-bonded to the rhodium center with a platinum-rhodium distance of 3.142(1) Angstrom. Complex 6a (C38H39O2P2PtRh) crystallizes in the triclinic system, space group P (1) over bar: a = 11.427(2) Angstrom, b = 12.882(2) Angstrom, c = 14.692(2) Angstrom, alpha = 99.098(14)degrees, beta = 108.339(12)degrees, gamma = 113.11(2)degrees, V = 1787.2(4) Angstrom(3), and Z = 2.