1,2-Bis[adiphenylphosphino)methyn(phenyl)phosphinolethane (dpmppe) was prepared as, a new tetraphosphine, and the corresponding rac and meso stereoisorners were successfully separated in view of their solubility difference in acetone. The substitution of PPh3 into Pt(PPh3)(2)(C CR)(2) (R = aryl) with rac- or meso-dpmppe gives Pt(rac-rdprnppe)(C CR)(2) or Pt(meso-dpmppe)-(C CR), respectively. Using Pt(rac-dpnippe):(C CR)(2) or Pt(mesodpmppe)(C CR)), as a precursor, PtAg2 heterotrinudear duster complexes were synthesized and characterized by X-ray crystallography. Depending on the conformations.- of tetraphosphine, the structures of PtAg2 complexes supported with rac- and meso-dpmppe are quite different. The higher molecular rigidity of rac-dpmppe-supported PtAg2 complexes results in stronger phosphorescent emission than that of PtAg2 species, with meso-dpmppe. The high phosphorescent quantum yields (as high as 90.5%) in doping films warrant these PtAg2 complexes as excellent phosphorescent dopants in organic light-emitting diodes (OLEDs). The peak current and external quantum efficiencies, in solution-processed OLEDs are 61.0 cd A(-1) and 18.1%, respectively. Electroluminescence was elaborately modulated by modifying the substituient in aroinatic acetylide and the conformations in tetraphosphine so as to achieve cyan, green, green-yellow, yellow, and orange-red emission.