The overarching goal of this study is to effect the elimination of platinum from adducts with cis -CΞC-Pt-CΞC- linkages, thereby generating novel conjugated polyynes. Thus, the bis(hexatriynyl) complex trans-(p-tol3P)2Pt((CΞC)3H)2is treated with 1,3-diphosphines R2C(C-H2PPh2)2to generate (R2C(CH2PPh2)2)2Pt((CΞC)3H)2(14; R = c, n-Bu; e, p-tolCH2). These con-dense with the diiodide complexes R2C(CH2PPh2)2PtI2(9a,c) in the presence of CuI (cat.) and excess HNEt2to give the title macrocycles [(R2C(CH2PPh2)2)Pt(CΞC)3]4(16c,e) as adducts of the byproduct [H2NEt2]+I-(30-66%). DOSY NMR experiments establish that this association is maintained in solution, but NaOAc removes the ammonium salt. The bis(triethylsilylpolyynyl) complexes (n-Bu2C(CH2PPh2)2)Pt((CΞC)nSiEt3)2(n = 2, 3) are synthesized analogously to 14c. They react with I2at rt to give mainly the diiodide complex 9c and the coupling product Et3Si(CΞCCΞC)nSiEt3. The possibility of competing reactions giving ICΞC species is investigated. Analogous reactions of the Pt4C24macrocycle 16c also give 9c, but no sp 13C NMR signals or mass spectrometric Cxz+ions (x = 24-100) could be detected. It is proposed that some cyclo[24]car-bon is generated, but then rapidly converts to other forms of elemental carbon. No cyclotetracosane (C24H48) is detected when this sequence is carried out in the presence of PtO2and H2.